Performance of a MBR pilot plant treating high strenght wastewater: analysis of biomass activity and fouling behaviour

Nowadays, due to the increasing awareness about environmental impact of discharges, it is necessary to realize biological processes that allow complete treatment of wastewater, able to produce high quality effluents that could be used for recycling and reuse purpose. A possible solution to cope with this issue is represented by membrane bioreactors (MBRs), which are combined systems including a bioreactor and a filtration unit. However, in presence of high strenght domestic or industrial wastewater, a modification in biomass kinetics as well as in sludge characteristics may occur. This situation is of importance, since microbial community characteristics can play an important role in membrane fouling, which still represents the major drawback of MBRs. The aim of the paper was to evaluate the performance of a laboratory scale MBR system treating high strength synthetic wastewater, in terms of biomass activity and fouling behaviour. The pilot plant showed high removal efficiencies, and high respiration rates, in terms of oxygen uptake rate values, especially for heterotrophic population, coupled to a storage phenomenon, typical of dynamic conditions occurring in the process. On the other hand, the batch tests carried out on the autotrophic population suggested a good development of nitrification activity