生命周期评价方法在城市生活垃圾管理中的应用研究述评

结合城市生活垃圾管理系统特征,系统归纳基于生命周期评价(Life cycle assessment,LCA)方法的城市生活垃圾管理模型的发展现状,并对LCA方法在城市生活垃圾管理中的实践以及在我国开展城市生活垃圾管理LCA研究的应用前景进行评述。分析表明,LCA是城市生活垃圾管理领域的重要工具之一,基于LCA方法的城市生活垃圾管理模型在全生命周期环境影响评价与识别、处置工艺选择与改进、可持续生活垃圾管理决策支持等方面具有十分重要的应用价值。中国在本地化生活垃圾管理系统LCA模型开发、清单数据库和评价指标体系构建以及与其他研究方法集成等方面面临挑战。     

Comparing technologies for municipal solid waste management using life cycle assessment methodology: a Belgian case study

Purpose

The present study aims at identifying the best practice in residual municipal solid waste management using specific data from Liège, a highly industrialized and densely populated region of Belgium. We also illustrate the importance of assumptions relative to energy through sensitivity analyses and checking uncertainties regarding the results using a Monte Carlo analysis.

Methods

We consider four distinct household waste management scenarios. A life cycle assessment is made for each of them using the ReCiPe method. The first scenario is sanitary landfill, which is considered as the base case. In the second scenario, the refuse-derived fuel fraction is incinerated and a sanitary landfill is used for the remaining shredded organic and inert waste only. The third scenario consists in incinerating the whole fraction of municipal solid waste. In the fourth scenario, the biodegradable fraction is collected and the remaining waste is incinerated. The extracted biodegradable fraction is then treated in an anaerobic digestion plant.

Results and discussion

The present study shows that various scenarios have significantly different environmental impact. Compared to sanitary landfill, scenario 4 has a highly reduced environmental impact in terms of climate change and particulate matter formation. An environmental gain, equal to 10, 37, or 1.3 times the impact of scenario 1 is obtained for, respectively, human toxicity, mineral depletion, and fossil fuel depletion categories. These environmental gains are due to energetic valorization via the incineration and anaerobic digestion. Considering specific categories, greenhouse gas emissions are reduced by 17 % in scenario 2 and by 46 % in scenarios 3 and 4. For the particulate matter formation category, a 71 % reduction is achieved by scenario 3. The figures are slightly modified by the Monte Carlo analysis but the ranking of the scenarios is left unchanged.

Conclusions

The present study shows that replacing a sanitary landfill by efficient incineration significantly reduces both emissions of pollutants and energy depletion, thanks to electricity recovery.     

Life cycle assessment of alternatives for recycling abroad alkaline batteries from Portugal

Purpose

The European legislation establishes collection rates and states that all identifiable batteries must undergo treatment and recycling. Due to the inexistence in Portugal of recycling plants for alkaline batteries, those collected there have been sent to Austria and France, and currently, it is pondered to send them to Spain. This study aims to know the potential environmental impacts associated with the management of spent domestic alkaline batteries from collection in continental Portugal to recycling abroad.

Methods

Three alternative recycling processes are considered: in Austria (A), France (F) and Spain (S). The system in study, from battery collection in continental Portugal to recycling abroad, includes complementary processes necessary for this circuit such as the production of boxes for battery collection and/or transportation and, for easiness of analysis and interpretation, is divided into: (i) container manufacture; (ii) distribution of empty containers; (iii) battery collection and sorting; (iv) international transport for the recycling; and (v) battery recycling. Recovered materials were also quantified. The LCA methodology and the method of impact assessment Eco-indicator 99, Hierarchist version, with two options, with and without inclusion of long-term emissions, were used. This method considers three damage categories: human health, ecosystem quality and resources, which group 11 impact categories.

