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Abiotic mineral resource assessment is a long lasting area of interest in Life Cycle Assessment (LCA) with major progress in the field of industry and research during the last ten years. The complex nature of abiotic mineral resource assessment has brought out a multitude of indicators based on different principles and foundations, making it sometimes difficult to choose and interpret LCA results. This paper aims at proposing a good practices framework (GPF) to guide LCA practitioners in choosing and interpreting LCA results dealing with the use of abiotic mineral resources. The GPF was built within workshop discussions of the EcoSD network. During these workshops, three crucial points have been identified by the participants to have a strong impact on LCA results: the choice of the characterization method, how these methods are implemented in LCA software and the great uncertainties and variability in LCA results associated with abiotic mineral resource assessment. Based on these results, the framework was centered upon a four-step decision tree. Each step follows LCA ISO standards but focuses on abiotic mineral resources. This framework was then applied on two LCA case studies that are sensitive to abiotic mineral resources: the use of indium in mobile phone and phosphorus recovery from sewage sludge.

International audience; Since phosphorus (P) is a non-renewable element essential for life, it is extremely important to explore any potential supply of P, including that recovered from human excreta and urban wastewater. This study aimed to assess, using Life Cycle Assessment (LCA), whether recovering dissipated P by producing sludge-based phosphate fertilizer can be a suitable method to reduce P depletion. Environmental impacts of four scenarios of production of sludge-based phosphate fertilizers were compared to those of production of triple super phosphate, a mineral phosphate fertilizer used as a reference scenario. The novelty of this study was to estimate environmental impacts of sludge-based phosphate fertilizer production using a "product" LCA perspective instead of a "waste" LCA perspective. Consequently, upstream production of sludge was considered by allocating part of the environmental burdens of wastewater treatment to sludge production. Life Cycle Impact Assessment was performed using the CML-IA characterization method. Results indicated that sludge-based phosphate fertilizers appeared less environmentally friendly than mineral phosphate fertilizers, due to the contribution of the upstream burden of sludge production and P recovery. Finally, although P recovery helps preserve the mineral P resource, the overall assessment remains unfavorable for sludge-based products due to the low yields of P recovery, low P concentration of the sludge and the large amounts of energy and reactants needed to recover the P.

International audience; Agricultural utilization of organic residues is often included in Life cycle assessment (LCA) studies on livestock and crop production as well as waste and wastewater treatment. A review on the current state-of-the-art practices in agricultural use of organic residues in LCA studies is presented. This reveals that agricultural use of organic residues in LCA studies can be represented in several ways and at different levels of detail. About 100 published references were thoroughly analyzed showing that agricultural use of organic residues usually replaces the use of a mineral fertilizer (substitution of avoided mineral fertilizer). The mineral fertilizer equivalents (MFE) applied are rarely documented, although LCA results can be significantly affected by the way avoided impacts are modeled. Accounting of field emissions from organic residue application varies with the topic of the LCA study. To facilitate nitrogen MFE and field emission calculations, an Excel-tool is proposed for determining the nitrogen MFE of organic residues, direct nitrogen field emissions from organic residue applications, as well as avoided emissions (avoided mineral fertilizers). Computation of the nitrogen MFE of organic residues is based on their nitrogen content and composition, and on nitrogen emissions from field applications of the organic residues. Nitrogen field emissions were estimated using simple models and average climate and soil conditions. A global sensitivity analysis revealed that the choice of the application method, which determines the extent of incorporation into the soil, is the main cause of uncertainty in calculated nitrogen MFE values.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]INSPIRE [TR2_IRSTEA]TED; International audience; Sludge is slowly moving away from providing basic by-products and towards providing value-added products (e.g. fertilisers); therefore, it is no longer perceived as waste but as a product. Consequently, wastewater treatment plants become multifunctional systems that produce two coproducts that are given a second life: sludge and “clean” water. An allocation factor in Life Cycle Assessment can partition environmental burdens of wastewater treatment between these two products, but doing so remains highly challenging. To address this challenge, we followed a four-step procedure to develop an allocation factor using a mesoscopic approach and process- and product-related parameters in a mathematical model. The first two steps consisted of determining and mathematically representing process- and product-related parameters and their associations to define a global allocation factor. The third step consisted of constructing a corrective inventory matrix to adjust the global allocation factor, since inventory flows can be specific to certain processes. The last step consisted of mathematical modelling of the final corrected allocation factor. Based on the parameters chosen, the global allocation factor equalled 45% for sludge and 55% for water. A sensitivity analysis was performed to assess the robustness of the sludge allocation factor, which varied from 39 to 49%. The allocation factor developed reflects technological performances of the system and considers environmental impacts of sludge production to assess environmental impacts of value-added sludge-based products.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]INSPIRE [TR2_IRSTEA]TED; International audience; Life cycle assessment was used to assess environmental impacts and a sensitivity analysis of 17 key technological parameters to identify the main environmental hotspots associated with the performance of a sewage sludge treatment. The scenario takes into account primary and secondary sludge and includes gravity and centrifugal thickening, anaerobic digestion with cogeneration of heat and electricity from biogas, mechanical dewatering and spreading on agricultural fields. All the relevant inputs (electricity, heat, reagents, infrastructure, fuel, transport) and outputs (emissions to air, water and soil) are accounted for in the assessment, including the sludge return liquors from thickening and dewatering processes. This study focuses on climate change, terrestrial acidification, freshwater eutrophication, human toxicity and ionizing radiation impact categories assessed using the ReCiPe E v1.08/Europe baseline method. The results showed that the most sensitive parameters are the biodegradation rate of volatile solids and the nitrogen mineralization rate during anaerobic digestion, phosphorus and nitrogen capture rates during the thickening and dewatering processes, and the consumption of FeCl3 for the treatment of sludge before dewatering. The results suggest that the environmental performances of the sewage sludge treatment line could be enhanced by increasing the production of biogas (by increasing the biodegradation rate of volatile solids), by decreasing the consumption of FeCl3 used for sludge treatment, and by finding alternative treatments for sludge return liquors.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]INSPIRE [TR2_IRSTEA]TED; International audience; This paper aims at highlighting considerations on the sludge status and subsequent Life Cycle Assessment modeling if a paradigm shift arose by moving from “waste” sludge to “product” sludge. Forty-four peer-reviewed papers of Life Cycle Assessment in the field of wastewater treatment have been critically reviewed to highlight the consequences of this paradigm shift on the Life Cycle Assessment method and to identify the impacts on the goal and scope step of Life Cycle Assessment questioned by the sludge status (“waste”, “waste-to-product” or “product” sludge). Results show that sludge is mainly considered as “waste-to-product” sludge. The “zero burden assumption” is always applied and sludge is never charged with an environmental burden associated with its production. This is not questionable when sewage sludge is considered as “waste” or “waste-to-product” sludge with energy recovery. However, this is becoming more debatable when sludge is considered as “product” sludge or as “waste-to-product” sludge with nutrient or material recovery.In such cases, the “zero burden assumption” is a no longer valid hypothesis as the sludge life-cycle needs to be fully considered. This can only be done if the sludge carries an upstream environmental burden. Allocating an environmental burden to the sludge appears as a challenging question requesting allocation factors between the sludge production and the water treatment for each step that generates sewage sludge.

