Comparison between MBR and A/O processes treating saline wastewater

Abstract

Abstract Membrane bioreactor MBR and A/O processes are employed to treat saline wastewater. The mixed liquid suspended solids in the MBR and A/O were 7,000 and 3,500 mg/L, respectively. With the same influents, MBR process was more suitable for the treatment of high-salinity wastewater. The chemical oxygen demand and ammonia removal efficiencies were 75 and 82%, respectively, with the salinity of 24.5 g/L. Both were higher than that through the A/O process. Autotrophic nitrifying bacteria could be enriched and had sufficient time to accommodate to the saline environment. Both sludge volume index (SVI) decreased with salinity increment. However, the SVI of MBR dropped more than that of A/O, which indicated a better sludge-settling property in the MBR process. Filamentous bacteria existed in the A/O reactor and made the sludge-settling property worse than that in the MBR process. Membrane fouling occurred inevitably during the MBR process. Microbes and organics could be removed by combined physical and chem...