Mitigation of Salinity Buildup and Recovery of Wasted Salts in a Hybrid Osmotic Membrane Bioreactor鈥揈lectrodialysis System
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文摘
The osmotic membrane bioreactor (OMBR) is an emerging technology that uses water osmosis to accomplish separation of biomass from the treated effluent; however, accumulation of salts in the wastewater due to water flux and loss of draw solute because of reverse salt flux seriously hinder OMBR development. In this study, a hybrid OMBR鈥揺lectrodialysis (ED) system was proposed and investigated to alleviate the salinity buildup. The use of an ED (3 V applied) could maintain a relatively low conductivity of 8 mS cmp>鈥? p> in the feed solution, which allowed the OMBR to operate for 24 days, about 6 times longer than a conventional OMBR without a functional ED. It was found that the higher the voltage applied to the ED, the smaller area of ion-exchange membrane was needed for salt separation. The salts recovered by the ED were successfully reused as a draw solute in the OMBR. At an energy consumption of 1.88鈥?.01 kWh mp>鈥? p>, the hybrid OMBR-ED system could achieve a stable water flux of about 6.23 L mp>鈥? p> hp>鈥? p> and an efficient waste salt recovery of 1.26 kg mp>鈥? p>. The hybrid OMBR-ED system could be potentially more advantageous in terms of less waste saline water discharge and salt recovery compared with a combined OMBR and reverse osmosis system. It also offers potential advantages over the conventional OMBR+post ED treatment in higher water flux and less wastewater discharge.