Performance and microbial surveying in submerged membrane bioreactor for seafood processing wastewater treatment

The main objective of this study is to evaluate the performance and the structure of the microbial community of a submerged membrane bioreactor (MBR) for seafood processing wastewater treatment and reuse. This system was operated continuously under favourable biological conditions, with complete biomass retention. In terms of organic removal and membrane performance, the MBR had a good efficiency to treat high strength with organic loading variation characteristic of real seafood processing wastewater. The overall results showed the importance of ecological microbial compositions in each stage of development that were different in MBR in comparison with conventional activated sludge. The MBR sludge could tolerate real stresses such as salinity and variation of COD and SS inlet in a wide range, with always good removal efficiencies in terms of BOD and COD. At the beginning period, bulking sludge was present. After 700 h of operation, the sludge characteristics not only showed healthy floc formations and good settling, but also confirmed the stable state of the system without overgrowth filamentous bacteria. In evaluating the fouling potential of membrane by cake filtration theory, it was found that soluble substances, soluble microbial products and/or residual organics play a key role in inducing membrane fouling. The αW values of the soluble fraction were three times higher than those of the particulates of bacterial floc.