Sewage sludge production increases continuously reaching almost 20% (946 700 tons of dry matters in 2003 to 1 118 795 tons of dry matters in 2007) during the last decade. In 2007, 70% of the produced sewage sludge was spread (directly or after composting). The remaining 30% was incinerated (with or without household wastes) or landfilled. Nowadays, sludge reduction is a major concern. This activity has to become more sustainable and stakeholders have to be careful to the environmental impacts of sludge treatment and disposal routes. To help stakeholders in that way, we developed a decision tool called GESTABoues. GESTABoues is a tool based on the "Bilan Carbone®" method (ADEME 2009). It was developed for stakeholders dealing with wastewater treatment plants (plant manager, public administration…) to quantify greenhouse gases (GHG) for each type of emissions and each process of sludge treatment and disposal routes. The tool was developed with VisualBasic programming language. This tool can be used in a four step procedure: (i) The user built as many wastewater treatment plants (WWTP) he wants. He should specify the WWTP capacity, the type of sewage network and the water treatment system. (ii) Then the user creates all the sewage sludge treatment processes used for each WWTP. He has to choose different parameters for each step of sludge treatment and disposal. The user has the opportunity to choose either its own data or data collected through a literature review and implemented as "default value" in the tool. (iii) Once each WWTP and the treatment and disposal routes of each WWTP created, the user can choose different graphic presentations to assess the impact of greenhouse gases emissions (Figure 1). GESTABoues calculate all emissions (direct and indirect) of carbon dioxide, methane and nitrous oxide for all steps of sewage sludge treatment (storage, thickening, anaerobic digestion, aerobic digestion, dewatering, alkaline stabilization, composting, drying) and sludge disposal route (land application, incineration, incineration with household wastes, landfilling). Emissions from infrastructures and transports are also considered. These graphs present emissions for each step (thickening, dewatering, land spreading…), each gas (dioxide carbon, methane and nitrous oxide) and each origin of greenhouse gases (combustible, electricity, direct emissions, avoided emissions, infrastructure, chemicals and transport). The graphs can be presented either as values or percentages. (iv) Finally, the user can compare different sewage sludge treatment processes and disposal routes options and create reports with Microsoft Word through an export button. Each report summarizes the mass and energy balance as well as the selected graphs to be exported. In this study, this tool is used to compare 3 systems on a same WWTP to help stakeholders to identify which processes have the worst environmental impact all along the treatment and disposal route, which emission is overwhelming and to help them selected the most interesting system from an environmental point of view.

In 2007, 1 100 000 tons of sewage sludge were produced in France. This figure is constantly increasing and sludges have to be eliminated. Four disposal routes are currently possible: land spreading (directly or after composting), incineration, incineration with household wastes and landfilling. These different disposal routes as well as the sludge treatments produce greenhouse gases (GHG). To help stakeholders to better understand the carbon footprint of sludge treatment and disposal options, we developed a tool called GESTABoues. This paper aims to present the underlying methodology used to quantify material and energy flows as well as GHG emissions all along the sludge treatment and disposal processes implemented in this tool. GHG emissions generated by our system are quantified for x tons of sludge produced by a wastewater treatment plant of x per-captia-equivalents (PCE) during one year. The carbon footprint method we developed is adapted to sludge treatment and disposal processes and based on the "Bilan Carbone®" method. The "Bilan Carbone®" method is a general method used to quantify GHG generated from all physical processes which are necessary for any activity or human organization (ADEME, 2009). In our method, three GHG are recorded: carbon dioxide, methane and nitrous oxide. Biogenic carbon was not taken into account but its sequestration was for two types of disposal routes (land spreading and landfilling). For each process involved in the sludge treatment and disposal routes system, three types of emissions are considered: direct, indirect and avoided emissions. (i) Direct emissions are generated by each process (storage, thickening, anaerobic digestion, composting, land spreading, incineration, incineration with household wastes, landfilling). (ii) Indirect emissions are due to energy and chemical consumptions (combustible or electricity) to operate each process. Transport emissions (for consumables, sludges and ashes) and civil engineering emissions were taken into account. The first ones were calculated for one ton of goods transported on one kilometre (t.km) and the second ones were the toughest to implement in GESTABoues tool. After a literature review, two main methods were identified. Renou (2006) considers that the most applicable methodology is to consider mass of all civil engineering and electrical/mechanical equipments whereas Doka (2007) considers that civil engineering emissions are defined by wastewater treatment plant for 5 classes of plants. We propose an intermediate methodology to assess these emissions : for each process, components (concrete, cast iron, steel…) of involved machineries and buildings were modelled for 3 sizes of wastewater treatment plants (<10 000 PCE, 10 000 – 100 000 PCE, >100 000 PCE). (iii) Avoided emissions are generated when products are not used and replaced by recyclable products (heat, electricity, fertilizer…). GHG data were collected through a literature review for each type of emissions and each process of sludge treatment and disposal routes. All collected data were implemented in GESTABoues, developed with VBA Excel to quantify GHG emissions generated by a wastewater treatment plant of x PCE.

