The LACSD Experience with Thermophilic Digestion: Start-up and Operation of a Full-Scale Reactor from Mesophilic Conditions
نویسندگان
چکیده
Research on achieving Class A material through thermophilic digestion at 55 C (131 F) in a continuously fed, single reactor configuration was performed at the Districts= Joint Water Pollution Control Plant (JWPCP) in Carson. Bench-scale (8.0 l) work showed that sufficient thermophilies for seeding purposes exist in mesophilic cultures at 35 C (96 F). After stable bench-scale thermophilic operation was demonstrated, a 14,000 m (3.7 million gal.) digester was converted from mesophilic operation to thermophilic operation. Conversion was complete in 3 months, and has led to stable operation and sustainable pathogen kill sufficient to meet the Class A pathogen standards. This level of pathogen destruction is possible because the Districts= digester design differs significantly from an idealized, continuous flow stirred tank reactor (CFSTR). Parameters investigated include pathogen destruction, gas production, VS destruction, volatile acids production, dewatering, steam usage, gas composition and odors. The energy requirement and odor generation potential make this process an unlikely choice for the Districts to pursue as a means of obtaining Class A material.
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