Ylva Magnusson ENVIRONMENTAL SYSTEMS ANALYSIS FOR UTILISATION OF BOTTOM ASH IN GROUND CONSTRUCTIONS SUPERVISORS: BJÖRN FROSTELL ERIK KÄRRMAN SUSANNA OLSSON STOCKHOLM 2005 Master of Science Thesis at INDUSTRIAL ECOLOGY ROYAL INSTITUTE OF TECHNOLOGY www.ima.kth.se Environmental Systems Analysis for utilisation of bottom ash in ground constructions Abstract Abstract To decrease the disposal of waste and to save natural resources, several political initiatives have been initiated both in Sweden and at a European level. Therefore an urgent task is to find suitable utilisation areas for residuals, such as construction materials. For residual products to be an interesting alternative to conventional aggregates, such as sand, gravel or crushed rock, it is important that the material is environmentally acceptable. So far, environmental evaluations of residuals mainly have focused on measurements of total chemical content and leaching behaviour. The result has been that the positive effects, like for example less disposal of material and reduced extraction of natural aggregates, not have been considered in the evaluations. At the Royal Institute of Technology (KTH) in Stockholm, a method that uses a broader system perspective has been developed. The method is based on an Environmental Systems Analysis (ESA) approach and can act as a complement to the current leaching test. The method has been used for studying the difference in environmental impacts that can be expected if bottom ash from municipal solid waste incineration (MSWI) is used in road construction or is disposed of. This study contributes with an expanded set of scenarios for application of the MSWI bottom ash and with an improvement of data quality for disposal of material. The new application of MSWI bottom ash is its use as a drainage material in covering structures in a landfill. The thesis showed that leaching of metals, resource use and emissions to air were the environmental flows that were of most importance for assessing the environmental impact of the studied scenarios. The use of MSWI bottom ash in road construction was found to be the most environmentally preferable alternative, compared to utilisation of the MSWI bottom ash as drainage material in a landfill structure or disposal of the ash. None of the applications were free from negative environmental impact and different categories of impact were dominating in the different applications. However, these results are strongly dependent on the chosen system boundaries. The results are sensitive to changes in parameters such as transport distance and the conditions affecting leaching, for example the amount of precipitation. Besides these results, new life cycle data for disposal of material is presented in the study. Previous data for the environmental impact from disposal of material were old and lacked important information, such as the environmental impact related to covering structure in the landfill. The ESA approach allowed both resource use and emissions to be considered and can therefore be seen as valuable complement to other studies that use a narrower system perspective. The results can be used to improve information for decision support concerning waste management. i Environmental Systems Analysis for utilisation of bottom ash in ground constructions Sammanfattning Sammanfattning Både på europeisk och svensk nivå finns politiska drivkrafter för att öka återvinningen och återanvändningen av avfall och på så vis minska mängden avfall som förs till deponi. Det ses därför som en angelägen uppgift att finna lämpliga sätt att återanvända restprodukter, exempelvis som konstruktionsmaterial. För att restprodukter överhuvudtaget ska vara ett alternativ till konventionella material såsom sand, grus eller bergkross är det viktigt att miljöbedömningar av materialet görs. Hittills har debatten om användningen av restprodukter präglats av ett snävt systemperspektiv, där man framförallt fokuserat på materialens utlakningsrisker. Positiva effekter i form av exempelvis minskad deponering och minskad naturresursutvinning har inte beaktats i samma utsträckning. Vid KTH i Stockholm har en metod utvecklats som har ett bredare systemperspektiv, vilket kan ses som ett komplement till dagens fokusering på utlakningsrisker. Metoden baseras på ett miljösystemanalysperspektiv och i de pågående studierna har man studerat skillnaderna i miljöeffekter som uppstår då bottenaska från avfallsförbränning används vid vägbyggnation eller deponeras. Den här studien syftar till att utvidga metoden med ännu ett alternativ av nyttiggörande av avfallsbottenaska, nämligen som dräneringsmaterial vid deponitäckning, samt förbättra kvalitén på livscykeldata för deponering av material. Tre viktiga aspekter för att bestämma miljöpåverkan visade sig vara utlakning av metaller från materialen, resurshushållning samt utsläpp till luft från energianvändningen. Resultatet visade att alternativet att använda askan vid vägbyggnation är att föredra i jämförelse med att använda askan som dräneringsmaterial vid deponitäckning eller att deponera askan. Inget alternativ i studien var dock fritt från miljöpåverkan och skilda typer av miljöpåverkan dominerade i de olika alternativen. Resultat från studien visade sig vara känsligt för förändring av transportavstånd och parametrar som påverkar utlakningen, exempel mängden regn. Dessa resultat ska dock ses mot bakgrund av de systemgränser som valts och de antaganden som gjorts i metoden. Vid sidan om dessa resultat presenteras nya livscykeldata för deponering av material som tagits fram i studien. Tidigare existerande värden för deponering av material var inaktuella och ofta var inte alla påverkande parametrar som exempelvis sluttäckning av deponin inkluderade. Examensarbetet visar att miljösystemanalys som metod inte bara beaktar utlakningsrisker vid miljöbedömning av omhändertagande av restmaterial utan tar även hänsyn till resursförbrukning och emissioner. Denna typ av riskbedömning kan exempelvis användas i beslutsunderlag för avfallshantering på regional nivå. ii Environmental Systems Analysis for utilisation of bottom ash in ground constructions Preface Preface This report is a Master thesis and is the last element in the Master of Science programme – Environmental Engineering and Sustainable Infrastructure at the Royal Institute of Technology (KTH) in Stockholm. The study has been carried out at the Department of Industrial Ecology in co-operation with the Department of Land and Water Resources Engineering. This thesis is one of two case studies in the project Environment systems analysis for the use of residuals – A regional perspective on the utilisation of ashes in ground construction (Q 248). The project is financed by Värmeforsk (Thermal Engineering Research Institute) and is lead by the consulting company Ramböll Sverige AB in co-operation with the department of Land and Water Resources Engineering at KTH, the consulting firm Ecoloop and ÅF Energi & Miljö AB. Susanna Olsson, department of Land and Water Resources Engineering, KTH, and Erik Kärrman, Ecoloop, were supervisors and Björn Frostell, department of Industrial Ecology, KTH, was examiner for the thesis. Finally I would like to express my appreciation to my supervisors and examiner for their heartfelt assistance during my work. Ylva Magnusson Stockholm, February 2005 iii Environmental Systems Analysis for utilisation of bottom ash in ground constructions Table of contents Table of contents 1. Introduction ______________________________________________________5 2. Objectives ________________________________________________________5 3. Production of ashes ________________________________________________6 3.1 Coal and peat - bottom and fly ash _____________________________________________ 7 3.1.1 Utilisation of peat and coal ash ______________________________________________________ 7 3.1.2 Examples of projects where coal and peat ash have been used ______________________________ 7 3.2 MSWI bottom and fly ash _____________________________________________________ 9 3.2.1 Utilisation of MSWI ash ____________________________________________________________ 9 3.2.2 Examples of projects where MSWI ash have been used___________________________________ 10 3.3 Biofuel - bottom and fly ash __________________________________________________ 11 3.3.1 Utilisation of biofuel ash __________________________________________________________ 12 3.3.2 Examples of projects where biofuel-ash has been used ___________________________________ 13 3.4 Examples of the use of fly ash independent of origin ______________________________ 14 4. Environmental Systems Analysis (ESA) ______________________________14 4.1 Previous studies in the area of ESA for waste management ________________________ 16 5. Method __________________________________________________________17 5.1 Part 1 - Inventory of ashes in Uppsala County ___________________________________ 17 5.1.1 Ashes in Uppsala County and their potential use _______________________________________ 5.1.2 Selection of ash _________________________________________________________________ 5.1.3 Selection of utilisation scenarios ____________________________________________________ 5.1.4 Description of the chosen scenarios__________________________________________________ 17 17 18 19 5.2 Part 2 - ESA for different possible uses of MSWI bottom ash ______________________ 21 5.2.1 General description of the method - ESA for the use of residuals in a regional perspective _______ 5.2.2 System boundaries and functional unit _______________________________________________ 5.2.3 Inventory ______________________________________________________________________ 5.2.4 Analysis of the result and Impact Assessment __________________________________________ 21 22 23 27 6. Result ___________________________________________________________27 6.1 Result part 1 - Inventory of ashes in Uppsala County _____________________________ 27 6.2.1 Environmental flows connected to the 15 environmental quality objectives ___________________ 6.2.2 Differences in resource use and emissions_____________________________________________ 6.2.3 Use of natural aggregates _________________________________________________________ 6.2.4 Leaching of metals _______________________________________________________________ 6.2.5 Energy use _____________________________________________________________________ 29 30 31 31 33 7. Discussion _______________________________________________________35 7.1.1 Result _________________________________________________________________________ 35 7.1.2 Method ________________________________________________________________________ 37 7.1.3 Proposals for future research ______________________________________________________ 38 8. Conclusions ______________________________________________________39 9. References _______________________________________________________40 Appendix 1: System boundaries for scenario 1, 2 and 3 Appendix 2: Inventory Appendix 3: Differences in substance flow when certain life cycle stages are excluded iv Environmental Systems Analysis for utilisation of bottom ash in ground constructions Introduction and Objectives 1. Introduction To decrease the disposal of waste and to save natural resources, several political initiatives have been initiated both in Sweden and at a European level. One example is the EU Sixth Community Environment Action Programme, which informs that natural resources management and waste recycling are areas that should be given priority. Another example is the Swedish Environmental Code that prescribes reuse and recycling of material. One of the Swedish environmental quality objectives, a Good Built Environment, is also relevant for the reuse material issue. The government has also attempted to decrease the overall volume of disposed solid waste with a landfill tax. The overall idea of the political initiatives is that it should be a matter of course to use alternative materials when possible and then decrease landfilling and reduce extraction from gravel/sand pits and rock quarries. According to Arm (2003), certain qualifications must be fulfilled before residual products can be an interesting alternative to conventional aggregates, such as sand, gravel or crushed rock. The alternative material must have suitable engineering properties, an acceptable environmental impact and reasonable costs. Approximately 1 million tonnes of ash is produced every year in Sweden.1 It has been shown in previous studies for example by Arm (2003), RVF (2002) and Mácsik (2004), that the ash has the technical properties to fulfil the qualifications for acting as substitute for conventional material in ground constructions. However, it has to be proven that the ash also is environmentally friendly before use. The environmental impacts from residuals can be analysed with different system perspectives and according to Roth and Eklund (2003) evaluations of residuals have so far mainly focused on measurements of total chemical content and leaching behaviour. Roth and Eklund argue that the current leaching tests have to be complemented by broader system boundaries in order to discuss the use of resources and environmental impacts from a wider perspective. 2. Objectives This thesis describes the potential for utilisation of different types of ashes in Uppsala County. Firstly, an inventory of ash-producers and possible applications where ash can be utilised was made. This was followed by an estimation of differences in environmental impacts that can be expected if ash is substituting conventional material in ground constructions. The environmental impacts are discussed in a wide perspective where both emissions and resource use are included. The intention is to produce useful information for decision-making concerning utilisation of ash. The aims in more specific terms were: • To identify the ashes produced in Uppsala County, quantify the ash flows and give examples of potential applications of these ashes. • To perform an Environmental Systems Analysis (ESA) for: - Utilisation of 1 tonne MSWI bottom ash as drainage material in the covering structure in a landfill (substituting sand). - Disposal of 1 tonne MSWI bottom ash. 1 Bjurström, personal communication 5 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Production of ashes • To compare these two scenarios for managing the MSWI bottom ash with the already investigated scenario; where crushed rock in the sub-base layer of a road is substituted by MSWI bottom ash. Questions addressed are how the scenarios differ regarding resource use and emissions and which processes that are significant for the difference in environmental impact. The study takes into account the whole life cycle of the constructions (all three constructions are assumed to be produced in all scenarios) and includes the environmental impacts generated when ash is treated as waste and disposed of in the landfill. 3. Production of ashes The secondary product ash is formed during the incineration process. The type of ash produced depends on the kind of fuel and furnace used and also on what kind of flue-gas cleaning devise that is installed in the incinerator. As stated in SGI (2003), different types of ash have different types of environmental and engineering properties, which lead to the varying characteristics and behaviour of different types of ash. Normally two fractions of ash are produced from incineration, known as bottom ash and fly ash. Bottom ash is the product that falls down and stays at the bottom of the furnace. The fly ash travels with the flue-gases through the exhaust system and is caught in the flue-gas cleaning system, for example an electric filter. In general, the bottom ash has been more investigated, considering the engineering and environmental properties, probably due to the fact that bottom ash is produced in higher amounts than the fly ash. Arm (2003) discusses several categories of combustion systems. One is mass-burning, where the fuel is fed directly into the furnace and burned on a gate without any pre-treatment; massburning is common for waste incineration. In other kinds of systems, a more homogenous fuel is needed. The fuel is prepared through sieving, crushing and is generally fired in suspension for example in a fluidised bed incinerator. Alvarez (1999) gives an example of a third system, furnace with powder burners and as the name indicates, the fuel is in the form of powder. The powder together with air is sprayed into the furnace, where it burns in suspension. Systems with powder-burners produce more fly ash than mass-burning. The ashes produced in Sweden are mainly generated from incineration of biofuels, municipal solid wastes, coal, and peat. As previously stated, characteristics vary significantly even if they originate from the same type of fuel. Moreover, coal ash produced in Uppsala may for example have a different behaviour than a coal ash produced in other parts of the country. In the following sections, short descriptions of the basic differences between ashes originating from different types of fuels are described. Examples of how the ashes can be used are also given. Projects in Uppsala County were considered to be the most interesting ones during the selection process of utilisation projects due to the objectives of this study. In order to get a more complete view of different kinds of ash utilisation, the examples were complemented with projects from other parts of the country. 6 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Production of ashes 3.1 Coal and peat - bottom and fly ash Chemical and physical properties According to SGI (2003), bottom ash has a relatively large particle-size. Further, the surface of the particles resembles glass but the inside is porous. Fly ash from coal and peat has, on the other hand, a very small particle-size, comparable to sandy clay. These small particles consist mainly of silica, aluminium and iron compounds. The fly ash often has a very low density and sets easily. Peat and coal ashes have very similar technical properties and are therefore treated as identical materials in this project. 