FULL-SCALE SEQUENCING BATCH THERMOPHILIC ANAEROBIC SLUDGE DIGESTION TO MEET EPA CLASS A BIOSOLIDS REQUIREMENTS

摘要

The City of Los Angeles, Terminal Island Treatment Plant started thermophilic anaerobicrndigestion operation in Feb 2000. Mesophilic digesters were converted to thermophilic digestionrnusing a rapid temperature increase to 130°F (54°C) without seeding. In May 2001, to meet thernEPA 40 CFR 503, Alternative I (thermal treatment-temperature and time) requirement forrnpathogen destruction, anaerobic digestion was converted from a continuous feed and draw modernto a Sequencing Batch Reactor mode with a draw/fill/hold sequence to prevent short circulatingrnand to allow all sludge particles to be heated for 24 h. Full-scale results show that the “rapidrnstartup method” produced a robust thermophilic culture and stable digestion. The thermophilicrnSBR operating mode met Class A biosolids fecal coliform and Salmonella requirements. Fecalrncoliforms, but not Salmonella, regrew during the dewatering and centrifuged cake storage.rnThermophilic digestion gave slightly higher pH, volatile acids and alkalinity than mesophilicrndigestion. Thermophilically digested sludge was more odorous than mesophilically digestedrnsludge, but following centrifuge dewatering the reverse was true.