pharmaceuticals) and metals (e.g. mercury) is increasing together with efforts to improve the energy balance (e.g. optimise biogas production) and resource recovery (e.g. phosphorus). The process steps in a typical conventional wastewater treatment plant (WWTP) are shown in Fig. 34.1. 34.2 Review of Existing LCA Case Studies on WWT At least more than 60 LCA studies on wastewater treatment have been performed since the mid 1990s, with the paper by Emmerson et al. (1995) being among the first ones. Today, several review papers exist with Larsen et al. (2007), Corominas Fig. 34.1 Conventional wastewater treatment plant (Doka 2007, with permission) LCA of Wastewater Treatment


et al. (2013) and Zang et al. (2015) being the most recent. The review by Larsen et al. (2007) includes 22 studies and focus on eco-toxicity-related impacts though conventional impact categories are also included. Corominas et al. (2013) reviewed 45 studies but excluded specific studies on sludge treatment. This is also the case for the review by Zang et al. (2015) that includes 53 studies (among these several Asian ones) on different technologies but focus on activated sludge plants. This chapter is mainly based on the review by Larsen et al. (2007) supplemented by the two other, more recent reviews (Corominas et al. 2013; Zang et al. 2015) together with some of the most comprehensive studies including Larsen et al. (2010). The results of the Larsen et al. (2007) review are briefly shown in Table 34.1 in Appendix. The reviewed studies include to varying degrees life cycle stages, LCA impact categories, micro-pollutants, and more, and present LCA profiles for wastewater treatment

Hauschild et al., LCA: Theory and Practice


The reviewed studies include to varying degrees life cycle stages, LCA impact categories, micro-pollutants, and more, and present LCA profiles for wastewater treatment. The results are presented and discussed in the following sections on the importance of different life cycle stages for the impact profile, the relevance of different impact categories for this application domain, and the degree to which wastewater specific issues like micro-pollutants and pathogens are included. Finally, spatial differentiation, normalisation and weighting are addressed. 34.2.1 Importance of Life Cycle Stages The life cycle of the service of wastewater treatment comprises different stages, i.e. material stage (production of raw materials, e.g. oil) including the construction of the plant, use stage (running the plant), transport “stage” (in some cases an integrated part of the other stages) and finally disposal, waste or reuse/recycling stage (e.g. landfill)


landfill). These stages are dealt with in the subsections below. Material and Construction Stage Some of the LCA studies included in Table 34.1 in Appendix, like Emmerson et al. (1995) and Tillman et al. (1998), have included the construction of the wastewater treatment plant(s) in a detailed way. In the case Emmerson et al. (1995), the results show that although the energy consumption is overall dominated by the operation stage at one of the WWTPs analysed, it is of the same order of magnitude in both the construction and the operation stages at the two other WWTPs included. Also the studies by Tangsubkul et al. (2005), Vlasopoulos (2004) and Vlasopoulos et al. (2006) point at the possible importance of infrastructure for several different processes, e.g. constructed wet lands and sand filters. Newer studies, not included in Table 34.1 in Appendix, like Larsen et al


constructed wet lands and sand filters. Newer studies, not included in Table 34.1 in Appendix, like Larsen et al. (2010) confirm that infrastructure/capital goods may play a significant role when dealing with newer and upcoming technologies like ozonation and sludge inertisation. That infrastructure needs to be addressed in all cases, either by including or arguing for excluding, is also stated in the review by Corominas et al. (2013). H.F. Larsen


Use Stage The use stage (or plant operation stage) plays an often dominating role is documented in almost all studies. The main reason is the typical use of electricity, fuels and especially the emission of pollutants from the wastewater to air, with effluents and sludge. Transport Transport may or may not play a significant role (but typically not dominating) in the LCA profile of a Wast Water Treatment Technology (WWTT) depending on the created scenario and its scoping. An example of significant importance of transport is the Australian study by Beavis and Lundie (2003) focusing on energetically efficient distance to place of application of biosolids (based on sludge) used for fertilisation of agricultural land. In their specific cases threshold transport distance of 172 km (aerobic digested sludge) and 143 km (anaerobic digested sludge) could be estimated


In their specific cases threshold transport distance of 172 km (aerobic digested sludge) and 143 km (anaerobic digested sludge) could be estimated. Another example of the importance of distance to place of application is described in the paper by Houillon and Jolliet (2005) showing by sensitivity analysis that doubling the distance results in a 23% increase in the overall energy consumption. In the study by Dixon et al. (2003) on small-scale WWTPs, the transport in the case of reed bed contributed with 30% of the total energy consumption. Also, transportation of the wastewater may be important in scenarios where it is collected in tanks and transported to the treatment plant over long distances. Disposal Stage The importance of including the disposal of waste (in some cases as a resource for reuse or recycling) in LCA studies on wastewater is documented in several studies. One example is the disposal of sludge for agricultural application


One example is the disposal of sludge for agricultural application. Including the substitution of fertiliser production and the potential impact from especially the metal content of the sludge is very important (Beavis and Lundie 2003; Tangsubkul et al. 2005; Hospido et al. 2005), which has also been shown in more recent studies like Larsen et al. (2010) not included in Table 34.1 in Appendix. Another example is whether or not the methane production from anaerobic digestion is utilised (substituting fossil energy) or is emitted to air and hereby contributing significantly to the global warming potential (Tillman et al. 1998). 34.2.2 Relevance of Different Impact Categories The environmental impact categories are here divided into the typical energyrelated ones and typical toxicity (or chemical)-related ones. This is because a typical challenge in wastewater treatment is the achievement of higher effluent water quality at the expense of higher energy consumption


This is because a typical challenge in wastewater treatment is the achievement of higher effluent water quality at the expense of higher energy consumption. The energy-related categories comprise global warming, acidification and photochemical ozone formation, in a wastewater treatment system all primarily attributable to the combustion of fossil fuels in stationary or mobile processes. The toxicity-related impact categories include ecotoxicity and human toxicity. Eutrophication which in many other cases LCA of Wastewater Treatment


is primarily energy related is here looked upon separately due to its high relevance for wastewater effluent. Resource consumption, stratospheric ozone depletion, land use, photochemical ozone formation, and waste generation are also treated separately. Energy-Related Impact Categories The typically high importance of the energy-related impact categories are documented in most of the studies reviewed. For example in the study by Clauson-Kaas et al. (2006), the induced potential impact (global warming, acidification, indirect eutrophication) related to the energy consumption from running two of the investigated treatment technologies (MBR and ozonation) is at least in the main scenario higher than the avoided potential impact (aquatic ecotoxicity) achieved by cleaning the water (normalised or weighted impact potentials)


In the study by Beavis and Lundie (2003) focusing on disinfection technologies for effluents and digestion of sludge, the potential impacts related to energy consumption also plays a dominating role. In the review by Corominas et al. (2013), global warming, acidification and eutrophication is evaluated in 38, 27 and 28 of the 45 studies included, respectively. Newer impact categories like ionising radiation and particulate matter formation are also important as they are typically related to energy production. Toxicity-Related Impact Categories The importance of the toxicity-related impact categories, i.e. ecotoxicity and human toxicity, when doing LCA on wastewater treatment—especially if the chemical/ toxic emission from the WWTP is actually included—is documented in several studies. In, for example, the Dutch study by Roeleveld et al


In, for example, the Dutch study by Roeleveld et al. (1997) focusing on municipal wastewater treatment, the normalised results show aquatic ecotoxicity to be the second most important impact category only exceeded by eutrophication. Main contributors to the ecotoxicity of the effluent are metals (about 90%; Hg, Cd) whereas the included non-specified organic micro-pollutants account for the rest. That other micro-pollutants than just metals can play an important role for aquatic ecotoxicity in the LCA comparison of different wastewater treatment options is documented in the study by Clauson-Kaas et al. (2006) including endocrine disruptors and other organics. Terrestrial ecotoxicity may also in some cases play an important role. This is seen especially in cases involving agricultural application of sludge containing metals. One example is the study by Hospido et al. (2005) comparing anaerobic digestion of sludge with different thermal alternatives


One example is the study by Hospido et al. (2005) comparing anaerobic digestion of sludge with different thermal alternatives. In this case, the anaerobic digestion scenario includes agricultural application and gets the overall highest normalised impact score on terrestrial ecotoxicity due to the content of metals in the sludge. In the same study and same scenario, the impact category on human toxicity gets the second highest normalised impact score (human exposure to metals via food chains) showing that at least in a few cases human toxicity may play an important role in an LCA study of wastewater treatment technologies. That also human toxicity related to air emission from energy production may play an at least not negligible role in this context is shown in, for example, two Danish studies (Clauson-Kaas et al. 2001, 2006). More recent studies including pharmaceuticals and more, like Larsen et al. (2010), confirm the overall H.F. Larsen


results of this review. The importance of toxicity-related impact categories is also reflected in the reviews by Corominas et al. (2013) and Zang et al. (2015). Eutrophication and Oxygen Depletion Due to Emission of Organic Matter Reduction in emission of organic matter (COD, BOD) and nutrients (N, P) has always been a key challenge for municipal WWTPs. That it is also important in LCAs of wastewater treatment is documented in many studies. For example in the paper by Roeleveld et al. (1997) focusing on municipal wastewater treatment in The Netherlands, the impact share of eutrophication is clearly the highest with 4.4%, whereas the second highest, aquatic ecotoxicity, only amounts to 2.4% and energy consumption only 0.6% (normalised on basis of the total potential impact of all Dutch societal activities). Another example is the study by Hospido et al