Results and discussion

For ecosystem quality, there is a preponderance of the impact of recycling processes F and S regarding all other processes and, in particular, regarding recycling process A. After these, the container production impact is the most significant followed by the transport to Austria. For human health, there is a preponderance of the impact of recycling process S followed by the impact of F, and then of the transport to Austria and, only after, the impact of recycling process A. For resources, process S impact is higher than the one of A and this is higher than system F. The transport shows an expectable impact (highest for Austria, lowest for Spain), but for Austria and for France, it is higher than the impact of the recycling process itself.

Conclusions

System F is the most negative in terms of ecosystem quality and S is the worst in terms of human health. In these two damage categories, system A is the best but the worst in the damage category of resources, where F is the best system. If the recovered materials are considered in this balance, the environmental advantage of system A is clear.     

A life cycle assessment of residential waste management and prevention

Purpose

The oft-cited waste hierarchy is considered an important rule of thumb to identify preferential waste management options and places waste prevention at the top. Nevertheless, it has been claimed that waste prevention can sometimes be less favorable than recycling because (1) recycling decreases only the primary production of materials, whereas waste prevention may reduce a combination of both primary and low-impact secondary production, and (2) waste prevention decreases the quantity of material recycled downstream and the avoided impacts associated with recycling. In response to this claim, this study evaluates the life cycle effects of waste prevention activities (WPAs) on a residential waste management system.

Methods

This life cycle assessment (LCA) contrasts the net impacts of a large residential solid waste management system (including sanitary landfilling, anaerobic digestion, composting, and recycling) with a system that incorporates five WPAs, implemented at plausible levels (preventing a total of 3.6 % of waste generation tonnage) without diminishing product service consumption. WPAs addressed in this LCA reduce the collected tonnage of addressed advertising mail, disposable plastic shopping bags, newspapers, wine and spirit packaging, and yard waste (grass).

Results and discussion

In all cases, the WPAs reduce the net midpoint and endpoint level impacts of the residential waste management system. If WPAs are incorporated, the lower impacts from waste collection, transportation, sorting, and disposal as well as from the avoided upstream production of goods, more than compensate for the diminished net benefits associated with recycling and the displaced electricity from landfill gas utilization.

Conclusions

The results substantiate the uppermost placement of waste prevention within the waste hierarchy. Moreover, further environmental benefits from waste prevention can be realized by targeting WPAs at goods that will be landfilled and at those with low recycled content.     

The legitimacy of life cycle assessment in the waste management sector

Purpose

Life cycle assessment (LCA) is commonly presented as a tool for rational decision-making. It has been increasingly used to support decision-making in situations where multiple actors possess diverse, and sometimes conflicting, perspectives, values and motives. Yet, little effort has been placed on understanding LCA in a social framework of action. This paper aims to analyse the legitimacy of LCA in public sector decision-making situations, the criticisms presented against LCA, and suggest potential ways to alleviate these criticisms.

Methods

This study consists of a case study of the application of LCA in the waste management sector in England and France. To gain an understanding of the justification and criticism of LCA, semi-structured interviews were undertaken with national and local level waste management actors. The justifications and criticism of the application of LCA was analysed through an analytical framework, the economies of worth. This suggests that in situations of disagreement, actors’ justifications are required to show their attachment to plural forms of common good. This work analyses the orders of worth in which justifications and criticisms of the application of LCA were based.

Results and discussion

LCA is applied primarily as a test of environmental efficiency, illustrating a collaboration between the industrial and green orders of worth. Actors apply LCA with the aspiration of replicating the scientific method and producing robust evidence to support the most efficient waste treatment option. In this case, efficiency is coupled with the green order of worth, where gains in efficiency mean lower environmental impacts. Internal criticisms of LCA, based in the industrial order of worth, highlights the limitations of LCA to act as a test of environmental efficiency. Furthermore, criticism based in the civic order of worth highlights the friction which arises in decision-making situations when LCA has been seen to subjugate the civic nature of waste management decisions.

Conclusions

One potential way forward for LCA may be to introduce aspects relevant in the civic order of worth which aims at achieving a compromise between the industrial and civic orders of worth. Envisioning LCA as a process-oriented tool, as opposed to an outcome-oriented tool, can allow for aspects on public involvement in the LCA process, thereby increasing its civic legitimacy.

