城市污水再生利用的深度处理新工艺原理

The project will aim at the effluent of municipal sewage treatment plant,taking the residual COD, N, P and micro-level or trace toxic pollutants as treatment objectives. The innovative advanced treatment technology for reclamation and reuse of municipal sewage will be researched and developed, mainly solving the common problems and key scientific issues of the reclamation and reuse of the effluent of municipal sewage treatment plant. The main research contents include: (1) To research and developo new pretreatment technology using advanced oxidation processes (AOPs), i.e., using heterogenous Fenton-like oxidation reaction, micro-bubble catalytic ozonation as pretreatment technology, special effort will be made to the high efficeincy catalysts. The effluent of the municipal sewage treatment plant will be pretreated, in order to remove the toxic pollutants and improve the biodegradability of the effluent, which is the first key issue for advanced treatment and reuse of wastewater. (2) To investigate the mechanisms for the removal of COD, N, P and toxic pollutants in biological aerated filter (BAF). The development of new packing materials, the introduction of denitrifying phosphate-accumulating microorganisms and other special strains capable of degrading toxic pollutants will be studied. The mechanism of biofilm formation, the microbial community structure dynamics and the removal characteristics of pollutants will be investigated. The solubel microbial products (SMPs) formed during the operation of the BAF will be determined and analyzed. (3) To develop a novel integrated process of AOP-pretreatment and biological aerated filter for advanced treatment of wastewater. The optimal combination of AOP and BAF will be investigated, the integrating mechanism of AOP and BAF will be probed, in order to make full use of their individual advantages and reduce the treatment cost, this is critical issue for practical application of the advanced treatment technology. The objective of this project is to develop the innovative technology for the reclamation and reuse of municipal sewage, to provide the theoretical foundation and technical support for research and development of new advanced treatment technology, to guarantee the sustainable development and utilization of municipal sewage.

本项目拟研究污水再生利用的深度处理新技术，综合去除城市污水二级处理出水中残留的COD、N、P及微量/痕量有毒有机污染物，重点解决污水再生利用中存在的共性问题和关键科学问题。（1）研究类Fenton氧化技术、微米气泡臭氧催化氧化技术及其高效催化剂，对城市污水二级处理出水进行预处理，改善废水的可生化性并去除残留的部分有毒有机污染物，这是废水深度处理需要考虑的首要问题。（2）研究新型曝气生物滤池（BAF）综合去除有机污染物、N和P的机制。开发新型填料、引入反硝化聚磷微生物及其他高效微生物，探讨BAF在低有机负荷、贫营养条件下生物膜的形成机制、微生物学特性及污染物去除机制，深入探讨曝气生物滤池的微生物代谢产物问题。（3）探讨高级氧化与生物处理组合技术的最佳结合点及其耦合作用机理，充分发挥两者的优势，降低处理成本，这是深度处理技术实用化的关键问题。本项目研究成果将为开发城市污水再生利用的深度处理新工艺提供理论依据和技术支持。

项目取得以下主要成果：(1) 制备了几种新型的掺铈及掺锰的类芬顿催化剂和臭氧氧化催化剂，并进行了结构性能表征。利用硼氢化钠还原制备了Fe0/Ce0催化剂，通过添加还原性氧化石墨烯(RGO)，制备得到Fe0/Ce0-RGO，有效的降低了催化剂的团聚。利用共沉淀法制备得到Fe3O4/Mn3O4，通过添加RGO，制备得到Fe3O4/Mn3O4¬-RGO，电镜观察表明Fe3O4与Mn3O4均匀分布在RGO表面。利用同晶替代法制备了Ce0.1Fe0.9OOH，掺入金属铈不影响针铁矿原本的晶体结构；利用水热法制备了纳米Fe-KCC-1，具有较高的比表面积（464.56 m2/g）；采用共沉淀法制备了纳米Fe3O4/MWCNTs复合物，拥有超顺磁性；利用共沉淀法制备了纳米Fe3O4-CeO2/MWCNTs复合物，长度粗细均匀，金属氧化物均匀分散在碳纳米管的表面。(2) 确定了多种因素，包括初始pH、污染物浓度、氧化剂浓度、温度及催化剂用量等对药物类化合物降解的影响。结果发现，在酸性条件(pH=3)下，Fe3O4/Mn3O4系列催化剂对污染物降解效率较高，且催化剂可重复利用；在中性条件下，Fe0/Ce0系列催化剂对污染物降解效率较高，但催化剂稳定性有待提高。污染物的降解符合一级动力学。催化臭氧氧化体系在一个广泛的pH范围内均表现出良好的催化氧化效果。臭氧用量、催化剂用量和污染物的初始浓度对抗生素的降解都有一定的影响。(3) 探讨了污染物的降解机理及催化剂的作用机理。通过添加自由基抑制剂，确定了类芬顿反应和臭氧催化氧化过程中活性自由基的作用；通过对催化剂反应前后的表征以及对污染物的降解中间产物分析，提出了污染物的可能降解途径以及催化剂的作用机理。(4) 将类芬顿法、臭氧催化氧化分别与曝气生物滤池相结合，对污水处理厂的二级出水进行深度处理，结果表明，类芬顿氧化处理后可提高废水的可生化性，但其生物毒性有所增加；后续曝气生物滤池进行处理，可有效降低废水的生物毒性。Fe3O4-CeO2/MWCNTs–O3体系对城市二级出水中微量有机污染物有较好的去除效率，二级出水对抗生素类污染物在该体系下的降解影响不大；类芬顿氧化、催化臭氧氧化分别耦合生物曝气滤池技术（BAF）组合工艺，可有效去除药物类污染物、硝氮及DOC也有一定的去除。