Another example is the study by Hospido et al. (2004) on a Spanish municipal wastewater plant showing that eutrophication is the dominating impact category after normalisation with a share of about 65%. The typical dominance of eutrophication when wastewater effluent is included is confirmed by newer studies as described in the reviews by Corominas et al. (2013) and Zang et al. (2015). Distinguishing between emissions to freshwater (typically P-deficient) and marine water (in many cases N-deficient), and if possible include spatial (and temporal) differentiation is important for this impact category. Stratospheric Ozone Depletion The impact category stratospheric ozone depletion is included in 6 out of the 22 reviewed studies. It may play some (minor) role in ranking different alternative wastewater treatment technologies as shown for advanced oxidation processes by, e.g. Muñoz et al. (2005, 2006) and García-Montaño et al. (2006)


Muñoz et al. (2005, 2006) and García-Montaño et al. (2006). However, after normalisation, the importance is typically negligible as regards WWTPs (Roeleveld et al. 1997; Hospido et al. 2004, 2005). This insignificant importance is confirmed by the Corominas et al. (2013) review but it should be noted that emission of N2O, which is in focus regarding global warming potential related to WWTPs, is considered to be today’s dominant ozone layer depleting emission (UNEP 2013). Photochemical Ozone Formation That the impact category on (tropospheric) photochemical ozone formation (POF) in some cases may play at least a minor role is shown in several studies. In the study by Vlasopoulos et al. (2006) comparing 20 different technologies for cleaning petroleum process waters, the POF is showing a normalised contribution, that is, at the same level as the one for eutrophication. Another example is the study by Tangsubkul et al


Another example is the study by Tangsubkul et al. (2006) analysing microfiltration processes where the POF plays a relative important role (due to its relation to energy production, in this case electricity production) and is shown to be microfiltration flux dependent. That the emission of volatile organic compounds (VOC) from fossil fuel combustion (transport vehicles, machines etc.) can make the impact category for photochemical ozone formation significant in the comparison of different sludge treatment scenarios is shown by Suh and Rousseaux (2002). However, in the study on a municipal WWTP by Hospido et al. (2005) the normalised contribution from POF was found to be negligible. LCA of Wastewater Treatment


Waste Generation The disposal of “waste”, for example, sludge produced during the wastewater treatment, is in a number of cases characterised by the use of the other impact categories. For example, the disposal of sludge on agricultural land is in some cases characterised by the use of the impact categories for terrestrial ecotoxicity, human toxicity and more (e.g. Hospido et al. 2005). The importance of addressing waste generation and its disposal is documented in several studies (e.g. Beavis and Lundie 2003; Tangsubkul et al. 2005). However, in many impact assessment cases and studies all or some of the waste is “only” included as, e.g. “hazardous waste”, “slag and ashes”, “solid waste” etc. (e.g. Clauson-Kaas et al. 2001; Tillman et al. 1998) or not at all (e.g. Dixon et al. 2003)


“hazardous waste”, “slag and ashes”, “solid waste” etc. (e.g. Clauson-Kaas et al. 2001; Tillman et al. 1998) or not at all (e.g. Dixon et al. 2003). One should always aim for characterising all waste disposals by the well-established impact categories including emissions to the biosphere (like freshwater ecotoxicity and human toxicity) and not just different waste categories. Land Use Only three studies have included land use in the LCA and only as occupied square metres or square metres times years of occupation. In the case of Muñoz et al. (2006), the land use is associated with the construction of the plant and reflects the large area needed for the solar field. The results of Dixon et al. (2003) reflect the difference between the land use for small conventional plantsanda constructed wetlandswith the same capacity, i.e. the included wetlands require a factor of 17–40 times larger area than the corresponding conventional plants. Mels et al


the included wetlands require a factor of 17–40 times larger area than the corresponding conventional plants. Mels et al. (1999) analysed three different large (100,000 p.e.) wastewater treatment plants (one reference and two alternatives) and come up with an area need of 8000–10,000 m2 depending on the plant. A general exclusion of land use can therefore not be recommended as it may play a role especially if the LCA includes constructed wetlands, high space demanding energy production or the like. That only a few studies have actually included land use until now is confirmed by the most recent review study by Zang et al. (2015). Resource Consumption 8 out of the 22 LCA studies reviewed include an impact category for resource consumption/depletion. However, in more cases resource consumption data is included in the inventory data presented


However, in more cases resource consumption data is included in the inventory data presented. That resource depletion may play an important role in the impact assessment of wastewater treatment and that, in many cases, it is associated with consumption of fossil fuels is shown by Roeleveld et al. (1997), Gasafiet al. (2004) and Suh and Rousseaux (2002). Later studies like Larsen et al. (2010) confirm this. Water consumption/use as a separate category has also been included in a few recent studies as described in Zang et al. (2015). 34.2.3 Micro-Pollutants and Pathogens in Effluent and Sludge The reviewed papers (Table 34.1 in Appendix) only include micro-pollutants to a limited degree and pathogens are not included at all in an impact relevant manner. H.F. Larsen


Regarding inorganic micro-pollutants, the evaluation of potential toxic impact from metals in effluent or sludge is included in 8 out of the 22 studies reviewed. Two studies include metals only in the assessment of the wastewater effluent (Clauson-Kaas et al. 2001, 2006), three studies apparently include metals in both effluent and sludge (Roeleveld et al. 1997; Beavis and Lundie 2003; Tangsubkul et al. 2005), and the other three studies only include metals in sludge (Suh and Rousseaux 2002; Hospido et al. 2004, 2005). Organic micro-pollutants in general are only dealt with in two studies and only specified as single substances (not groups) in one case (i.e. Clauson-Kaas et al. 2006). The Clauson-Kaas study includes linear alkyl benzene sulphonate (LAS), diethylhexyl phthalate (DEHP) and polycyclic aromatic hydrocarbons (PAHs), i.e. benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene, benzo(k)fluoranthene and indeno(1,2,3-cd)pyrene for effluent emissions


benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene, benzo(k)fluoranthene and indeno(1,2,3-cd)pyrene for effluent emissions. A newer study by Larsen et al. (2010), not included in Table 34.1 in Appendix, is one of the most comprehensive ones regarding organic micro-pollutants and includes pharmaceuticals/ metabolites for effluent emissions, and LAS, nonylphenol, DEHP and benzo(a) pyrene for sludge applied on agricultural land. Potential impacts of pathogens are not included in any of the 22 LCA studies. Reduction of pathogens by WWT is, however, included in two studies (Clauson-Kaas et al. 2006; Beavis and Lundie 2003) and pointed out as an important issue for sludge used for agricultural application (Hospido et al. 2004). Further, the lack of including human health risk caused by the presence of pathogens in wastewater is pointed out as a limitation “that can affect the use of LCA in decision support in water recycling planning” (Tangsubkul et al. 2005)


2005). A preliminary method on how to include pathogens in LCA has been developed by Larsen et al. (2009) and most recently this issue has been addressed regarding sewage sludge management (Harder et al. 2016). 34.2.4 Spatial Differentiation Site dependency with regard to aquatic ecotoxicity is only included on a general level as a differentiation between fresh water aquatic environment and marine (saltwater) aquatic environment and only in six of the reviewed studies. However, several studies include site-dependent inventory data when specific existing wastewater treatment works are looked upon (e.g. Tillman et al. 1998; Emmerson et al. 1995; Muñoz et al. 2006). For WWT spatial differentiation seems especially relevant for impacts related to aquatic ecotoxicity and eutrophication. 34.2.5 Normalisation and Weighting Twelve of the reviewed studies use normalisation with five of them supplementing with a weighting based on value choices


34.2.5 Normalisation and Weighting Twelve of the reviewed studies use normalisation with five of them supplementing with a weighting based on value choices. The normalisation is typically done on LCA of Wastewater Treatment


basis of the total societal (land, region or global) potential impact per citizen within a reference year and the normalised results, for example, expressed in percentages of the total societal impact in each impact category (see also Sect. 10.3 on normalisation). By introducing value choices weighting factors may be estimated for each impact category or anticipated weighting factors (e.g. 0.5 and 1) may be used in sensitivity analysis as in the study by Suh and Rousseaux (2002). In the study by Clauson-Kaas et al. (2006), weighting factors (1.0–1.7) based on distance to political reduction targets, i.e. governmental and international conventions on reduction targets (actually the same as a normalisation reference for a future scenario) are used. In the case of Tillman et al. (1998) and Svanström et al. (2004), the “monetary” principle “willingness to pay”, i.e. the willingness of society to pay for restoration of impacts on “areas of protection” is used


(1998) and Svanström et al. (2004), the “monetary” principle “willingness to pay”, i.e. the willingness of society to pay for restoration of impacts on “areas of protection” is used. In the recent review by Corominas et al. (2013), the use of the hierarchist perspective (archetypes) for weighting is found in WWT LCA cases. The strength of using normalisation and weighting is that it makes comparison between different WWT alternatives more simple and creates the opportunity to aggregate all the impact potentials into one common impact score. On the other hand, the weakness is that weighting is based on value choices and not natural science and therefore debatable. Probably due to this and a very stubborn (site-specific) risk-based approach on how to do environmental assessment within this applicationdomain, the LCA approach has had a hard time gaining a foothold


Using normalisation references at different scales (catchment, region, nation etc.) and different weighting principles may therefore be a good idea in trying to test the robustness of a result and gain acceptance. 34.3 Methodological Issues When modelling LCA cases on wastewater the issue in focus is typically the service of treating one volume unit (i.e. m3) of more or less contaminated water. The processes leading to the contamination (e.g. sanitation and consumption) are only included in a limited way and in most cases not at all. Goal and Scope The most commonly used functional unit (see Sect. 8.4.2) is one cubic metre of (ingoing) wastewater. If comparison among technologies is the aim, it is highly important to define the wastewater composition strictly (P content, COD content, etc.) in order to avoid introducing a bias in the comparison. Depending on the goal and scope “population equivalents” (e.g


Depending on the goal and scope “population equivalents” (e.g. based on BOD5) or nutrient content (kg phosphorus content) may also be used as functional unit. Defining the life time of the technologies in question is also important and may play a significant role. Scoping according to the goal is essential and may include the whole water cycle if the goal is mapping hot spots in a region’s sanitary system or only specific process parameters if the aim is assessing the environmental performance of different technical process optimisations. It may, for example, be of high importance for the H.F. Larsen


impact contribution from infrastructure whether or not the sewer system is included. Including all (relevant) emissions and resource consumption/recovery like the handling/treatment and final disposal of sludge are very important as this emission route in many cases contains the major part of the pollutants (heavy metals, eutrophying substances). The direct emission of greenhouse gases (CO2, CH4 and N2O) from the sewer system and/or from processes like activated sludge treatment (including nitrification/denitrification), sludge processing (e.g. anaerobic digestion), special treatments like ANaerobic AMMonium OXidation (ANAMMOX) and even emissions after disposal of sludge to agricultural land or landfill, may be important depending on the goal of the study. In this context, one should be aware of the content of fossil-based carbon in the sewage water, which may be at a level of up to 25% according to the review by Zang et al. (2015)


In this context, one should be aware of the content of fossil-based carbon in the sewage water, which may be at a level of up to 25% according to the review by Zang et al. (2015). For more information on the definition of goal and scope, see Chaps. 7 and 8, respectively. Inventory Foreground data is typically based on real plant measurement, laboratory/pilot tests or a combination with literature values and estimates. Background data (both upstream and downstream) are in most cases based on LCI databases like ecoinvent and GaBi. Transparency is always important in order to secure the possibility of a third part reproducingthestudy.FormoredetailedinformationoninventoryinLCA,seeChap. 9. Impact Assessment In order to achieve as robust an impact assessment as possible, the use of more than one impact assessment method is recommended (see Chap. 10 on life cycle impact assessment). Depending on the goal and scope, presentation of results at all relevant levels, i.e


10 on life cycle impact assessment). Depending on the goal and scope, presentation of results at all relevant levels, i.e. inventory, impact potentials, normalised and weighted (single score) results should be done. Both midpoint and endpoint (damage) results should be included (see Chap. 10). This may be achieved using, for example, the ILCD recommended methods (EU 2013) and the ReCiPe method (Goedkoop et al. 2013). As described above, the typically important impact categories for LCIA on wastewater include the toxicity related ones (human toxicity, freshwater ecotoxicity, marine ecotoxicity, terrestrial ecotoxicity and particulate matter formation), eutrophication (marine and freshwater), global warming, acidification, ionising radiation and (in some cases) water use, land use and stratospheric ozone depletion. Attempts to include special impact categories like pathogens and acute toxicity (due to, e.g. water emission of ammonia), and spatial and temporal differentiation (e.g


Attempts to include special impact categories like pathogens and acute toxicity (due to, e.g. water emission of ammonia), and spatial and temporal differentiation (e.g. regarding eutrophication) when doing site-specific assessments may be relevant depending on the goal and scope of the study. Interpretation With the aim of optimising the reliability and robustness of the result the use of sensitivity analysis but also uncertainty estimations if possible is highly recommended (see Chap. 12 on interpretation). An Alternative Approach on How to Do LCA on Wastewater Treatment The approach used to reach the goal of an LCA on wastewater treatment is typically based on the general approaches like hot spot identification in the life cycle of a specific LCA of Wastewater Treatment


technology or comparing the impact profile of different technologies performing the same service, e.g. phosphorus removal down to a specific level. An alternative is the “avoided against induced impacts” approach, where the impacts avoided by, e.g. introducing a new technology are compared to the impacts induced by this technology. This approach is illustrated in Figs. 34.2 and 34.3 and reflects a typical challenge in wastewater treatment, i.e.theachievement of higher effluent water quality at the expense of higher energy consumption or higher consumption of, e.g. precipitation chemicals. This approach has now been used in several studies and was introduced by Wenzel et al. (2008) and in a more comprehensive way by Larsen et al. (2007, 2010). The approach puts special demands on the toxicity related impact categories and the eutrophication potential


(2008) and in a more comprehensive way by Larsen et al. (2007, 2010). The approach puts special demands on the toxicity related impact categories and the eutrophication potential. 34.4 Concluding Remarks When performing LCA on wastewater treatment, one should be aware of the following more or less domain specific issues: • A typical functional unit is the treatment of one cubic metre of wastewater. Defining its composition/characteristics and/or using limit values for effluent is crucial for the reliability of the study in case of comparative studies • All life cycle stages have the potential of being significant, and therefore need to be considered even though decommissioning and disposal of infrastructure in many cases seems to be the least important for the impact profile • It is not generally possible in advance to consider some inventory data as unnecessary, but depending on the goal and scope large parts of the product system may be omitted (e.g


parts equal among alternatives) • None of the conventional impact categories (except stratospheric ozone depletion if emission of N2O is not included) should be excluded but eutrophication and ecotoxicity are in many cases among the dominating ones Fig. 34.2 By avoiding an obvious problem in one place we may induce a bigger problem somewhere else (sub-optimisation) (Larsen et al. 2010) H.F. Larsen


Furthermore, if the aim is to perform an environmental product declaration (EPD), one should consult the already existing product category rules (PCR) for “Wastewater collection and treatment services” (Environdec 2014). It should be noted that a future change in the relative importance of the different impact categories is likely due to coming improved inventory data and enhanced LCIA methodology including an increase in the number of characterisation factors or the use of, e.g. whole effluent toxicity (Larsen et al. 2009) regarding aquatic ecotoxicity. As discussed by Larsen et al. (2010), existing methodologies only cover a minor part of the possible toxicity impact of pollutants in wastewater due to lack of (good) characterisation factors. Including the specific toxic modes of action of, e.g. endocrine disrupters in a proper way, have the potential of increasing the importance of aquatic ecotoxicity significantly as shown in Larsen et al. (2009, 2010)


endocrine disrupters in a proper way, have the potential of increasing the importance of aquatic ecotoxicity significantly as shown in Larsen et al. (2009, 2010). Another example is the achievement of better inventory data on N2O and CH4 emissions from WWT which might change the importance of global warming drastically (Zang et al. 2015). Appendix See Table 34.1. INFLUENT Substance Concentration (mg/m3) 4-MBC DEHP Ibuprofen DeBDE Trimethoprim - - - - PLANT CONSTRUCTION Materials (kg) Life time of plant (years) MWWTP PLANT OPERATION Energy (kWh/d) Chemicals (kg/d) Emissions (kg/d) EFFLUENT Substance Concentration (mg/m3) 4-MBC DEHP Ibuprofen DeBDE Trimethoprim - - - - WWTT Wetlands Sand filtration Activated carbon Ozonation PLANT DISPOSAL Materials (kg) (disposal ways) Induced impact: (impact construction + impact operation + impact disposal) Avoided impact: (impact influent ÷ impact effluent) Avoided against induced impacts Sludge disposal or handling Fig


34.3 The principle of avoided against induced impact illustrated for micro-pollutant polishing, by different wastewater treatment technologies (WWTT), e.g. ozonation of wastewater from a municipal wastewater treatment plant (MWWTP) (Larsen et al. 2007) LCA of Wastewater Treatment


Table 34.1 Results of review on 22 LCA WWT cases (Larsen et al. 2007) Study on Impact categories included for LCIA Scoping, functional unit (FU) and life time Potential impact of effluent quantified by [micro-pollutants] Industrial wastewater: process water from extraction of oil and gas Sand filtration, ozonation and 20 other technologies GW, DAR, AC, NE/ET, POF + Material stage + Construction + Use stage  Transport  Waste treatment FU: Cleaning of 10,000 m3 wastewater to certain water quality levelsa Life time: 15 years No quantification [none] Vlasopoulos et al. (2006) Vlasopoulos (2004) Municipal wastewater, related to the WFD Sand filtration Membranbioreactor Ozonation GW, AC, NE/ET, POF, CHTS, CHTW, AHTA, CETS, CETF, AETF, CETSW + Material stage + Construction + Use stage  Transport + Waste treatmentb FU: Further treatment of 1 m3 wastewater treated conventionally, i.e


MBNC Life time: 20 years CETF, CETSW [Cd, Pb, Ni, NPE, LAS, DEHP, EE2, E2, PAH, (Zn, Cu, Hg, Cr)] Clauson-Kaas et al. (2006) Industrial wastewater: kraft mill bleaching wastewater Heterogeneous photocatalysis (PhC) GW, DAR, AC, NE/ET, POF, HT, CETF, OLD + Material stage  Constructiond + Use stage + transport  Waste treatment FU: Removal of 15% DOC from 1 m3 kraft pulp mill wastewater Life time: ? (laboratory experiment in Pyrex cells) No quantification [none] Muñoz et al. (2005) (continued) H.F. Larsen


