A PILOT-SCALE EVALUATION OF AEROBIC ANOXIC SLUDGE-DIGESTION

A pilot-scale (300 L) evaluation of waste-activated sludge digestion by a cyclical aerobic - anoxic mode of operation was undertaken at ambient liquid temperatures (14-17°C). Three experimental runs were conducted over a 2-year period. The first run compared the aerobic - anoxic process to a conventional, continuously aerated, digestion process. During the second run, the aerobic - anoxic digester was compared to a lime-supplemented conventional aerobic process. The third run compared two aerobic - anoxic digester units, operating at reduced (50 and 25% of normal) aeration rates during the aerobic period. In addition, basic data from batch tests are outlined and discussed. Results from the various experimental runs indicated numerous potential advantages for the aerobic - anoxic mode of digester operation, which the paper discusses.