城市污水深度净化处理后作为可饮用性水源已经成为污水再生领域发展趋势,能够有效缓解水资源危机。再生水间接饮用性回用的处理工艺通常采用膜过滤、高级氧化和活性炭工艺组合,以达到同时去除颗粒物、小分子有机物和致病菌的目的。本论文采用具有催化功能的陶瓷膜,构建了原位臭氧/陶瓷膜-生物活性炭(Biological activated carbon,BAC)耦合工艺,实现了膜和催化氧化过程一体化集成,缩短了工艺流程。通过实验室小试和现场中试进行了全面系统研究,评估陶瓷膜耦合工艺用于再生水间接饮用性回用的可行性。现场中试研究揭示了原位臭氧/陶瓷膜-BAC耦合工艺之间的协同效应。原位臭氧氧化能够比预臭氧氧化更有效地控制膜污染,保持比较高的膜通量和有机物去除率,后续BAC过滤能够进一步去除有机物、氨氮和N-二甲基亚硝胺(NDMA)类消毒副产物。臭氧/陶瓷膜过滤能够高效去除颗粒物,延长BAC运行周期,反冲洗周期达到30天以上。臭氧/陶瓷膜过滤降低了后续BAC中微生物群落的多样性和丰富度,抑制了致病菌和蓝藻的繁殖,提高了出水水质安全性。原位臭氧化对新型氧化锰陶瓷膜污染的控制效果优于传统的氧化铝陶瓷膜。与对照组相比,臭氧投加量为5 mg/L时,氧化锰陶瓷膜过滤?TMP降低了81.0%,而氧化铝陶瓷膜过滤?TMP仅降低了57.1%。单独陶瓷膜过滤过程中,膜污染属于复合滤饼层-完全堵塞型;原位臭氧氧化后,膜污染转变为中间-标准堵塞型。氧化锰陶瓷膜可以显著催化臭氧氧化,大幅提高羟基自由基生成率,有效去除再生水和滤饼层中DOC、多糖和蛋白质等,提高生物多聚物和类腐殖酸物质去除率,降低滤饼层和凝胶层阻力,有效缓解陶瓷膜污染。 中试系统运行结果表明,氧化锰陶瓷膜在膜通量为80 LMH条件下,投加4~5 mg/L臭氧,能够有效控制膜污染,具有比有机超滤膜更好的系统运行稳定性和更高的产水率。原位臭氧/氧化锰陶瓷膜-BAC耦合工艺能够高效去除常规污染物和新兴微量有机物,出水水质DOC≤2 mg/L,能够满足再生水间接饮用性回用-地下水回灌水质标准要求,耦合工艺显著改善了再生水生物稳定性,其吨水运行成本估算为0.324元,具有较好的经济性。本研究为传统再生水厂在现有构筑物基础上实现升级改造提供了理论依据和技术支持,有重要的工程和理论意义。
Advanced treatment of urban wastewater to supplement drinking water source has become the development trend in the field of wastewater reclamation, which can effectively alleviate the water scarcity. Membrane filtration, advanced oxidation and activated carbon filtration technologies are usually used in wastewater reclamation for indirect potable reuse, so as to achieve the purpose of simultaneous removal of particulate matter, small-molecular organic matter and pathogenic bacteria. The integrated process of coupling in-situ ozonation, ceramic membrane filtration (CMF) and biological activated carbon (BAC) filtration was constructed, which realized the integration of membrane separation and catalytic oxidation process, and shortened the treatment process train. The feasibility of this integrated process for indirect potable reuse of reclaimed water was comprehensive and systematic evaluated by both of laboratory-scale and pilot-scale studies. The synergistic effects of coupling ozonation, CMF and BAC for wastewater reclamation was demonstrated by pilot-scale test. Compared with pre-ozonation, in-situ ozonation could effectively control membrane fouling and maintain a relatively high membrane flux and organic matter removal rate. Subsequent BAC filtration could further remove organic matter, ammonia nitrogen and NDMA disinfection by-products. Ozonation / CMF could effectively remove particulate matter, prolong the BAC filtration operation cycle, and the backwashing interval up to more than 30 days. Ozonation / CMF reduced the diversity and richness of microbial community in the follow-up BAC filter, inhibited the reproduction of pathogenic bacteria and cyanobacteria, ensuring the microbial safety of effluents. The effectiveness in controlling membrane fouling by in situ ozonation on new type manganese oxide ceramic membrane filtration was higher than that of traditional alumina ceramic membrane. Compared to the control, at the ozone dosage of 5 mg/L, △TMP of membrane filtration with manganese oxide ceramic membrane was decreased by 81.0%, while that with alumina ceramic membrane was only 57.1%. Membrane fouling of ceramic membranes could be fitted by cake layer-complete plugging model without ozone dosing. After adding ozone in situ, it changes to intermediate-standard plugging model. Manganese oxide ceramic membrane could effectively catalyze ozonation, increased the generation rate of hydroxyl radicals, effectively removed DOC, polysaccharides and proteins in the reclaimed water and the fouling layer as well, promoted the removal efficiency of biopolymer and humic substances, reduced the resistance of cake layer and gel layer, and effectively mitigated the ceramic membrane fouling.The results of pilot-scale test showed that membrane fouling was effectively controlled during filtration with flux of 80 LMH and ozone dosage of 4-5 mg/L. Ceramic membranes demonstrated better system operation stability and higher water recovery rate than polymeric ultrafiltration membranes. Moreover, the integrated process had an excellent performance in removing both conventional pollutants and emerging contaminants. The DOC concentration in the treated water was less than 2 mg/L, meeting the suggested guideline values for water reuse - groundwater recharge by injecting into potable aquifers. The effluent of the process significantly improved the biological stability of reclaimed water. The operational cost of the coupled process was estimated to be 0.324 yuan per ton of reclaimed water, indicating its good economic efficiency.The integrated process provides theoretical and technical support for the upgrading of traditional water reclamation plants based on existing infrastructures, which has important engineering and theoretical significance.