1998 Volume 34 Issue 1 Pages 17-28
Influence of amount of organic matter in sludge and population density of denitrifiers on denitrification performance was studied using suspended sludge obtained from the denitrification tank of a bench plant operated by a combined nitrification / denitrification process with recycled mixed-liquor nitrified by immobilized microorganisms. In batch denitrification tests, the amount (A) of organic matter in sludge decreased according to the relation in which the metabolism rate of organic matter in sludge was proportional to A, and the denitrification rate (KDN) was obtained by an equation with KDN proportional to A. Under a condition of A of more than around 40 mg-BOD / g-SS, the population density of denitrifiers increased with decreasing A, thus the decreasing KDN was attributable to the significant decrease of the amount of organic matter per one cell of denitrifier. While, under a condition of A of less than around 40 mg-BOD / g-SS, the population density of denitrifiers decreased with A, thus the denitrification reaction was assumed to be in endogenous stage using the organic matter derived from bacterial lysis.