3.1.1 Utilisation of peat and coal ash Construction material According to The City of Helsinki - Real Estate Department (1983) - both the bottom ash and fly ash from coal and peat can be used in construction, for example in smaller roads where it often substitutes crushed rock. Constructions of coal and peat ash have showed to have good strength, a higher isolation capacity and only half of the density compared to natural rock material. Fly ash has the advantage that it sets and becomes hard and is therefore suitable for construction where high strength is needed. Fly ash is also useful when the construction is exposed to a dynamic load. Unlike the fly ash, the bottom ash particles become crushed when exposed to heavy loads, which can lead to subsidence. On the other hand, bottom ash is very good to use in other applications, such as filling material in excavation trenches. The reason for this is that the bottom ash never becomes hard which facilitates digging when reparation is needed. The use of coal and peat ash in construction is not recommended when the ground water level is high, since substances can be dissolved in water and the fly ash can also lose the strength during contact with groundwater. In Uppsala County, Vattenfall Värme Uppsala AB is one of the largest producers of coal and peat ash. They also have experiences in using both fly ash and bottom ash in ground constructions. They mix the ash with 30 % gravel and 20 % water to get a faster setting and the construction can be used almost directly (construction with only ash extend the setting process with 2-3 months). Problems can arise when it rains heavily, since this leads to an extension of the setting process. The disadvantages that Vattenfall Värme has faced by using ash are mainly logistic problems during winter, since ash can not be stored for a long period of time. A lack of time to mix the ash with gravel occurs during the winter. This since more ashes is produced during winter and ashes cannot be stored indefinitely without losing its properties.2 3.1.2 Examples of projects where coal and peat ash have been used Librobäck - recycling station, Uppsala Librobäck is a recycling station owned by Uppsala Teknik och Service. Librobäck was built during the winter 2001 and is constructed with a layer of fly ash originating from coal and peat combustion. The total amount of ash used during construction was approximately 6000 tonnes. This construction benefits from the fact that fly ash only has half of the weight compared to crushed rock. Lower weight has the benefit that the underlying clay layer doesn’t have to be stabilised with pillars of cement, which reduces the costs. Another benefit is the time saving, since the ash doesn’t need to set before adding the asphalt layer. A monitoring 2 Munde, personal communication 7 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Production of ashes program for the station has been set up consisting of water sampling in the area, which makes it easy to detect possible leaching. Uppsala Teknik och Service is very satisfied with the recycling station, since it has showed good technical properties. The station is constructed (from top to down) as follows: Asphalt Coal and peat fly ash (1m) Geofabric Figure 1: Cross-section of Librobäck recycling station Figure 2: Librobäck recycling station, Uppsala Danmark’s football field, Uppsala A recently built ash project is Danmark’s football field just outside Uppsala. This is an example of a combined use of bottom and fly ash from peat and coal incineration. In the beginning of the construction, it was noted that the construction site included valuable topsoil, which led to the decision that the soil should be sifted and sold. The consequence of this was that even more ash was needed than estimated. The total amount of ash needed for the construction was estimated to approximately 8000 tonnes substituting gravel and crushed rock. Vattenfall Värme Uppsala AB will generate all the ash and they are also responsible for the construction. The design of the construction is presented in Figure 3.3 Grass Soil Coal and peat fly ash (0,3 m) Coal and peat bottom ash Figure 3: Cross-section of Danmark’s football field Börje – farm roads, Uppsala Smaller roads are the main utilisation area for coal and peat ash. One example is several farm roads at Börje in Uppsala municipality. In total 3000 m3 fly ash generated from incineration of coal and peat is needed to construct a 2 km long road (Larsson and Lejon, 2003). The technical properties of roads of coal and peat ash have shown to be beneficial and have led to that Vattenfall Värme Uppsala AB easily finds customers who are willing to use ash for farm roads. The responsibility for the roads is always the owner, which often is a private person. So far, the owners of ash farm roads have been very positive to the results. Stabilization of soil with high sulphide content, Uppsala Sulphidic soil is a sensitive soil type with low strength, easily leading to an occurring subsidence when the soil is exposed to heavy loads. Therefore, this kind of soil often is excavated and replaced before construction. Sulphidic soil has the problem that under aerobic conditions, acidification and leaching of sulphides and iron may occur. Therefore, the soil 3 Munde, personal communication 8 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Production of ashes should be stabilized if there is a risk that it will be in contact with oxygen.4 An experimental work to stabilize the soil with peat bottom ash was carried out in cooperation between the companies JM, Bjerking and Vattenfall Värme Uppsala AB. Firstly, a layer of bottom ash was spread on the ground, covered by a layer of sulphdic soil mixed with bottom ash and finally covered with a layer of bottom ash. A week after the application, a regular blending process started to help oxygen to infiltrate into the pile. Due to the high pH of the ash, the pH of the acidic soil increased. In total 200-300 tonnes of peat bottom ash were used to stabilise soil from excavation at construction sites.5 Covering structures for the landfill Dragmossen, Älvkarleby 3 km south of Älvkarleby, the 2000 m3 landfill Dragmossen is located. According to Mácsik (2004), Dragmossen was covered with four layers during May 2004, where two of them consisted of fly ash (the pre-covering layer and barrier layer). The bottom layer was constructed from fly ash generated from incineration of wood splinter and the second layer from the bottom was a mixture of sewage sludge and peat fly ash. The two types of fly ash used were 250 tonnes from Vattenfall Värme in Uppsala and 300 tonnes from Mälarenergi in Västerås. The covering was performed as shown in Figure 4. Control and monitoring of the technical properties and possible formation of gas will proceed until one year after the covering. Protection layer Drainage material 50 % fly ash from Vattenfall Värme and Mälarenergi mixed with 50 % sewage sludge (0,5 m) Fly ash from Mälarenergi (0,5 m) Figure 4: Cross-section of the covering structures at the landfill Dragmossen 3.2 MSWI bottom and fly ash Chemical and physical properties According to SGI (2003), the MSWI bottom ash resembles dark greyish sandy gravel and consists of melt or unburned material, for example glass, metals and ceramics. MSWI bottom ash is often sorted, which means that unburned material and metals are removed. After sorting, the ash can be sifted to desired fraction. The environmental and engineering properties of the ashes are affected by the composition of the waste, the combustion-process and how well the ash is sorted. The fly ash, produced from MSWI, often has an exceptionally high content of heavy metals and is, today, considered as hazardous waste (Larsson and Lejon, 2003). According to Arm (2003), it is recommended to store the bottom ash before utilisation since the storage reduces the water content and the alkalinity, which improves the environmental and mechanical properties. 3.2.1 Utilisation of MSWI ash Construction material Arm (2003) states that according to present Swedish regulations, MSWI bottom ash cannot be used as construction material, unless the organic matter content is less than 2 % (measured by colorimetric method). Nor should bottom ash from incineration of hazardous waste be used. It 4 5 Mácsik, personal communication Munde, personal communication 9 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Production of ashes is important that only bottom ash is used, since the fly ash is far more contaminated. One example of a construction using bottom ash is roads. Bottom ash can be laid 25-35 cm below the road surface, depending on the type and thickness of the surface layers. The same stiffness as for natural gravel may be assumed. Construction traffic on the compacted layer should be avoided and the bottom ash should be stored outdoors before use. MSWI fly ash as a cement substitute Studies by Lin et al (2003) have shown that MSWI fly ash can act as substitute for up to 20 % of the cement in mortar, without sacrificing the quality of the resultant concrete. In fact, the concrete thus produced has greater compressive strength, 10 % higher than the one without the substitution. The setting time of the fresh mortar becomes longer and increases with the increasing amounts of cement replaced. Filling material The MSWI fly ash is not used directly today, since it often contains very varying and high amounts of heavy metals (Larsson and Lejon, 2003), but theoretically the fly ash could be used as filling material, for example in old pits and limestone quarries. The problem is that MSWI fly ash together with water can form hydrogen-gas and therefore implies a risk for explosion. Why MSWI fly ash to some extent form hydrogen-gas is under investigation.6 Acid leaching To get the fly ash cleaner, acid leaching could be a potential option. Acid leaching is based, according Hernhag et al (2003), on the fact that metals dissolve when exposed to acidic conditions. In the acid leaching process of fly ash, the ash is put into a reactor containing process water with pH 1 and 2. The metal oxides are then forced to dissolve into the process water and there is also an ion exchange of metals bound to the surface of the ashes main components, Ca, Si, Al, Na and K, releasing metals into the water. After the leaching, there is a phase separation where inert ash residue is taken away and the metals in solution are ready to be enriched. No acid leaching exists in Sweden today. There are also other kinds of recycling methods to reuse the metals in the ash, but they are often considered as too expensive. 3.2.2 Examples of projects where MSWI ash have been used Törringevägen-road, Malmö Törringevägen, built in 1998 and owned by the municipality of Malmö, is probably the most well-known project where MSWI ash has been used in Sweden. The road is situated 10 km southeast of Malmö. According to RVF (2002), the road is composed of three different parts; each part is constructed from different recycled materials in the sub-base layer. The materials used are recycled bricks, recycled concrete and MSWI bottom ash. Between each section, a sub-base layer consisting of crushed rock serves as a reference material. The total amount of ash used was 320 tonnes, with a cross-section shown in Figure 5. It has been shown that the strength of the sub-base with MSWI ash is higher then the strength of the reference material. Asphalt Crushed granite MSWI bottom ash (0,465 m) Figure 5: Cross-section of the ash part of Törringevägen 6 Munde, personal communication 10 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Production of ashes Test road at Hovgården, Uppsala Another road described in RVF (2002), is situated within the landfill site Hovgården, northeast of Uppsala. It is owned by the municipality of Uppsala and was built of 100 m3 MSWI bottom ash in 1996. Since the road is situated within the disposal site, it is only used for internal transports. The bottom ash was sorted to the fraction 20-50 mm and stabilised before use. The intended purpose of the test road was to investigate the behaviour of the ash as road construction material and to examine any possible long-term leaching from the material. No visible subsidence has occurred even tough the road have been daily exposed to heavy traffic. Area for composting, Hovgården, Uppsala Not only a test road of MSWI bottom ash is built at Hovgården, but also a 20 000 m2 area for composting has been constructed. The total amount of unsorted ash that was used during construction was approximately 30 000 tonnes.7 The area is constructed as follows: Asphalt MSWI bottom ash 0,3 m Gravel/Crushed rock Figure 6: Cross-section of the compost area, Hovgården Drainage material, Dragmossen, Älvkarleby In the landfill Dragmossen (see section 3.1.2), not only peat ash was used for the covering structure. Also bottom ash from incineration of wastes from the paper industry was used. The ash was used as a drainage material during covering the landfill, see Figure 4. The ash came from Söder Energi`s district-heating plant and had a size distribution of 0-100 mm. Traditionally, sand is used in drainage layer in landfills. Since there weren’t enough bottom ash for coving the whole landfill, also sand was used in some parts of the drainage course at Dragmossen.8 SYSAV, combined heat and power plant, Malmö It is stated in RVF (2002) that during construction of SYSAV`s new waste incineration plant, in the years 2000-2002, MSWI bottom ash was used in several different applications. For example, the ash was used in ground constructions where the soil was weak and polluted. Further more, ash was used as filling material in excavation trenches and as a material against walls. 14700 m3 bottom ash was used in total, substituting crushed rock. Today when SYSAV`s new plant produces MSWI ash, all generated bottom ash is used in different constructions. According to Kärrman et al (2004) in total six external projects have been performed and 10000 tonnes of ashes have been used in each project. Examples of projects are recycling stations in Malmö and the road Törringevägen. 3.3 Biofuel - bottom and fly ash Biofuel is often defined as biomass. Biomass is mainly composed of carbon, hydrogen and oxygen and has been created by metabolic activity of living organisms. In this report, the expression biofuel refers to wood material, for example bark, recycled wood waste, Salix etc. 7 8 Kjällman, personal communication Mácsik, personal communication 11 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Production of ashes As discussed in Ek and Westling (2003), the content and structure of the ash resulting from incineration of biofuel depends on the type of furnace and on kind of biofuel used. Biofuel has a significantly varying quality and characteristics due to the fact that soil conditions differ. For example, different fertilisers are used in different areas giving the biofuels specific characteristics. The most notable difference between the fly and the bottom ash is the particle size. The fly ash has a smaller particle size and a higher content of lead, cadmium, and zinc. 3.3.1 Utilisation of biofuel ash Ash recycling As declared in Ek and Sundqvist (1998), biofuel ash is nutrient-rich, which can counteract unwanted changes of the soil in the forest, and therefore the majority of biofuel ash producers, are involved in some manner of different projects where the ash is spread on forestland. The main purpose is to return nutrients to the soil in an effort to compensate the withdrawal of biofuel, leaching and acidification. For the ash to be suitable for spreading, it has to fulfil specific criteria, such as having a low metal content and it has to originate from biofuel. Factors that have to be considered before using ash as a fertiliser are: • The ash has to be stabilised and dry, but not dusty. • The leaching of nutrients has to be slow. • The ash should not contain a high amount of heavy metals and organic compounds. According to the National Board of Forestry, ash intended for use as a fertiliser to counteract withdrawal, can only be used on the following soil types: • Strongly acidic soil. • Peat. • Where a large withdrawal of branches has occurred. • Where there have been several withdrawals. The biofuel ash effectively sets and together with water forms a material with low permeability. This material can be crushed and sifted to appropriate size to give the right leaching properties (Ek and Westling, 2003). Construction material According to Ek and Westling (2003), mainly the biofuel bottom ash should be considered in construction, because fly ash does not have satisfactory strength. A problem with the bottom ash is the high variability and relatively high content of unburned material, which can lead to subsidence. Therefore only smaller roads, such as farm roads are built of biofuel ash today. Another example of construction where the bottom ash has started to be more frequently used is in excavation trenches for water and waste pipes, where in the past traditional crushed rock or natural gravel were used (Eriksson, 2001). Method from Econova The Econova method (Figure 7) is according to Ek and Westling (2003) based on drying the fly ash originating from biofuel and then using it for soil improvement or for incineration. The drying process is natural, consisting of wind and sun only, by placing the ash on a flat foundation. As soon as the surface is dry the material is turned, usually with the result that the ash is totally dry within a year and can then be used. 12 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Production of ashes Figure 7: Stages applied in the Econova method Source: www.econova.se Ash as a landfill covering material In Sundberg et al (2003), it is described how stabilised sludge from wastewater treatment plants mixed with ash from incineration of biofuel, gives a product that can be used as landfill covering material. When the materials are added together, beneficial properties of both materials can be utilised, such as the low permeability of the sludge and the high strength and gasket properties of the ash. 3.3.2 Examples of projects where biofuel-ash has been used Landfill covering, Kristianstad Sundberg et al (2003) also gives an example from the municipality of Kristianstad, where they have been working with a mix of ash, sludge, and gravel as a covering material at a landfill, since the year 2000. Several different mixes have been tested and today the mix consists of 50 % sludge, 25 % ash (both fly and bottom ash) and 25 % gravel. After mixing, the material has to be stored for 4-6 weeks to get a good consistency easy to work with. The mix is flattened out on the landfill and the final thickness of the cover is 0,8-1 m. Earlier, when a higher percentage of ash in the mix was tested, there was a problem with smell of ammonia. Another problem was leakage of nutrients, especially during wintertime, since the vegetation on the landfill could not assimilate the nutrients. Spreading of ash on Salix cultivation, Enköping Salix is an energy crop and is only cultivated with the purpose to act as fuel, in, for example, district-heating plants. ENA Kraft in Enköping uses a mix of 15 % Salix and 85 % wood splint for incineration and the bottom ash produced is stored during the wintertime and is mixed later with sludge from the municipal wastewater treatment plant. During the spring, the mix is spread on the Salix-cultivation with a traditional fertilizer spreader (Figure 8). This is an experiment for a period of ten years. The farmers have so far been very positive to the experiment.9 9 Johansson, personal communication 13 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Environmental Systems Analysis Figure 8: Ash recycling in Enköping Source: Eklund, personal communication Farm roads, ash from Hylte Bruk Ek and Sundqvist (1998) have described how bottom ash originating from bark incineration at Hylte Bruk, has been used in smaller roads, with a length of only 3-4 km. The road core is 70 cm, which implies that 3-4 tonnes of ash was needed per meter of road. A layer of gravel was placed on top of the ash and the slopes were covered with sludge. An evaluation of the project showed that the road had slightly less strength than roads of conventional material, especially for the slopes. Restrictions concerning the proximity of the ash constructions to watercourses and the groundwater level, led to addition of an extra layer in order to fulfil the construction restrictions. 