Ultrafiltration behaviour of extracellular and metabolic products in activated sludge system with UF separation process

Ultrafiltrations were conducted using a stirred batch cell for the batch culture supernatants containing extracellular and metabolic products released into culture medium from activated sludge bacteria mixture and Sphaerotilus natans strains responsible for aerobic bulking of the conventional activated sludge process. There existed differences in time-dependent relative permeate flux among growth phases for the same organisms and among the organisms grown to the same stationary growth phases, respectively. The retained ratio of protein to sugar during filtration may be one of the factors affecting the magnitude of time-dependent relative permeate flux decline, suggesting different degrees of interactive effect of both protein and sugar dependent on organism species and their growth phases on permeate flux decline characteristics of culture solutions.