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.