The role of food/microorganism ratio in denitrification reactors: how it affects the sizing and operation of the denitrification process

O papel da fração alimento/microrganismos nos reatores de desnitrificação: como afeta o dimensionamento e a operação do processo de desnitrificação

Abstract

Two calculation models of the Specific Denitrification Rate (SDNR) are analyzed to highlight the sensitivity of this parameter to the Food:Microorganisms ratio in the denitrification reactor (F:M_DEN). One of these models is empirical while the second was elaborated on a deterministic basis. Both models reveal a linear dependence of SDNR_20°C on F:M_DEN and in a first approximation they are comparable only in a narrow range of concentration of dissolved oxygen (DO) in denitrification, specifically DO=0.25-0.35 mg L^-1. These values frequently occur in well designed and well operated sewage treatment plants. Outside this range, the role of F:M_DEN must necessarily be examined in combination with DO because of the relevant influence of the latter on the efficiency of the denitrification process.

Keywords:
activated sludge; biological process; denitrification; nitrogen removal; sewage treatment