     

Comparative life cycle assessment of two landfill technologies for the treatment of municipal solid waste

Goal and Scope  The potential environmental impacts associated with two landfill technologies for the treatment of municipal solid waste (MSW), the engineered landfill and the bioreactor landfill, were assessed using the life cycle assessment (LCA) tool. The system boundaries were expanded to include an external energy production function since the landfill gas collected from the bioreactor landfill can be energetically valorized into either electricity or heat; the functional unit was then defined as the stabilization of 600 000 tonnes of MSW and the production of 2.56x10⁸ MJ of electricity and 7.81x10⁸ MJ of heat. Methods  Only the life cycle stages that presented differences between the two compared options were considered in the study. The four life cycle stages considered in the study cover the landfill cell construction, the daily and closure operations, the leachate and landfill gas associated emissions and the external energy production. The temporal boundary corresponded to the stabilization of the waste and was represented by the time to produce 95% of the calculated landfill gas volume. The potential impacts were evaluated using the EDIP97 method, stopping after the characterization step. Results and Discussion  The inventory phase of the LCA showed that the engineered landfill uses 26% more natural resources and generates 81% more solid wastes throughout its life cycle than the bioreactor landfill. The evaluated impacts, essentially associated with the external energy production and the landfill gas related emissions, are on average 91% higher for the engineered landfill, since for this option 1) no energy is recovered from the landfill gas and 2) more landfill gas is released untreated after the end of the post-closure monitoring period. The valorization of the landfill gas to electricity or heat showed similar environmental profiles (1% more raw materials and 7% more solid waste for the heat option but 13% more impacts for the electricity option). Conclusion and Recommendations  The methodological choices made during this study, e.g. simplification of the systems by the exclusion of the identical life cycle stages, limit the use of the results to the comparison of the two considered options. The validity of this comparison could however be improved if the systems were placed in the larger context of municipal solid waste management and include activities such as recycling, composting and incineration.     

Regionalization of agri-food life cycle assessment: a review of studies in Portugal and recommendations for the future

Purpose

One of the main trends in life cycle assessment (LCA) today is towards increased regionalization in inventories and impact assessment methods. LCA studies require the collection of activity data but also of increasingly region-specific background data to accurately depict supply chain processes and enable the application of an increasing number of geographically explicit impact assessment models. This is particularly important for agri-food products. In this review, we assess progress in Portugal towards this goal and provide recommendations for future developments.

Methods

We perform a comprehensive review of available LCA studies conducted for Portuguese agri-food products, in order to evaluate the current state of Portuguese agri-food LCA. Among other issues, we assess availability of data, methods used, level of regionalization, impact assessment model relevance and coherence for inter-product comparability. We also provide conclusions and recommendations based on recent developments in the field.

Results and discussion

We found 22 LCA studies, covering 22 different products. The analysis of these studies reveals limitations in inter-study comparability. The main challenges have to do with a lack of country-specific foreground data sources applied consistently in the studies found, with discrepancies in impact assessment categories, and with the use of simple functional units that may misrepresent the product analyzed.

Conclusions

We conclude that Portuguese agri-food LCA studies do not have a systematic and country-scale approach in order to guarantee regional accuracy and comparability. We propose a research strategy to engage the Portuguese agri-food LCA community in devising a consistent framework before practical application studies are conducted.

