Anaerobic Digestion of Spoiled Milk in Batch Reactors: Technical and Economic Feasibility

The economic feasibility of the energy conversion through anaerobic digestion of spoiled milk was assessed for the microscale biogas production and heating value was determined experimentally on a pilot plant with a mixture of spoiled milk and an inoculum previously optimized with Anaerobic Biomethanation Potential tests. Results shows that the feasibility of a 100 kWel plant is characterized by a quite short return time of the investment. Considering a discount rate of 5% and a timespan of investment equal to 20 years, payback period is equal to 8-9 years, Net Present Value is equal to 806,903 € and Internal Rate of Return is equal to 16%.