Assessment biogas production in Argentina from co-digestion of sludge and municipal solid waste

CAMPANELLA , ENRIQUE A.; MORERO, BETZABET; R.VICENTÍN

Buenos Aires

Conferencia; 2da Conferencia Panamericana sobre Sustentabilidad en Biocombustibles y Bioenergía; 2016

AICHE

In Argentina there is an important potential to utilize organic waste as a source of bioenergy generation. This work analyzes the environmental impacts, economic and energetic and economic requirements of biogas production by digestion of the sludge (SS) produced in a wastewater treatment plant of a medium city of Argentina. The SS is co-digested with the organic fraction of municipal solid waste (OFMSW) and the basis of the study is the life cycle assessment (LCA). The LCA is performed according to ISO 14040-44 using the SimaPro simulator. In a first stage, the transport of the different raw materials to the biogas plant was defined. Then, the co-digestion and the biogas treatment for final use were evaluated. The co-digestion was improved with glycerol and the generation of biogas was estimated with the GPS-X software. Two alternatives of biogas end use were considered: combined heat and power (CHP) and biomethane generation. For the first option H2S is removed from the raw biogas stream, while the second option also removes CO2. The H2S removal process was simulated in the SuperPro software by anaerobic biofiltration. The same software was used to simulate the removal of CO2 absorption-desorption with water as solvent. Finally the environmental impacts related to the end use of biogas (CHP and biomethane) were evaluated.The environmental analysis showed that the use of organic waste as an energy source, solving problems related to waste disposal, generates less environmental impact and lower costs than conventional disposal in a landfill. The feed to the digester needs to be big enough for a more economic attractive biogas production; then the disposal of organic waste (OFMSW + SS) of a medium-sized city should be complemented with waste from nearby towns or agricultural/livestock waste. The energy balance is highly positive with the use of energy for the overall process (Feedstock collection and transport, Anaerobic Digestion, Digestate Management and Biogas Treatment Plant) between 30 to 39% of the energy generated.