Department of Civil Engineering, Architecture and Georesources (DECivil) & Centre for Hydrosystems Research (CEHIDRO), Technical University of Lisbon, Instituto Superior Técnico (IST), Avenida Rovisco Pais, 1049-001 Lisbon, Portugal E-mail:
Water Sci Technol. 2014;69(2):262-8. doi: 10.2166/wst.2013.702.
Odor nuisance and sulfide corrosion in sewers carrying septic wastewater are accelerated at points of turbulence such as drops in manholes, but accurate methods or empirical expressions to evaluate the gas stripping rate at those particular sites are still missing. With the aim of improving the current knowledge on the influence of free-fall drops on the release of hydrogen sulfide gas, an experimental set-up was built allowing different free-fall drops heights and flows. Three types of experiments were carried out: reaeration tests without sulfide; sulfide oxidation tests; and hydrogen sulfide release tests. With the increase of the free-fall drop height or of the flow, a higher rate of air-to-water mass oxygen transfer was observed. Results regarding sulfide oxidation tests with reaeration through the free-fall have shown that the oxidation rate was correlated with flow. In the hydrogen sulfide release tests, the maximum concentration in the atmosphere reached 500 ppm. Results also showed that increasing the flow rate decreased the time at which the maximum concentrations in the atmosphere were observed.
污水管道中的异味问题和硫化物腐蚀会在检查井等湍流点加速，但仍缺乏评估这些特定地点气体汽提速率的准确方法或经验表达式。为了提高当前对自由落体下降对硫化氢气体释放影响的认识，建立了一个实验装置，允许不同的自由落体下降高度和流量。进行了三种类型的实验：无硫化物的再曝气测试；硫化物氧化测试；和硫化氢释放测试。随着自由落体下降高度或流量的增加，观察到空气到水的传质氧转移率更高。通过自由落体进行再曝气的硫化物氧化测试的结果表明，氧化速率与流量相关。在硫化氢释放测试中，空气中的最大浓度达到了 500ppm。结果还表明，增加流速会缩短空气中最大浓度出现的时间。
