Study On Performance Of Moving Bed Membrane Bioreactor (MBMBR) For Wastewater Treatment

Moving bed membrane bioreactor (MBMBR) was proposed and its performance was investigated for simultaneous chemical oxygen demand (COD) and nitrogen removal under different hydraulic retention times (HRT) of 18 and 24 hours. In the bioreactor, during the whole experiments period, the dissolved oxygen (DO), temperature and pH were constantly kept between 6-7mg/L, 20-24℃and 7-8 respectively while Mixed liquor suspended solid (MLSS) varied between 2800 and 4895mg/L. The suction of the treated wastewater was continuously applied through membrane filtration under pump action. Results showed that COD removal efficiency was above 96% regardless of HRT for 300.3-610.0mg/L of influent COD concentration. However, the ammonia nitrogen and total nitrogen removal efficiency increased with increased HRT. Ammonia nitrogen removal efficiency averaged above 94% when the HRT was 24h for both 17.34mg/L and 35.51mg/L of NH₄⁺-N influent concentration while only 89.3% was reached with 30.33mg/L of NH₄⁺-N influent at HRT of 18H. The current MBMBR was capable to remove nitrogen compound up to 55.89% - 62.45% with HRT of 24h while only 45.65% was achieved at HRT of 18h.The effect of membrane fouling was also investigated with and without periodic membrane shaking process. It had been shown that for both cases filtration performance depend on the concentration of mixed liquor suspended solid (MLSS) which directly rely on influent organic loading rate. Results have proved that the filtration process with membrane shaking gave an additional efficiency by increasing the operation time of the reactor about 21.4% - 25.7%. Shaking action allowed the collisions between fiber membranes and mixed liquor which mitigated the formation of biofilms on the surface of the hollow fiber. Thus, the membrane permeability was greatly enhanced.