Experimental Study on Submerged Membrane Bioreactor for Domestic Wastewater Treatment

Domestic wastewater was treated with MBR,in which a polypropylene hollow fiber membrane module was submerged.The efficiencies of SMBR,effects of different operation parameters and different cleaning methods on membrane fouling were studied.The results show that when the influent COD and NH3-N concentrations vary from 172 mg/L to 331 mg/L and 23 mg/L to 27 mg/L respectively,NH3-N and COD removal rates stably attain higher than 90%.Diminishing the ratio of suction time to pause time can alleviate membrane fouling.Higher suction pressure can increase initial membrane flux.The optimum ratio of suction time to pause time is 8 ∶2.The critical suction pressure is 30 kPa.Cleaning the fouled membrane by air scouring,water washing,water/NaOH,water/HCl and water/NaOH/HCl can recover the membrane flux to 30%,46.3%,86.54%,82.36% and 92% of new membrane flux respectively.