Technical aspects of options and potential for energy recovery from anaerobically digested wastewater solids.

Energy recovery from biogas produced by anaerobic digestion of wastewater solids is an important step towards sustainable wastewater treatment. Options for the three components of energy recovery---anaerobic digestion, biogas treatment, and energy conversion---have received limited comprehensive study. This thesis examined technical aspects of energy recovery to better understand the options for, and relationships between, the components.The energy recovery potential depends on the biogas composition and production rate, the types and efficiencies of energy conversion technologies used, and how biogas and natural gas are allocated to them. Operational data from literature, manufacturers and treatment plants were used to predict the energy recovery potential with respect to plant energy demands for a hypothetical 100,000 m3/day plant. The eight cogeneration technologies studied were predicted to produce 35-70% of the plant"s electricity demand, 26-58% of the winter digester heating demand, and six cogeneration technologies met all the summer digester heating demand.