Enhancement of anaerobic membrane bioreactor performance using microbe activator in palm oil mill effluent treatment

Anaerobic membrane bioreactors (An-MBRs) are a proven technology in wastewater treatment. However, the operation of anaerobic membrane bioreactors (An-MBRs) is inevitably plagued by membrane fouling due to the action of foulants that hinders its effectiveness. Among the foulants, extracellular polymeric substances (EPS) had been identified as the major contributor towards membrane fouling, which suggest that controlling EPS production is crucial towards membrane fouling reduction. Polysaccharide and protein are the two recognized major components of EPS. This explains why in this research, polysaccharide and protein concentrations were used to measure the presence of EPS in the bioreactors. Microbe activator was added into the anaerobic membrane bioreactor (An-MBR) under different dilution factors to assess their efficiencies in promoting the performance of An-MBRs in terms of EPS and membrane fouling control. The An-MBR that was added with 1/500 dilution of microbe activator showed the highest chemical oxygen demand removal efficiency which is 79.47% ± 2.76%, while the other 3 An-MBRs with 1/125 dilution, 1/1,000 dilution and without added with microbe activator had removal efficiencies of 55.09% ± 4.25%, 56.42% ± 3.36% and 53.49% ± 4.09%, respectively. The bioreactors added with microbe activator with the dilution of 1/500 also achieved the highest EPS removal efficiency mainly in terms of polysaccharides. Also, it had the lowest membrane fouling rate during membrane filtration among the An-MBRs. It is speculated that the introduction of suitable doses of microbe activator would contribute a suitable amount of light metal cations into the bioreactor. Right concentration of light metal cations could enhance microbial activities which may help to control EPS productions. For other dilution factors, the performance of An-MBR was not enhanced. This may be due to the excessive or too little concentration of microbe activator would not improve the performance of An-MBR.