The European community cannot address the issue of bio-waste solely in terms of collection and waste management, as such activities generate costs. Today, waste prevention in Europe must involve waste reduction and prevention at a local level, targeting all producers of bio-waste, not only consumers and households, and promoting the use of a number of waste reduction practices including composting, mulching, grinding, use of slow-growing plant species, using bio-waste as animal feed, reducing food wastage and the use of ramial wood chips. The Miniwaste project, supported by the European Life+ program (2010-2012), aims to provide evidence that it is possible to significantly reduce the production of bio-waste generated in the European Union, as well as provide tools and points of further reflection on bio-waste prevention. The partnership (Rennes Métropole, Irstea, City of Brno, LIPOR in Porto, and ACR+) wishes to set up a computerised tool for local authorities within Europe. This project will help users to conduct a bio-waste management programme including territorial diagnosis, the implementation and monitoring of specific preventive actions and the evaluation of these actions. The overall structure will be based on three different modules: 1-A decision making assistance module that includes a territorial diagnosis chart offering several scenarios associated with different potential possible actions in the field of bio-waste prevention: Composting (home, community, apartment blocks, vermi-composting, catering services), food waste (household,restaurant), smart gardening and animal feeding. The territorial diagnosis is produced on the scale chosen by the user in order to get homogeneous data. It could be a neighbourhood, district, town, etc. For a given sector, the decision making module consists in entering data of 15 territorial indicators in terms of population, current waste management and current preventive actions on the territory, etc. Meanwhile, a calculation of potential waste reduction is processed by the computer using an algorithm. The result of the diagnosis is displayed for the whole territory and for each sector according to the list defined. Corresponding to the results, synthetic worksheets are proposed as a real decision making tool with the following information: target, type of waste concerned, linked indicators, main actions, participants involved, materials necessary, personnel necessary, an estimate of cost, and expected results. With such information (diagnosis and worksheets), the users are able to choose one or several preventive actions to implement in their territory. 2-Some guidelines to implement the actions and especially some data sheets proposing activity indicators and impact indicators: depending on the preventive actions chosen, the user can download the corresponding procedural sheet which explains step by step how to implement the actions in detail. Moreover, a data sheet is available with a list of relevant indicators (awareness, number of composters, etc.) 3-A results display module, producing graphs to help visualise the results. This web tool will be available on the Miniwaste website by subscription, from 2013 (www.miniwaste.eu). More information will be provided and a tool demonstration will be organized during the final conference scheduled in Rennes in November 2012.

