Abstract
Effects of inoculation, sulfate concentration, DO and anaerobic shock on filamentous bulking due to growth of type 021N were examined using the laboratory scale activated sludge reactors. Inoculation of filamentous bacteria and sulfate reducing bacteria did not affect the occurrence of bulking. The high sulfate concentration of the wastewater is one of the courses of filamentous bulking. However, when the sulfate concentration was low, filamentous bulking occurred. Low DO and anaerobic shock were important factors of filamentous bulking. The number and the activities of sulfate reducing bacteria in the bulking sludge was higher than those in the non-bulking sludge. And sulfate reducing bacteria coexist with sulfur oxidation bacteria. From the results by the FISH method, filamentous bacteria grew in the bulking sludge after anaerobic shock was Type 021N group II and sulfate reducing bacteria were observed in the bulking sludge.
