Sewer odour generation and mitigation in Edmonton's sewer systems

埃德蒙顿市一直在经历严重的下水道气味问题和相关的管道腐蚀问题，由于在其下水道系统中产生硫化氢（H2S）。当下水道系统处于缺氧状态时，存在于废水中的硫酸盐被存在于管壁和底部沉积物上的生物膜中的硫酸盐还原菌还原为硫化物。污水中溶解的H2S可排入下水道顶部空间，通过人孔、放空管、泵站等逸出地面，并引起异味投诉。下水道顶部空间中的H2S也可氧化成硫酸并导致下水道管道腐蚀。为了帮助埃德蒙顿市制定和评估其下水道气味控制策略，提出了基础研究，以调查H2S的产生和排放，潜在的结构和操作改进H2S控制，以及最佳的化学处理方法。城市的深层下水道系统被认为是产生过度流动湍流和污水中大量H2S排放的主要原因。H2S的排放机制在下降的结构将被研究，以及使用下降的空气处理和充氧结构的潜力。将研究固体沉积/侵蚀过程，并检查下水道清洁方法的潜力，以控制下水道生物膜和底部固体产生H2S。还将研究泵站的结构和操作改进，以防止过多的固体积聚。作为最后的防御，将研究化学处理，以了解它们如何对生物膜起作用并控制H2S的产生。考察各种化学药剂对生物膜和污水的影响，以获得最佳的化学处理方法。这项研究的结果将有助于埃德蒙顿市制定和实施创新的，具有成本效益的气味控制/缓解战略，并协助其他城市的下水道气味预防和腐蚀控制工作。本研究将培养3名博士生、2名硕士生、2名博士后和1名本科生。

The City of Edmonton has been experiencing severe sewer odour issues and related pipe corrosion problems due to the generation of hydrogen sulfide (H2S) in its sewer systems. When anoxic conditions prevail in a sewer system, sulfate present in the wastewater is reduced to sulfide by sulfate-reducing bacteria residing in the biofilms on the pipe walls and bottom sediments. The dissolved H2S in the sewage can emit into the sewer head space, escape to the ground through manholes, vent pipes, pump stations, etc., and cause odour complaints. H2S in the sewer head space can also be oxidized to sulfuric acid and cause sewer pipe corrosion. To assist the City of Edmonton in developing and assessing its sewer odour control strategies, fundamental research is proposed to investigate the generation and emission of H2S, potential structural and operational improvements in H2S control, and optimal chemical treatment methods. The City's deep sewer system is believed to be a leading cause for generating excessive flow turbulence and significant H2S emission from the sewage. The H2S emission mechanism at drop structures will be studied as well as the potential of using drop structures for air treatment and oxygenation. The solid deposition/erosion process will be studied, and sewer cleaning methods will be examined for their potential to control H2S generation at sewer biofilms and bottom solids. Structural and operational improvements at pump stations will also be investigated to prevent excessive solids accumulation. As the final defense, chemical treatments will be studied to understand how they work on biofilms and control H2S generation. The effects of various chemicals on biofilms and sewage liquid will be examined to obtain optimized chemical treatment methods. The results of this study will help the City of Edmonton develop and implement innovative, cost-effective odour control/mitigation strategies and assist other municipalities in their sewer odour prevention and corrosion control efforts. The proposed study will train 3 PhD students, 2 MSc students, 2 Postdoctoral fellows and 1 undergraduate student.