Enrico Benetto

Life cycle assessment of ecological sanitation system for small-scale wastewater treatment

Ecological sanitation (EcoSan) concepts, relying on an environmentally sound management of water, nutrient and energy fluxes, have been poorly characterized in literature and are widely ignored by public planning authorities, architects or engineers. A comparative life cycle assessment (LCA) of an EcoSan system at an office building and of conventional systems was carried out in order to provide practical data and information to (partially) fill this gap. Compared to conventional systems, EcoSan can reduce the contribution to ecosystem quality damage by more than 60%. EcoSan leads, however, to higher damages on resources and human health and higher impact on climate change. Key improvement possibilities and research needs related to these results are discussed throughout the paper. Ecological sanitation appears to be a promising alternative to small-scale wastewater treatment. At higher scales, low water consumption conventional systems are better performing and are not likely to be replaced by EcoSan systems in the short term. Standard conventional systems have very poor environmental performances and should be upgraded as far as possible.

Improvements to Emergy Evaluations by Using Life Cycle Assessment

Life Cycle Assessment (LCA) is a widely recognized, multicriteria and standardized tool for environmental assessment of products and processes. As an independent evaluation method, emergy assessment has shown to be a promising and relatively novel tool. The technique has gained wide recognition in the past decade but still faces methodological difficulties which prevent it from being accepted by a broader stakeholder community. This review aims to elucidate the fundamental requirements to possibly improve the Emergy evaluation by using LCA. Despite its capability to compare the amount of resources embodied in production systems, Emergy suffers from its vague accounting procedures and lacks accuracy, reproducibility, and completeness. An improvement of Emergy evaluations can be achieved via (1) technical implementation of Emergy algebra in the Life Cycle Inventory (LCI); (2) selection of consistent Unit Emergy Values (UEVs) as characterization factors for Life Cycle Impact Assessment (LCIA); and (3) expansion of the LCI system boundaries to include supporting systems usually considered by Emergy but excluded in LCA (e.g., ecosystem services and human labor). Whereas Emergy rules must be adapted to life-cycle structures, LCA should enlarge its inventory to give Emergy a broader computational framework. The matrix inversion principle used for LCAs is also proposed as an alternative to consistently account for a large number of resource UEVs.

Integrating fuzzy multicriteria analysis and uncertainty evaluation in life cycle assessment

The interpretation phase of Life Cycle Assessment (LCA) studies is often hampered by the number and the heterogeneity of impact assessment results as well as by the uncertainties arising from data, models and practitioners choices. While decision-aiding methods have proven to support this key LCA phase, the inclusion of uncertainty evaluations in these methods is still a new topic in the LCA community. The fuzzy multicriteria method NAIADE [Munda G., 1995. Multicriteria Evaluation in a Fuzzy Environment. Heidelberg: Springer-Verlag.] has already been used in several LCA case studies and its framework is well suited for the consideration of uncertainty evaluations as well. This paper proposes a modified version of NAIADE, which conforms to the LCA requirements and to the type of uncertainties to be addressed, with an application example. The discussion of the rankings obtained showed how the integration of uncertainty results could help focusing on critical LCA issues and could be coupled with dominance, contribution and gravity analysis for the interpretation of LCA results, especially when the rankings are not fully consistent. This could support engineers and scientists working in LCA discipline as well as managers and decision-makers faced with decision-making problems based on LCA.

Application of three independent consequential LCA approaches to the agricultural sector in Luxembourg

PurposeConsequential Life Cycle Assessment (C-LCA) is a “system modelling approach in which activities in a product system are linked so that activities are included in the product system to the extent that they are expected to change as a consequence of a change in demand”. Hence, C-LCA focuses on micro-economic actions linked to macro-economic consequences, by identifying the (marginal) suppliers and technologies prone to be affected by variable scale changes in the demand of a product. Detecting the direct and indirect environmental effects due to changes in the production system is not an easy task. Hence, researchers have combined the consequential perspective with different econometric models. Therefore, the aim of this study is to assess an increase in biocrops cultivation in Luxembourg using three different consequential modelling approaches to understand the benefits, drawbacks and assumptions linked to each approach as applied to the case study selected.MethodsFirstly, a partial equilibrium (PE) model is used to detect changes in land cultivation based on the farmers’ revenue maximisation. Secondly, another PE model is proposed, which considers a different perspective aiming at minimising a total adaptation cost (so-called opportunity cost) to satisfy a given new demand of domestically produced biofuel. Finally, the consequential system delimitation for agricultural LCA approach, as proposed by Schmidt (Int J Life Cycle Assess 13:350–364, 2008), is applied.Results and discussionThe two PE models present complex shifts in crop rotation land use changes (LUCs), linked to the optimisation that is performed, while the remaining approach has limited consequential impact on changes in crop patterns since the expert opinion decision tree constitutes a simplification of the ongoing LUCs. However, environmental consequences in the latter were considerably higher due to intercontinental trade assumptions recommended by the experts that were not accounted for in the economic models. Environmental variations between the different scenarios due to LUCs vary based on the different expert- or computational-based assumptions. Finally, environmental consequences as compared with the current state-of-the-art are lame due to the limited impact of the shock within the global trade market.ConclusionsThe use of several consequential modelling approaches within the same study may help widen the interpretation of the advantages or risks of applying a specific change to a production system. In fact, different models may not only be good alternatives in terms of comparability of scenarios and assumptions, but there may also be room for complementing these within a unique framework to reduce uncertainties in an integrated way.