3.4 Examples of the use of fly ash independent of origin Granulated cement stabilised fly ash To granulate ash, means that the fine ash particles bind together during rotation in a drum, forming larger particles. According to Larsson and Lejon (2003), this can be performed by wet ash powder moving in a loop in a rotating plate or drum, during transport allowing the particles to pick up the fine material and grow bigger. Cement stabilised means that the granulated ash is mixed with cement and water. The resulting product can be used in several areas, for example in road construction, as drainage material, fertiliser, soil stabilisation, and as barrier material. The granulate ash should be used in an as dry environment as possible to minimise leaching. 4. Environmental Systems Analysis (ESA) Social awareness concerning protection of the environment and possible effects on the environment from the products used today has increased in the last years. This has led to an interest in developing methods to understand and reduce the impact on the environment. Moberg et al (1999) describe different kinds of Environmental Systems Analysis (ESA). The one that will be used in this thesis will show the environmental impact from a system in a holistic view, including all subsystems and their interrelations. An ESA can be one way to 14 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Environmental Systems Analysis help a decision-maker with a problem of complex character. The purpose is to contribute to a good decision-making, by investigating the different alternatives and comparing the consequences of each alternative. Utilisation of ash will lead to both positive effects like less disposal of ash and negative effects like risk for contaminant leaching. To get a view of what types of environmental impacts that is of high importance an ESA can be useful. An ESA approach will also give the opportunity to discuss the differences of environmental impact between utilisation of ash and disposal of ash. The ESA-method will thus be a helpful tool to give the study a wide perspective. One well-known example of ESA is a life cycle assessment (LCA), which consists of, 1) definition of problem, 2) inventory, 3) impact assessment, 4) analysis of the result (Rydh et al, 2002). Definition of the problem This part should include a description of why the LCA is being performed and what the result is going to be used for. For comparisons of different systems, a common denominator is needed. In a LCA, the denominator is the functional unit, which has to be measurable. The environmental impact must be related to this unit for each alternative in order to make the comparison stringent. It is not only the functional unit that has to be decided at this moment, also the technical, time and geographical system boundaries have to be formulated in detail. The system boundaries are important because they describe the limits of the study. Inventory According to Rydh et al (2002), the inventory process contains the data collection and calculation of material and energy flows in and out from the systems. The result of the inventory is the sum of all in - and outflows related to the functional unit. The increasing amount of information concerning the system acquired during the data collection, can lead to new demands and maybe new limitations have to be defined. This can lead to a change of direction during the process of data collection in order to fulfil the aim of the study (ISO 14040:1997). Impact assessment Rydh et al (2002) describes that an environmental impact assessment in an LCA should be made to evaluate the major effects on the environment. The purpose is to transform the data from the inventory to a few values that are easy to interpret. The assessment can be divided into three steps; classification, characterisation and valuation. • • • Classification, the data is sorted in different environmental impact categories; examples of these kinds of categories are eutrophication, green house effect and acidification. Characterisation, the data from the inventory is multiplied with a characterisation factor, which is specific for each data and category of environmental impact. The aim of the characterisation is to quantify the mutual relationship between the different forms of environmental impact that has been grouped in the respective environmental impact category. Valuation, consists of ranking, weighting and finally adding the result from the inventory to only one number. There are several weighting methods, which are based on individual or political and/or moral valuations. Examples of valuation methods are; Environmental 15 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Environmental Systems Analysis priority in product development (EPS), ECO-indicator 95, Tellus, Critical volume, Critica Surface-Time and Energy Consumption Reduction (Peterson, 2004). Analysis of the result The result from the inventory and the result from the environmental impact assessment are at this stage combined in consensus with the aim of the study. Questions about what are large and small environmental problems respectively have to be answered for all alternatives. This will display how the different alternatives can be optimised from an environmental point of view. The result of the analysis can take the form of conclusions and recommendations to decision-makers (ISO 14040:1997). There are different types of analysis that can be used. Below is a short description of three of them (Strand, 2003). • • • Dominance analysis – identifies the data that is contributing relatively most to the result. Uncertainty analysis – describes the variance in the amount of data. It is made to quantify the uncertainties in the three phases: Definition of the problem, inventory and impact assessment. Sensitivity analysis – measures how changes can affect the result. 4.1 Previous studies in the area of ESA for waste management There are some examples where ESA has been used for evaluation of ash utilisation in road constructions and other types of ground constructions. A progressing research by Olsson et al (2004) at the Royal Institute of Technology in Stockholm, has the aim to describe the differences in environmental impact that can be expected if crushed rock in the sub-base of a road, in the Stockholm region, is substituted by MSWI bottom ash. It has been shown that the ESA approach allows both resource use and emissions to be considered and therefore gives a different result then a more narrow study. A master thesis has also been done within the area. Here the aim was to compare and estimate the environmental load from different lightweight materials in road construction with an ESA approach (Peterson, 2004). In Finland, there is a successful example from Mroueh et al (2001), where the ESA-approach was used for comparison and evaluation of alternative road and earth constructions. An Excel-based life cycle inventory analysis was developed. Also for other parts of the waste management system, the LCA approach has shown to be a useful tool for assessing environmental impacts. One example is from Sonesson et al (1997), where the model ORWARE (Organic Waste Research) was used to illustrate the consequences of different waste handling systems in Uppsala. The result showed that the model was versatile and that it produced useful information about complex systems, but at the same time a number of general problems with this type of analysis became apparent. The most important of these problems are; lack of reliable input data, difficulties in defining and applying appropriate system boundaries, selection of appropriate scenarios and evaluation problems. 16 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Method 5. Method 5.1 Part 1 - Inventory of ashes in Uppsala County 5.1.1 Ashes in Uppsala County and their potential use Part 1 of this thesis will give a view of the different types of ashes produced in Uppsala County. The ashes included in the investigation were those produced in quantities of more than 1000 tonnes/year and plant. This amount can be considered as the critical level for utilisation for example in different types of ground constructions. Information about the companies and plants in the area, that produce large quantities of ash, was received from the County Administrative Board. More detailed information was found in the environmental reports from each plant. Interviews were also performed to get more complete information. 5.1.2 Selection of ash The result from section 5.1.1 shows what types of ashes that are produced in Uppsala County. The question now is which type of ashes should be investigated further in the ESA? To solve this problem four selection criteria were formulated: • • • • Produced amount of ash. Expected environmental impact. Documented applications. Data availability. The reason for inclusion of the first and second criteria is that a higher amount of ash gives a greater opportunity for utilisation. If the ash is also expected to have a high environmental impact, it can be seen as a “worst-case scenario” compared to the other ashes. The criterion documented applications means, that it should be proven by existing examples of utilisation, that the ash has the technical properties needed for the utilisation purpose. Finally data availability is also important to make the ESA reliable. Considering the selection criteria, the following arguments contributed the most to the final decision: - The MSWI bottom ash, the coal and peat fly ash are produced in large amounts. The MSWI bottom and fly ash are expected to give a relatively high environmental impact due to the content of heavy metals. The ashes that have the most documented applications, together with high data availability, are the fly ash from coal and peat and the MSWI bottom ash. The MSWI fly ash does not have any documented utilisation areas, since it is considered as a hazardous waste. The MSWI bottom ash and the coal and peat fly ash were chosen to be the investigation objects for the two case studies in the project by Värmeforsk Q 248 (see preface). Of these two ashes the MSWI bottom ash was selected to be the investigation object for this thesis. 17 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Method 5.1.3 Selection of utilisation scenarios A requirement of the selected utilisation scenarios were that they should be viable in a technical view and therefore the utilisation areas exemplified in section 3.2, are given priority. Three potential scenarios were studied for the MSWI bottom ash as theoretical cases, but they are based on experiences from real projects. The three scenarios were as follows: 1. MSWI bottom ash used as drainage material in a covering structure in a landfill. Source of information: the landfill Dragmossen, Älvkarleby. 2. MSWI bottom ash used as sub-base material in road construction. Source of information: the road Törringevägen, Malmö. 3. Disposal of MSWI bottom ash. Source of information: the landfills Dragmossen, Älvkarleby and Hovgården, Uppsala. Scenario 2 is already done in a progressing-reach study from Olsson (2004) and was included in the thesis for a comparison purpose. At the landfill Dragmossen, the drainage layer was made of bottom ash originating from incineration of waste from the paper industry. However, the construction of the drainage layer was performed in the same way as if the ashes originated from incineration of municipal solid waste. The case of Dragmossen was therefore used as an information source.10 To understand the scenarios, a basic knowledge of landfill structures is needed. A short description of the different layers in a landfill covering structure and their function follows below. Landfill structures According to Mäkelä and Höynälä (2000), the cover of a landfill is divided into the following structures (from the top): • • • • • Vegetation layer – Servers as a substratum on top of the landfill cover in which plants and trees are planted. Furthermore, the structure protects lower layers from erosion. Surface layer - Protects lower structure layers from the roots of the upper plants and trees and from other mechanical loads. In addition, the layer slows down the penetration of rain and thawing waters into the lower drainage layer. Drainage layer - The drainage layer is the part of the landfill that directs upper rain and thawing waters into the collecting ditches outside the landfill area. The requirements for the drainage layer are: sufficient water permeability and frost resistance. Barrier layer - The barrier layer prevents the entrance of upper seepage water to the lower structures and the waste itself. Besides, the barrier layer must stop the waste gases so that the gases do not escape into air. The functionality and durability of the structure are particularly important so that the whole landfill structure serves as designed. Pre-covering layer - With the pre-covering layer, the surface of the waste material is shaped and levelled down so that the upper layers can be built in a relevant way. In the section below, a more specific description of the studied scenarios is given. 10 Tham, personal communication 18 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Method 5.1.4 Description of the chosen scenarios Scenario 1 In scenario 1, the MSWI bottom ash is used as a drainage material in a covering structure in a landfill. The studied drainage layer of the MSWI bottom ash is 0,1 m thick. Geofabric is placed both on the top and on the bottom of the drainage layer. The function of the geofabric is to hold the drainage material in the right position. The geofabric also facilitates recycling of the material during a future demolition of the landfill. The dimensions of the drainage layer can be seen in Figure 9. Geofabric 0,0018 m MSWI bottom ash 0,1 m Geofabric 0,0018 m Figure 9: Cross-section of drainage layer of MSWI bottom ash. Included in scenario 1. In this scenario, the sub-base layer in the road will be built of the conventional material crushed rock and there is no landfill of MSWI bottom ash (Table 1). For dimensions of the base-course and sub-base layer in the road, see Figure 10. Table 1: The inflows of material in scenario 1 Drainage layer MSWI bottom ash Road Crushed rock Landfill - Base-course Crushed granite 0,08m Sub-base Crushed granite 0,465 Figure 10: Cross-section of the road. Scenario 2 In scenario 2, the MSWI bottom ash is used as a sub-base material in road construction. Since the presence of the MSWI bottom ash in the sub-base layer requires a somewhat thicker basecourse layer, both these layers have been included in the study. Information considering the dimensions can be seen in Figure 11. 19 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Method Base-course Crushed granite 0,15 m Sub-base Bottom ash 0,465 m Figure 11: Cross-section of road with a sub-base layer of bottom ash A traditional drainage layer in a covering structure is made of sand. The only difference between the traditional drainage layer of sand and the drainage layer of MSWI bottom ash are that geofabric is not needed (Figure 12). There is no landfill of ash in this scenario (Table 2). 0,1 m sand Figure 12: Cross-section of drainage layer of conventional material, sand. Included in scenarios 2 and 3. Table 2: The inflows of material in scenario 2 Drainage layer Sand Road MSWI bottom ash Landfill - Scenario 3 Scenario 3 implies disposal of the MSWI bottom ash. The dimensions and different material in the landfill structures have been discussed with people working in the sector, to get an as realistic scenario as possible. The chosen structure can be seen in Figure 13. 