Sludge anaerobic digester in many countries including South Korea suffers from low organic loading. Co-digestion could be a feasible option to enhance the performance of anaerobic digesters. Livestock waste and organic fraction of municipal solid waste including food waste, the problematic organic wastes, can be used as the co-substrate for sludge digestion. In this work, the author conducted an economic analysis of biogas utilization from co-digestion of sewage sludge with food waste leachate and swine waste for M city. Combined heat and power (CHP) generation with a new equipment was compared with heat generation by the existing boiler. The installation cost for CHP was converted to the present value for the comparative analysis. The co-digestion, which produces 4.3 times higher methane, will support the digester heating and sell the excess power and heat in market even at cold temperature in both biogas use methods. CHP generation will gain 277,527 thousand Korean won as the annual net benefit including the installation cost, while boiler will provide 179,738 thousand Korean won.