污水管网系统是现代城市的重要基础设施。然而，污水管网内由硫酸盐还原菌驱动的硫化物生成造成了管网腐蚀、恶臭中毒等问题，大大缩短污水管网服务寿命，并引发严重健康风险。由于重力管网条件复杂多变，使得沉积物内硫循环发生机制异常复杂，涉及微生物的协同与竞争、不同底物的微观传质与扩散等方面。目前仍缺少经济高效的硫化物控制方法，导致管网运行维护极具挑战。本论文系统地研究了沉积物界面的碳硫反应过程及动力学特征，阐明了流速氧气等典型管网条件对沉积物界面的微观影响机制，提出了基于沉积物活性层调控的硫化物原位控制策略，并开展了硫化物动态预测与控制的优化与应用研究，旨在为大规模管网硫化物控制提供实际指导。论文首先针对实际污水管网复杂多变运行条件对硫化物生成过程影响，研究了实际污水管网的硫化物生成与排放特征，发现气相硫化氢排放受到了管网结构、水质水量、季节温度等因素综合影响，沉积物是硫化物的重要生成源，其活性可达2 g S/(m2·d)，且沉积物内具有硫化物生成活性的复杂分层现象。论文进一步探索了污水管网沉积物界面硫循环发生机制，揭示了决定界面活性特征的临界流速条件在0.07 m/s附近，当低于临界值时，沉积物界面扩散边界层厚度逐渐增大（150 μm-950 μm），而复氧刺激表层硫氧化菌生长并驱动深层（>1 cm）硫化物生成活动。在此基础上，构建了描述沉积物界面微观扩散与多种生物协同作用的机制模型。论文针对沉积物界面高活性区的硫化物生成特点，提出了基于沉积物活性层调控的三种方法，分别为物理冲刷扰动、游离氨生物灭活、自由基原位形成。通过对沉积物主导活性层原位结构破坏及微生物灭活/抑制，可以实现沉积物内硫化物的高效控制，恢复周期超过1周。最终，建立了污水管网硫化物生成热点的快速预测方法，成功实现了实际管网硫化物生成与排放的动态预测，以支持硫化物控制策略的定点实施，选择所开发的游离氨生物灭活法实现了硫化物生成热点区域~50%的硫化物甲烷同步控制。相比传统化学药剂投加方法，所开发的方法可减少90%以上经济成本。
The sewer system is a significant infrastructure of modern cities. However, hydrogen sulfide (H2S) driven by sulfate-reducing bacteria is harmful to public health and the environment due to its corrosion, odor nuisance, and toxicity, shorting the service life of the sewer system, thus posing a great challenge in operation and maintenance. Due to the sophisticated and changeable conditions of sewer systems, the mechanism of the sulfur cycle in sediments is more complicated, involving the cooperation and competition of microorganisms, and the substrate mass transfer and diffusion. Until now a great gap has existed in efficient and economical control of sulfide. In this work, we systematically studied the carbon and sulfur conversation and dynamic characteristics at the sediment interface, illustrating the oxygen flow rate on the influence of mechanism at the sediment interface, proposing a sulfide in-situ control strategy based on the regulation of sediment active layer, providing a variety of in-suite control strategies to application and optimized methods, aiming to provide practical guidance for sulfide control on a large scale.Investigating the characteristics of sulfide production and emission in the sewer system, and it was found that the structure, water quality and water quantity, seasonal temperature, etc. affect the emission of gas-phase H2S emission. The sediment is a critical source of sulfide production, which sulfide activity can reach 2 g S m-2 d-1, and along with the depth there found stratification phenomenon of sulfide production activity in the sediment. Further exploring the mechanism of the sediment sulfur cycle, it was revealed that the critical flow rate is ~0.07 m/s which regulates the biologically active layer of the sediment. When it was lower than the critical value, the diffusion boundary layer thickness increased gradually (150 μm-950 μm), and reoxygenation stimulated the growth of sulfur-oxidizing bacteria on the surface layer and drove sulfide generation in the deep layer (>1 cm). Based on this, a mechanical model for accurately describing the microscopic diffusion of sediment interfaces and various biological actions was constructed.In view of the characteristics of sulfide generation in the surface sediment, three methods were developed to control the active layer of sediments, including physical disturbance, free ammonia inactivation and hydroxyl radical in-situ formation, etc. They can achieve in-situ structural failure or biological inhibition, thereby realizing the high efficiency control of sulfide in sediments, and the recovery period is more than 1 week. Finally, a rapid prediction method for sulfide generation hotspots in sewers was established, to support the optimal implementation of sulfide control. The biological inactivation of free ammonia achieves the synchronous control of about 50% sulfide and methane in hotspots. Compared with traditional chemical addition, the economic cost can be effectively reduced (over 90%).
