Wang Yufei, Fan Linhua, Jones Oliver A H, Roddick Felicity
School of Engineering, RMIT University, GPO Box 2476, Melbourne, Victoria 3000, Australia.
School of Science, RMIT University, Bundoora West Campus, PO Box 71, Bundoora, Victoria 3083, Australia.
Sci Total Environ. 2021 Apr 15;765:142733. doi: 10.1016/j.scitotenv.2020.142733. Epub 2020 Oct 8.
Photochemically produced reactive oxygen species in wastewater lagoons upon sunlight exposure are important in the attenuation of emerging contaminants (ECs). The production of reactive radicals in wastewater lagoons depends on both environmental factors and the composition of effluent organic matter (EfOM) in the wastewater. Knowing the steady state concentrations of these reactive species produced in a particular lagoon wastewater is critical to the prediction of the persistence and attenuation of ECs in that sunlit wastewater treatment lagoon. This study quantified the formation of four photochemically produced reactive intermediates (PPRIs): hydroxyl radical, carbonate radical, singlet oxygen, and triplet excited state EfOM in 11 samples collected from a municipal wastewater lagoon over a full year. The temporal distribution of these key PPRIs in the lagoon under investigation was determined in relation to sunlight irradiance, wastewater composition and temperature. Greater sunlight intensity led to greater PPRI production over the year. Increasing wastewater temperature from 12 to 25 °C led to greater production of singlet oxygen, a moderate decrease in hydroxyl radical and increase in triplet excited state EfOM, and minimal impact on carbonate radical production. The optical properties of the lagoon wastewater of Napierian absorption coefficient (A) and E:E ratio could be used as indicators of the formation of singlet oxygen (Pearson's r = 0.79) and triplet excited EfOM (Pearson's r = 0.76) produced upon solar irradiation. The concentration of carbonate radical formed was strongly correlated to the nitrate level in the wastewater (Pearson's r = 0.85). The findings could be used for modelling the seasonal sunlight-induced photolysis process of ECs during lagoon-based wastewater treatment, with a view to optimising the treatment process, predicting the efficacy of EC removal, and risk assessment of the treated water.
废水泻湖在阳光照射下通过光化学作用产生的活性氧物种对于新兴污染物（ECs）的衰减具有重要意义。废水泻湖中活性自由基的产生既取决于环境因素，也取决于废水中流出物有机物（EfOM）的组成。了解特定泻湖废水中产生的这些活性物种的稳态浓度对于预测阳光照射下的废水处理泻湖中ECs的持久性和衰减至关重要。本研究对从城市废水泻湖全年采集的11个样品中四种光化学产生的反应中间体（PPRIs）的形成进行了量化：羟基自由基、碳酸根自由基、单线态氧和三线态激发态EfOM。根据阳光辐照度、废水组成和温度，确定了所研究泻湖中这些关键PPRIs的时间分布。全年阳光强度越大，PPRIs的产生量就越大。将废水温度从12℃提高到25℃会导致单线态氧的产生量增加，羟基自由基略有减少，三线态激发态EfOM增加，而对碳酸根自由基的产生影响最小。泻湖废水的光吸收系数（A）和E：E比等光学性质可作为太阳辐射产生的单线态氧（皮尔逊相关系数r = 0.79）和三线态激发态EfOM（皮尔逊相关系数r = 0.76）形成的指标。形成的碳酸根自由基浓度与废水中的硝酸盐水平密切相关（皮尔逊相关系数r = 0.85）。这些研究结果可用于模拟基于泻湖的废水处理过程中季节性阳光诱导的ECs光解过程，以优化处理过程、预测ECs去除效果以及评估处理后水的风险。
