Membrane bioreactor performances: effluent quality ofcontinuous and sequencing systems for water reuse

The aim of this work is to study and compare the performances of two immersed membrane bioreactors especially respect to effluent quality for water reuse; one is operating in a sequencing way (MSBR), the other one in a continuous way (MCBR). Organic matter removal and membrane permeability were studied and analysed. The COD removal efficiency was higher for the continuous operation and reached a value — after a period of biomass adaptation — higher than 97% with a COD in the effluent lower than 50 mg/L. The COD removal efficiency was close to 94% with a COD in the effluent lower than 125 mg/L for the sequential operation. The filtration performance was better for the continuous operation, with a nearly constant evolution of transmembrane pressure. In this case the filtration conditions allowed a long time operation period (3600 h) without the requirement of membrane regeneration. The results show better performance for the continuous membrane reactor respect to the organic matter removal and filtration performances. In both systems the quality of water treated was conform to the legislative France constrains (COD < 125 mg/L), but in the context of water reutilization the potential of the continuous system is higher than the sequential one.