MAKING ANAEROBIC DIGESTION WORK WITH HIGH STRENGTH WASTES: LESSONS LEARNED FROM PILOT TO FULL SCALE

摘要

Codigestion of wastewater solids and food wastes has been practiced in Europe to increase gasproductions in the existing anaerobic digester systems and energy generation. Although a reviewof the codigestion technologies and food waste sources indicate that various types of highstrength wastes including food wastes can be amenable for codigestion, optimization of gasproduction and system performance requires a thorough analysis as well as the available wastesources within the vicinity of the host facility. The food processing waste digestion showed a35% greater biogas generation compared to the control digester that has not received anysupplemental waste. The tests also confirmed that the wastes did not cause inhibition of biologicactivity under the mesophilic conditions. Benefits due to the increased biogas production byanaerobic digestion of FOG wastes at the Johnson County facility were calculated to increase thebiogas generation by more than 50%. Following implementation, the overall program will reducethe treatment plant’s electricity purchase costs by over $500,000 per year under averageconditions utilizing the new cogeneration system. At Pinellas County, FL the payback period ofthe evaluated biogas cogeneration project was estimated to be from 5.5 to 7.5 years, withassociated 20-year lifecycle benefits in the order of $5.5 to $9 million, depending on the cost ofelectricity and natural gas.