Table 34.1 (continued) Study on Impact categories included for LCIA Scoping, functional unit (FU) and life time Potential impact of effluent quantified by [micro-pollutants] Industrial wastewater (synthetic)c Heterogeneous photocatalysis (PhC) GW, AC, NE/ET, POF, HT, CETF, OLD, LU, EC + Material stage + Constructiond + Use stage + Transport + Waste treatmente FU: Treatment of 1 m3 synthetic a-methyl-phenyl-glycine (MPG) solution (500 mg/L) in order to obtain an inherent biodegradable effluent Life time: 15 years Only for DOC, COD, Nammonia and N-nitrate [none] Muñoz et al


(2006) Industrial wastewater (synthetic)f Photo-Fenton (PhF) process GW, DAR, AC, NE/ET, POF, HT, CETF, CETS, CETSW, OLD + Material stage  Constructiond + Use stage + Transport + Waste treatmentg FU: Removal of 80% DOC from 1.2 L of 250 mg/L Cibacron RED FN-R synthetic wastewater from simulated batch dyeing Life time: ? (laboratory experiment in Pyrex cells) Only for DOC, COD, Nammonia and N-nitrate [none] García-Montaño et al. (2006) Municipal wastewater in the Netherlands (total sustainability in society) GW, DAR, AC, NE/ET, POF, HT, CETF, CETS, OLD, (discharge of + Material stage + Construction + Use stage COD, NE/ET, CETF Roeleveld et al. (1997) (continued) LCA of Wastewater Treatment


Table 34.1 (continued) Study on Impact categories included for LCIA Scoping, functional unit (FU) and life time Potential impact of effluent quantified by [micro-pollutants] Activated sludge FeCl3 (phosphor removal) Activated carbon COD), (production of normal, toxic and nuclear waste) + Transport ( Waste treatment) FU: 24,000,000 p.e


(not defined) Life time: Not defined [Hg, Cu, Cd, Zn, organic phosphorus containing compounds] Municipal wastewater in Australia (focus on disinfection and nutrients) UV Chlorination/dechlorination by chlorine or hypochlorite Dissolved air flotation GW, AC, NE/ET (freshwater and marine), POF, HT, CETS, CETF, CETSW + Material stage  Construction + Use stage + Transport ( Waste treatment) Case study I: FU: Disinfection (measured by CFU) of 1000 m3 tertiary treated wastewater (chlorine residual less than 0.01 mg/L) Case study II: fu: 1000 m3 wastewater yielding 714 kg biosolids (25% solids, anaerobic digestion) or 1250 kg biosolids (18% solids, aerobic digestion) Life time: Not defined Case study I: CFU-measurements Case study II: At least CETF Sludge: (At least CETS, but not specified) [common concentrations of metals, pesticides and chlordane assumed] Beavis and Lundie (2003) Municipal wastewater in Australia (focus on recycling for irrigation application) GW, NE/ET, HT, CETS, CETF,


concentrations of metals, pesticides and chlordane assumed] Beavis and Lundie (2003) Municipal wastewater in Australia (focus on recycling for irrigation application) GW, NE/ET, HT, CETS, CETF, CETSW, salinisation + Material stage + Construction + Use stage + Transport Effluent as irrigation water, i.e


emission to soil: NE/ET, HT, CETS, CETF, CETSW, salinisation Tangsubkul et al. (2005) (continued) H.F. Larsen


Table 34.1 (continued) Study on Impact categories included for LCIA Scoping, functional unit (FU) and life time Potential impact of effluent quantified by [micro-pollutants] Ozonation + continuous microfiltration (CMF) Membrane bioreactor (MBR) + reverse osmosis (RO) ( Waste treatment) FU: 1000 m3 recycled wastewater meeting national threshold limits for irrigation of sensitive crops (incoming raw sewage of “medium” strength, i.e. 500 mg/L, 40 mg/L tot-N, etc.) Life time: Not defined Sludge as biosolids, i.e. emission to soil: NE/ET, HT, CETS, CETF, CETSW [besides mentioning metals no specification] Municipal wastewater in Spain (focus on environmental performance, i.e


emission to soil: NE/ET, HT, CETS, CETF, CETSW [besides mentioning metals no specification] Municipal wastewater in Spain (focus on environmental performance, i.e. removal of organic matter and hotspots) Only primary and secondary treatment GW, DAR, AC, NE/ET, POF, HT, CETS, OLD + Material stage  Construction + Use stage + Transport + Waste treatment FU (1): 53,349 m3/day (humid season) FU (2): 49,214 m3/day (dry season) Life time: Not defined NE/ET, (HT) Sludge: CETS, HT (GW, DAR, AC, NE/ET, POF, OLD) [Cd, Cr, Cu, Hg, Ni, Pb and Zn] Hospido et al. (2004) Municipal wastewater (focusing on energy consumption and reuse potential) Constructed wetlands, UV, Sequencing batch reactor “No impact categories”, i.e


(2004) Municipal wastewater (focusing on energy consumption and reuse potential) Constructed wetlands, UV, Sequencing batch reactor “No impact categories”, i.e. only comparison of removal efficiency (BOD, Tot-N and Tot-P), nutrient recycling and energy consumption  Material stage  Construction + Use stage  Transport (+ waste treatment) FU: 1 m3 Life time: Not defined No quantification [none] Brix (1999) (continued) LCA of Wastewater Treatment


Table 34.1 (continued) Study on Impact categories included for LCIA Scoping, functional unit (FU) and life time Potential impact of effluent quantified by [micro-pollutants] Municipal wastewater (focusing on small-scale treatment) Constructed wetland Besides LU (included as m2 occupied by plant) impact categories are only included as CO2 emitted, energy consumption and solid emission (i.e. waste) + Material stage + Construction + Use stage + Transport  Waste treatment FU: 1 p.e. (0.2 m3/day) treated to acceptable discharge standards, i.e. 10 mg/L BOD, 25 mg/L SS and 5 mg/L ammonia: Scales: 12, 60 and 200 p.e. Life time: 10 years No quantification [none] Dixon et al


(0.2 m3/day) treated to acceptable discharge standards, i.e. 10 mg/L BOD, 25 mg/L SS and 5 mg/L ammonia: Scales: 12, 60 and 200 p.e. Life time: 10 years No quantification [none] Dixon et al. (2003) Sludge form municipal wastewater plant (focus on hotspots and process design) Supercritical water gasification (SCWG) GW, DAR, AC, NE/ET + Material stage  Construction + Use stage + Transport (+ Waste treatment) FU: 1 ton DM undigested sewage sludge (3% DM equals 33 ton wet sludge) Life time: Not defined Effluent from SCWG plant via WWTP: NE/ET [none] Gasafiet al. (2004) Industrial wastewater, brewery (focus on operation conditions for membrane filtration) GW, NE/ET, HT, CETS, CETF, CETSW, POF + Material stage + Construction + Use stage + Transport ( Waste treatment) No quantification (assumed to be equal for all scenarios) [none] Tangsubkul et al. (2006) (continued) H.F. Larsen


Table 34.1 (continued) Study on Impact categories included for LCIA Scoping, functional unit (FU) and life time Potential impact of effluent quantified by [micro-pollutants] FU: 1000 m3/day (produced from incoming settled effluent water from a sequencing batch reactor (SBR), 40 mg/L TSS and permeate turbidity’s of <1 NTU) Life time: 20 years (membrane 5 years) Municipal wastewater (focus on physical-chemical pre-treatment) activated sludge, Pre-precipitation, Flotation No characterization only inventory (energy balance, final sludge production, effluent quality, use of chemicals, space requirements, i.e. LU)  Material stage  Construction + Use stage ( Transport) ( Waste treatment) FU: 7,120,000 m3/year (19,500 m3/day) (treated to acceptable discharge standards, i.e. <10 mg/L BOD, <50 mg/L COD, <10 mg/L Tot-N, <1 mg/L Tot-P, <10 mg/L SS) Life time: Not defined No quantification (assumed to be equal for all scenarios) [none] Mels et al


<10 mg/L BOD, <50 mg/L COD, <10 mg/L Tot-N, <1 mg/L Tot-P, <10 mg/L SS) Life time: Not defined No quantification (assumed to be equal for all scenarios) [none] Mels et al. (1999) Sludge form municipal wastewater plant (focus on final disposal), Incineration Agricultural land application GW, NE/ET, HT, CETS, CETF, CETSW, POF, DAR + Material stage  Construction + Use stage + Transport (+ Waste treatment) No quantification For sludge: GW, NE/ET, HT, CETS, CETF, CETSW, POF, DAR, AC Suh and Rousseaux (2002) (continued) LCA of Wastewater Treatment


Table 34.1 (continued) Study on Impact categories included for LCIA Scoping, functional unit (FU) and life time Potential impact of effluent quantified by [micro-pollutants] Landfill FU: 1 ton DM mixed sewage sludge Life time: Not specified but more than 30 years mentioned in argumentation for leaving out construction [Substances and concentrations according to threshold limits in French regulation on leachate from landfills and content of sludge for agricultural land application. Only metals included for land application. No further specification] Predominantly municipal wastewater sludge (focusing on hot spots and energy consumption) Supercritical water oxidation GW, POF, DAR For EPS2000: Human health, biological diversity, ecosystem production, resources and aesthetic values) For EcoIndicator99: Human health, ecosystem health and resources + Material stage  Construction + Use stage + Transport ( Waste treatment) FU: 1000 kg wet sludge (7% TS) treated at specific plant


Water effluent and gases assumed to have no adverse impacts Life time: Not defined No quantification (assumed to have no adverse impact for both water effluent and wet solid effluent) [none] Svanström et al. (2004) Sludge form municipal wastewater plant (focus on energy and global warming) Agricultural land application Incineration Wet oxidation GW + Material stage  Construction + Use stage + Transport (+ Waste treatment) FU: 1000 kg DM sludge disposed No quantification [none] Houillon and Jolliet (2005) (continued) H.F. Larsen


Table 34.1 (continued) Study on Impact categories included for LCIA Scoping, functional unit (FU) and life time Potential impact of effluent quantified by [micro-pollutants] Pyrolysis Incineration in cement kilns Landfill (wet sludge: 0.3% dry solid content) Life time: Not defined Municipal wastewater treatment plant in Denmark (focus on hot spots) Activated sludge: nitrification/denitrification, phosphor removal, sludge incineration GW, AC, NE/ET, Persistent toxicity ((CETS + CETF + CHTS + CHTW)/ 4), AHTA, AETF, slag and ashes + Material stage  Construction + Use stage ? Transport ( Waste treatment) FU: 29,800,000 m3 wastewater treated (i.e. 1 year, 1998) Life time: Not defined NE/ET, Persistent toxicity, AETF [Pb, Hg, Cu, Zn, Cr, Ni, Cd, Se, As, dioxin] Clauson-Kaas et al


1 year, 1998) Life time: Not defined NE/ET, Persistent toxicity, AETF [Pb, Hg, Cu, Zn, Cr, Ni, Cd, Se, As, dioxin] Clauson-Kaas et al. (2001) Sludge form municipal wastewater plant (focus on post-treatments) Anaerobic digestion + agricultural land application Incineration Pyrolysis GW, DAR, AC, NE/ET, POF, HT, CETS, OLD + Material stage  Construction + Use stage + Transport (+ Waste treatment) FU: 1000 kg DM sludge managed (thickened mixed: 1% dry matter) Life time: Not defined No quantification For sludge: GW, DAR, AC, NE/ET, POF, HT, CETS, OLD [Cd, Cr, Cu, Hg, Ni, Pb and Zn] Hospido et al. (2005) (continued) LCA of Wastewater Treatment


Table 34.1 (continued) Study on Impact categories included for LCIA Scoping, functional unit (FU) and life time Potential impact of effluent quantified by [micro-pollutants] Municipal wastewater (focus on energy consumption and sludge production) Activated sludge: nitrification/denitrification, biological P-removal No characterization only inventory (oxygen requirements, sludge production and auxiliaries requirement/production (methanol, FeCl3 and methane)  Material stage  Construction + Use stage  Transport  Waste treatment FU: 2750 m3/day wastewater treated (fixed discharge levels: <15 mg/L BOD5, <15 mg/L TSS, <0.5 mg N/l ammonia, <10 mg/L Tot-N, <1 mg/L Tot-P Life time: Not defined No quantification (assumed to be equal for all scenarios) [none] Bagley (2000) Municipal wastewater (focus on small-scale WWTPs) Activated sludge No (quantitative) characterization only inventory (energy consumption, material use, waste, air emission from energy production—especially CO2 (but also


(focus on small-scale WWTPs) Activated sludge No (quantitative) characterization only inventory (energy consumption, material use, waste, air emission from energy production—especially CO2 (but also SO2, CO and more) + Material stage + Construction + Use stage + Transport (+ Waste treatment) FU: 15 years of functioning, i.e


1,095,000 m3 (compliance of effluent and sludge (agricultural application) with regulatory framework) Life time: 15 years No quantification (assumed to be equal for all scenarios [none] Emmerson et al. (1995) (continued) H.F. Larsen


Table 34.1 (continued) Study on Impact categories included for LCIA Scoping, functional unit (FU) and life time Potential impact of effluent quantified by [micro-pollutants] Municipal wastewater (focus on change from conventional central WWTPs to local systems), sand filter, filter bed, urine separation No specification, only inventory data used in detailed impact assessment, i.e. energy consumption; air emission of CO2, methane, SO2 etc.; water emission of N-tot, P-tot, BOD etc.; waste such as sludge, hazardous waste etc. + Material stage + Construction + Use stage + Transport (+ Waste treatment) FU: The treatment of wastewater from 1 p.e. during 1 year. p.e. not defined in paper Life time: Stated that this is taken into account (full technical life time for each component) but not specified in paper No direct specification in paper of impact categories but at least assessed on basis of COD, BOD, N-tot and P-tot. [No specification] Tillman et al


(1998) MWWTP Municipal wastewater treatment plant; WWT Wastewater treatment; ST Sludge treatment; WFD Water framework directive (EC 2000, 2001); MBNC Mechanical (settlement)/biological/nitrification-denitrification/chemical phosphate removal; GW Global warming; POF Photochemical ozone formation; AC Acidification; NE/ET Nutrient enrichment/eutrophication; DAR Depletion of abiotic resources (sometimes divided into mineral resources and fossil energy resources); OLD Ozone depletion; LU Land use; EC (non-renewable) Energy consumption; HT Human toxicity; CHTS Chronic human toxicity soil; CHTW Chronic human toxicity water; AHTA Acute human toxicity air; CETS Chronic ecotoxicity soil; CETF Chronic ecotoxicity fresh water; AETF Acute ecotoxicity fresh water; CETSW Chronic ecotoxicity salt water; DOC Dissolved organic carbon p.e.: “wastewater” person equivalents; CFU Colony forming units; NTU Nephelometric turbidity units; + included;  not included aRelated to end-use categories (irrigation


DOC Dissolved organic carbon p.e.: “wastewater” person equivalents; CFU Colony forming units; NTU Nephelometric turbidity units; + included;  not included aRelated to end-use categories (irrigation of wheat, cotton, barley, alfalfa, sorghum, rhodes, citrus and for industrial use ‘cooling system feed’ and ‘boiler feed’) bTreatment of waste from decommissioning of equipment included


For sludge only sludge incineration as disposal included cSynthetic solution of a-methyl-phenyl-glycine (a pharmaceutical precursor) dSame type of UVA lamp used in all cases—only differences in running time for achieving 15% reduction in DOC eTransport and land filling of used catalyst included. For sludge only sludge incineration as disposal included fSynthetic solution of the reactive azo dye Cibacron Red FN-R (C.I. Reactive Red 238) gFor sludge: dewatering, thickening and finally deposited at a landfill. Leachate (COD, BOD7, NO3 −and NH4 +) and gas emission (CO2, CH4, NOx and NH3) estimated by ORWARE. 50% capture of gas (burned) and 90% capture of leachate (treated in WWTP) assumed LCA of Wastewater Treatment


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Author Biography Henrik Fred Larsen long term experience as both a researcher and a consultant with environmental sustainability assessment and environmental impact assessment (RA of chemicals, cleaner technology assessments). Contributed to UNEP/SETAC working groups on LCA methodology. Main LCIA interest is ecotoxicity impacts. H.F. Larsen


Chapter 35 LCA of Solid Waste Management Systems Ioannis Bakas, Alexis Laurent, Julie Clavreul, Anna Bernstad Saraiva, Monia Niero, Emmanuel Gentil and Michael Z. Hauschild Abstract The chapter explores the application of LCA to solid waste management systems through the review of published studies on the subject. The environmental implications of choices involved in the modelling setup of waste management systems are increasingly in the spotlight, due to public health concerns and new legislation addressing the impacts from managing our waste. The application of LCA to solid waste management systems, sometimes called “waste LCA”, is distinctive in that system boundaries are rigorously defined to exclude all life cycle stages except from the end-of-life. Moreover, specific methodological challenges arise when investigating waste systems, such as the allocation of impacts and the consideration of long-term emissions


Moreover, specific methodological challenges arise when investigating waste systems, such as the allocation of impacts and the consideration of long-term emissions. The complexity of waste LCAs is mainly derived from the variability of the object under study (waste) which is made of different materials that may require different treatments. This chapter attempts to address these challenges by identifying common misconceptions and by providing methodological guidance for alleviating the associated uncertainty. Readers are also provided with the list of studies reviewed and key sources for reference to implement LCA on solid waste systems. I. Bakas (&)  A. Laurent  M. Niero  M.Z. Hauschild Division for Quantitative Sustainability Assessment, Department of Management Engineering, Technical University of Denmark, Kongens Lyngby, Denmark e-mail: ioannis.bakas@bobagroup.dk J


Hauschild Division for Quantitative Sustainability Assessment, Department of Management Engineering, Technical University of Denmark, Kongens Lyngby, Denmark e-mail: ioannis.bakas@bobagroup.dk J. Clavreul Residual Resources Engineering, Department of Environmental Engineering, Technical University of Denmark, 2800 Kongens Lyngby, Denmark A.B. Saraiva SAGE/COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil E. Gentil Copenhagen Resource Institute, Copenhagen K, Denmark © Springer International Publishing AG 2018 M.Z. Hauschild et al. (eds.), Life Cycle Assessment, DOI 10.1007/978-3-319-56475-3_35


35.1 Over the past century, both material use and waste generation have been constantly increasing in quantity and complexity at an unsustainable pace. Globally, waste generation from all sources amounts to around 17 billion tonnes, and is expected to reach 27 billion tonnes by 2050 (Karak et al. 2012). Municipal waste generation has also been increasing and, in Europe, only a few examples exist of decoupling municipal waste generation from economic growth, although recently efforts towards waste prevention are undertaken (EEA 2014). Currently, it is estimated that about 1.3 billion tonnes of municipal solid waste is generated worldwide and trends show that this number will increase in the future due to population increase, urbanisation and socioeconomic development of low-income populations (Hoornweg and Bhada-Tata 2012). The organised and systematic collection and central treatment of waste originally begun for reasons pertaining to public health and safety, e.g