     

基于混合生命周期评价的生活垃圾处理系统生态效率分析

基于混合生命周期评价(Hybrid life cycle assessment,HLCA)提出一种改进生态效率模型,系统评价卫生填埋、卫生填埋⁃填埋气利用、焚烧发电、堆肥+卫生填埋和堆肥+焚烧发电5种我国典型生活垃圾处理情景的生态效率,并探究可持续性包含的环境、经济和社会多维权衡关系。结果表明,具有最大生态效率的生活垃圾处理情景因可持续性维度选取不同而异,如考虑人体健康损害影响,焚烧发电情景具有最大经济生态效率,而卫生填埋⁃填埋气利用情景具有最大社会生态效率。生活垃圾处理系统的可持续性评价维度之间具有显著的权衡关系,忽略某些影响类型可能带来问题转移。5种生活垃圾处理情景的环境影响各异,非焚烧情景气候变化影响和焚烧情景人体毒性影响突出。机器设备和燃料使用对资源消耗影响贡献最大,而生活垃圾处理过程对经济效益和其他环境影响贡献最大。本文提出的改进生态效率模型可以定量评价生活垃圾管理系统生态效率及权衡关系,为有效制定生活垃圾管理政策提供全面的信息支持。     

A survey of life cycle approaches in waste management

Background, aim, and scope  

Life-cycle thinking and life-cycle approaches are concepts that are getting increased attention worldwide and in particular in EU Policies related to sustainability. The European Commission is launching a number of activities to strengthen life-cycle thinking in policy and business. EU policies aim to decrease waste generation through new waste prevention initiatives, better use of resources and shift to more sustainable consumption patterns. The approach to waste management is based on three principles: waste prevention, recycling and reuse and improving the final disposal and monitoring. In particular, concerning the prevention and recycling of waste, the definition of a waste hierarchy should be the basis for the prioritisation of waste management options. The benefit of using Life Cycle Assessment (LCA) in analysing waste management systems is the provision of a comprehensive view of the processes and impacts involved. However, it is also clear that the studies will always be open for criticism as they are simplifications of reality. Moreover, in order to become the LCA, a leading tool within businesses and government to understand and manage risks or opportunities related to waste management and treatment technologies, there are methodological choices required and a number of aspects that still need to be worked out. It is therefore important to review open and grey literatures, EU guidelines, relevant environmental indicators and databases for the waste sector and data easily usable in waste policy decision-making, with an agreed approach and methodology based on life-cycle thinking. The following survey gathers and describes the existing guidelines and methodologies based on life-cycle thinking and applicable in waste policy decision-making.     

The incorporation of waste prevention activities into life cycle assessments of municipal solid waste management systems: methodological issues

Background, aim, and scope  

Municipal solid waste (MSW) management organizations commonly address both waste treatment and diversion activities in their management plans, yet the application of life cycle assessment (LCA) to MSW rarely incorporates the effects of waste prevention activities (WPAs) in an explicit manner. The primary objective of this paper is to further develop the methodological options for attributional LCAs of MSW to address waste prevention, including product reuse.     

Analysis of raw cork production in Portugal and Catalonia using life cycle assessment

Purpose

This study aims to (1) evaluate the environmental impacts associated with the three types of raw cork produced in Portuguese cork oak woodlands (in Alentejo region) considering two alternative practices for stand establishment (plantation and natural regeneration), (2) compare the environmental impacts of raw cork production in Portuguese cork oak woodlands and in Catalonian cork oak forests, and (3) assess the influence of different allocation criteria for partitioning the environmental impacts between the different types of raw cork produced.

Methods

A cradle-to-gate approach was adopted starting with stand establishment up to cork storage in a field yard. The system boundaries include all management operations undertaken during the following stages: stand establishment, stand tending, cork stripping, and field recovery. The allocation of the environmental impacts to reproduction, second, and virgin cork was based on mass and market price criteria. An alternative allocation approach was simulated by allocating environmental impacts also to the wood produced in the cork oak stands. The impact assessment was performed using the characterization factors recommended by the International Reference Life Cycle Data System (ILCD).

Results and discussion

In Portugal, cork produced from naturally regenerated stands has a better environmental performance than cork produced from planted stands, but the differences are smaller than 10 %. Different management models of cork oak stands in Portugal and Catalonia (agro-silvopastoral system and forest system, respectively) originate different impact levels, which tend to be significantly lower in Catalonia. The environmental hot spots in the two regions are also distinct. In Catalonia, they are associated with cleaning, road maintenance, and worker and cork transport. In Portugal, they are fertilization, pruning, and cleaning. The two allocation criteria affect significantly the results obtained for virgin cork in Portugal and for virgin and second cork in Catalonia. Besides, when impacts are also allocated to wood, mass allocation should be avoided as it would not create incentives for a sustainable management of cork oak stands.