Agriculture substantially contributes to anthropogenic emissions of both N2O and CH4 as well as ammonia (NH3). As signatories to international conventions, EU Member States must reduce their emissions. Moreover, the European Council (December 12, 2008) defined the energy-climate package and implemented a target called "3 X 20". The aim of this target is to reduce GHG emissions by 20% by 2020 compared to 1990 levels. It also aims to bring to a 20% share of renewable energy in the final consumption and to increase energetic efficiency by 20%. In response to these commitments, anaerobic digestion of livestock wastes is expected to expand in France in the coming years. The objectives of economic performance lead to a particular interest in centralized treatment plants involving other wastes, specifically wastes with high potential for energy production (agri-food waste, crop residues, etc.) which may be collected over long distances. However, such development is complex and requires the awareness of social and technical constraints (heat recovery, access to bio-resources...) as well as adhering to legal restrictions in the concerned areas. In this context of potential development of collective biogas plants in France, the use of Geographic Information Systems (GIS) in order to georeference the bio-resources and then to locate the optimal sites appears very interesting and useful tools. Such investigations have been carried out on both national and regional scales (Batzias, 2005; Dagnall, 2010) but need to be adapted for local diagnosis. For this purpose, a research project is devoted to the development of such methodologies, then applied in the “Pays de Fougères”, a 1000 km² wide rural area located in the north-eastern Brittany in France. Firstly, a bio-resource mapping is drawn by applying a calculation method specific for each substrate. A derived layer, the energy potential grid (EPG), is calculated as the sum of the energy potential at any point in the area (100 m resolution per pixel) considering for each substrate a maximum distance proportional to the energetic potential of the substrate. Next, sensitive areas (wetlands, distances from housing…) are identified as areas where the development of biogas plants is restricted, resulting in a constraint map (CM). A final suitability map is constructed by combining the CM and the EPG, synthesized in the form of a raster GIS file. To go further on this issue, the network analysis capability of GIS is used, in order to take into account the actual transport route and competitive access to bio-resources. As a result, it allows refining the diagnosis of candidate sites. This study initiates the construction of a GIS model to determine optimal sites for collective biogas plants. The specificity of the approach is that methodologies are implemented to reach a very fine level of spatialization. The precise geolocation of farms is successfully obtained through the analysis of aerial photographs and Landsat imagery is used to help the identification of crop residues. However, some improvements could be implemented in the future, such as assigning a weight factor to the bio-resources reflecting their relative importance (liquid/solid form, no additional N content in the digestate, etc.). Although this mapping provides a basis for discussion in the context of decision support, it does not allow itself to make a choice on a future location, particularly since in the investigated area, the availability of bio-resources is not a major barrier (range from 6800 to 9300 ton of oil equivalent (toe)/year). Complementary parameters could be considered like social acceptance and environmental concerns generated by such a collective biogas plant. To explore this aspect in depth, the question of local impacts like eutrophication should be taken into consideration. Thus, beyond this GIS-based model, in order to test different scenarios for the development of collective biogas plants, a Life Cycle Assessment (LCA) is realised, assessing the environmental impacts of three scenarios as described in the paper of Aissani (2012). Future work will be to link more closely the GIS in LCA studies through the integration of spatial data and the spatial differentiation of local environmental impacts, the ultimate goal being to build a generic model for maximizing energy recovery from bio-resources in conjunction with a low environmental impact.

The European legal framework about solid waste management has been considerably reinforced for more than a decade. One of the most important changes is the EC landfill directive (99/31/EC), which requires the reduction of organic matter in municipal solid waste going to landfill. In an attempt to solve this problem, France has developed for about less than 10 years the Mechanical Biological Treatment (MBT). It is a waste treatment combining on one plant stages of mechanical sorting and biological treatment like composting, stabilisation and anaerobic digestion. Nevertheless, some detractors support the development of a biowaste source-separated collection and its specific treatment. How to compare environmental performances of these MBT scenarios? What weight could be given to the environmental impacts of waste management scenarios, when decision makers consider only market costs as invest and operating costs? Two mean goals are followed. First, we want to highlight the environmental strengths and weaknesses of several waste management scenarios including MBT are highlighted. Then these environmental results are used for a monetization step in order to obtain some individual trade-offs between environmental impacts through an exploratory monetization approach. This paper focuses consequently on the assessment of four residual household solid waste (HSW) management scenarios, which are representative from trends that exist in France: a referential scenario (incineration of residual HSW) and three alternatives that integrate a biological treatment for the organic fraction of the residual HSW. The first alternative is a MBT plant which provides compost through an aerobic degradation of residual HSW. The second alternative is quite similar to the first one but it is built with an additional step of anaerobic degradation, prior to composting, which provides energy recovery from biogas. The third alternative is made up of a source-separated biowaste collection, which is biologically treated in order to produce compost. Remaining HSW are directly burned in an incinerator. Waste management systems studied are limited to residual waste and biowaste flows and take into account collection, transport, treatment, refusal management and by-products valorisation according to the Life Cycle Thinking. Life Cycle Assessment (LCA) is an internationally standardized methodology (ISO 14040 and 14 044) that is considered as one of the most effective environmental management tools. It was chosen to carry out the environmental assessment (Del Borghi et al., 2009). Only three impact categories are presented in this paper: climate change, effects on human health and abiotic resources depletion. A stated preferences method, called Choice Experiment (Hoyos, 2010), and derived from marketing research, is adapted and tested for the monetization of environmental impacts. Through the setting up of an experimental design and survey we have got marginal Willingness to Pay (WTP) for each impact category, which allows trade-offs between these impacts. Judging by our first assessment, environmental impacts results of waste management scenarios with MBT seem to strongly depend on compost spreading process and its fate in agricultural soil, which are the most sensitive steps too, because of their current modelling limits. These results point out a need of a further research concerning knowledge of compost spreading emissions in the fields and they beg the question of the relevance of the organic matter back to soil. Indeed the referential scenario has globally lower impacts than the others, due to the avoided impacts of energy substitution. On the contrary, the second alternative with MBT is the most impacting due to compost spreading. The adaptation of a Choice Experiment (CE) for the monetization of environmental impacts provides certainly WTPs for each impact category mentioned above. These marginal WTPs are sensibly higher for climate change and effects on human health than for abiotic resources depletion. These values are not usable at the moment for several reasons. Firstly, CE is based on individual preferences aggregation. Is it the right scale to weight these environmental impacts? Secondly, the adaptation of this monetization method was tested by bringing additional information on environmental impacts to the respondents and then by taking into accounts the individual level information in the econometric modelling. Further works should be led in this direction to reduce this uncertainty and to set more precisely the adaptation possibilities for environmental impacts.

