Abstract |
The gas-tight biological reactor with 2.5 hour detention time or less insolubilized the biodegradable organics to less than 5 mg/l of soluble BOD. The organisms in the mixed liquor were maintained between 4000 and 8000 mg/l. Above a solids retention time (SRT) of six days, the rate of activity in the oxygen volatile solids was greater than in a parallel step aeration system. Ninety-five percent of the oxygen supplied was consistently used in the staged reactor, which employed co-current liquid and gas flow contacting. The liquid solids separation was accomplished by conventional clarification. The clarification efficiency was a function of mixed liquor concentration, particle shape, particle density and seasonal variation (i.e., temperature, metabolic changes, and load variation). Above an SRT of six days, the total production of solids was significantly less than the solids production in a similarly operated step aeration system. At an SRT of 13 days, 0.35 lb. of solids/lb. of BOD were produced. (Modified author abstract) |