The Brazilian average daily effluent generation rate by inhabitants is 0.15 m3 per inhabitant per day according to Chernicharo (2007). S0 is the affluent COD concentration, S is the COD effluent concentration, Y is the solid production yield, f(T) is a volumetric correction factor due to temperature, C is the concentration of methane in the biogas (a value of 60% was adopted), and η is the efficiency of the energy conversion technology. Two technologies were examined: microturbines and Otto cycle gas engines. Il is the index of gas losses in installations or dissolved in the effluent, which was suggested as being equal to 40% by Chernicharo (2007). LHV is the calorific value of biogas (21.3 [MJ/m3] for a methane content of 60%; CETESB, 2006), P is the available power, Δt is the annual hours of plant operation (20 h per day in this paper), and E is the energy likely to be generated annually.