1) Vegetation layer, topsoil, 1,35 m 2) Surface layer, excavated soil, 0,5 m 3) Drainage layer, sand, 0,1 m 4) Barrier layer, geosynthetic clay liner, 0,1 m 5) Pre-covering layer, sand, 0,2 m Figure 13: Covering structures for the theoretical landfill case (included in scenario 3) This scenario includes that the road and the drainage layer is built of conventional material (Table 3). For dimensions of the drainage layer see Figure 12 and for the road see Figure 10. Table 3: The inflows of material in scenario 3 Drainage layer Sand Road Crushed rock Landfill MSWI bottom ash 20 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Method 5.2 Part 2 - ESA for different possible uses of MSWI bottom ash The method used in this part of the study is an Environmental Systems Analysis (ESA), based on the concepts of life cycle analysis (LCA). The method is under development in a progressing research at the Royal Institute of Technology, by Olsson et al (2004) and in the project by Värmeforsk Q 248 (which this thesis is a part of). In the research by Olsson et al (2004), the method has been used for utilisation of MSWI bottom ash in the sub-base layer during road construction. This thesis will contribute with an expandsion of scenarios of utilisation areas for MSWI bottom ash within the method and an improvement of data quality. In the next section, a short general description of the method follows. 5.2.1 General description of the method - ESA for the use of residuals in a regional perspective First the scope of the study and the system boundaries are defined. The system boundaries should include all significant stages of the product’s life cycle. The system should also include disposal of the studied material if this is a realistic alternative. This enables evaluation of how the utilisation of the residuals may impact the overall environmental performance of the system. By including disposal, the effects of less landfilling can be considered. Different products that are used in the system for example fuel and machineries, are included to a limited extent, see Figure 14 for a view over products and the stages of their life cycles that are taken into account in the ESA. Fuel Electricity Raw material System boundaries Products Emissions to air Emissions to water Rawmatrial Figure 14: Life cycle steps for the products that are included in the study. Source: Olsson et al (2004) In the next stage, the functional unit is to be decided and defined. The functional unit should consist of utilisation of a certain amount of residuals in a certain region. The functional unit should also include the products and functions that the residuals can be used for. The following step in the method is an inventory; this is where the emissions from the system are quantified. Only the flow of resources or emissions that have potential to affect the environmental impact categories in the forms that are described by SETAC-Europe (1999) are taken under consideration. Other criteria for the choice of environmental flows are that there should be available data to enable quantification and that the flows should be significant for the study. The data collection should be based on experiences from real projects. It is also good if the data is representative for the region and is as up-to-date as possible. Factors that are specific for the region, for example distance for transport should undergo a sensitivity analysis. Finally, the result is analysed. The result will address how the alternatives differ 21 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Method regarding resource use and emissions. The following sections describe how the method has been applied in this thesis. 5.2.2 System boundaries and functional unit The system includes production of material, construction and use and maintenance of the construction for 100 years. The production of MSWI bottom ash and possible demolition phases are not included in the system, depending on lack of data. A sketch of the system is given in Figure 15. Resources and MSWI bottom ash Production of material to and account during the study of sub-base Sketch over system boundaries and Production life cycle stages taken into drainage layer base-course material Waste Disposal Construction of drainage layer Construction of sub-base and base-course layers Use and maintenance of drainage layer for 100 years Use and maintenance of the road for 100 years Emissions Figure 15: Sketch over system boundaries and life cycle stages taken into account during the study MSWI bottom ash and resources are flows that enter the system, outflows from the system are emissions. The system also includes disposal of MSWI bottom ash as a life cycle stage. The system also implies that the different scenarios will always be performed; this means that the system is producing three services. Firstly the drainage layer in a landfill, secondly the subbase and the base-course layers of a road and finally the disposal of certain amount of MSWI bottom ash. Since the presence of MSWI bottom ash in the sub-base layer requires a somewhat thicker base-course layer, both these layers have been included. The MSWI bottom ash will in each case substitute the conventional material. A drainage layer in a landfill is traditionally made of sand. In sub-base and base-course layers in roads the ash substitutes crushed granite. This implies that the scenarios have different inflows of material see Appendix 1 for more detailed information. Scenario 3 is in some way different compared to the other scenarios. For example this scenario includes production of many different materials since all this material is needed for the covering structure in a landfill. See Figure 16 for a description of the life cycle stages taken into account in scenario 3. 22 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Method Resources and the MSWI bottom ash Production of the material needed for the landfill structure: soil, sand, and geosynthetic clay liner. Construction of the landfill structure: vegetation layer, surface layer, drainage layer, barrier layer and pre-covering layer Use and maintenance of the landfill for 100 years. Includes the leachate from each covering layer and the leachate from the MSWI bottom ash disposed in the landfill. Emissions Figure 16: Life cycle stages taken into account for scenario 3 As the method prescribes, the functional unit should consist of both utilisation of a certain amount of residues and the products/functions that the residues can be used for. According to this the following functional units were chosen: - Utilisation of 1 tonne MSWI bottom ash. - Production of 0,5714 m3 drainage layer in the landfill. - Production of 0,1536 m road. 5.2.3 Inventory The criteria for the choice of flows were that there should be data available to enable quantification and that the flows should be significant for the study. Based on this, the following environmental flows were included: natural aggregates and energy and emissions to air and water. One example, where not enough data was available, was the uses of human resources and occupation the of land area. Therefore these parameters have not been considered in the study. Only those life cycle stages that were different from scenario to scenario were included in the analysis; similar parts of the system thus were excluded. As mentioned earlier, the data for the scenario to use the MSWI bottom ash in the sub-base layer during road construction has been obtained from Olsson et al (2004). Data for the remaining scenarios was obtained from literature and interviews with people working in the sector. It was intended to assemble the data that was representative for Uppsala County and as currently valid as possible. A more specific description of the data collection and assumption made for the study is given in the following sections, and the whole inventory with references can be found in Appendix 2. 23 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Method Parameters for the MSWI bottom ash All parameters connected to the engineering properties of the MSWI bottom ash, for example density, were obtained from Vattenfall Värme Uppsala AB. Production of drainage material from the MSWI bottom ash The distribution of the ash from the plant to the sifting area is not taken into account, since the ash always will be transported to a sifting/storing area before utilisation.11 This transport can be seen as a part of the production of the MSWI bottom ash, and is therefore not included in the life cycle stage production of the drainage material. To produce drainage material from MSWI bottom ash, the ash has to be sifted to remove metals and organic compounds. To get information about the sifting procedure, interviews where performed with the company Slag Recycling AB. During the inventory it became clear that the sifting procedure could be excluded from the analysis, since the MSWI bottom ash will be sifted in all scenarios (even if the ash will be disposed of). 12 After sifting, 80 % of the ash remains, which means that the life cycle stages construction and use and maintenance of the drainage layer have a 20 % lower inflow of the MSWI bottom ash, than the life cycle stage production of drainage material (RVF, 2002). The geofabric used in the study was produced by Naue Fasertechnik in Luebbecke, Germany, and transports of the geofabric were calculated to be from here. Emissions factors for production of geofabric were taken from Svingby and Båtelsson (1999). Production of drainage material from sand The production of the drainage material from sand includes the extraction of sand and the loading of sand to truck. The data for the inflows to this life cycle stage were obtained in interviews with the company Jenaders Grus, who has the experience in delivering sand for the purpose to be used as drainage material in landfills. According to Jenaders Grus, a loading machine of the type Volvo L180 E is used for extraction and loading of sand and therefore figures for this machine were used. Construction of drainage layer (of both sand and MSWI bottom ash) At the source of information, Dragmossen in Älvkarleby, some parts of the drainage layer are constructed with sand and some parts constructed with bottom ash. The machine used for the construction of the layer was an excavator of the type Volvo EC240 for both materials. During interviews with people producing excavators, it was discovered that an excavator has a big difference in energy consumption depending on if the scoop is filled or not. Based on the experience from Dragmossen, the excavator was assumed to be working with a filled scoop 50 % of the time and with an empty scoop 50 % of the time. The geofabric used in scenario 1 is manually put on the MSWI bottom ash. The drainage layer cannot be driven on and is therefore not compacted; therefore the density for non-compacted MSWI bottom ash has been used in all calculations for the drainage layer.13 Use and maintenance of the drainage layer (of both sand and MSWI bottom ash) Data about the leachate from the MSWI bottom ash was obtained from the The Swedish Association of Waste Management (RVF, 2002). The leaching data for sand was found in the studies from Mroueh et al (2001) and Gustafsson et al (2003). The amount of leachate is dependent on how much water the material is in contact with. A drainage layer is supposed to direct rain coming from above and based on this the calculations have been made on the 11 Ericsson, personal communication Reference group, personal communication 13 Mácsik, personal communication 12 24 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Method assumption that all infiltrated water (200 mm) will reach the drainage layer. To get a view of how the contamination have varies over time, the leachate from both materials were calculated for time perspectives of 50, 100 years and infinity. The leaching approximations are based on different tests, for different time perspectives. For the infinity perspective, data from the standardized availability test Nordtest NT ENVIR 003 have been used. For the two shorter time perspectives, data from batch leaching tests was used. The batch leaching tests were done according to the CEN-method. This means that the leaching at the liquid-solid (L/S)-ratio of 2 or 10 may be approximated as being equivalent to the leaching from the different scenarios during a 100-year period. The ratio that has been used depends on the time it takes to reach L/S 2 or L/S 10, see Table 4. The ratio closest to 100 years has been used. This lead to for example that leaching from scenario 2 is obtained by a liquid-solid ratio of 2 for both the ash and the crushed rock and leaching data for the drainage layer of MSWI bottom ash is estimated from CEN tests using a liquid-solid ratio of 10 (Table 4). The geosynthetic clay liner and the geofabric have a lifetime of more than 100 years.14 It has therefore been assumed that no leaching from the geofabric and the geosynthetic clay liner during 100 years occurs. Table 4: Time to reach L/S 2 respective L/S 10 Time to reach L/S 2 for MSWI BA in drainage layer (scenario 1) 1,4 years Time to reach L/S 10 for MSWI BA in drainage layer (scenario 1) 6,9 years Time to reach L/S 2 for sub base with MSWI BA (scenario 2) 99,2 years Time to reach L/S 10 for sub-base with MSWI BA (scenario 2) 496 years Time to reach L/S 2 for base course with crushed rock, (scenario 2) 40 years Time to reach L/S 10 base course with crushed rock, (scenario 2) 200 years Time to reach L/S 2 for crushed rock road (scenario 1 and 3) 145 years Time to reach L/S 10 for crushed rock road (scenario 1 and 3) 727 years Time to reach L/S 2 drainage layer of sand (scenario 2 and 3) 1,6 years Time to reach L/S 10 for drainage layer of sand (scenario 2 and 3) 7,9 years Time to reach L/S 2 for pre-covering layer of sand (scenario 3) Time to reach L/S 10 pre-covering layer of sand (scenario 3) 12,8 years 64 years Time to reach L/S 2 for MSWI BA disposed in a landfill (scenario 3) 960 years Disposal of MSWI bottom ash The leachate from the landfill has been assumed to go through a water treatment plant the first 20 years. This means that chemicals needed for the treatment was included in the analysis, but neglecting that a landfill contains more residuals than MSWI bottom ash. Since this scenario includes many parameters, each layer is described below to give a clear view. Vegetation layer: The calculations are based on the assumptions that an excavator does the excavation of soil and the soil is loaded directly to a lorry. The distance from the excavation site to landfill has been assumed to be 20 km. The leachate from the soil layer in the landfill will be the same in natural conditions; therefore no leaching is taken into account. 14 Burton and Sjöholm, personal communication 25 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Method Surface layer: By discussions with people in the landfill sector, it became clear that the soil used in the surface layer often is soil that already exists in the landfill area. The soil comes from excavation during different ground-constructions, and is considered as waste.15 Therefore the soil is only considered as a direct inflow to this life cycle stage. However, the soil used in the surface layer cannot be contaminated; it means that the leaching from the soil is assumed to be the same as in natural conditions. Therefore no leaching from this layer has been assumed. An excavator makes the construction. Drainage layer: All calculations and assumptions are the same as for the drainage layer of sand (see above). Barrier layer: The geosynthetic clay liner in the barrier layer is produced by Naue Fasertechnic in Luebbecke16, Germany, and the transports are assumed to be from there. It was very hard to find information about resource use during production of the geosynthetic clay liner. However, since the information about the geofabric was relatively good the geosynthetic clay liner in this study was simplified to consist of a bentonite layer with geofabric on top and at the bottom. According to Gävle Väg trummor AB the geosynthetic clay liner consist of 95 % bentonite and 5 % geofabric. Bentonite is extracted through strip mining, where core drilling machines, dozers and front-end loaders are used17, but reliable information about working capacity and fuel consumptions for machines were not found. It was decided to do two calculations one where the barrier layer is excluded from the analysis, and one were values from an LCA of mining of magnetite ore is substituting the life cycle stage production of material for the barrier layer. Pre-covering layer: Sand is used in the pre-covering layer, therefore the same parameters and assumptions are used as for the drainage-layer of sand. The only differences are the dimensions and the infiltration rate. According to Swedish regulations, the maximum water going through a landfill is 50 l/m2 year and this amount of water has been assumed to reach the pre-covering layer. Transports According to Jehanders Grus, sand is distributed by the aid of a lorry with a trailer. This lorry could take a maximum load of 35 tonnes. To facilitate the study, it was assumed that the same kind of lorry and trailer were used for all transports; distribution of MSWI bottom ash, soil, geofabric, and geosynthetic clay liner. The calculations were also made with the assumption that the lorry had maximum load during distribution and returned empty. It should be noted that spillage of material during transport has not been taken into account. The average velocity during transport was assumed to be: Table 5: Assumed velocity Distance Less than 7 km 7 – 20 km More than 20 km Assumed velocity 50 km/h 70 km/h 90 km/h According to the County Administrative Board in Uppsala (2004) there are two landfills that will be closed before 2008, Annelund in Enköping, and Gatmots in Tierp. This means that these two need drainage material for their landfill structure. The average distance from Uppsala to these landfills is 55 km. This distance has been assumed for transport of MSWI 15 Laurell, personal communication www.naue.com 17 Burton, personal communication 16 26 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Method bottom ash from production site to construction site. If these two landfills will build theirs drainage layer of sand instead, the most reasonable solution would be to take sand from the closest sand pits. The landfills Annelund and Gatmots have a distance of 5 respectively 8 km to the nearest sandpits (SGU, 2003). Electricity The emission factors for electricity are taken from Stripple (2001). These values only represent the production of electricity; no impacts from extraction of raw materials and transport are included in these values. Fuel consumption For the use of fuel, pre-combustion values for fuel production have been included according to Stripple (2001). Machine use Estimations of the lifetime of the different machineries have been made together with people that produce the machineries included in the study. During the lifetime the machines have been assumed to be working eight hours per day and five days per week. All the machines are made of steel. 