NITRIFICATION IN ROTATING-DISK SYSTEMS .2. CRITERIA FOR SIMULTANEOUS MINERALIZATION AND NITRIFICATION

The criteria for nitrification and correction of the nitrification rate in the presence of mineralization are presented on the basis of biofilm kinetics for triple substrate conditions (soluble organic matter, ammonia and oxygen) in a rotating disc system. To verify the theoretical criteria, data from the literature have been used. It has been shown that the ratio between bulk soluble BOD5 and oxygen concentration should be less than five for achieving nitrification (nitrification criterion). For simultaneous mineralization and nitrification in the system, nitrification rate must be reduced compared to pure nitrification by two factors, namely the mixture and distribution of heterotrophs and nitrifiers within the biofilm, and oxygen penetration into the biofilm to allow the growth of nitrifiers. © 1990.