Do You Really Want that FOG? Some Considerations for Starting a FOG Co-digestion Program

摘要

Co-digestion of organic high strength wastes (HSW) with municipal sludge is becoming more widely practiced throughout the country. Some of the drivers include keeping grease out of the collection system and liquid stream processes, generating more biogas for energy recovery, and providing an outlet for industries and haulers. The type of HSW processed varies substantially, and often includes fats, oils and grease (FOG) from restaurant grease traps as well as industrial wastes, such as a diverse array of food and animal processing wastes. These wastes have high organic content and low inert solids content, which make them ideal for co-digestion and generating biogas with limited impact on solids production. Despite the value of these programs, they can add significant operational difficulties for operators and managers. The diversity of these wastes, the irregularity of their deliveries, and the contaminants that can be found in the materials, can make co-digestion a daily challenge. The purpose of this paper is to use experiences from existing programs to illustrate some of the issues that operators consistently manage with co-digestion programs.