高铁酸盐对排水管网生物膜及挥发性硫化物协同控制机制与新技术研究

Sewer networks are important infrastructures. Corrosion and odor problems associated with sewer networks would not only result in high maintenance costs, but also cause odor nuisance to the nearby residents. The primary reason leading to the corrosion and odor problems is the production of volatile sulfur compounds, including hydrogen sulfide and volatile organic sulfur compounds (VOSCs), through the metabolism of microorganisms in sewer biofilms. However, current chemical dosing technologies for sewer corrosion and odor control requires continuously dosing large amount of chemicals, as these chemicals could not inhibit the microbial processes in sewer biofilms. Also, current technologies could not effectively remove VOSCs in sewers. This project will conduct a study on using ferrate (Fe(VI)) to fully control the biofilms, hydrogen sulfide and VOSCs in sewer networks, based on the unique characteristics of Fe(VI), namely, its biocidal effect and its ability to oxidize and precipitate sulfide. The study will be carried out by means of microbiological characterization, morphological measurements, physicochemical analysis, kinetics analysis, and multiscale mathematical modeling. The mechanisms of controlling biofilms, hydrogen sulfide and VOSCs by Fe(VI) will be revealed. The effect of Fe(VI) dosing conditions and environmental factors on controlling efficiency will be analyzed. The intermittent dosing strategy with small amount of Fe(VI) to sewer networks will be explored. On this basis, a new technology for controlling sewer corrosion and odor problems using Fe(VI) with intermittent dosing will be developed. With the help of this new technology, the corrosion and odor problems in the sewer networks are expected to be fully controlled, and in the meantime, the chemical dosing amount can be largely decreased, and consequently the process operation and management can be simplified.

排水管网是重要的市政基础设施，其腐蚀和嗅味问题不仅导致高额的维修费用，也对生活环境造成不良影响。管网内生物膜中微生物代谢产生的挥发性硫化物，包括硫化氢和挥发性有机硫化物（VOSCs），是引起腐蚀和嗅味的根本原因。但现有的化学药剂控制法因无法控制生物膜内微生物代谢而需连续投加大量药剂，且无法实现VOSCs的有效去除。本项目拟研究利用高铁酸盐（Fe（VI））杀菌和氧化沉淀硫化物的特性，实现对管网中生物膜、硫化氢和VOSCs的全面控制。通过生物学解析、影像学观测、物理化学分析、动力学表征、多尺度模型描述等手段，揭示Fe（VI）对管网中生物膜、硫化氢和VOSCs的控制机制，解析投加条件及环境因素对协同控制能效的影响，探索Fe（VI）在排水管网中的少量间歇投加模式。在此基础上，构建基于Fe（VI）间歇投加的排水管网腐蚀与嗅味控制新技术，以达到全面控制腐蚀和嗅味问题，降低药耗，简化运行管理的目的。

管网腐蚀和嗅味是排水管网安全运行面临的重要问题，而管网内生物膜中微生物代谢产生的挥发性硫化物是引起腐蚀和嗅味的根本原因。本项目通过利用新型水处理药剂高铁酸盐（Fe(VI)）对排水管网生物膜及其代谢产物进行协同控制，以达到全面控制管网腐蚀和嗅味问题的目的。项目系统性研究了Fe（VI）对排水管网生物膜及其代谢产物的作用机制，其主要表现在：（1）Fe(VI) 对管道生物膜中微生物具有快速而强大的灭活能力，在广泛的pH 范围内都能够发挥灭活作用，（2）Fe(VI) 可显著降低生物膜的种群丰富度与多样性，并且能有效降低关键功能微生物的丰度。（3）Fe(VI) 对生物膜聚集状态具有极大的破坏能力，生物膜胞外聚合物含量减少，微生物分布松散，生物膜整体稳定性下降。（4）Fe(VI)可对管网中微生物代谢产生的挥发性硫化物通过氧化及沉淀的形式去除。基于Fe（VI）的灭活效果及对生物膜破坏的作用机制和特点，研发了Fe(VI)脉冲式投加新技术，并证实了其对管网生物膜、微生物及挥发性硫化物的协同控制能力。并进一步将Fe(VI) 与游离亚硝酸联用，在较低的药耗和较短的作用时间下，达到满意的控制效果。针对排水管网生物膜经Fe（VI）投加后，其活性恢复周期长的特点，提出Fe(VI)间歇投加的策略。模型预测及经济分析表明，该策略在有效控制管网腐蚀和嗅味问题的同时，可以大幅度降低运行成本及运行难度。因此本项目提出的基于Fe(VI)的排水管网腐蚀与嗅味控制技术可行性好、耗药量少、经济成本低，在排水管网系统提质增效与安全运行方面具有巨大的应用潜力。