Life cycle assessment of coal by-products based electric power production scenarios

Abstract In the next future coal will play an increasing important role in electricity production due to the abundant reserves worldwide. In order to design new production scenarios, environmental issues have to be carefully considered. We used Life Cycle Assessment (LCA) to compare, from an environmental point of view, six scenarios of electricity production by combustion of coal, coal cleaning by-products, biomass and petroleum coke, considering two existing combustion plants, de-NO x and de-SO x processes and coal ash valorisation options. The results showed that the more environmentally responsible scenarios include biomass co-combustion and gas treatment techniques and enlightened some options for further improvements. Finally the results confirmed the usefulness of LCA in the environmental innovation of industrial systems.

Is it better to remove pharmaceuticals in decentralized or conventional wastewater treatment plants? A life cycle assessment comparison.

After ingestion, pharmaceuticals are excreted unchanged or metabolized. They subsequently arrive in conventional wastewater treatment plants and are then released into the environment, often without undergoing any degradation. Conventional treatment plants can be upgraded with post treatment, alternatively the removal of pharmaceuticals could be achieved directly at point sources. In the European project PILLS, several solutions for decentralized treatment of pharmaceuticals at hospitals were investigated at both pilot plant and full scale, and were then compared to conventional and upgraded centralized treatment plants using Life Cycle Assessment (LCA). Within the scope of the study, pharmaceuticals were found to have a comparatively minor environmental impact. As a consequence, an additional post treatment does not provide significant benefits. In the comparison of post treatment technologies, ozonation and activated carbon performed better than UV. These results suffer however from high uncertainties due to the assessment models of the toxicity of pharmaceuticals in LCA. Our results should therefore be interpreted with caution. LCA is a holistic approach and does not cover effects or issues on a local level, which may be highly relevant. We should therefore apply the precautionary ALARA principle (As Low As Reasonably Achievable) and not conclude that the effect of pharmaceuticals is negligible in the environment.

Integrated earth system dynamic modeling for life cycle impact assessment of ecosystem services

Despite the increasing awareness of our dependence on Ecosystem Services (ES), Life Cycle Impact Assessment (LCIA) does not explicitly and fully assess the damages caused by human activities on ES generation. Recent improvements in LCIA focus on specific cause-effect chains, mainly related to land use changes, leading to Characterization Factors (CFs) at the midpoint assessment level. However, despite the complexity and temporal dynamics of ES, current LCIA approaches consider the environmental mechanisms underneath ES to be independent from each other and devoid of dynamic character, leading to constant CFs whose representativeness is debatable. This paper takes a step forward and is aimed at demonstrating the feasibility of using an integrated earth system dynamic modeling perspective to retrieve time- and scenario-dependent CFs that consider the complex interlinkages between natural processes delivering ES. The GUMBO (Global Unified Metamodel of the Biosphere) model is used to quantify changes in ES production in physical terms - leading to midpoint CFs - and changes in human welfare indicators, which are considered here as endpoint CFs. The interpretation of the obtained results highlights the key methodological challenges to be solved to consider this approach as a robust alternative to the mainstream rationale currently adopted in LCIA. Further research should focus on increasing the granularity of environmental interventions in the modeling tools to match current standards in LCA and on adapting the conceptual approach to a spatially-explicit integrated model.