Landfilling of biodegradable waste must decrease to fulfil the Council Directive 99/31/EC on landfills, in order to reduce the emission of gaseous and liquid pollutants during the landfill lifetime. Therefore, pre-treatment of the organic fraction of municipal waste prior to landfilling is being developed in several countries. In France, the organic fraction is either separated and treated through selective collection of biowaste, or through mechanical sorting in the plant followed by biological treatments (anaerobic or aerobic), the refuses only being landfilled. Or the mixed waste is stabilized by an aerobic process before landfilling. These different processes emit gases which may be harmful for health or the environment (toxic, explosive, odorants, greenhouse gases...). Some of the emissions can be collected and treated through biofilters, while other gases are emitted by surfaces (typically, compost windrows) and cannot be collected unless they are enclosed. Also, the efficiency of the biofilters must be assessed. IRSTEA and INERIS have been working together for several years on the use, comparison and improvement of surface emission measurement methods, applied to biological treatment plants of solid waste. Gaseous emissions were studied on: composting process of pre-sorted organic matter from mixed waste, with a small or larger mesh and porosity, in either turned or aerated windrows, on biofilters, and on landfills which are located beside the composting plants. Depending on the ventilation air flux, different measurement methods were used: static (accumulation), dynamic or chimney type chambers, and a total cover of a biofilter with a plastic tarb. Several of these measurements were undertaken in order to evaluate the global gaseous emissions from those sites, to provide data to an environmental technology validation exercise (ETV). Measurement campaigns presented here comprise: comparison of fluxes measurement techniques, calculation of gas fluxes (CO2, CH4, NH3 and N2O) emitted from composting windrows and biofilters, calculation of biogas emission (methane + CO2) before and after a final cover was set on a landfill. Comparisons of the two first chambers have been made since 2007 on several sites (composting of the organic fraction of municipal solid waste or stabilization prior to landfilling). On the first site (non aerated windrows and small mesh) the difference between the measured fluxes was a factor of 2. This factor is rather small: differences between flux measurements using different devices can lead to differences as large as a factor of 100. More recent tests, presented here, show a better agreement: the difference between the two techniques lies within the measurement uncertainty. Comparison of surface air speed measured by two different chimney chambers lead to comparable results. During one experiment, the global air flow interpolated from chamber data was underestimated compared to input flow measurement, because of preferred pathways of the air flow along the wall of the biofilter. When the border effect is correctly taken into account, the total gas flow measured with the chimney chamber and the one measured by a total cover of the biofilter show a good agreement. Biogas surface emissions were measured with the static chamber, on a landfill which receives biologically stabilized waste. This landfill was partly uncovered, so only a part of the biogas was collected and flared. After the final cover was installed, the total biogas flow which was collected and flared was comparable to the sum of (the surface emissions + the collected biogas) without the total cover. The results presented here show that on different sites, different emission measurement methods were used, and that generally there is a good agreement between the methods, providing the care of use are respected. Advantages and care of use for the different methods, depending on the aeration conditions, have been established and some recommendations are given.