The organised and systematic collection and central treatment of waste originally begun for reasons pertaining to public health and safety, e.g. for combating diseases or reducing odours in public space. Only in recent years has waste been associated with environmental concerns, such as climate change, toxicity to humans and ecosystems or resource depletion. The links between waste management activities and emissions that cause specific environmental impacts have now been proven, e.g.: methane emissions from landfills contribute to climate change, halocarbons in discarded cooling systems or in-use foams contribute to stratospheric ozone depletion, while insufficient or inefficient recycling leads to increased resource depletion. In light of these environmental concerns, pieces of legislation around the world have attempted to regulate waste management activities and to promote more sustainable systems for waste handling (e.g. Directive 2008/98/EC)


Directive 2008/98/EC). The regulations may address technical issues, such as quality standards for recyclables or management issues, such as the promotion of recycling and the reduction of landfilling. In recent years, the role of waste as a pool for material resources extraction has been acknowledged and waste is now more and more viewed as a valuable resource instead of unwanted materials. Along these lines, new legislation and initiatives attempt to integrate waste management into a new vision of a circular economy, with increased quantity and quality of recycling. In order to conform with legislation, but also to tackle significant environmental considerations, and motivated by issues around the effectiveness and cost of waste treatment, public authorities have started designing integrated management systems that comprehensively address waste generation and that are differentiated according to waste source or waste material (fraction)


Although, there are relatively few options to consider regarding waste treatment (the three main ones being recycling —or biological treatment for organic waste, incineration and landfilling), their combinations for each waste type (defined by source of waste) and waste fraction are numerous. Therefore, the complexity of integrated waste management systems has become significant, highlighting the need to adopt systems approaches.


It is thus necessary to use appropriate tools that address activities related to waste management in a systematic and comprehensive manner. LCA can credibly assess the full environmental consequences of waste management, in particular accounting for the interlinks between the waste sector and other sectors of the economy. For example, the energy produced in an incineration plant or processed scrap metals feed respectively into the energy and metal manufacturing sectors. Life cycle thinking helps map all exchanges with other sectors and estimate environmental impacts accurately. LCA applied to waste management systems is often termed “waste LCA” as it includes only the End-of-Life phase of a product. Waste LCAs are mostly of a comparative nature (e.g. assessing different treatment options for a material or a waste type) and thus, the previous life cycle stages of a material/product in question can be omitted. This is also called the “zero-burden assumption” (Ekval et al. 2007)


This is also called the “zero-burden assumption” (Ekval et al. 2007). In this respect, waste LCAs use different system boundaries assumptions than product LCAs. Another particularity of waste LCAs is that waste treatment in many cases happens locally, close to the waste source. This fact facilitates the collection of site-specific data and thus increases the geographical resolution of the assessment. 35.1.1 Definition and Scope A straightforward and descriptive definition of waste is as follows: “Waste is a left-over, a redundant product or material of no or marginal value for the owner and which the owner wants to discard” (Christensen 2011). In this chapter, only management of solid waste is addressed. Although, several definitions of solid waste exist, it is defined here as waste, which is neither water (wastewater) nor airborne (flue gases) (Christensen 2011). For application of LCA to wastewater management systems, see Chap. 34


For application of LCA to wastewater management systems, see Chap. 34. Towards their end-of-life, most goods and commodities eventually become discarded and typically enter solid waste management systems. The waste product thus goes through a number of activities, which can be divided in four main phases: (1) generation, (2) collection and transport, (3) treatment, and (4) recycling, utilisation or landfilling, illustrated in Fig. 35.1 (Christensen 2011). Within the domain of waste management, the primary use of LCA is to inform about the environmentally preferable option when decision-making or policy-making communities evaluate different alternatives of solid waste management in a specific region. For instance when assessing the impact of integrating recycling in an existing municipal waste management system based on landfilling and incineration


For instance when assessing the impact of integrating recycling in an existing municipal waste management system based on landfilling and incineration. The applications of LCA encompassed in this chapter are therefore service-oriented, focusing on assessments of processes, technologies and systems handling solid waste, and do not consider upstream activities prior to waste generation. The uses of specific types of waste as feedstock for manufacturing products are only discussed when describing the environmental offsets from LCA of Solid Waste Management Systems


material recycling and energy recovery, which can be credited to the assessed waste management systems (see Sect. 8.6.1). 35.1.2 Solid Waste Management Technologies and Practices The technologies and practices involved in a solid waste management system can be arranged into distinct system stages. The collection and transport stages refer to the collection of waste from its source of generation, which may include a large number of fractions (e.g. households) or fewer (e.g. industrial waste) depending on the waste type. Waste is then transported to central facilities for processing and/or treatment. The collection of waste may take place either as mixed waste or by targeting specific fractions that are separated at source (e.g. paper and cardboard destined to recycling). The type of collection system usually depends on the further treatment, e.g. for recycling waste is usually separated at the source in order to increase the homogeneity of the collected material


The type of collection system usually depends on the further treatment, e.g. for recycling waste is usually separated at the source in order to increase the homogeneity of the collected material. The treatment stage refers to the processing of waste in order to modify its physical or chemical properties. Physical treatment may involve shredding and compacting of waste in order to reduce its volume. On the other hand, mechanical and biological treatment (MBT) facilities and thermal plants (such as incineration) mainly affect the chemical properties of waste, aiming at reducing its volume and environmental hazardousness. The Recycling-Utilisation-Landfilling stage includes all final treatment options that follow the waste processing stage. The state and composition of waste determines the suitability of each of the alternative final options. Homogenous materials are suitable for recycling or utilisation (e.g


The state and composition of waste determines the suitability of each of the alternative final options. Homogenous materials are suitable for recycling or utilisation (e.g. composting of organic waste), while GeneraƟon CollecƟon & Transport Treatment Recycling – UƟlisaƟon - Landfilling Mechanical Biological Thermal Recycling Landfilling UƟlizaƟon Secondaryproducts (incl. materials, energy) Fig. 35.1 The four phases of solid waste management systems (based on Christensen 2011)


mixed waste usually ends up in landfills. This stage includes a large variety of technologies for recycling waste, composting (central composting or anaerobic digestion) and landfilling (engineered landfills, collection of landfill gas and leachate). The selection of a treatment technology (but also the design of an integrated waste management system in general) has direct implications for the environmental impacts caused. Since 1980s many countries around the world have established a waste hierarchy to prevent or limit the impacts of waste management operations on the natural resources, ecosystems and human health. The hierarchy (see Fig. 35.2) has been included in the EU legislation as a legally binding framework for designing or improving a waste management system (see Directive 2008/98/EC or the EU Waste Framework Directive). The hierarchy is based on a “rule of thumb” regarding the environmental ranking of waste treatment options


The hierarchy is based on a “rule of thumb” regarding the environmental ranking of waste treatment options. Deviations from the hierarchy, according to the legislation are accepted if justified by means of appropriate tools such as LCA. Waste prevention is mentioned as the first priority in the waste hierarchy. The assessment of prevention in LCA terms is fundamentally different compared to the other steps of the hierarchy as it involves upstream processes of a waste material, thus extending the system boundaries. 35.1.3 Main Environmental Concerns The recent shift in the perception of waste as a resource is reflected in the waste hierarchy. Re-use and recycling are the highest ranking treatment options. The ambition of the legislators is to integrate waste management in a circular economy structure, where waste activities deliver recovered resources and close loops in material cycles


The ambition of the legislators is to integrate waste management in a circular economy structure, where waste activities deliver recovered resources and close loops in material cycles. The reduction of the depletion of natural resources, such as fossil fuels, metals, as well as nitrogen and phosphorus is, therefore, a priority for waste management operations. The main environmental concerns related to waste management, besides resource efficiency, are: Fig. 35.2 Waste hierarchy indicating a scale of environmental preference for the five main treatment alternatives (EU-JRC 2011) LCA of Solid Waste Management Systems


• Climate change and the related energy security issue. Greenhouse gases are emitted from various processes in waste management such as transport or landfilling. A major opportunity for climate change mitigation lies in the avoided emissions through waste materials recycling in a system expansion approach (see Sect. 8.6.1). Climate benefits also arise through waste incineration, where electricity and/or heat is produced locally, substituting other (usually fossil) sources of energy. • Toxic emissions (to ecosystems and to humans) related to (1) processing waste (e.g. incineration) and (2) the eventual disposal of waste (e.g. in landfills). Toxic emissions also have a temporal aspect, since they may be released at a very slow rate (e.g. from landfills) and create problems at a much later time than when the waste deposition takes place


Toxic emissions also have a temporal aspect, since they may be released at a very slow rate (e.g. from landfills) and create problems at a much later time than when the waste deposition takes place. Different impacts are related to different waste technologies: • Landfilling: leachate created by water infiltrating the waste mass and not collected may pollute the surrounding soil and groundwater with organic and inorganic (metals) pollutants. Landfill gas created by the anaerobic degradation of organic matter contains methane, a strong greenhouse gas. • Incineration: airborne emissions can affect local ecosystems. CO2 is emitted from the incineration of carbon (e.g. fossil carbon in waste plastics). Bottom ash contains significant concentrations of toxic heavy metals that can potentially leach after its deposition. Benefits from incineration depend strongly on the local energy mix, substituted by the energy delivered by incineration


Benefits from incineration depend strongly on the local energy mix, substituted by the energy delivered by incineration. • Recycling: recycling operations are linked mainly to energy use for processing the waste and chemicals used for recovery operations (e.g. de-inking of paper). The complexity and variety of environmental issues arising from waste management calls for a comprehensive approach such as LCA that addresses all potential environmental impacts (e.g. JRC 2011). 35.2 LCA Applied to Solid Waste Management Systems (SWMS) LCA is increasingly used to assess solid waste management systems. Two comprehensive review articles were published in 2014 on how LCA is applied on waste systems and which issues require special attention due to particularities in the field of waste LCA: 1. Laurent A, Bakas I, Clavreul J, Bernstad A, Niero M, Gentil E, Hauschild MZ, Christensen TH (2014) Review of LCA studies of solid waste management systems—Part I: Lessons learned and perspectives


Laurent A, Bakas I, Clavreul J, Bernstad A, Niero M, Gentil E, Hauschild MZ, Christensen TH (2014) Review of LCA studies of solid waste management systems—Part I: Lessons learned and perspectives. Waste Management 34 (2014) 573–588


2. Laurent A, Clavreul J, Bernstad A, Bakas I, Niero M, Gentil E, Christensen TH, Hauschild MZ (2014) Review of LCA studies of solid waste management systems—Part II: Methodological guidance for a better practice. Waste Management 34 (2014) 589–606 The review and its results provide a useful background for describing the operational aspects of LCA applied to solid waste management systems. The authors analysed a wide range of peer-reviewed scientific articles and reports for their methodological approach to the LCA and contrasted it with the guidelines of the ILCD Handbook (JRC 2011). Key findings of the review are presented in this section, but the reader is referred to the original papers for a more in-depth analysis. 35.2.1 Review Process and Focus Areas The selection of the studies was performed by choosing studies in English, peer-reviewed and referring to solid waste, excluding sewage sludge


35.2.1 Review Process and Focus Areas The selection of the studies was performed by choosing studies in English, peer-reviewed and referring to solid waste, excluding sewage sludge. The results of the review were summarised into a table, a version of which is presented in Table 35.3. The original version of the table included all elements of the review, namely: 1. References/sources 2. Type of LCA studies (public report, scientific article...) 3. Standard compliance (e.g. None, ISO, ILCD, ...) 4. Goals (intended use/users of study) 5. Context situation (situation A, B, C1, C2) 6. Object(s) of study considered/compared 7. Type of waste (e.g. only organic waste included in study) (goal/scope) 8. Defined functional unit 9. System boundaries: Included/Excluded processes; included phases within the MSW based on intro definition (e.g. collection, incineration...). 10. Impact coverage (e.g. GW only) 11. Geographical coverage 12. Time scope (for validity of LCA results) 13


collection, incineration...). 10. Impact coverage (e.g. GW only) 11. Geographical coverage 12. Time scope (for validity of LCA results) 13. Date(s) of the collected primary (specific) data and secondary data (database) (to identify data representativeness in time, e.g. old/up-to-date) 14. Handling of multifunctional processes: approaches (e.g. allocation or syst. expansion) and type of data used to solve them (e.g. marginal/average data) 15. LCA software/Databases used for secondary data 16. LCIA method used 17. Use of normalisation and/or weighting (incl. method description for weighting if any) 18. Use of sensitivity analysis: what key parameters were identified and changed? LCA of Solid Waste Management Systems


19. Main findings (e.g. significant impacts, comparative performances of 2 alternatives) ) also in relation to goals is possible 20. Identified method shortcomings (incl. “solutions” or “actions taken” for each identified problem) 21. Identified modelling shortcomings (incl. “solutions” or “actions taken” for each identified problem) 22. Identified data uncertainties (e.g. which data are difficult to collect...) (incl. “solutions” or “actions taken” for each identified problem) Table 35.3 in “Appendix” only includes some descriptive elements of the review, in order to inform about the external characteristics and variations of the reviewed studies. The more elaborate LCA elements of the review are included in Sects. 35.2.2–35.2.6 and 35.3. In these subsequent sections, the most important review findings are listed and methodological considerations are analysed in order to outline how a credible LCA should be applied on solid waste systems


The majority of the studies reviewed (around 94%) were scientific articles published in peer-reviewed journals. Most of the studies claimed compliance with the ISO standards, namely that the methodology proposed by ISO was followed by the studies. In fact, many studies did not actually comply with the ISO provisions, despite their claim to do so. The review revealed that only about one out of five studies actually complied with the ISO standards. This is because of a number of elements (or combinations of elements) missing that are essential in the ISO standards provisions. In the following sections, these omissions that lead to deviations from the standards are described more in detail. 35.2.2 Goal According to the ISO standards, the goal definition refers to the intended uses of the LCA case study and its potential users (ISO 2006)


35.2.2 Goal According to the ISO standards, the goal definition refers to the intended uses of the LCA case study and its potential users (ISO 2006). Moreover, the ILCD Handbook, launched by EU’s Joint Research Centre, specifies the definition even further into six aspects, namely the intended applications, limitations in using the results, drivers for performing the study, target audience, disclosure to the public and the commissioner of the study (EC 2010a, b) (see also Chap. 7). Since the majority of the studies reviewed come from scientific journals, they are rarely commissioned directly by an entity intending to use the results for decision support (some articles are based on larger reports that might be more complete and support decisions). This means that the goal definition is often out of focus for the study authors, which do not refer to potential users as the ISO standards require


This means that the goal definition is often out of focus for the study authors, which do not refer to potential users as the ISO standards require. Many of the studies only describe the intended use of the study, while many others do not have a specific purpose except for analysing methodological aspects of waste LCAs or tackling specific issues. Omitting the adequate description of the goal has a profound effect on the interpretation of the studies by the readers. The absence of context when considering the results might lead to overlooking the weaknesses of


the study (such as the inclusion of only a small part of impact categories) or unjustified generalisations (e.g. generalising the environmental superiority of a treatment option over another when the results of the study refer to specific local conditions). These identified shortcomings might also apply to LCA studies from other technology fields published as scientific articles. Another consolidated reference to the intended use of the study and the size of the consequences of the study’s results is the decision context situation. The ILCD Handbook describes four cases of decision contexts: A (micro-level decision support), B (meso/macro-level decision support), C1 and C2 (accounting with no decision support) (see also Sect. 7.4). Most of the reviewed studies belong to situation B, followed by A. This was expected as normally the investigation of waste management systems happens on a larger scale (national, regional or municipal geographical units)


This was expected as normally the investigation of waste management systems happens on a larger scale (national, regional or municipal geographical units). Situation A refers to studies mainly assessing specific technologies or comparing them to others. However, although the classification of the study into a decision context situation helps put the results in perspective, none of the reviewed studies explicitly referred to a context situation. 35.2.3 Scope Definition The object of the reviewed studies varies greatly among the studies. Different waste systems or parts of systems were assessed, while referring to various types of waste. Figure 35.3 shows the amount of studies investigating each distinct aspect of a solid waste management system. The traditional treatment options, as well as collection and transport feature as the most popular topics for investigation, while emerging technologies such as thermal and some forms of biological treatment are starting to gather attention


Due to the difficulty in framing LCAs on waste prevention in appropriate system boundaries or the lack of focus on prevention by decision-makers, only two studies were found that deal with this topic. The functional unit in waste LCAs is expressed mainly according to four types: (1) unitary, (2) generation-based, (3) input-based and (4) output-based (see Box 35.1. with examples). Box 35.1. Examples of Functional Units Used in the Reviewed Studies 1. Unitary: “management of 1 tonne of municipal solid waste” 2. Generation-based: “Management of the waste generated in Copenhagen municipality” 3. Input-based: “100 tonnes of waste entering a waste incineration plant” 4. Output-based: “Production of 500 kWh from a dedicated incineration plant for industrial waste” LCA of Solid Waste Management Systems


Although, the definition of a functional unit is relatively straightforward, in many cases LCA practitioners neglect to specify an adequate functional unit, as shown in Fig. 35.4. It also seems that a unitary functional unit is by far preferred in the reviewed studies reflecting a more theoretical or methodological goal for the LCA or potentially a confusion of the functional unit with the reference flow of the system. The functional unit refers to a quantified description of the primary function of the system under study, while the reference flow refers to the physical flow required for the system to fulfil its function (see also Sect. 8.4). The use of a reference flow in the cases, where the functional unit is defined as unitary neglects the appropriate description of the functional unit in several aspects, such as the composition of the waste that is treated


As already mentioned, the system boundaries in waste LCAs are set in order to include only the end-of-life stage of the products’ life cycles. This is justified as waste LCAs are normally of comparative nature and it is therefore assumed that for the waste in question in each case, the previous life cycle stages are identical for the systems compared and therefore can be omitted. Similar to all types of LCAs, a central issue in defining system boundaries is the inclusion of capital goods, i.e. the construction and use of infrastructure, plant facilities and equipment used in the assessed system. 62% of the studies reviewed did not mention the capital goods at all, 12% included them and 26% of the studies excluded them with justification. Collection and transport processes are also occasionally excluded from the system boundaries, due to their minor contribution to the overall impact categories’ Fig. 35.3 Waste management technologies assessed in the studies


35.3 Waste management technologies assessed in the studies. Many studies investigate more than one aspect of the system


results. 16% of studies chose to exclude such processes due to reasons such as their lack of relevance or identical contribution to all scenarios assessed. Another set of processes that is often excluded from the system boundaries refers to secondary products (i.e. valuable outputs such as digestate from anaerobic digestion) and secondary waste stemming from waste treatment processes (e.g. air pollution control ashes from incineration). Secondary products and secondary waste are only included in 44 and 53% of the reviewed studies respectively. Regardless of the impact of including/excluding such processes from the system boundaries, it is always recommended to address the issue transparently and in a case-by-case manner, as different systems with varying characteristics may justify opposite decisions regarding the definition of system boundaries. The literature review also analysed LCA practitioners’ preferences with respect to included impact categories


