收录:
摘要:
A bench-scale UCT-type submerged membrane bioreactor was operated to treat synthetic municipal wastewater regarding the influences of aeration and recirculation ratios on process performance and membrane fouling. The results show that variations of aeration intensity and recirculation rations in UCT-MBR process have no effects on the COD and NH4+-N removals, with removal efficiencies of COD (chemical oxygen demand) and NH4+-N stabilizing at 89.4% and 99.7% on an average and with effluent concentrations of 31.8 and 0.2 mg/L respectively. In the feed condition of ρ(COD)/ρ(N)/ρ(P) at 49.1/8.31/1.0, the increase of recirculation ratio (r1 from 200% to 400%) strengthens the denitrifying phosphorus removal, during which in the condition of lower aeration intensity (100-125 L/h, ρ(DO)=1-2 mg/L) and the recirculation ratio of 400%, the ratio of DPAOs to PAOs reaches the maximum value, and stabilizes at about 50.7%. The increase of the aeration intensity (250-300 L/h, ρ(DO)=2-3 mg/L) inhibits anoxic phosphorus removal efficiency (Rano-p) and removal efficiencies of TP and TN, decreasing to 78.0%, 77.0% and 70,0% from 93.0%, 92.6% and 79.6% respectively. Furthermore certain positive correlations between effluent concentrations of TN and TP, removal efficiencies of TN and TP are observed (R12=0.6360; R22=0.6786). In addition, the increase of the aeration intensity induces the increase amount of Bound-EPSs (bound extracellular polymeric substances, Bound-EPSs), whereas the scouring effect of the gas-water two-phase flow significantly reduces the resistance of the cake layer; the increase of recirculation ratio (r1 from 200% to 400%) also increases shear stress for activated sludge resulting in the decrease in particle size and the increase of SMPs (soluble microbial productions, SMPs), which become the main reason for the increased resistance of deep pore clogging. FT-IR (Fourier translation infrared spectroscopy, FT-IR) analysis of the membrane foulants shows that the variations of aeration intensity and the recirculation ratios have no effects on their compositions.
关键词:
通讯作者信息:
电子邮件地址: