Improving the Performance and Economics of Co-Digestion and Energy Production

Co-digestion of wastewater solids along with other feedstocks has received increasing attention in recent years as wastewater utilities recognize the advantages and benefits of such programs. For some utilities, these programs have helped to reduce wastewater user rate increases by increasing revenue and/or reducing purchased electrical power costs. However, there are risks from co-digestion – these include potential adverse impacts (or upsets) to the anaerobic digestion process, as well as economic reliance on private companies which may take their wastes/resources elsewhere for processing. There are, however, ways in which utilities are learning to protect themselves from feedstocks that may prove problematic or from changing economic conditions. Technological innovations are occurring to help make co-digestion more cost-effective. Drivers for co-digestion and energy production are strong and many utilities have digester, gas management, and energy production capacity available to accept co-digestion feedstocks.