The literature review also analysed LCA practitioners’ preferences with respect to included impact categories. Figure 35.5 demonstrates their preference for already established, traditional impact categories. Almost all reviewed studies included, at least partially, non-toxic impact categories, while toxicity was considered by more than half of the studies. Resource impact categories such as land and water use were underrepresented, but as research in these fields advances, it is likely that they will become more central in future waste LCA evaluations. However, it should be underlined that incomplete assessments, as in the majority of the reviewed studies, may reduce credibility of the results: maybe the burden is shifted to one of the impact categories that is not assessed. In order to better understand the characteristics of the reviewed studies, their distribution over space and time offers valuable insights


In order to better understand the characteristics of the reviewed studies, their distribution over space and time offers valuable insights. Figure 35.6 shows the geographical distribution of the studies with European countries and the US dominating the map. China, Australia and Japan follow in number of studies assessing waste produced in these countries. It is evident from the map that Africa and large parts of Asia are underrepresented in the waste LCA applications. The time evolution of the studies as well as their distribution among the main scientific journals are shown in Fig. 35.7. As expected, the number of LCAs performed increases with time, alongside with the popularity of the tool and its Unitary Generation-based Output-based Input-based Others Unspecified Proportion of studies 0% 10% 20% 30% 40% 50% 60% Fig. 35.4 Proportions of studies for each class of functional unit


35.4 Proportions of studies for each class of functional unit. A number of studies are classified into more than one category, including studies, for which the functional unit was only implicitly mentioned LCA of Solid Waste Management Systems


establishment as a mainstream evaluation method for waste management systems. The figure also shows the adoption of important European legislation to illustrate the influence of legislative measures on the intensity of the research on waste management’s environmental impacts. Non-toxic impacts Toxic impacts Non-renewable resources Land use Water use Proportions of studies 0% 20% 40% 60% 80% 100% Complete assessment All non-toxic but ozone depletion Partial assessment Not included Fig. 35.5 Proportions of impacts covered in the assessments. Non-toxic impacts include climate change, stratospheric ozone depletion, acidification, photochemical ozone formation, eutrophication. Toxic impacts include aquatic and terrestrial ecotoxicity, human toxicity and impacts from particulate matters Fig. 35.6 Geographical distribution of case studies based on locations of waste management systems under study. Generic cases and European cases as well as technical reports were excluded from the figure


35.2.4 Inventory Modelling The inventory part of waste LCAs is given particular attention by practitioners due to its role in increasing the results’ credibility. The accurate representation of the studied system with appropriate data is decided in the inventory preparations. In the reviewed studies of LCA applied to solid waste management systems, the authors tried in general to use site-specific information and when not possible, search for data in literature and databases. Around 70% of the reviewed studies included at least partly primary data, as Fig. 35.8 shows, but in most of the studies, practitioners had to supplement their inventory analysis with literature information and/or generic data. Although, as mentioned before, waste LCAs typically refer to a specific geographical region, the quest for primary data is rarely fruitful


Although, as mentioned before, waste LCAs typically refer to a specific geographical region, the quest for primary data is rarely fruitful. The reason is that data collection for LCIs is a difficult and time consuming process, leading many researchers to use generic data from widespread LCA databases, such as ecoinvent. These databases aim mainly at modelling the background system, but in the absence of relevant information they are often used as data sources for the foreground system as well. This solution also has the drawback that time representativeness is not followed. Databases are updated irregularly and usually after many years. Therefore, the use of generic database information in general reduces the relevance and representativeness of the study. The use of LCA databases and the compilation of the inventory data are facilitated by the inclusion of LCA databases in LCA software


The use of LCA databases and the compilation of the inventory data are facilitated by the inclusion of LCA databases in LCA software. Both generic and waste-customised LCA tools are used, the latter ones enabling the specific modelling of different waste fractions through processes that can be parameterised (see EU Thematic Strategy on the Prevention and Recycling of Waste ISO 14044:2006 EU Waste Framework Directive 2012 * Case study articles in waste sector Int. J. Life Cycle Assessment Waste Management Resources Conservation and Recycling Waste Mangement and Research J. Cleaner Production Other journals Fig. 35.7 Distribution of publications describing LCAs of solid WMS across peer-reviewed journals. For multiple articles describing the same case study, only the main article supporting the case was accounted for. Literature search was stopped mid-2012, hence 2012 is an incomplete year (indicated by asterisk) LCA of Solid Waste Management Systems


e.g. Clavreul et al 2014 for an example of such tools). The most popular LCA software among the reviewed studies was the generic LCA tool SimaPro (Fig. 35.9). One important aspect in waste LCAs is the long-term emissions associated with waste landfilling. The issue around handling long-term emissions has been a subject of strong debate within the LCA community (Hischier et al. 2010). LCA in principle integrates emissions regardless of when they occur. This principle works well when considering relatively short time spans. But the time integration of emissions occurring in low concentrations over very long time spans (such as metal emissions leaching from landfills) leads to an estimation of very high and unrealistic impacts in toxic impact categories which are linked to toxic metal emissions when landfilling waste (Bakas et al. 2015)


2015). A suggestion has been to cut off all long-term emissions beyond the arbitrary threshold of 100 years from the waste deposition Primary data Databases Litterature data Proportion of studies 0% 20% 40% 60% 80% 100% Used Adequately used Inadequately used Not relevant Unspecified Fig. 35.8 Types of data sources used in studies. Primary data refers to site-specific data from, e.g. field investigations. Databases mainly refer to LCA software-embedded databases. Adequacy of literature data was based on a rough consistency check with the temporal and geographical scopes of the study SimaPro EASEWASTE GaBi ORWARE IWM DST WISARD Others None Unspecified Proportions of studies 0% 5% 10% 15% 20% 25% 30% 35% Fig. 35.9 LCA software used in studies. The category “Others” includes TEAM, UMBERTO, GEMIS, WRATE, LCAiT, JEMAI-LCA, EIME, WAMPS software


and either discard them (Hischier et al. 2010) or treat them in a separate impact category (Hauschild et al. 2008). These suggestions along with other proposals, all have inherent problems that do not allow them to become operational and widely accepted in the LCA community (Bakas et al. 2015). The lack of consensus and the absence of an adequate method to account for long-term emissions in LCA has led many practitioners in the reviewed studies to omit or assign less credibility to toxicity-related impact categories. Within the LCI phase, reference needs to be made to the handling of multifunctional processes (see Sects. 8.5 and 9.2.2). This choice is particularly relevant as waste operations often lead to the production of secondary products such as secondary materials (recycling) and energy (incineration, landfill gas extraction). According to the ISO standards, system expansion is the preferable option for dealing with such processes and, as Fig


According to the ISO standards, system expansion is the preferable option for dealing with such processes and, as Fig. 35.10 shows, practitioners follow this recommendation to a great extent (around 75%), with a few cases of studies reported to resort to allocation. The allocation key varied among the studies with mass, heat value, waste volume, exergy and economic value all used by practitioners. On the other hand, the choice between marginal and average data for crediting a waste system delivering secondary products is more evenly divided. In many cases, also, the choice is not sufficiently justified, which could be attributed to the difficulties of practitioners in identifying the proper approach and the lack of adequate framing of the goal and scope of their study. The choice between marginal and average data depends on the goal of the study and the context situation it belongs to (see Chap. 7)


The choice between marginal and average data depends on the goal of the study and the context situation it belongs to (see Chap. 7). System expansion is often very crucial for estimating the final results, as it strongly influences the benefits of one waste treatment option over another. Thus, the lack of transparency in how this is performed may substantially reduce the Proportions of studies 0% 20% 40% 60% 80% 100% System expansion (crediting) System expansion & allocation Allocation Not relevant Unspecified Energy crediting - Data type 0% 20% 40% 60% 80% 100% Average data Unspecified/Not relevant Marginal data Marginal & Average Material crediting - Data type 0% 20% 40% 60% 80% 100% Unspecified/Not relevant Specified Fig. 35.10 Handling of multifunctional processes. Energy includes both heat and electricity


35.10 Handling of multifunctional processes. Energy includes both heat and electricity. The differentiation between marginal and average data for material crediting is largely omitted in the studies, and is hence not reported in the figure LCA of Solid Waste Management Systems


credibility of the final results and conclusions. A systematic framework for consistent modelling of recycling, co-production and energy recovery has recently been developed by Schrijvers et al. (2016), describing the relation between the LCA goals and the attributional/consequential approach. Most of the reviewed studies assume a 1:1 substitution ratio between primary and secondary material production and/or quality similar to the substituted product. However, an overestimated substitution ratio or grade of the recovered materials can significantly impact the benefits gained from recycling and alternative methods based on the average market consumption mixes of primary and secondary materials have been proposed for calculating the environmental credits of end-of-life material recovery in attributional LCA (Gala et al. 2015)


2015). One of the main challenges for LCA in the circular economy is to address the continuous loop of materials and account for the benefits from recycling in a consistent way (Niero et al. 2016). 35.2.5 Life Cycle Impact Assessment The constant updating of existing and development of new impact assessment methods (see also Chaps. 10 and 40) makes it difficult to accurately map the popularity of specific LCIA methods among LCA practitioners in solid waste management. Figure 35.11 attempts to map the use of LCIA methods among the researchers and practitioners of the reviewed studies. CML is strongly preferred, followed by EDIP and Ecoindicator 99. Interestingly, around 20% of the studies failed to report on the LCIA method choice. This mapping reveals information on the selection criteria applied by practitioners, and also the perception of credibility of LCIA methods by LCA practice