Polymer Addition Combined with Rapid Decrease in Solids Retention Time is an Effective Nocardia Foam Control Method
Abstract:In this studyNocardia foam control using a combination of polymer addition and solids retention time (SRT) reduction was investigated at the San Jose/Santa Clara Water Pollution Control Plant (SJ/SC WPCP). A three-week continuous polymer addition at increased dosing rates of 0.35 mg/l, 0.5 mg/l and 0.75 mg/l reduced Nocardia foam coverage from 100% to less than 5%. But, foam accumulation returned to 95% coverage when polymer dosing was stopped for a week. It only took a week to eliminate Nocardia foam from the aeration tanks when 0.5 mg/l polymer addition was accompanied by SRT reduction from eleven days to four days. A potential effluent ammonia permit violation associated with SRT reduction was avoided by aerating the anoxic compartment of the aeration tanks and converting the step-feed biological process to plug flow mode. Except an increase in secondary effluent solids concentrations during plug flow operations, polymer addition to the return activated sludge (RAS) and Nocardia wasting to the digesters via dissolved air floatation did not cause foaming in the digesters nor was it detrimental to effluent filtration.
Document Type: Research Article
Publication date: January 1, 2010
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