Bio-entrapped membrane reactor for organic matter removal and membrane fouling reduction

This study investigated the performance of a novel bio-entrapped membrane reactor (BEMR) in removal of organic matter and its membrane fouling condition in treating food processing wastewater. Three different hydraulic retention times (HRTs) with 6, 12 and 18 h, continuous aeration and intermittent aerations (1 h aeration and 1 h non-aeration; 1 h aeration and 2 h non-aeration) were studied. The results show that the HRT and aeration have significant impacts on the BEMR performance. The chemical oxygen demand and ammonia (–N) removal efficiencies increased as the HRT increased with the continuous aeration condition. Results of this study indicated that the membrane fouling was severe at lower HRTs and intermittent aeration modes in the BEMR with a constant flux of 20 L/m2 h. Conventional membrane bioreactor (CMBR) took 57 min to reach 55 kPa of trans-membrane pressure at HRT of 12 h while the BEMR could operate 215 min before reaching 55 kPa, which was 3.8 times longer than the CMBR. This may be attributed to the higher yield of biomass and production of soluble microbial products in the CMBR, because the CMBR produced 17% more of carbohydrate and 33% more of protein than the BEMR. Better performance of the BEMR was found at the longer HRTs (18 h > 12 h > 6 h) and continuous aeration was better than intermittent aeration.