Maximizing Energy Recovery through Digester Gas Management System Enhancement

Advanced anaerobic digestion practices and maximum energy recovery call for a digester gas system that reliably allows for complete biogas collection and utilization. This paper will describe the planning, design, and construction of a new digester gas management system at the East Bay Municipal Utility District's (District) Main Wastewater Treatment Plant. The need for an upgraded system arose from the District's digester modification program –including conversion from floating to fixed covers, the addition of digester mixing, modifications to the feed cycle, and addition of thermophilic temperature capability. Upgrades accommodated the District's plan to be more energy self-sufficient and its Resource Recovery program, which dramatically increased the quantity and variability of digester gas production. The new system optimizes existing gas storage facilities and simplifies control. The design is complete, construction is underway, and operation will begin in fall 2006.