During the last years, a big strength has been put on organic resources recovery in order to achieve our aspiration towards a "Recycling Society" and climate stabilisation. Energy, nutrients and organic matter needs have thus driven sustainable management of resources and wastes and promoted new technological developments. In this context, biological processing of organic wastes and the use of natural resources to recover nutrients as phosphorus, to produce soil improvers and to supply energy is of great interest. However regulations on the management of organic resources waste are fragmented. So the current legislation in Europe might be not sufficient to achieve the stated objectives of its effective management. Moreover there is an open question on the tools that can be used to assess the efficiency of management systems for organic resources and waste which lead to the adequate processes selection. Especially the increasing use of Life Cycle Assessment tools has to be carefully addressed with a special focus on the considered indicators and the local applicability of the results. Following the ORBIT conferences tradition, ORBIT2012 deals with all aspects of organic resources and waste management with a special focus on the assessment of technologies with environmental, social and economical point of view. A large place is given to climate change and decision making tools between waste treatment options. Traditional themes as energy recovery (Biofuels, biogas, hydrogen production), biological treatments (composting and anaerobic digestion) and also mechanical biological treatment still remain central issues that are discussed in order to improve technologies and product quality, especially for land application. More local approaches such as home and community composting are also discussed as they may represent solutions that have to be considered in an integrated organic waste management plan which includes prevention. Special emphasis is also laid on EU policies and strategies for sustainable management of organic resources and waste. The conference presents high quality and innovative research in all the aforementioned topics and includes oral presentations, poster sessions and specific workshops.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]TED [Axe_IRSTEA]TED-SOWASTE | International audience | The European community cannot address the issue of bio-waste solely in terms of collection and waste management, as such activities generate costs. Today, waste prevention in Europe must involve waste reduction and prevention at a local level, targeting all producers of bio-waste, not only consumers and households, and promoting the use of a number of waste reduction practices including composting, mulching, grinding, use of slow-growing plant species, using bio-waste as animal feed, reducing food wastage and the use of ramial wood chips. The Miniwaste project, supported by the European Life+ program (2010-2012), aims to provide evidence that it is possible to significantly reduce the production of bio-waste generated in the European Union, as well as provide tools and points of further reflection on bio-waste prevention. The partnership (Rennes Métropole, Irstea, City of Brno, LIPOR in Porto, and ACR+) wishes to set up a computerised tool for local authorities within Europe. This project will help users to conduct a bio-waste management programme including territorial diagnosis, the implementation and monitoring of specific preventive actions and the evaluation of these actions. The overall structure will be based on three different modules: 1-A decision making assistance module that includes a territorial diagnosis chart offering several scenarios associated with different potential possible actions in the field of bio-waste prevention: Composting (home, community, apartment blocks, vermi-composting, catering services), food waste (household,restaurant), smart gardening and animal feeding. The territorial diagnosis is produced on the scale chosen by the user in order to get homogeneous data. It could be a neighbourhood, district, town, etc. For a given sector, the decision making module consists in entering data of 15 territorial indicators in terms of population, current waste management and current preventive actions on the territory, etc. Meanwhile, a calculation of potential waste reduction is processed by the computer using an algorithm. The result of the diagnosis is displayed for the whole territory and for each sector according to the list defined. Corresponding to the results, synthetic worksheets are proposed as a real decision making tool with the following information: target, type of waste concerned, linked indicators, main actions, participants involved, materials necessary, personnel necessary, an estimate of cost, and expected results. With such information (diagnosis and worksheets), the users are able to choose one or several preventive actions to implement in their territory. 2-Some guidelines to implement the actions and especially some data sheets proposing activity indicators and impact indicators: depending on the preventive actions chosen, the user can download the corresponding procedural sheet which explains step by step how to implement the actions in detail. Moreover, a data sheet is available with a list of relevant indicators (awareness, number of composters, etc.) 3-A results display module, producing graphs to help visualise the results. This web tool will be available on the Miniwaste website by subscription, from 2013 (www.miniwaste.eu). More information will be provided and a tool demonstration will be organized during the final conference scheduled in Rennes in November 2012.