Department of Civil Engineering, Architecture and Georesources (DECivil) & Civil Engineering Research and Innovation for Sustainability (CERIS), Instituto Superior Técnico (IST), University of Lisbon, Avenida Rovisco Pais, Lisbon 1049-001, Portugal E-mail:
Department of Civil Engineering, Aalborg University, Sofiendalsvej 11, Aalborg DK-9200, SV, Denmark.
Water Sci Technol. 2017 May;75(10):2257-2267. doi: 10.2166/wst.2017.103.
Over the last decades, considerable progress has been made in the understanding of the sulfur cycle in sewer systems. In spite of a wealth of experimental and field studies that have addressed the release of hydrogen sulfide from free surface flows in gravity sewers and the corresponding air-water mass transfer, little is known about hydrogen sulfide emission under highly turbulent conditions (e.g., drop structures, hydraulic jumps). In this study, experimental work was carried out to analyze the influence of characteristics of drops on reaeration. Physical models were built, mimicking typical sewer drop structures and allowing different types of drops, drop heights, tailwater depths and flow rates. In total, 125 tests were performed. Based on their results, empirical expressions translating the relationship between the mass transfer of oxygen and physical parameters of drop structures were established. Then, by applying the two-film theory with two-reference substances, the relation to hydrogen sulfide release was defined. The experiments confirmed that the choice of the type of drop structure is critical to determine the uptake/emission rates. By quantifying the air-water mass transfer rates between free-fall and backdrop types of drop, the latter resulted in considerably lower oxygen uptake rates.
在过去的几十年中，人们对污水系统中硫循环的理解取得了相当大的进展。尽管有大量的实验和现场研究解决了重力污水中自由表面流动释放硫化氢以及相应的气-水质量转移问题，但对于高度紊流条件（例如液滴结构、水力跳跃）下的硫化氢排放知之甚少。在这项研究中，进行了实验工作来分析液滴特性对复氧的影响。建立了物理模型，模拟典型的污水液滴结构，并允许使用不同类型的液滴、液滴高度、尾水深和流速。总共进行了 125 次测试。根据测试结果，建立了氧传质与液滴结构物理参数之间关系的经验表达式。然后，通过应用双膜理论和两种参考物质，定义了与硫化氢释放的关系。实验证实，选择液滴结构的类型对于确定吸收/排放速率至关重要。通过量化自由落体和背景类型液滴之间的气-水质量转移率，后者导致氧气吸收速率显著降低。