An integrated “process modelling-life cycle assessment” tool for the assessment and design of water treatment processes

PurposeThe application of Life Cycle Assessment (LCA) to the design of water treatment plants is hampered by: (1) a large diversity of unit processes, (2) the high variability of the operation conditions in relation with the water quality input, and (3) the range of possible technical solutions to fulfil the treatment needs. For a consistent prospective assessment, the LCA should be based on the simulated functioning of the unit processes rather than on average data, as it is most often the case when no real data are available. Here, a novel, integrated and flexible process modelling-life cycle assessment (PM-LCA) tool for design and LCA of water treatment technologies is presented.MethodsThe tool (EVALEAU) was developed in Umberto® (v5.5) using the Python language for code scripting. A library of unit process (UP) modules was built. Each module is a detailed and highly parameterized model of a specific water treatment process, which is further linked with the software PHREEQC® for water chemistry calculation. Input data are: water composition, design, operation parameters, including literature or user-defined values. The modules are linked to Ecoinvent datasets (v2.2) for background processes. By combining the modules, water treatment chains can be designed and evaluated in Umberto® with a high level of detail and specifications. A sensitivity analysis toolbox (Morris method) was included for the identification of the process parameters mainly affecting the impact results.Results and discussionThe tool was successfully applied to the test bed case of an existing drinking water plant located in the Paris region. The conventional LCA results, based on average recorded data, were compared with the results obtained using the PM-LCA tool. Modelling results for technical parameters were also compared with data collected on site. An overall good agreement between simulations and real data was obtained, proving the relevance of the developed tool. Sensitivity analysis indicated that ozone production and transfer into water are the main technological parameters influencing climate change (taken as example since it is of high interest for stakeholders), which have therefore to be fine-tuned.ConclusionsThe EVALEAU tool successfully solves the challenge of linking LCA results to the related engineering design choices, from the assessment and eco-design perspectives. The concepts and methodologies embedded within the tool provide the user with complementary views of the designed system, in terms of potable water quality, design and operation parameters and environmental impacts generated over its life cycle.

Cost-performance indicator for comparative environmental assessment of water treatment plants

To compare potable water production plants on the basis of the environmental impacts generated by the treatment, including water resource depletion, Life Cycle Assessment (LCA) methodology is often used as referential. A comparison based only on the environmental impacts can however be misleading. Criteria for drinkability are usually defined as thresholds and the actual water quality gain achieved by different treatment chains shall be considered in the assessment for a fair comparison. Otherwise, chains treating low quality water resources could be disadvantaged as compared to alternatives using higher quality water resource, also when the depletion of the raw resource is included in the impact assessment. In this study, a novel Cost-Performance (CP) indicator has been developed and tested for the case of two existing water treatment plants located in the Paris Region. CP is the ratio between the total environmental impact generated by the treatment (i.e. the LCA score, eventually monetarised) and the total quality gain from raw to treated water. For the test case, three life cycle impact assessment methods, ReCiPe, Stepwise and Eco-costs (the latter two including monetarisation) have been considered. The water quality gain is based on 8 relevant parameters measured before and after treatment. The parameters are further aggregated using the French water quality valuation system SEQ-Eau. Paired t-test is then used to calculate the confidence interval for the average quality gain which then determines the confidence interval of the CP. Independent t-test on the CPs of the two alternative plants allows checking if their performances can be distinguished. Although in the specific test case the comparison is not conclusive, due to the similarity between the water quality gains, realistic breakthrough values have been obtained, especially using ReCiPe. The meaningfulness of the monetarisation of the LCA results has been highlighted as well.

Implications of a consumer-based perspective for the estimation of GHG emissions. The illustrative case of Luxembourg.

The Kyoto protocol has established an accounting system for national greenhouse gas (GHG) emissions according to a geographic criterion (producer perspective), such as that proposed by the IPCC guidelines for national GHG inventories. However, the representativeness of this approach is still being debated, because the role of final consumers (consumer perspective) is not considered in the emission allocation system. This paper explores the usefulness of a hybrid analysis, including input-output (IO) and process inventory data, as a complementary tool for estimating and allocating national GHG emissions according to both consumer- and producer-based perspectives. We assess the historical GHG impact profile (from 1995 to 2009) of Luxembourg, which is taken as a case study. The countrys net consumption over time is estimated to generate about 28,700 Gg CO2e/year on average. Compared to the conventional IPCC inventory, the IO-based framework typically shows much higher emission estimations. This relevant discrepancy is mainly due to the different points of view obtained from the hybrid model, in particular with regard to the contribution of imported goods and services. Detailing the GHG inventory by economic activity and considering a wider system boundary make the hybrid IO method advantageous as compared to the IPCC approach, but its effective implementation is still limited by the relatively complex modeling system, as well as the lack of coordination and scarce availability of datasets at the national level.