Effects of Substate Concentration, Specific Surface Area and Hydraulic Loading on the Treatment Efficiency in a Submerged Biological Filter

Effects of substrate concentration, specific surface area and hydraulic loading on the treatment efficiency in a submerged biological filter were investigated experimentally. BOD removal efficiency was influenced by three factors, that is, substrate concentration of BOD (X1), specific surface area (X2) and hydraulic loading (X3), and the multiple regression equation between BOD residual rate and these parameters was obtained as follows : Y = 4.66·X10.546·X2-0.503·X30.747 where Y was BOD residual rate. The multiple correlation coefficient of this equation was 0.94, and the predicted values of BOD residual rate were approximately in agreement with the observed values of that. When 200 mg·l-1 of BOD as substrate concentration and 50 m2·m-3 as specific surface area were substituted in our equation, we found the relationship between hydraulic loading and the predictive value of BOD removal rate was nearly in accord with the tendency calculated by Horasawa's equation which was derived from data of actual plants. Consequently, our equation was effective to estimate the removal efficiency in the submerged biological filter.