Environmental impact of rejected materials generated in organic fraction of municipal solid waste anaerobic digestion plants : comparison of wet and dry process layout

Anaerobic digestion of source separated organic fraction of municipal solid waste is an increasing waste valorization alternative instead of incineration or landfilling of untreated biodegradable wastes. Nevertheless, a significant portion of biodegradable wastes entering the plant is lost in pre-treatments and post-treatments of anaerobic digestion facilities together with other improper materials such as plastics, paper, textile materials and metals. The rejected materials lost in these stages have two main implications: (i) less organic material enters to digesters and, as a consequence, there is a loss of biogas production and (ii) the rejected materials end up in landfills or incinerators contributing to environmental impacts such as global warming or eutrophication. The main goals of this study are (i) to estimate potential losses of biogas in the rejected solid materials generated during the pre- and post-treatments of two full-scale anaerobic digestion facilities and (ii) to evaluate the environmental burdens associated to the final disposal (landfill or incineration) of these rejected materials by means of Life Cycle Assessment. This study shows that there is a lost of potential biogas production, ranging from 8% to 15%, due to the loss of organic matter during pre-treatment stages in anaerobic digestion facilities. From an environmental point of view, the Life Cycle Assessment shows that the incineration scenario is the most favorable alternative for eight out of nine impact categories compared with the landfill scenario. The studied impact categories are Climate Change, Fossil depletion, Freshwater eutrophication, Marine eutrophication, Ozone depletion, Particulate matter formation, Photochemical oxidant formation, Terrestrial acidification and Water depletion

Towards the implementation of new regional biowaste management plans : environmental assessment of different waste management scenarios in Catalonia

In the present work, different scenarios for the treatment of the organic fraction of municipal waste at regional scale are proposed and assessed by means of LCA. The geographical area under study is Catalonia (Spain). The current Catalan waste management scenario treating 1218 Gg of organic waste is analyzed and compared to a new scenario treating the same amount of waste but fulfilling the European Landfill Directive and the new recently approved Catalan waste management plan. As final disposal (incineration and sanitary landfill) of untreated municipal solid waste is not permitted, the new scenario includes increasing anaerobic digestion treatment of source selected organic fraction of municipal solid waste while maintaining the existing composting plants for this type of waste. Gaseous emissions treatment equipment will be provided when not installed in composting plants. Home composting is also included. Non-source selected organic fraction of municipal solid waste will be treated by composting. Different scenarios for sensitivity analysis have also been proposed dealing with the influence of transport, fugitive methane emissions from anaerobic digestion plants and the use of compost among other issues. The new scenario proposed decreases the impact in five out of the six impact categories studied (from a 49% in eutrophication potential to a 9% in ozone depletion potential). The inclusion of methane fugitive emissions in anaerobic digestion installations in impacts calculation impairs the environmental benefits of this type of treatment facilities (increasing global warming potential value up to a 31%). Improvement of landfill gas collection is of utmost importance in decreasing global warming potential

Environmental impact of rejected materials generated in organic fraction of municipal solid waste anaerobic digestion plants : comparison of wet and dry process layout

Anaerobic digestion of source separated organic fraction of municipal solid waste is an increasing waste valorization alternative instead of incineration or landfilling of untreated biodegradable wastes. Nevertheless, a significant portion of biodegradable wastes entering the plant is lost in pre-treatments and post-treatments of anaerobic digestion facilities together with other improper materials such as plastics, paper, textile materials and metals. The rejected materials lost in these stages have two main implications: (i) less organic material enters to digesters and, as a consequence, there is a loss of biogas production and (ii) the rejected materials end up in landfills or incinerators contributing to environmental impacts such as global warming or eutrophication. The main goals of this study are (i) to estimate potential losses of biogas in the rejected solid materials generated during the pre- and post-treatments of two full-scale anaerobic digestion facilities and (ii) to evaluate the environmental burdens associated to the final disposal (landfill or incineration) of these rejected materials by means of Life Cycle Assessment. This study shows that there is a lost of potential biogas production, ranging from 8% to 15%, due to the loss of organic matter during pre-treatment stages in anaerobic digestion facilities. From an environmental point of view, the Life Cycle Assessment shows that the incineration scenario is the most favorable alternative for eight out of nine impact categories compared with the landfill scenario. The studied impact categories are Climate Change, Fossil depletion, Freshwater eutrophication, Marine eutrophication, Ozone depletion, Particulate matter formation, Photochemical oxidant formation, Terrestrial acidification and Water depletion

Towards the implementation of new regional biowaste management plans : environmental assessment of different waste management scenarios in Catalonia

In the present work, different scenarios for the treatment of the organic fraction of municipal waste at regional scale are proposed and assessed by means of LCA. The geographical area under study is Catalonia (Spain). The current Catalan waste management scenario treating 1218 Gg of organic waste is analyzed and compared to a new scenario treating the same amount of waste but fulfilling the European Landfill Directive and the new recently approved Catalan waste management plan. As final disposal (incineration and sanitary landfill) of untreated municipal solid waste is not permitted, the new scenario includes increasing anaerobic digestion treatment of source selected organic fraction of municipal solid waste while maintaining the existing composting plants for this type of waste. Gaseous emissions treatment equipment will be provided when not installed in composting plants. Home composting is also included. Non-source selected organic fraction of municipal solid waste will be treated by composting. Different scenarios for sensitivity analysis have also been proposed dealing with the influence of transport, fugitive methane emissions from anaerobic digestion plants and the use of compost among other issues. The new scenario proposed decreases the impact in five out of the six impact categories studied (from a 49% in eutrophication potential to a 9% in ozone depletion potential). The inclusion of methane fugitive emissions in anaerobic digestion installations in impacts calculation impairs the environmental benefits of this type of treatment facilities (increasing global warming potential value up to a 31%). Improvement of landfill gas collection is of utmost importance in decreasing global warming potential