Within the framework of sustainable development, a quadruple transition (demographic, food, energetic and environmental) is necessary. The integrated biomass valorization, including the production of biofuels via the biorefinery concept lies at the cross section of these global challenges. Biofuels production competes for water and land use with respect to feed and food production. Securing these resources in an uncertain geopolitical environment is a strategic issue for many countries. It also has favorable (climate change mitigation) and adverse implications (fertilizers consumption, local pollutions). Therefore, the topic leads to huge political and economic debates at national and international scales. The results obtained from the implementation of supportive strategies for the development of this “new” bioeconomy indicate, at least in the near future, mixed results in comparison to the objectives that have been set. This may be explained by windfall effects created on the international markets and underline two imperative needs. The development and improvement of environmental methods, such as life cycle assessment expanded to the scope of international trade and not restricted to the regional or national economies will be necessary in order to install ambitious and unambiguous agreements for policymaker’s in the future international conferences such as the ones on climate change.

International audience; Spatial data warehouses and Spatial OLAP systems are business solutions that can be used for environmental applications. Indeed, in order to better assess the impacts of human activities on the environment, many spatio-temporal data should be collected in order to calculate indicators at different levels of aggregation. Spatial OLAP tools are well adapted to analyze these indicators in a multi-dimensional way for identifying and implementing policies to improve practices in order to minimize impacts. In this study, we focus on farms energy consumption in order to identify the tasks and work environments that consume the most energy. We show how SOLAP tools can be used for the spatio-multidimensional analysis of these indicators, and the research issues related to agricultural data warehousing and analysis process.

International audience; Organic waste land application generates nitrogenous emissions that have impacts on acidification, eutrophication and global warming. To assess these impacts with Life Cycle Assessment, emission factors are commonly used without taking into account neither the type and performance of land application techniques nor the type of organic waste applied. This paper proposes a methodological framework to assess the nitrogenous emissions by coupling technological performances of spreader and biophysical models, focusing on sewage sludge spreading in different weather and soil conditions. The first step consists of creating several spreading scenarios by combining a cropping system and a ‘‘spreader/sewage sludge’’ couple. The second step consists of testing the technological spreader performances regarding spatial distribution, application rate and soil compaction with a spreading simulator and the COMPSOIL model. Nitrogenous emissions are then simulated with STICS and DEAC models for different application rates and soil bulk densities. Finally, the simulated nitrogen losses from the models are linked with the real amounts of sewage sludge applied and the compacted soil due to spreader performances. Our approach shows that ammonia emissions during sewage sludge spreading can be directly linked to the spreader performances whereas nitrate leaching depends more on the soil and on the weather conditions. Nitrous oxide emissions mostly depend on the spreader weight and to the soil and the weather conditions. This method paves the way to new approaches: integrating technological performances of machines into biophysical and agricultural models in order to assess environmental impacts of agricultural practices.

International audience; Agricultural energy consumption is an important environmental and social issue. Several diagnoses have been proposed to define indicators for analyzing energy consumption at large scale of agricultural farm activities (year, farm, family of production, etc.). However, to define ad-hoc environmental energetic policies to better monitor and control energy consumption, new indicators at a most detailed scale are needed. Moreover, by defining detailed scale indicators, large quantities of geo-referenced data need to be collected to feed these energetic diagnoses. This huge volume of data represents another important limitation of systems that implement these diagnoses because they are usually based on classical data storage systems (such as spreadsheet tools and Database Management Systems). These systems do not allow for interactive analysis at different granularities/scales of huge volumes of data and do not provide any cartographic representation. By contrast, Spatial OLAP (SOLAP) and spatial data warehouse (SDW) systems allow for the analysis of huge volumes of geo-referenced data by providing aggregated numerical values visualized by means of interactive tabular, graphical and cartographic displays. Thus, in this paper, we (i) propose new appropriate indicators to analyze agricultural farm energy performance at a detailed scale and (ii) show how SDW and SOLAP technologies can be used to represent, store and analyze these indicators by simultaneously producing expressive reports.