Conclusions

The environmental impact from Catalonian cork may be reduced by decreasing mechanized shrub cleaning and road maintenance operations through the introduction of livestock in cork oak forests, and also by a better planning of management operations. For the Portuguese cork, improvements may be achieved by optimizing fertilizer dosage, planting nitrogen-fixing crops and pastures that improve soil quality, avoiding unnecessary operations, improving the efficiency of management operations, and increasing tree density.     

Solid waste treatment within the framework of life cycle assessment

Due to a lack of available methods and data, the Inventory Analysis in many Life Cycle Assessments (LCA) often exclude important information concerning emissions from landfills. In light of this, a method for estimating emission factors for metals from municipal solid waste has been developed and is presented herewith. Emission factors, expressing the emitted fraction of the landfilled amount of the element during a surveyable time period (corresponding to several decades or a century), is suggested for several metals. It is suggested that these can be used in initial (screening) LCAs where the aim is to identify key-issues, i.e. important aspects of the system under study.     

Using anticipatory life cycle assessment to enable future sustainable construction

The built environment is the largest single emitter of CO₂ and an important consumer of energy. Much research has gone into the improved efficiency of building operation and construction products. Life Cycle Assessment (LCA) is commonly used to assess existing buildings or building products. Classic LCA, however, is not suited for evaluating the environmental performance of developing technologies. A new approach, anticipatory LCA (a‐LCA), promises various advantages and can be used as a design constraint during the product development stage. It helps overcome four challenges: (i) data availability, (ii) stakeholder inclusion, (iii) risk assessment, and (iv) multi‐criteria problems. This article's contribution to the line of research is twofold: first, it adapts the a‐LCA approach for construction‐specific purposes in theoretical terms for the four challenges. Second, it applies the method to an innovative prefabricated modular envelope system, the CleanTechBlock (CTB), focusing on challenge (i). Thirty‐six CTB designs are tested and compared to conventional walls. Inclusion of technology foresight is achieved through structured scenario analysis. Moreover, challenge (iv) is tackled through the analysis of different environmental impact categories, transport‐related impacts, and thickness of the wall assemblies of the CTB. The case study results show that optimized material choice and product design is needed to reach the lowest environmental impact. Methodological findings highlight the importance of context‐specific solutions and the need for benchmarking new products.     

Life cycle assessment of a waste lubricant oil management system

Purpose

This paper compares 16 waste lubricant oil (WLO) systems (15 management alternatives and a system in use in Portugal) using a life cycle assessment (LCA). The alternatives tested use various mild processing techniques and recovery options: recycling during expanded clay production, recycling and electric energy production, re-refining, energy recovery during cement production, and energy recovery during expanded clay production.

Methods

The proposed 15 alternatives and the actual present day situation were analyzed using LCA software UMBERTO 5.5, applied to eight environmental impact categories. The LCA included an expansion system to accommodate co-products.

Results

The results show that mild processing with low liquid gas fuel consumption and re-refining is the best option to manage WLO with regard to abiotic depletion, eutrophication, global warming, and human toxicity environmental impacts. A further environmental option is to treat the WLO using the same mild processing technique, but then send it to expanded clay recycling to be used as a fuel in expanded clay production, as this is the best option regarding freshwater sedimental ecotoxicity, freshwater aquatic ecotoxicity, and acidification.

Conclusions

It is recommended that there is a shift away from recycling and electric energy production. Although sensitivity analysis shows re-refining and energy recovery in expanded clay production are sensitive to unit location and substituted products emission factors, the LCA analysis as a whole shows that both options are good recovery options; re-refining is the preferable option because it is closer to the New Waste Framework Directive waste hierarchy principle.