SRT对UCT-MBR反硝化除磷性能与膜污染行为的影响

采用脱氮除磷膜生物反应器(UCT-MBR)工艺处理冀南地区城市污水,考察了SRT对UCT-MBR工艺反硝化除磷性能与膜污染行为的影响.结果表明:较短(15d)与较长(40d)SRT均不利于反硝化聚磷菌(DPAOs)的富集;SRT控制在25d时系统的反硝化除磷性能得到最大程度强化,反硝化聚磷菌(DPAOs)占聚磷菌(PAOs)的数量比例及缺氧除磷率达到最大值,分别稳定在50.9%和88%,并且此时系统总磷(TP)、总氮(TN)去除率也达到最大值91.7%、73.6%,出水浓度分别稳定在0.48,13.3mg/L左右;SRT对系统COD、氨氮(NH_4~+-N)的去除效能影响不大,COD、NH_4~+-N平均去除率分别为89.8%、99.7%,出水浓度分别稳定在30.8,0.15mg/L;随着SRT的延长,膜池混合液固体(MLSS)浓度升高,分子量大于100k Da、小于1k Da的溶解性微生物代谢产物(SMP)浓度和胞外聚合物(EPS)比污泥浓度升高及污泥粒径(PSD)减小,是导致膜池污泥可滤性变差的主要原因,从而致使系统膜渗透性加速降低、持续运行周期缩短,而红外光谱(FT-IR)分析表明SRT对膜污染物质的组成无显著影响,光谱折射率与SMP、EPS含量呈现一致性.

Influence of sludge retention time on denitrifying dephosphatation propensity and membrane fouling behavior in a UCT-MBR process

A bench-scale nitrogen and phosphorus removal membrane bioreactor (UCT-MBR) was operated to treat municipal wastewater in southern parts of Hebei province regarding on the influence of sludge retention time on the denitrifying dephosphatation propensity and membrane fouling behavior. Either shorter (15d) or longer (40d) SRT could deteriorate the accumulations of DPAOs; denitrifying dephosphatation was strengthened to the maximum degree under SRT of 25d, the ratio of the DPAOs to PAOs and anoxic dephosphatation efficiency reaching the maximum values of 50.8% and 88%, with TP,TN maximum removal efficiencies of 91.7%, 73.6% and effluents of 0.48, 13.3mg/L respectively. SRT had slight effects on the COD and ammonia removals, with average removal efficiencies of 88.9%, 99.7% and effluents of 30.8, 0.15mg/L respectively; with the prolonged SRT, the increase of MLSS concentration, the SMP < 1kDa, SMP > 100kDa concentration, EPS < 1kDa, EPS > 100kDa specific concentration and decrease of PSD resulted in the sludge filterability deterioration, accelerating membrane permeability decline and shortening of sustainable operational cycle, whereas FT-IR analysis of membrane surface foulants showed that SRT had no significant effects on the compositions and refractive index of infrared spectroscopy presented the consistence with the amounts of SMP and EPS.