5.2.4 Analysis of the result and Impact Assessment The Swedish parliament has established 15 environmental quality objectives to guide Sweden towards a sustainable society. The Swedish Environment Protection Agency defines the 15 objectives as follows; they will function as benchmarks for all environment-related development in Sweden, regardless of where they are implemented and by whom and the overriding aim are to solve all major environmental problems within a generation.18 To get a view of the kind of resulting effects from the different flows from the system, each flow was connected by the environmental objectives that are influenced the flow. As mentioned above, all parts of the system that were similar in all scenarios were excluded from the study. This means that the result does not show the total environmental impact caused by each case. It shows the specific environmental flows that occur from each scenario. To enable comparisons between the scenarios, data on all flows were normalized by division with the national flow of each kind per person in Sweden. These values can be seen as an indication of what is large and small. The flows that are of greater significance than others were discussed more deeply and the assumptions made for calculation of these flows were more specified. 6. Result 6.1 Result part 1 - Inventory of ashes in Uppsala County The inventory showed that two district-heating plants and two combined heat and power plants produce more than 1000 tonnes/year (fly ash and bottom ash are added together). The specific amounts of ash are shown in Table 6. 18 www.naturvardsverket.se 27 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Result Table 6: Ash production in Uppsala County Producer and location Type of fuel and type of furnace Fly ash [tonnes/year] and water content Bottom ash [tonnes/year] and water content Vattenfall Värme Uppsala AB District-heating plant Vattenfall Värme Uppsala AB Combined heat and power plant Municipal and industrial solid waste Mass-burn-type with moving grates Coal and peat powder Solid fuel furnace with powder burners Biofuel: wood splinter and bark Mass-burn-type with moving grates 5749, 36 % H2O 26 838, 20 % H2O 37 830, 20 % H2O 1 9616, 55 % H2O 1 485, 46% H2O 728 , 46 % H2O 2 Biofuel: wood splinter (85 %) and energy crop; Salix (15 %) Mass-burn-type with moving grates and solid fuel boiler with powder burners 915, 50 % H2O 1410, 25 % H2O 3 Vattenfall AB Värme Norden Små och Medelstora Anläggningar, Knivsta. District-heating plant ENA Kraft AB, Enköping District-heating plant 1) Miljörapport Uppsala, Vattenfall Värme Uppsala AB 2003 and Ericsson, personal communication. 2) Miljörapport Knivstaverket, Vattenfall AB Värme Norden Små och Medelstora Anläggningar 2003 and Strömbäck, personal communication. 3) Eklund and Johansson, personal communication. Vattenfall Värme´s combined heat and power plant uses peat powder more than coal as fuel, but the ash from both has been added because characteristics are similar. It should also be noted that there is only production of ash from the municipal solid waste incineration and fly ash from Enköping during the summer. Vattenfall Värme Uppsala AB is currently in the middle of a construction expansion, which is scheduled for completion in February 2005. This expansion will add a new furnace for incineration of municipal solid waste, which will increase their amount of bottom ash to 56580 tonnes/year and the amount of fly ash to 9500 tonnes/year.19 The district-heating plant in Knivsta is constructed to give only one ash fraction after incineration; in this fraction the fly ash and the bottom ash are mixed. It is therefore difficult to estimate the percentage of the fly respectively bottom ash. In this case the estimation has been 40 % fly ash and 60 % bottom ash of a total yearly production of 1212 tonnes.20 This is also the reason why the fly ash and the bottom ash have the same water content. The remaining ash that is produced in the County, comes mainly from small district-heating plants, one exception is the fifth top producer of ash in the area, the paper mill Skutskärs bruk, which has a yearly production of 960 tonnes.21 19 Ericson, personal communication Strömbäck, personal communication 21 Bjurström, personal communication 20 28 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Result 6.2 Result part 2 - ESA for different possible uses of MSWI bottom ash 6.2.1 Environmental flows connected to the 15 environmental quality objectives The different flows from the system have all different impacts on the environment. Emissions of metals may cause ecological toxicity. Further, emissions of CO2 may cause climate change, emissions of SO2 may cause acidification and emissions of NOx may cause eutrophication, photochemical ozone formation and acidification. To decrease the environmental impact and reach the goal of a sustainable society the Swedish Parliament has established 15 environmental quality objectives. To get a view over which of the objectives that are affected by the flows from the system, the flows have been related to the environmental quality objectives (Table 7). Table 7: The different environmental flows from the system connected to the 15 environmental quality objectives Environmental flow Environmental quality objectives Resource use Energy Sand Crushed rock Emissions to air SO2 NOx CO CO2 CH4 VOC (VOC+NMVOC) HC N 2O Particles Emissions to water COD N-tot Oil Phenol As Cd Secondary impact on: Reduced Climate Impact, A safe Radiation Environment and Flourishing Lakes and streams A Good Built Environment A Good Built Environment Clean Air and Natural Acidification Only Clean Air, Natural Acidification Only, Zero Eutrophication and Reduced Climate Impact Secondary impact on: Reduced Climate Impact Reduced Climate Impact Reduced Climate Impact Clean Air Clean Air Reduced Climate Impact Clean Air Flourishing Lakes and Streams Zero Eutrophication and Flourishing Lakes and Streams Flourishing Lakes and Streams Flourishing Lakes and Streams Flourishing Lakes and Streams Flourishing Lakes and Streams The resource use mainly affects the objective A Good Built Environment (Table 7). This objective prescribes for example that the amount of disposed waste shall decrease with 50 % from 1994 to 2005 and that 15 % of the utilisation of natural aggregates shall consist of recycled material during year 2010. The emissions to air affect the four objectives Clean Air, Zero Eutrophication, Natural Acidification Only and Reduced Climate Impact. The four objectives direct a reduction of the content of particles, green house gases, hydrocarbons, SO2, NOx, and VOC in the air. Finally, the emissions to water from the system affect mainly the objective Flourishing Lakes and Streams. The objective Flourishing Lakes and Streams was established to improve the qualities of surface waters by for example decreasing the load of nutrients in lakes and streams and prevent that emissions like heavy metals will reach the water.22 22 www.miljomal.nu 29 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Result 6.2.2 Differences in resource use and emissions The scenarios differ in their resource use and emissions (Table 8). The data on the flows were also normalized by division with the Swedish national flow per person and year and multiplied with a factor of 1000 (Table 8). The National values per person in Sweden were taken from the progressing research by Olsson et al (2004). Table 8: Flows from the three different scenarios, and their normalized values. Scenario 1, MSWI bottom ash used as drainage material in a covering structure in a landfill. Scenario 2, MSWI bottom ash used as sub-base material in road. Scenario 3, disposal of MSWI bottom ash. Substance flow Resource use 1 Energy [MJ] Sand [tonnes] Crushed rock [tonnes] Emissions to air 2 SO2 [g] NOx [g] CO [g] CO2 [g] CH4 [g] VOC [g] Scenario 1 Scenario 2 Scenario 3 National values per person Normalized values scenario 1 Normalized values scenario 2 Normalized values scenario 3 269 79 139 250000 1,1 0,3 0,6 0 0,9 0,9 2,5 0 360 360 1,2 0,3 1,2 4,4 266 73 266 6 91 14 11590 0,01 2 36 5,6 4570 0,004 3 48 7,2 6030 0,007 6450 26900 85900 6180000 634000 0,9 3,4 0,2 1,9 0,00002 0,4 1,3 0,1 0,7 0,000006 0,5 1,8 0,1 1,0 0,00001 (VOC+NM VOC) 0,04 0,008 0,03 667000 0,00005 0,00001 0,00004 HC [g] 5,9 2,4 3,2 No data No data No data No data N2O [g] 0,2 0,09 0,1 930000 0,0003 0,0001 0,0001 Particles [g] 2,0 0,8 1,3 9730 0,2 0,1 0,1 Emissions to water 3 COD [g] 0,2 0,07 0,09 56000 0,003 0,001 0,002 Ntot [g] 0,03 0,01 0,02 2800 0,01 0,004 0,005 Oil [g] 0,06 0,02 0,03 No data No data No data No data Phenol [g] 0,08 0,03 0,04 No data No data No data No data As [g] 0,1 0,4 0,4 No data No data No data No data Cd [g] 0,04 0,01 0,01 0,07 596 190 175 Cr [g] 0,5 0,2 0,2 1,4 335 173 167 Cu [g] 43 2,0 0,2 20 2127 98 10 Ni [g] 0,8 0,3 0,3 1,4 558 185 177 Pb [g] 0,3 0,2 0,2 4,3 71 56 55 Zn [g] 1,8 2,4 2,4 49 37 49 49 1) National values based on official statistics 2003. These values are divided by the total amount of inhabitants in Sweden 2003. The national value for sand value is taken from SGU (2003). 2) National values are based on official statistics 2002 for emissions to air; these values are divided by the total amount of inhabitants in Sweden 2003. 3) National values are based on official statistics 2000 for emissions from municipal wastewater treatment plants, pulp and paper industry and some other coastal-based industries in Sweden. 30 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Result The normalization results in Table 8 show that some environmental flows may be considered more important than others. The use of sand and crushed rock and the release of metals were of greater significance than other flows. The release of metals is according to the normalized values the most important environment flow in scenario 1. This depends on the fact that the MSWI bottom ash is in contact with a significantly higher amount of water than in the other scenarios (see section 6.2.3). The use of natural aggregates is of higher significance than the use of energy. Scenario 1 generates more emissions in almost every flow. This can be explained by the fact that scenario 1 have the highest energy use. All investigated emissions, except the release of metals are caused by energy use. Since scenario 1 uses most energy, it is also causing the most energy-dependent emissions. There are two main reasons to a high energy use in scenario 1, firstly long transports of the MSWI bottom ash, secondly production of geofabric to the drainage layer and crushed rock to the conventional road, see section 6.2.4. Scenario 2 has the lowest flow of energy-dependent emissions. The result (Table 8) is based on the fact that the production of machines is not included in the system. The environmental impact due to production of machines was investigated for a part of the system, production of material, construction, and use and maintenance of a drainage layer of MSWI bottom ash. It was discovered that the production of machineries did not have a significant effect on the final result except for particles (see Appendix 3). According to the method, life cycle stages that do not have a significant effect on the system can be excluded. A second reason for excluding the production of machines was that it was hard to find data about machine use during production of crushed rock. However, it should be noted that the flow changes to some extent if the production of machines is included; the biggest changes are the amount of particles. The particles increase with 20 %, the reason to this is that the machines were assumed to be made of steel and the production of steel has a high emission factor for particles. The barrier layer in scenario 3 is also excluded from the system, due to lack of realistic data for the production of geosynthetic clay liners. To give a view of how much the use of geosynthetic clay liner affects the result, data for mining of magnetite ore were used as a substitute for data of bentonite mining. The result showed that there were almost no changes of the result when the geosynthetic clay liner was included in the system (Appendix 3). 6.2.3 Use of natural aggregates According to the normalized values, the use of sand and crushed rock was of higher importance than other types of flow such as emission to air and energy use. All scenarios use natural aggregates, but scenario 2 has the highest flows since the MSWI bottom in this scenario is not substituting any conventional material. 6.2.4 Leaching of metals The leaching from the system during the next coming 100 years can be seen in Figure 17. 31 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Result Metal leaching, 100 years Scenario 1 100 Total amount leached (g) Scenario 2 Scenario 3 10 1 0,1 0,01 0,001 As Cd Cr Cu Ni Pb Zn Figure 17: The leaching from the system during 100 years. Scenario 1 has the highest emissions of all metals except for Arsenic (As) and Zinc (Zn) (Figure 17). This depends on that the MSWI bottom ash is in contact with a significantly higher amount of water than in the other scenarios. The drainage layer is built to direct upper rain and is assumed to have an infiltration through the layer of approximately 200 mm per year. The road has an infiltration rate of 15 mm per year. In L/S-test the leaching partly is dependent on the substances that are connected to organic material. Since Copper (Cu) is bound to organic material, the result shows a high amount of Copper. If the leaching had been based on availably test instead, Zinc should probably have higher values than Copper since the availability test is made at a very low pH. The low pH results in a dissolving of hydroxides. Zinc is often bound to hydroxides, which explains the high values for Zinc from availability tests. It can be argued that for sand, the leaching of metals is the same as in natural conditions and therefore should be excluded from the system. The metal leaching from the system when sand is excluded can be seen in Figure 18. Metal leaching, 100 years, sand excluded Scenario 1 Scenario 2 Total amount leached (g) 100 Scenario 3 10 1 0,1 0,01 0,001 As Cd Cr Cu Ni Pb Zn Figure 18: Leaching from the system during 100 years, sand excluded 32 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Result The differences between the scenarios are significantly bigger when the leaching from sand is excluded from the system and those scenarios that contain sand (scenario 2 and 3) have a large decrease in their total leaching. 6.2.5 Energy use Energy is mainly derived from fossil fuel. Therefore, emissions to air and to some extent emissions to water, depend on the amount of energy used during the different life cycle stages. The energy consumption in the different life cycle stages is important for the relative contribution to the overall environmental impact of each scenario. As can be seen in Figure 19 below, the life cycle stages that have the largest energy consumption are transports and production of material in scenario 1. The reason to the long transports is that only two landfills, Gatmots and Annelund, in Uppsala County will be finally covered before year 2008. Since the ash is assumed to be produced in Uppsala city, this will result in relatively long transports (55 km). Scenario 1 also includes a transport of geofabric from Germany. However, even if the transport from Germany is taken away from the system, the energy use for the transport of material in scenario 1 will still be the highest. The sand and the crushed rock have a short transport distance to respective construction site (6 respective 20 km) due to the high number of pits and quarries in Uppsala County. Scenario 1 Energy use Scenario 2 Scenario 3 Energy use [MJ] 250 200 150 100 50 0 Disposal of MSWI-BA Production of material Transport of material Construction Total energy consumption Activity Figure 19: Use of energy by each life cycle stages in the system The high energy consumption during production of material in scenario 1 is mainly due to the production of crushed rock needed for the conventional road but is also an effect of the production of geofabric needed for the drainage layer. It can also be seen that the construction stage has a small contribution to the total amount in all scenarios. It should also be noted that the disposal of MSWI bottom ash has a small influence on the result. It was discovered during the study that the MSWI bottom ash was sifted even if it will be disposed in a landfill. Thus, sifting was a part of all scenarios and could therefore be excluded. This information is dependent on the demand and price of recycled metals. However, the sifting machine has also relatively high energy consumption. Based on this, a comparison was made between sifting and non-sifting. It was shown that the energy consumption for production of the drainage material respective sub-base material increased with approximately 40 MJ/tonne MSWI bottom ash if the ash was sifted. 33 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Result The energy used in the system is diesel and electricity. The percentage of each type is shown in Figure 20. Here, it can be seen that scenario 3 has the highest percentage of electricity use, mainly coming from production of crushed rock but also from production of chemicals needed for cleaning of the leachate from the landfill during the first 20 years. 100% 90% 80% 70% 60% Diesel 50% Electricity 40% 30% 20% 10% 0% scenario 1 scenario 2 scenario 3 Figure 20: The percentage of diesel and electricity use for each scenario The transport distance for MSWI bottom ash, is a parameter that may vary considerably both in scenario 1 and 2, since there is a limited amount of sources for the material. A sensitivity analysis was performed for different transport distances for the MSWI bottom ash (Figure 21). Energy consumption [MJ] Total energy consumption, scenario 1 Total energy consumption, scenario 2 500 400 Total energy consumption, scenario 3 300 200 Energy consumption, scenario 1 at varying distance 100 Energy consumption scenario 2, at varying distance 0 0 20 40 60 80 100 120 140 160 Distance for transport of MSWI-bottom ash [km] Figure 21: Sensitivity analysis, distance for transports of MSWI bottom ash It was shown that for scenario 2 the MSWI bottom ash can be transported 50 km before the energy consumption is higher than the total energy consumption in scenario 3, and 120 km before it is higher then scenario 1. Even if there is no transport of the ash scenario 1 would still use more energy than the other two scenarios, due to high energy consumption in the production of material. Hence, the transport distance was an important parameter for the outcome of the comparison. 34 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Discussion 7. Discussion 7.1.1 Result For all the environmental flows, scenario 2 was the most preferable, which depends mainly on the amount of crushed rock in the remaining scenarios. The production of crushed rock is a very energy consuming process and is the single process that affected the result the most. It can also be argued that scenarios 1 and 3 to some extent suffers from that the system boundaries imply that all scenarios always will be performed, since the result would be different if the drainage-layer would be compared with another type of construction than a road. The environmental impacts may have been even lower for scenario 2, if the base-course layer not had been included in the system. It is sometimes argued that a thicker base-cause layer is not needed for construction of a sub-base layer of MSWI bottom ash.23 The reason why the base-course layer was included in this study was that all dimensions are taken from the source for information, Törringevägen. However, these results depend strongly on the chosen system boundaries and the assumption made during the inventory. The environmental flows are also based on regional specific data and should therefore only be discussed in general. The flows would be different if the scenarios were realised in a geographically disparate region. If the result from the study is to be used in other cases, corrections should be made for important parameters such as transport distances, different methods for extraction of natural resources and the amount of precipitation. Differences in resource use and emissions Usually leaching of metals is the only flow considered in environmental assessments of alternative materials. According to the normalization result, it is reasonable to consider leaching as an important flow, but the other consequences caused by the substitution of material for example energy use and utilisation of natural aggregates should not be neglected. It should be noted that the total amount of leached metals is almost the same in all scenarios (even in scenario 3 that only includes conventional material). This indicates that other factors than leaching should be discussed during utilisation of different residuals. Perhaps future studies would wish to concern health aspects more deeply, should machineries not be excluded, since these particles from machine operation affect the human health. During the study, there have been discussions whether the barrier layer should be included in scenario 1 or not. The reason is that traditionally the barrier layer in the cover structure often contained the clay bentonite. According to RVF (2001), there are two big threats for the chemical stability of a barrier layer containing bentonite, very low or high pH in the infiltrated water, or if the water has high chloride content. The MSWI bottom ash’s high content of chloride leads to increased permeability of the barrier layer and therefore ash is sometimes not recommended to be used together with a barrier layer of bentonite. According to the Swedish Geotechnical Institute the increased permeability of the barrier layer is relatively small, and will therefore not have a significant affect on the leaching from the landfill. This recommendation is only valid for landfills without hazardous waste.24 Natural clay is here an alternative to use a barrier layer containing bentonite. However, the natural clay has more negative qualities than barrier layers containing bentonite. Natural clay is also very seldom used for this type of constructions in Sweden. The final decision was to use a geosynthetic 23 24 Reference group, personal communication Rogbeck, personal communication 35 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Discussion clay liner (consists of geofabric and bentonite) as a barrier layer. The results would have become different if the natural clay had been chosen. Use of natural aggregates About 70 million tonnes of natural aggregates are used every year in Sweden for road and ground constructions (SGU, 2003). At the same time industries produce large quantities of secondary products, which may be suitable for use. One of the barriers to the wide-ranging utilisation of the secondary products from energy production has been uncertainty about the environmental impacts. Because of the risk of that secondary products could leach toxic substances into the nearby environment. Therefore, the environmental evaluation mainly has focus on measurements of total chemical content and leaching behaviour. According to the normalized values from this study, it should be reasonable to also consider decreased use of natural aggregates in future evaluation of residuals. Another incentive to consider the use of natural aggregates is the objective A Good Built Environment that prescribes that 15 % of the utilisation of natural aggregates shall consist of recycled material year 2010.25 Leaching of metals According to the normalized values given in Table 8, the leaching of metals is an important parameter. This conclusion is however to some extent uncertain, since in practice numerous factors e.g. the conditions of the structure and its surface as well as the environment conditions, affect leaching. According to Nyhlén (2004), the standardised tests cannot fully reflect these factors. For example the batch test will not show what will happen if the parameters such as pH and redox potential change. The test gives only information about the average concentration in the leaching water and nothing about the variation over time. Therefore, long-term predictions of the effect on the environment based on this type of test contain a high degree of uncertainty. However, the leaching test is toady the best available tool to predict leaching, if you are aware of the defects and uncertainties associated with them. The importance of the metal flows can also be proven by the fact that it is the only outflow leaving the system during 100 years; the remaining flows are “one time outflows” and occur only during production respectively the construction stage. If the leaching is such an important parameter it would be interesting to investigate if cleaning of the MSWI bottom ash is motivated. There are several kinds of recycling methods to reuse the metals in the ash. By cleaning the ash, the amount of metals leaching from the system will be reduced. A low L/S ratio also allows little water to get in contact with the material. Scenario 1 includes a high amount of infiltrated water; this conveys that value of L/S 10 is reached after only 7 years. The leaching value that corresponds to 7 years is then multiplied to be representative for 100 years. This is a very rough estimation and higher L/S ratios would have been preferable, but were not found. There were also uncertainties in selection of infiltration rate, because of the high dependence of the precipitation. Here, all the infiltrated water was assumed to be in contact with the ash, which probably is an over estimation since it is likely that the water will be heterogeneously distributed. Due to the overestimations, the leaching values in reality are probably lower in all the scenarios. Energy use Energy is one of the main resources used by the system. The result from the study is dependent on the case-specific data and are affected by the construction itself and the processes included, such as pre-treatment of the materials, transportation and the construction. 25 www.miljomal.nu 36 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Discussion In this case, the transports had a key role; in other geographical regions the result may be different. The reason to this is for example that the number of sand pits and rock quarries is high in Uppsala County. For scenario 1 the most preferable situation is that the MSWI bottom is used on the same site where it is sifted, to reduce the transport-distance. Scenario 2 is not to the same degree dependent of the transport-distance for the MSWI bottom ash, but maximum distance should be 50 km. 7.1.2 Method ESA with an LCA-approach The utilisation of residuals is normally environmentally evaluated from a narrow perspective of the material itself, mainly studied by leaching tests. This type of evaluation consists of chemical analysis for determination of total content, and what can possibly leach out from the residuals. The ESA allowed both resource use and emissions to be considered, thereby giving a different and wider result than a more narrow study. The LCA-approach is often criticized for being an uncertain method with a lot of assumptions and predictions. However, it is important to clearly describe assumptions and weaknesses in the analysis and that sensitivity analysis is continuously carried out during the ESA-process. Today, the LCA within an ESA probably is one of the best available methods to investigate complex systems such as the waste handling system in a region. In this thesis there has been a decision to only present the different flows in a non-aggregated form in the different scenarios and leave a further valuation to the decision makers. It can be discussed if this is right or wrong. Since a big amount of parameters can make the result complex and difficult to interpret, a valuation can be a helpful tool to reduce the number of parameters. According to Rydh et al (2002), a valuation can also be uncertain, since it is dependent on the system boundaries. The different weighing-methods also describe something that in general is not accepted though they are based on different valuations for example individual, political and or moral. For a decision-maker, it is easier to handle aggregated parameters, but the more aggregated value the more uncertain. To handle this problem, the flows were normalised, meaning that the values are to some extent aggregated but not totally valuated. The method used in this thesis gives a presentation of the flows that can be considered as important flows. However, which utilisation scenario is the most preferable one depends on which environmental quality objectives are prioritised. The project of Värmeforsk (Q248) will go more deeply into this question. System boundaries The primary interest was not to analyse the environmental impact from the incinerationprocess and the production-processes generating the MSWI bottom ash have therefore been excluded from the study. A relevant question is in what way the choice of excluding the production-process, and thereby considering the ash as a waste, has influenced the result? Roth and Eklund (2003) say that this kind of decision certainly affects the outcome of the study and favours the residuals and the excluded effects could sometimes be dominating environmental flows. Therefore, it is important to remember that no conclusions about possible environmental benefits or disadvantages during incineration of municipal solid waste can be drawn from this study. The demolition phases for the road and landfill were not considered due to the fact that demolitions of these kinds of constructions are rather rare today. However, there are progressing discussions about how to recycle the material in old 37 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Discussion roads and landfills and in further studies this life cycle stage should be included. Use of geofabric would facilitate the recycling of the material after demolition, but it should be noted that the result showed that production of geofabric is one of the most energy-consuming processes within the system. It seems that the ESA-approach has some limitations regarding those flows that are strongly related to the time frame used, for example the leaching. According to Finnveden and Nielsen (1999), the environmental impacts from landfills can be seriously underestimated if the period after 100 years is neglected. Some elements in the ash can be transported to the water phase and then leach comparatively quickly while others have a slower emission rate. Leaching of soluble salts will gradually change the chemical compositions of the ash. For example the pH can change even after a fairly long time period. If the pH changes, the solubility of different minerals will change and consequently there will be a change in the composition of leachate. It may be argued that the landfill is a part of the technical system for a certain time period. Leaching on an infinite time scale is of limited interest. This is since the environmental impacts from metals often are due to peaks in concentration rather then average emissions (Olsson et al, 2004). Inventory New life cycle data for disposal of materials were collected during the inventory phase, which is valuable since previous data for the different environmental impact from disposal of materials were old and since there was a lack of important data such as the environment impact connected to the covering structure of the landfill. The ambition has been to use data that are region specific and as up-to-date as possible. To decrease the uncertainties, it would be of help to have access to more detailed data, especially for machineries, production of geosynthetic clay liner and also leaching parameters for the different materials. 7.1.3 Proposals for future research • To expand the scenarios of utilisation areas for MSWI bottom ash – for example, in a pre-covering layer of a landfill or as a filling material. • To include a demolition phase for the road and the landfill in the study. • To investigate other possible secondary materials that may be used as drainage material –this can provide good information for comparing purposes. • To complement the study with a socioeconomic perspective – can it be motivated from a socioeconomic point of view to clean MSWI bottom ash? 38 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Conclusions 8. Conclusions According to this study, the use of MSWI bottom ash in the sub-base layer in road construction is more environmentally preferable, compared to use the MSWI bottom-ash as drainage material in a landfill structure or to dispose of the ash. Use of the MSWI bottom ash in the sub-base layer in a road would lead to the use of less resources such as use of natural aggregates and energy. This also means less energy-derived emissions. The single process that affected the result most was production of crushed rock due to the very high energy consumption connected to this process. It was shown that scenario 1 and 3 to some extent suffer from that the system boundaries imply that all scenarios always are performed since the result would be different if the drainage-layer would be compared with other types of construction than a road. Parameters with potential to change the result are: transportdistances that are dependent on the regional conditions and metal leaching, where the current leaching test only is an approximation of leaching over time and though not reflect all processes that will affect the leaching. Besides these results, new life cycle data for disposal of material was collected. Previously existing values for the environmental impact of material disposal were old and lacked important information such as the environment impact connected to the covering structure of the landfill. However, the results are strongly dependent on the chosen system boundaries and the assumptions made during the inventory. The ESA approach allowed both resource use and emissions to be considered and can therefore be seen as a valuable complement to other studies that use a more narrow system perspective. The results can be used to obtain information for decision support concerning waste management. 39 Environmental Systems Analysis for utilisation of bottom ash in ground constructions References 9. References Literature Alvarez, H. (1999) Energiteknik. Studentlitteratur, Lund (In Swedish). Arm, M. (2003) Mechanical Properties of Residues as Unbound Road Materials – experimental tests on MSWI bottom ash, crushed concrete and blast furnace slag. Doctoral Thesis, Royal Institute of Technology, Stockholm. Bjurström, H. (2002) En bedömning av askvolymer. Not published, Svenska Energiaskor AB, Stockholm, (In Swedish). City of Helsinki, Real Estate Department. (1983) Användning av stenkolaska vid anläggningsarebeten, tekniska anvisningar. Helsinki. County Administrative Board in Uppsala. (2004) Avfallshantering I Uppsala län – Behandlingsbehov och behandlingskapacitet år 2002 och 2009. Länsyrelsens meddelande 2004:2, (In Swedish). Ek, M. & Sundqvist, J. (1998) Skogsindusriellt avfall, ideér angånde utnyttjande och omhändertagande. IVL Swedish Environmental Research Institute, Stockholm, (In Swedish). Ek, M. & Westling, O. (2003) Dagsläget beträffande skogsindustrins avfall. IVL Swedish Environmental Research Institute AB, Stockholm, (In Swedish). Eriksson, M. (2001) Alternativa fyllningsmaterial till ledningsgravar för VA- en jämförelse mellan nya och traditionella material. Degree thesis, Royal Institute of Technology, Stockholm, (In Swedish with an English summary). Finnveden, G., Nielsen, P. (1999) Long-Term Emissions from Landfills Should Not be Disregarded. Int. J. LCA 4 (3), 125-126. Hernhag, C., Holmberg, C., Almqvist., Deloche, Y. (2003) Treatment options for waste fly ash. Not published, Vattenfall Värme Uppsala AB, Uppsala. Kärrman, E., Moeffaert, D., Bjurström, H., Berg, M., Svedberg, B. (2004) Förutsättnigar för att askor kommer till användning i vägar. Thermal Engineering Research Institute (Värmeforsk), (In Swedish). Larsson, M., Lejon, A. (2003) Cementstabiliserad granulerad flygaska och dess tekniska egenskaper. Degree thesis, Luleå University of Technology, Luleå, (In Swedish with an English summary). Lin, K., Wang, K., Tzeng, B., Lin, C. (2002) The reuse of municipal solid waste incinerator fly ash slag as a cement substitute., Resources, Conservation and Recycling 39, 315-324. Mácsik, J. (2004) Pilotförsök med flygstabiliserat avloppsslam (FSA) som tätskikt. Thermal Engineering Research Institute (Värmeforsk), (In Swedish with an English summary). 40 Environmental Systems Analysis for utilisation of bottom ash in ground constructions References Moberg, Å., Finnveden, G., Johansson, J., Steen P. (1999): Miljösystemanalytiska verktyg – en introduktion med koppling till beslutssituationer. The Swedish Environmental Protection Agency, Stockholm, (In Swedish). Mroueh, U., Eskola, P., Laine-Ylijoki, J. (2001) Life-cycle impacts of the use of industrial byproducts in road and earth construction. Waste Management 21, 271-277. Mäkelä, H., Höynälä, H. (2000) By-products and Recycled Materials in Earth Structures – Material and Applications. National Technology Agency, Helsinki. Nyhlén, E., (2004): Laktester för riskbedömning av förorenad mark. Degree thesis, Swedish University of Agricultural Sciences, Uppsala, (In Swedish with an English summary). Olsson, S., Kärrman, E., Gustafsson, J.P. (2004) Environmental systems analysis of the use of bottom ash from incineration of municipal waste for road construction. Proceedings of the 19th International Conference on Solid Waste Technology and Management, March 21-24, 2004, Philadelphia, PA USA. Peterson, A. (2004) Miljösystem analys för alternativa lättfyllnadsmaterial i vägar. Degree thesis, Royal Institute of Technology, Stockholm, (In Swedish with an English summary). Brundin, H., Kihl, A., Lagerkvist, A., Pusch, R., Rihm, T., Sjöblom, R., Tham, G. (2001) Långtidsegenskaper hos tätskikt innehållande bentonit. The Swedish Association of Waste Management, RVF 01:12, (In Swedish). Roth, L., Eklund, M. (2002) Environmental evaluation of reuse of by-products as road construction materials in Sweden. Waste Management 23, 107-116. RVF (The Swedish Association of Waste Management). (2002) Kvalitetssäkring av slaggrus från förbränning av avfall. RVF 02:10, (In Swedish). Rydh, C., Lindahl, M., Tingström, J., (2002): Livscykelanalys – en metod för miljöbedömning av produkter och tjänster. Studentlitteratur, Lund, (In Swedish). SETAC-Europé. (1999) Best Available Practice Regarding Impact Categories and Category Indicators in Life Cycle Assessment. Int. J. LCA 4 (3), 167-174, Brussels. SGI (Swedish Geotechnical Institute). (2003) Inventering av restprodukter som kan utgöra ersättningsmaterial för naturgrus och bergkross i anläggningsbyggande. Linköping, (In Swedish, with an English summary). SGU (Geological Survey of Sweden). (2003) Aggregates – roduction and resources 2002. SGU 2003:4, Uppsala, (In Swedish, with an English summary). Sonesson, U., Dalemo, M., Mingarini, K., Jönsson, H. (1997) ORWARE – A simulation model for organic waste handling systems. Part 2: Case study and simulation results. Resources, Conservation and Recycling 21, 17-37. 41 Environmental Systems Analysis for utilisation of bottom ash in ground constructions References SS-EN-ISO 14040. (1997) Environmental management- Life cycle assessment- Principles and framework. ISO14040:1997, Swedish Standards Institutions, Stockholm. Strand, A. (2003) Life cycle assessment for manufacturing stainless steel – a cradle to gate study for Avesta Polarit AB in Avesta. Degree thesis, Högskolan Dalarna, Borlänge, (In Swedish with an English summary). Stripple, H. (2001) Livscykelanalys av väg - En modellstudie för inventering. Swedish Environmental Research Institute (IVL), Göteborg, (In Swedish with an English summary). Sundberg, J., Carling, M., Ländell, M., Svensson, B. (2003) Täckning av deponier med blandning av avloppslam och aska, erfarenheter, beständighet och andra egenskaper. The Swedish Water & Wastewater Association, Stockholm, (In Swedish). Svingby, M., Båtelsson, O. (1999) LCA av lättfyllnadsmaterial för vägbankar. National Road Administration, Vägverket1999:67, Borlänge, (In Swedish). Vattenfall Värme Uppsala AB. (2003) Miljörapport Uppsala 2003, (In Swedish). Personal references Bjurström Henrik, ÅF, Stockholm Burton George, Texas Sodium Bentonite Inc., Houston, USA Eklund Urban, ENA Kraft AB, Enköping Ericson Johan, Vattenfall Värme AB, Uppsala Johansson Eddie, ENA Kraft AB, Enköping Kjällman Magnus, VA och Avfallskontoret, Uppsala Kommun, Uppsala Laurell Johan, VA och Avfallskontoret, Uppsala Kommun, Uppsala Mácsik Josef, Ecoloop, Stockholm Munde Hanna, Vattenfall Värme AB, Uppsala Reference group for the project by Värmeforsk (Q 248), meeting at Ramböll Sverige AB, 2004-10-21 Rogbeck Jan, Statens Geotekniska Institut, Linköping Sjöholm Markus, Gävle Vägtrummor AB, Gävle Strömbäck Niklas, Vattenfall AB Värme Norden Små och Stora Anläggningar, Knivsta Tham Gustav, Telge Återvinning AB, Södertälje 42 Environmental Systems Analysis for utilisation of bottom ash in ground constructions References Internet Econova AB. (2003) The Econova Method. Available: www.econova.se [2004, September 13] Environment Objectives Secretariat. (2004) Environmental Quality Objectives. Available: www.miljomal.nu [2004, November 3] Swedish Environmental Protection Agency. (No date) Environmental Objectives. Available: www.naurvardsverket.se [2004, November 5] 43 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Appendix 1 Appendix 1 A1.1 System boundaries for each scenario Scenario 1: MSWI bottom ash as drainage material in a covering structure in a landfill MSWI bottom ash Crushed granite Production of drainage material Production of sub-base and base-course material Construction of drainage layer Construction of sub-base and base-course layers Use and maintenance of drainage layer for 100 years Use and maintenance of the road for 100 years Figure A1: System boundaries, scenario 1, MSWI bottom ash as drainage material in a covering structure in a landfill Scenario 2: MSWI bottom ash as sub-base material in road construction Sand MSWI bottom ash Production of drainage material Production of sub-base and base-course material Construction of drainage layer Construction of sub-base and base-course layers Use and maintenance of drainage layer for 100 years Use and maintenance of the road for 100 years Figure A2: System boundaries, scenario 2, MSWI bottom as sub-base material in road construction Environmental Systems Analysis for utilisation of bottom ash in ground constructions Appendix 1 Scenario 3: Disposal of MSWI bottom ash Sand Crushed granite Production of drainage material Production of sub-base and base-course material Construction of drainage layer Construction of sub-base and base-course layers Use and maintenance of drainage layer for 100 years Use and maintenance of the road for 100 years MSWI bottom ash Waste disposal Figure A3: System boundaries, scenario 3, disposal of MSWI bottom ash Environmental Systems Analysis for utilisation of bottom ash in ground constructions Appendix 2 Appendix 2 A2.1 Inventory A2.1.1 General data Material Value Density of crushed rock (non-packed) Density of crushed rock (packed in sub base or base-course layer of a road) Density of MSWI BA generally, (packed) Density of MSWI BA from Vattenfall, (packed) Density of MSWI BA from Vattenfall, (non-packed) Density of sand (Stallmon) Density of excavated soil Density of soil Weight of geofabric (in geosynthetic clay liner) Weight of bentonite (in geosynthetic clay liner) Percentage of bentonite in geosynthetic clay liner Percentage of geofabric in geosynthetic clay liners Weight of geofabric Density of geofabric Density of geofabric (in geosynthetic clay liner) Density of bentonite (in geosynthetic clay liner) Energy Energy content in diesel Pre-combustion diesel Energy consumption during loading, (light density) Energy consumption during loading, (high density) Diesel use by transporting lorry (max load 35 tonnes, halfway full and halfway empty assumed) Use of diesel during excavating of material with excavator (material density 1.4-1.6 tonnes/m3) (Volvo EC240) Use of diesel during excavating sand with loading shovel (Volvo L180E) Use of diesel by sifting machine Use of electricity per tonne sifted MSWI BA Use of diesel by crushing rock Use of electricity for crushing rock Energy use for road production Energy use for road production Unit Reference 1,62 tonnes/m3 Stripple, 2001 2,0 1,6 1,6 1,4 1,6 1,42 1,68 110 4600 95 5 150 83,333333 366,66667 807,01754 tonns/m3 tonnes/m3 tonnes/m3 tonnes/m3 tonnes/m3 tonnes/m3 tonnes/m3 g/m2 g/m2 % % g/m2 kg/m3 kg/m3 kg/m3 Olsson et al, 2003 RVF, 2002 Vattenfall Värme Uppsala AB Vattenfall Värme Uppsala AB Jehanders Grus AB Stripple, 2001 Stripple, 2001 www.naue.com 2003 www.naue.com 2003 Gävle Vägtrummor AB Gävle Vägtrummor AB www.naue.com 2004 www.naue.com 2004 www.naue.com 2003 www.naue.com 2003 Value Unit Reference 35,1 0,1 1,72 3 MJ/l MJ/MJ oil or diesel MJ/m3 loaded material MJ/m3 loaded material Stripple, 2001 Stripple, 2001 Stripple, 2001 Stripple, 2001 0,45 l/km Jehanders Grus AB 10,75 21,25 1,0416667 2,006 0,484 21,19 7,02 0,083333 l/h l/h l/tonne MSWI BA kWh/tonne sifted MSWI BA l/tonne crushed rock MJ/tonne crushed rock MJ/ton l/tonne material Swecon Anläggningsmaskiner AB Jehanders Grus AB Slag Recycling AB SYSAV, Malmö Stripple, 2001 Stripple, 2001 Stripple, 2001 Värmdö schaktmaskiner AB, Järfälla Environmental Systems Analysis for utilisation of bottom ash in ground constructions Appendix 2 Precipitation and infiltration Value Precipitation in Uppsala per year Infiltration on landfill top layer Infiltration through asphalt layer in a road 509 40 0,015 Landfill parameters Value Thickness of drainage layer (both with sand and MSWI BA) Thickness of vegetation (soil) layer Thickness of surface layer Thickness of drainage layer Thickness of geofabric Thickness of barrier layer, geosynthetic clay liner Thickness of geofabric, in geosynthetic clay liner Thickness of bentonite, in geosynthetic clay liner Thickness of pre-covering layer Thickness of the landfill Max water going through the landfill Amount of cleaned leachate water per year Use of NaOH for water treatment Use of iron chloride (PIX-111) for water treatment 0,1 1,35 0,5 0,1 0,0018 0,006 0,0003 0,0057 0,2 15 50 67274 10 22 Unit Reference l/m2 % of precipitation tonne/m3 Uppsala Kommun VA- och Avfallskontoret, 2003 Assumption Assumption Unit m m m m m m m m m m l/m2 and yr tonnes/yr tonnes/year tonnes/year Reference Ecoloop Ecoloop Ecoloop Ecoloop www.naue.com 2004 www.naue.com 2003 www.naue.com 2003 www.naue.com 2003 Ecoloop Ecoloop Ecoloop Uppsala Kommun VA- och Avfallskontoret, 2003 Uppsala Kommun VA- och Avfallskontoret, 2003 Uppsala Kommun VA- och Avfallskontoret, 2003 A2.1.2 Factors for resources use Processes Combustion of 1 MJ diesel in working machine Combustion of 1 MJ diesel during transport Pre-combustion of 1MJ diesel Production of 1 MJ electricity Combustion of 1MJ diesel in loading shovel (Volvo L180) Combustion of 1 MJ diesel in excavator Production of 1 kg geofabric Production of 1 kg steel Production of 1kg NaOH Production of 1 kg Iron cloride (PIX-111) Production of 1 kg bentonite (mining of 1 kg magnetite ore) Reference Oil (MJ) Biofuel (MJ) Stripple, 2001 1 Stripple, 2001 Stripple, 2001 Stripple, 2001 1 0,1 0,06 Stripple, 2001 Stripple, 2001 Svingby and Båtelsson, 1999 Stripple, 2001 Wallén, Almemark et al, 2003 Almemark et al, 2003 Peat (MJ) Coal (MJ) Natural gas (MJ) Uranium (MJ) Water power (MJ) 0,05 0,005 0,04 0,009 1,6 0,47 0,189 0,02 0,039 1, 8 0,016 6,7 1,974 2,8 0,8225 Iron (g) Crude oil (g) Water (g) Waste (g) 0,07 1,1 1,1 11,2 3,6 0,15 0,0788 0,008 11,1 15,3 0,07 0,13 0,002 0,0002 0,002 0,28 0,07 0,0204 0,043 0,013 0,001 0,01 0,003 0,48 0,140 1100 0,29 1000 784 0,12 0,006 0,02 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Appendix 2 A2.1.3 Factors for emission to air Process Combustion of 1 MJ diesel in working machine Combustion of 1 MJ diesel during transport Pre-combustion of 1MJ diesel Production of 1 MJ electricity Combustion of 1MJ diesel in loading shovel (Volvo L180) Combustion of 1 MJ diesel in excavator Production of 1 kg geofabric Production of 1 kg steel Production of 1 kg NaOH Production of 1 kg Iron cloride (PIX111) Reference SO2 (g) (air) CO2 (g) (air) Nox (g) (air) CO (g) (air) HC (g) (air) CH4 (g) (air) N2O (g) (air) VOC (g) (air) Particles (g) (air) COD (g) (aq) N-tot (g) (aq) Oil (g) (aq) 0,00 04 Stripple, 2001 0,02 75 0,7 0,09 0,04 0,0001 0,002 0,03 Stripple, 2001 0,02 75 0,6 0,1 0,03 0,0001 0,002 0,01 Stripple, 2001 Stripple, 2001 0,01 0,007 4 3,8 0,004 0,009 0,0001 0,002 0,01 0,0012 0,0002 0,0001 0,0004 0,0005 0,00007 Stripple, 2001 0,04 79 0,7 0,09 0,05 0,0001 0,002 0,03 0,0012 0,0002 Stripple, 2001 Svingby and Båtelsson, 1999 Stripple, 2001 Wallén, 1999 Almemark et al, 2003 0,04 79 0,7 0,09 0,05 0,0001 0,002 0,03 0,0012 0,0002 0,028 7,34 0,013 16 2200 9,38 0,04 4,86 0,04 0,0003 39 0,001 0,007 0,17 0,0004 0,0018 0,03 0,0008 1,83E05 0,009 0,02 0,0006 9,1 0,0002 6,09E06 0,005 1,2 0,0019 0,0003 0,01 1 0,0066 9,13E05 4,78E-05 3,04E-06 0,001 0,00 04 0,00 04 Phenols (g) (aq) 0,0006 0,0006 0,0006 A2.1.4 Factors for emissions to water Process Potential leaching (all available) from MSWI BA (Nordtest NT ENVIR 003) Lechate from 1 tonne MSWI BA (L/S 2) CEN-method Lechate from 1 tonne MSWI BA (L/S 10) CEN-method Lechate from 1 tonne sand (L/S 2), method CEN prEN 12457 Lechate from 1 tonne sand (L/S 10), method CEN prEN 12457 Potential leaching (all available) from crushed rock (Nordtest NT ENVIR 003 with some modification) Lechate from 1 tonne crushed rock (L/S 2) (CEN 8361), fresh material Potential leaching (all available) from sand (NT ENVIR 003) Reference RVF, 2002 RVF, 2002 RVF, 2002 Cl (g) (aq) 3375 1617 1856 SO4 (g) (aq) 1617 3375 7518 As (g) (aq) Cd (g) (aq) Cr (g) (aq) Cu (g) (aq) 0,4 0,007 0,01 3,5 0,002 0,004 2,2 0,02 0,04 Mroueh et al, 2001 0,006 0,0002 Mroueh et al, 2001 Tossavainen and Håkansson, 1999 Tossavainen and Håkansson 1999 Gustafsson et al, 2003 0,03 1086 2,4 3,7 Ni (g) (aq) Pb (g) (aq) Zn (g) (aq) 68,8 0,04 0,07 207 0,009 0,03 1766 0,067 0,15 0,004 0,004 0,004 0,04 0,001 0,02 0,02 0,02 0,2 0,2 0,04 0,3 0,16 1,5 0,35 2,8 0,008 0,0002 0,001 0,01 0,005 0,0006 0,007 1,7 0,03 0,2 0,46 1,2 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Appendix 2 A2.2 Calculations for case study Data Amount of water that infiltrates in drainage layer Distance from MSWI BA production site to landfill Amount of water that is contact with the MSWI BA in the drainage layer per year Amount of water that is contact with the MSWI BA in the landfill Corresponding time to reach L/S 2 for MSWI BA drainage layer Corresponding time to reach L/S 10 for MSWI BA drainage layer Corresponding time to reach L/S 2 for MSWI BA in landfill Corresponding time to reach L/S 10 for MSWI BA in landfill Distance from sand production site to landfill Amount of water that is contact with the sand in drainage layer per year Corresponding time to reach L/S 2 (sand) in landfill drainage layer Corresponding time to reach L/S 10 (sand) in landfill drainage layer Amount of water that is in contact with the sand in pre-covering layer Corresponding time to reach L/S 2 (sand) in landfill pre-covering layer Corresponding time to reach L/S 10 (sand) in landfill pre-covering layer Distance from MSWI BA production site to road Distance from crushed rock production site to road Distance from production site of geofabric and geosynthetic clay liner MSWI BA road: Amount of water that is contact with the MSWI BA per year MSWI BA road: Time to reach L/S 2 for sub base with MSWI BA MSWI BA road: Time to reach L/S 10 or sub base with MSWI BA MSWI BA road: Amount of water that is in contact with the crushed rock in base course per year MSWI BA road: time to reach L/S 2 for base course with crushed rock MSWI BA road: time to reach L/S 10 base course with crushed rock Crushed rock road: Amount of water that is contact with the crushed rock per year Crushed rock road: time to reach L/S 2 Crushed rock road: time to reach L/S 10 Value 0,20 55 1,45 0,002 1,38 6,88 960 4800 6 1,27 1,57 7,86 0,16 12,8 64 20 20 1225 0,02 99,2 496 5,0E-02 4,0E+01 2,0E+02 1,38E-02 1,5E+02 7,3E+02 Unit tonnes/m2 km tonnes water/ tonne MSWI BA tonne water/ tonne disposed ash years years years years km tonnes water/ tonne sand years years tonnes water/ tonne sand years years km km km tonne water/ tonne MSWI BA years years years years years tonne water/ tonne crushed rock years years Note Assume 60% evaporation www.viamichelin.com . Average distance from Uppsala to landfill that need drainage material All MSWI BA assumed to have contact with infiltrated water and assumed area is 1m2. All MSWI BA assumed to have contact with infiltrated water SGU, 2003. Average distance from Uppsala to sand pit All sand assumed to have contact with infiltrated water and assumed area are 1m2 All material assumed to have contact with infiltrated water www.viamichelin.com All material assumed to have contact with the infiltrated water Assumed that all water that infiltrates will reach the material Assumed that all water that infiltrates will reach the material Environmental Systems Analysis for utilisation of bottom ash in ground constructions Appendix 2 A2.2.1 Dimensions for the case study Data Use of MSWI bottom ash Factor for amount of MSWI BA left after sifting 1 tonne Volume drainage layer on a landfill that can be produced per tonne MSWI BA Area of drainage layer Use of geofabric, drainage layer Use of sand for drainage layer Use of soil for vegetation layer in landfill Use of excavated soil for surface layer in landfill Use of sand for drainage layer per tonne disposed ash Use of clay for barrier layer Use of geofabric barrier layer (in geosynthetic clay liner) Use of bentonite, barrier layer (in geosynthetic clay liner) Use of sand for pre-covering layer per tonne disposed ash Length of road that can be produced per tonne MSWI BA Use of crushed rock for MSWI BA road Use of crushed rock for crushed rock road Use of geofabric, barrier layer (in geosynthetic clay liner) per tonne disposed MSWI BA Use of bentonite, barrier layer (in geosynthetic clay liner) per tonne disposed MSWI BA Value 1 0,8 0,571428571 5,714285714 1,714285714 0,914285714 0,0756 0,023666667 0,005333333 4,285714286 1,257142857 26,28571429 0,010666667 0,153609831 0,322580645 1,172043011 0,003666667 0,153333333 Unit tonne tonnes m3 m2 kg/unit drainage layer tonnes sand/unit drainage layer tonnes/tonne disposed MSWI BA tonnes/tonne deposed MSWI BA tonnes/tonne disposed MSWI BA tonnes/unit drainage layer kg/unit drainage layer kg/unit drainage layer tonnes/tonne disposed MSWI BA m tonnes tonnes / unit road kg/tonne disposed MSWI BA kg/tonne disposed MSWI BA A2.2.2 Energy use Value Activity Production of drainage material from MSWI BA Use of diesel during loading of sifted MSWI BA, alt A Use of diesel during loading of sifted MSWI BA, alt B Use of geofabric Transport of MSWI BA from production site to landfill (truck maxload 35 tonnes) 0,8196 0,9829 1,714 Unit MJ/tonne MSWI BA MJ/tonne MSWI BA kg /tonnes MSWI BA Oil (MJ) Construction of drainage layer of MSWI BA Use of diesel by excavator 79,426 MJ/tonne MSWI BA 3,7908 MJ/tonne MSWI BA 0,7187 MJ/tonnes MSWI BA Peat (MJ) Coal (MJ) Natural gas (MJ) Uranium (MJ) Water power (MJ) 0,067 11,52 3,384 0,983 1,081 19,23 87,369 Diesel use, transport of MSWI BA Diesel use, transport of geofabric Bio fuel (MJ) 4,1698 0,8625 0,32 0,032 19,059 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Appendix 2 Activity Value Unit Oil (MJ) Bio fuel (MJ) Peat (MJ) Coal (MJ) Natural gas (MJ) Uranium (MJ) Water power (MJ) Production of drainage material from sand (per unit drainage layer produced with 1 tonne MSWI BA) Use of diesel for excavating sand with loading shovel (Volvo L180E) (includes loading) 0,8196 MJ/unit drainage layer 0,9836 9,902 MJ/unit drainage layer 0,7187 MJ/unit drainage layer 0,862 0,068 0,0136 MJ/tonne disposed MSWI BA MJ/tonne disposed MSWI BA MJ/tonne disposed MSWI BA MJ/tonne disposed MSWI BA MJ/tonne disposed MSWI BA MJ/tonne disposed MSWI BA MJ/ disposed MSWI BA MJ/tonne disposed MSWI BA MJ/tonne disposed MSWI BA MJ/tonne disposed MSWI BA kg NaOH/tonne disposed MSWI BA kg PIX-111 /tonne disposed MSWI BA 5,48 6,8354 MJ/unit road MJ/unit road Transport of sand from production site to landfill (per unit drainage layer that may be produced with 1 tonne MSWI BA) (truck maxload 35 tonnes) Diesel use, transport of sand Construction of drainage layer of sand Use of diesel by excavator Disposal of one tonne MSWI bottom ash Diesel use during production of material to vegetation layer 0,0566 Use of diesel during construction of vegetation layer Diesel use for transport of soil to vegetation layer Diesel use for construction of surface layer 0,0566 2,729 0,021 Diesel use for production of sand to drainage layer 0,0048 Diesel use for construction of drainage layer 0,0042 Use of diesel for transport of sand for drainage layer Use of diesel for production of material to pre-covering layer Use of diesel for construction of pre-covering layer 0,0578 0,00956 0,008 Transport of sand for pre-covering layer 0,1155 Use of NaOH for cleaning of leachate water in 20 years Use of PIX-111 (iron cloride) for cleaning of leachate water in 20 years Production of crushed rock to MSWI BA road Use of diesel Use of electricity 0,006 10,89 0,0679 3,0023 0,025 0,0057 0,0050 0,0635 0,011475 0,01 0,127 0,0009 0,0005 4,9E-05 0,0004 0,0001 0,0173 0,005 0,0018 3E-05 2,7E-06 2,4E-05 0,0038 0,0009 0,0003 6,03 0,437 0,3076 0,0308 0,2734 0,0636 10,937 3,2127 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Appendix 2 Activity Use of diesel for loading crushed rock with loading shovel (Volvo L180E), alt A Use of diesel for loading crushed rock with loading shovel (Volvo L180E), alt B Value Unit Oil (MJ) 3E-01 MJ/unit road 3,43E-01 0,597 MJ/unit road 0,7168 36,10 MJ/tonne MSWI BA 2,339990 64 MJ/tonne MSWI BA Bio fuel (MJ) Peat (MJ) Coal (MJ) Natural gas (MJ) Uranium (MJ) Water power (MJ) 0,23 39,73 11,67 Transport of MSWI BA from production site to road (maxload 35 tonnes) 39,713 Diesel use Construction of road of MSWI ash Use of diesel for construction of sub base layer 2,5739 1,0379 Use of diesel for construction of base course layer 0,9435 MJ/unit road 19,911 24,83 MJ/unit road MJ/unit road 21,902 1,589 1,04 MJ/unit road 1,14 2,17 MJ/unit road 2,39 36,1 MJ/tonne MSWI BA Production of crushed rock to road with crushed rock Use of diesel Use of electricity Use of diesel for loading crushed rock with loading shovel (Volvo L180E), Alt A Use of diesel for loading crushed rock with loading shovel (Volvo L180E), Alt B Transport of crushed rock from production site to road Use of diesel for road construction 3,4282 1,1176 0,111 0,9934 39,713 3,771 MJ/unit road A2.2.3 Emissions to air Activity SO2 (g) (air) CO2 (g) (air) NOx (g) (air) CO (g) (air) HC (g) (air) CH4 (g) (air) N2O (g) (air) VOC (g) (air) H2S (g) (air) PAH (g) (air) Particles (g) (air) Production of drainage material from MSWI BA Use of diesel during loading of sifted MSWI BA, alt A 0,0426 68,03 0,585 0,0698 0,0487 4,1E-05 0,0013 0,023 Use of diesel during loading of sifted MSWI BA, alt B 0,0373 77,65 0,70 0,08 0,0505 4,91-05 0,0016 0,02799 0,048 27,36 0,066 0,015 0,001 0,003 3,0182 6274,7 47,98 7,953 0,00397 0,127 Use of geofabric Transport of MSWI BA from production site to landfill (truck maxload 35 tonnes) 0,01 0,000504 0,832 Diesel use, transport of MSWI BA 3,05 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Appendix 2 Activity Diesel use , transport of geofabric SO2 (g) (air) CO2 (g) (air) NOx (g) (air) CO (g) (air) HC (g) (air) CH4 (g) (air) N2O (g) (air) VOC (g) (air) H2S (g) (air) PAH (g) (air) Particles (g) (air) 0,144 299,47 2,29 0,3796 0,1456 0,00019 0,006 0,037 59,65 0,513 0,061 0,04 3,6E-05 0,0011 0,04269 68,03 0,585 0,0698 0,0487 4,1E-05 0,0013 0,376 782,3 5,98 0,99 0,380 0,0005 0,0158 0,0104 0,03737 59,653 0,513 0,061 0,04 3,59E-05 0,0011 0,02 0,0029 4,6977 0,0404 0,0048 0,003 2,84E-06 0,0001 0,0016 0,0029 4,698 0,0404 0,0048 0,003 2,8E-06 0,0001 0,0016 215,6 1,6488 0,273 0,0001 0,004 0,001 1,7 0,01 0,1048 0,0017 8 1,0E-06 0,0002 0,39684 0,0034 2,39E-07 0,0002 0,35 0,00299 0,0004 0,0003 6 0,0012 0,0002 8 0,0002 2,0E-07 0,002 4,56 0,03 0,0058 0,0022 2,89E-06 0,0005 0,79 0,0068 0,0008 0,0006 4,78E-07 0,0004 0,696 0,00599 0,0007 0,0005 4,2E-07 215,62 0,0000 3 0,0000 08 0,0000 07 9,2E05 0,0000 2 0,0000 1 0,004 9,1268 0,06979 0,01 0,0044 5,8E-06 0,0002 0,0397 Construction of drainage layer of MSWI BA Use of diesel by excavator Production of drainage material from sand (per unit drainage layer produced with 1 tonne MSWI BA) 0,02 Use of diesel for excavating sand with loading shovel (Volvo L180E) (includes loading) 0,023 Transport of sand from production site to landfill (per unit drainage layer that may be produced with 1 tonne MSWI BA) (truck maxload 35 tonnes) Diesel use, transport of sand Construction of drainage layer of sand Use of diesel by excavator Disposal of one tonne MSWI bottom ash Diesel use during production of vegetation layer Use of diesel during construction of vegetation layer Diesel use for transport of soil for construction of vegetation layer Diesel use for construction of surface layer Diesel use for production of sand for drainage layer Diesel use for construction of drainage layer Use of diesel for transport of sand for drainage layer Use of diesel during production of material to precovering layer Diesel use for construction of pre-covering layer 0,0286 0,0006 0,0001 0,00012 0,0006 0,00027 0,0002 Transport of sand to landfill for pre-covering layer 0,001 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Appendix 2 SO2 (g) (air) Use of NaOH for cleaning of leachate water in 20 years Use of PIX-111 (iron chloride) for cleaning of leachate water in 20 years MSWI BA road Use of diesel, production of crushed rock Use of electricity, production of crushed rock Use of diesel for loading crushed rock with loading shovel (Volvo L180E), alt A Use of diesel for loading crushed rock with loading shovel (Volvo L180E), alt B Diesel use, transport of MSWI BA from production site Use of diesel for construction of sub base layer Use of diesel for construction of base course layer CO2 (g) (air) NOx (g) (air) CH4 (g) (air) CO (g) (air) HC (g) (air) 1,09E05 1,5E-06 0 8,3E-08 2,7E-04 N2O (g) (air) 4,895 E-06 2,5E07 8,1E-05 0,058 0,00025 3,97E-06 0,002 5,45E-06 4,1E05 1,2E06 2,08E-01 4,3E+02 3,9E+00 4,7E01 2,8E01 0,05 25,97 0,06 1,70E02 1,43E-05 8,8E03 0,0028 7 4,57E04 0,00096 VOC (g) (air) 1,2E05 6,5E07 H2S (g) (air) PAH (g) (air) Particles (g) (air) 6,759E06 4,1E-08 1,6E-01 1,49E-02 237 2,04E-01 0,01 2,4E02 0,0075 0,0005 0,031 49,58 0,43 0,051 0,035 2,99E-05 0,001 1,37 2852,1 21,8 3,6 1,386 0,0018 0,058 0,0889 184,88 1,67 0,199 0,120 0,0001 0,0037 0,036 74,54 0,674 0,08 0,048 4,7E-05 0,0015 0,0666 0,02687 0,7566 1572,98 14,2 1,695 1,023 0,000996 0,03 0,567 0,166 94,375 0,228 0,003 5,3E02 1,1E01 1,09E-04 0,010 1,66E03 3,5E03 8,1E-03 0,017 0,378 Crushed rock road Use of diesel, production of crushed rock Use of electricity, production of crushed rock Use of diesel for loading crushed rock with loading shovel (Volvo L180E), Alt A Use of diesel for loading crushed rock with loading shovel (Volvo L180E), Alt B Transport of crushed rock from production site to road Use of diesel for road construction 3,9E-02 8,2E+01 7,4E-01 8,3E-02 1,7E+02 1,55 0,05 8,8E02 1,85E01 1,37 2852,1 21,8 3,61 1,386 0,0018 0,0578 0,378 0,13 270,8 2,448 0,29 0,176 0,00017 0,005 0,098 5,2E-05 0,027 0,0017 2,96E-02 6,18E-02 Environmental Systems Analysis for utilisation of bottom ash in ground constructions Appendix 2 A2.2.4 Emissions to water As (g) (aq) 0,40 0,12 0,20 0,06 0,33 Hg (g) (aq) 0 0 0 0 0 Cd (g) (aq) 0,128 0,04 0,06 0,02 2,78 Cr (g) (aq) 1,04 0,476 0,52 0,2379 1,75 Cu (g) (aq) 141,0 42,50 70,50 21,25 868,8 Ni (g) (aq) 2,059 0,78 1,0 0,39 55,04 Pb (g) (aq) 0,523 0,30 0,26 0,15 165,6 Zn (g) (aq) 3,961 1,782 1,98 0,891 1412,8 Leachate from drainage layer sand, 100 yr (based on L/S 2) Leachate from drainage layer sand, 100 yr (based on L/S 10) Leachate from drainage layer sand, 50 yr (based on L/S 2) Leachate from drainage layer sand, 50 yr (based on L/S 10) Leachate from drainage layer sand, infinity 0,349 0,349 0,17 0,17 1,54 0 0 0 0 0 0,01 0,01 0,0058 0,0058 0,02 0,23 0,23 0,116 0,116 0,197 0 0 0 0 0,42 0,23 0,23 0,116 0,116 1,097 0,23 0,23 0,116 0,116 0,8 2,3 2,3 1,16 1,16 4,75 Use and maintenance of drainage layer (disposal of ash) Leachate from drainage layer sand, 100 yr ( based on L/S 2) Leachate from drainage layer sand, 100 yr ( based on L/S 10) Leachate from drainage layer sand, 50 yr ( based on L/S 2) Leachate from drainage layer sand, 50 yr ( based on L/S 10) 0,002 0,0016 0,0006 0,0006 0 0 0 0 6,79E-05 5,43E-05 2,0E-05 2,0E-05 0,001 0,001 0,0004 0,0004 0 0 0 0 0,001 0,001 0,0004 0,0004 0,001 0,001 0,0004 0,0004 0,01 0,01 0,004 0,004 Use and maintenance of pre-covering layer Leachate from pre-covering layer, 100 yr (based on L/S 2) Leachate from pre-covering layer sand, 100 yr ( based on L/S 10) Leachate from pre-covering layer sand, 50 yr ( based on L/S 2) Leachate from pre-covering layer sand, 50 yr ( based on L/S 10) Leachate from pre-covering layer sand, infinity 0,0004 0,0004 0,0002 0,0002 0,01797 0 0 0 0 0 1,3E-05 1,3E-05 0,000005 0,000005 0,000267 0,000267 0,000267 0,0001 0,0001 0,002 0 0 0 0 0,004907 0,000267 0,000267 0,0001 0,0001 0,01 0,00027 0,00027 0,0001 0,0001 0,00987 0,0027 0,0027 0,001 0,001 0,055 Use and maintenance of the landfill Leachate from MSWI BA in landfill,100yr (based on L/S2) Leachate from MSWI BA in landfill, 100 yr (based on L/S 10) Leachate from MSWI BA in landfill, 50 yr (based on L/S 2) 0,00046 0,00046 0,00017 0 0 0 0,0001 0,0001 0,000055 0,001 0,001 0,0004 0,16 0,16 0,06 0,002 0,002 0,000885 0,00454 0,00454 0,0017 Leachate from MSWI BA in landfill, 50 yr (based on L/S 10) Leachate from MSWI BA in landfill, infinity 5,45E-05 0,4 0 0 0,000018 3,48 0,000205 2,19 0,018267 1086 0,0003 68,8 0,0006 0,0006 0,0002 0,000130 5 207 0,000766 1766 Use and maintenance of MSWI BA road Leachate from sub base with MSWI ash, 100yr ( based on L/S 2) Leachate from sub base with MSWI ash, 100yr ( based on L/S 10) Leachate from sub base with MSWI ash, 50yr ( based on L/S 2) Leachate from sub base with MSWI ash, 50yr ( based on L/S 10) Leachate from sub base with MSWI ash, infinity Leachate from base course with crushed rock, 100 yr ( based on L/S 2) 0,005568 0,001759 0,002784 0,000879 0,33408 6,27E-03 0 0 0 0 0 0,00E+00 0,001774 0,000581 0,000887 0,00029 2,784 1,94E-04 0,014435 0,006597 0,007218 0,003298 1,752 8,06E-04 1,954758 0,589258 0,977379 0,294629 868,8 8,90E-03 0,028548 0,010823 0,014274 0,005411 55,04 4,37E-03 0,007258 0,0042 0,0036 0,0021 165,6 5,08E-04 0,054919 0,0247 0,027 0,01235 1412,8 5,24E-03 Use and maintenance of drainage layer of MSWI BA Leachate from drainage layer MSWI BA, 100 yr (based on L/S 2) Leachate from drainage layer MSWI BA, 100yr (based on L/S 10) Leachate from drainage layer MSWI BA, 50yr (based on L/S 2) Leachate from drainage layer MSWI BA, 50 yr (based on L/S 10) Leachate from drainage layer MSWI BA, infinity Use and maintenance of drainage layer of sand Leachate from drainage layer sand, infinity Environmental Systems Analysis for utilisation of bottom ash in ground constructions Appendix 2 As (g) (aq) Leachate from base course with crushed rock, 50 yr ( based on L/S 2) Leachate from base course with crushed rock, infinity Use and maintenance of crushed rock road Leachate from sub base and base course with crushed rock, 100 yr (based on L/S 2) Leachate from sub base and base course with crushed rock, 50 yr (based on L/S 2) Leachate from sub base and base course with crushed rock, infinity Hg (g) (aq) 3,14E-03 6,13E-02 0,00E+00 0,00E+00 Cd (g) (aq) 9,68E-05 1,29E-02 Cr (g) (aq) 4,03E-04 9,35E-02 Cu (g) (aq) 4,45E-03 5,16E-02 Ni (g) (aq) 2,19E-03 4,84E-01 Pb (g) (aq) 2,54E-04 1,13E-01 Zn (g) (aq) 2,62E-03 9,03E-01 0,02 0 0,0007 0,002 0,03 0,01588 0,0018 0,0190 0,011 0,22 0 0 0,00035 0,04688 0,001 0,33989 0,016 0,1875 0,0079 1,758 0,00092 0,4102 0,0095 3,2817 A2.3 Reference - appendix 2 Literature Almemark, M, Carlsson, AS, Palm, A. (2003) Jämförande miljöbedömning av tre fällningskemikalier PIX-111, PIX-110 och PIX-118. Swedish Environmental Research Institute (IVL), (In Swedish). Gustafsson, M., von Bahr, B., Carlson-Ekvall, A., Johansson, P., Reuterhage, Å., Wallman, S. (2003) Inledande laboratorieförsök, projekt AIS32, delrapport 1. Swedish Agency for Innovation Systems (Vinnova), Göteborg. Mroueh, U., Eskola, P., Laine-Ylijoki, J., (2001): Life-cycle impacts of the use of industrial by-products in road and earth construction. Waste Management 21, 271-277. Olsson, S., Kärrman, E., Gustafsson, J.P. (2004) Environmental systems analysis of the use of bottom ash from incineration of municipal waste for road construction. Proceedings of the 19th International Conference on Solid Waste Technology and Management, March 21-24, 2004, Philadelphia, PA USA. RVF (The Swedish Association of Waste Management). (2002) Kvalitetssäkring av slaggrus från förbränning av avfall. RVF 02:10, (In Swedish). SGU (Geological Survey of Sweden). (2003) Aggregates –production and resources 2002. SGU 2003:4, Uppsala, (In Swedish, with an English summary). Stripple, H. (2001) Livscykelanalys av väg - En modellstudie för inventering. Swedish Environmental Research Institute (IVL), Göteborg, (In Swedish with an English summary). Svingby, M., Båtelsson, O. (1999) LCA av lättfyllnadsmaterial för vägbankar. National Road Administration, Vägverket1999:67, Borlänge, (In Swedish). Tossavainen, M., Håkansson, K. (1999) Reference data of leaching of natural materials and effects on its leaching properties of ageing. Swedish Environmental Protection Agency, 1999: AFR-Report 254. Stockholm. Environmental Systems Analysis for utilisation of bottom ash in ground constructions Appendix 2 Uppsala Kommun VA-och Avfallskontoret. (2004) Miljörapport 2003 – Hovgårdens avfallsanläggning. Uppsala ( In Swedish) Wallén, E. (1999) Livscykelanalys av dricksvatten – en studie av ett vattenverk i Göteborg. Degree thesis, Chalmers University of Technology, Göteborg, (In Swedish). Internet Naue Fasertechnik GmbH &Co. KG. (2003) Fibre-reinforced geosynthetic clay liner.Available:www.naue.com [ 2004, September 18] Naue Fasertechnik GmbH &Co. KG. (2004) Geotextiles for road construction Secutex GRK. Available: www.naue.com [2004, September 18] ViaMichelin. (No date): Route planner. Available: www.viamichelin.com Environmental Systems Analysis for utilisation of bottom ash in ground constructions Appendix 3 Appendix 3 A3.1 Difference in substance flow when certain life cycle stages are excluded Table: Difference in substance flow when certain life cycle stages are excluded. Substance flow Scenario 3 Scenario 3 Drainage Drainage without with barrier layer of layer of barrier layer MSWI BA MSWI BA layer without with machineries machineries Resource use 1 Energy [MJ] 138 138 147 148 Sand [tonnes] 0,93 0,93 0 0 Crushed rock [tonnes] 1,17 1,17 0 0 Waste [g] 1,74 1,74 0,50 0,50 Emissions to air 2 SO2 [g] 3,0 3,1 3,3 3,9 NOx [g] 48 49 51 52 CO [g] 7,2 7,2 8,5 8,6 CO2 [g] 6030 6050 6729 6924 CH4 [g] 0,007 0,007 0,005 0,8 VOC [g] 0,027 0,027 0,0079 0,11 (VOC+NMVOC) HC [g] 3,2 3,3 3,3 3,3 N2O [g] 0,13 0,13 0,14 0,14 Particles [g] 1,3 1,3 0,9 4,4 Emissions to water 3 COD [g] 0,09 0,09 0,10 0,10 Ntot [g] 0,014 0,014 0,016 0,017 Oil [g] 0,03 0,03 0,03 0,03 Phenol [g] 0,04 0,04 0,05 0,05 As [g] 0,3 0,3 0,13 0,13 Cd [g] 0,01 0,01 0,04 0,04 Cr [g] 0,19 0,19 0,48 0,48 Cu [g] 0,23 0,23 42,5 42,5 Ni [g] 0,2 0,2 0,78 0,78 Pb [g] 0,19 0,19 0,30 0,30 Zn [g] 1,90 1,90 1,78 1,78
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