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]INSPIRE | International audience | Sewage sludge production increases continuously reaching almost 20% (946 700 tons of dry matters in 2003 to 1 118 795 tons of dry matters in 2007) during the last decade. In 2007, 70% of the produced sewage sludge was spread (directly or after composting). The remaining 30% was incinerated (with or without household wastes) or landfilled. Nowadays, sludge reduction is a major concern. This activity has to become more sustainable and stakeholders have to be careful to the environmental impacts of sludge treatment and disposal routes. To help stakeholders in that way, we developed a decision tool called GESTABoues. GESTABoues is a tool based on the "Bilan Carbone®" method (ADEME 2009). It was developed for stakeholders dealing with wastewater treatment plants (plant manager, public administration…) to quantify greenhouse gases (GHG) for each type of emissions and each process of sludge treatment and disposal routes. The tool was developed with VisualBasic programming language. This tool can be used in a four step procedure: (i) The user built as many wastewater treatment plants (WWTP) he wants. He should specify the WWTP capacity, the type of sewage network and the water treatment system. (ii) Then the user creates all the sewage sludge treatment processes used for each WWTP. He has to choose different parameters for each step of sludge treatment and disposal. The user has the opportunity to choose either its own data or data collected through a literature review and implemented as "default value" in the tool. (iii) Once each WWTP and the treatment and disposal routes of each WWTP created, the user can choose different graphic presentations to assess the impact of greenhouse gases emissions (Figure 1). GESTABoues calculate all emissions (direct and indirect) of carbon dioxide, methane and nitrous oxide for all steps of sewage sludge treatment (storage, thickening, anaerobic digestion, aerobic digestion, dewatering, alkaline stabilization, composting, drying) and sludge disposal route (land application, incineration, incineration with household wastes, landfilling). Emissions from infrastructures and transports are also considered. These graphs present emissions for each step (thickening, dewatering, land spreading…), each gas (dioxide carbon, methane and nitrous oxide) and each origin of greenhouse gases (combustible, electricity, direct emissions, avoided emissions, infrastructure, chemicals and transport). The graphs can be presented either as values or percentages. (iv) Finally, the user can compare different sewage sludge treatment processes and disposal routes options and create reports with Microsoft Word through an export button. Each report summarizes the mass and energy balance as well as the selected graphs to be exported. In this study, this tool is used to compare 3 systems on a same WWTP to help stakeholders to identify which processes have the worst environmental impact all along the treatment and disposal route, which emission is overwhelming and to help them selected the most interesting system from an environmental point of view.

[Departement_IRSTEA]Ecotechnologies [TR1_IRSTEA]INSPIRE | International audience | In 2007, 1 100 000 tons of sewage sludge were produced in France. This figure is constantly increasing and sludges have to be eliminated. Four disposal routes are currently possible: land spreading (directly or after composting), incineration, incineration with household wastes and landfilling. These different disposal routes as well as the sludge treatments produce greenhouse gases (GHG). To help stakeholders to better understand the carbon footprint of sludge treatment and disposal options, we developed a tool called GESTABoues. This paper aims to present the underlying methodology used to quantify material and energy flows as well as GHG emissions all along the sludge treatment and disposal processes implemented in this tool. GHG emissions generated by our system are quantified for x tons of sludge produced by a wastewater treatment plant of x per-captia-equivalents (PCE) during one year. The carbon footprint method we developed is adapted to sludge treatment and disposal processes and based on the "Bilan Carbone®" method. The "Bilan Carbone®" method is a general method used to quantify GHG generated from all physical processes which are necessary for any activity or human organization (ADEME, 2009). In our method, three GHG are recorded: carbon dioxide, methane and nitrous oxide. Biogenic carbon was not taken into account but its sequestration was for two types of disposal routes (land spreading and landfilling). For each process involved in the sludge treatment and disposal routes system, three types of emissions are considered: direct, indirect and avoided emissions. (i) Direct emissions are generated by each process (storage, thickening, anaerobic digestion, composting, land spreading, incineration, incineration with household wastes, landfilling). (ii) Indirect emissions are due to energy and chemical consumptions (combustible or electricity) to operate each process. Transport emissions (for consumables, sludges and ashes) and civil engineering emissions were taken into account. The first ones were calculated for one ton of goods transported on one kilometre (t.km) and the second ones were the toughest to implement in GESTABoues tool. After a literature review, two main methods were identified. Renou (2006) considers that the most applicable methodology is to consider mass of all civil engineering and electrical/mechanical equipments whereas Doka (2007) considers that civil engineering emissions are defined by wastewater treatment plant for 5 classes of plants. We propose an intermediate methodology to assess these emissions : for each process, components (concrete, cast iron, steel…) of involved machineries and buildings were modelled for 3 sizes of wastewater treatment plants (<10 000 PCE, 10 000 – 100 000 PCE, >100 000 PCE). (iii) Avoided emissions are generated when products are not used and replaced by recyclable products (heat, electricity, fertilizer…). GHG data were collected through a literature review for each type of emissions and each process of sludge treatment and disposal routes. All collected data were implemented in GESTABoues, developed with VBA Excel to quantify GHG emissions generated by a wastewater treatment plant of x PCE.