Farzam Allafchi , Caterina Valeo , Jianxun He , Norman Neumann
{"title":"A mechanistic model for estimating bacteria levels in stormwater ponds","authors":"Farzam Allafchi , Caterina Valeo , Jianxun He , Norman Neumann","doi":"10.1016/j.jher.2021.06.002","DOIUrl":null,"url":null,"abstract":"<div><p>This paper presents a three-dimensional CFD based hydro-environmental model that simulates fate and transport of bacteria in water bodies. The model numerically solves unsteady incompressible Reynolds-Averaged Navier-Stokes equations on a structured grid. Free-floating and particle-attached bacteria were modelled separately regarding both fate and transport. Therefore, a sediment transport model was integrated into the main model in order to model particle-attached bacteria transport. In addition, Volume of Fluid approach was implemented to capture the water surface movements. Wind effect was also considered in the modelling using shear stress on the water surface. Since stormwater reuse is the source of some public health concerns, a stormwater pond was chosen as the test case for the model. The model was applied to simulate the distribution of bacterial indicator organisms in the Inverness Stormwater Pond in Calgary, Alberta, which is a large T-shaped pond with several inlets and outlets. The bacteria distribution in the pond was simulated for three rain events that occurred in the area. In six locations of the pond the modelled bacteria distribution was compared to collected data using non-dimensional bacteria concentrations. The comparison showed good agreement and indicated that the middle of the pond, close to the surface had the lowest levels of bacteria and thus, was considered the optimal location for withdrawal for reusing pond water. Furthermore, planting a tree barrier on the north bank of the West wing of the pond was shown to mitigate bacteria transport away from the inlets into the pond body and substantially decrease the risk of contamination at the optimal water withdrawal location.</p></div>","PeriodicalId":49303,"journal":{"name":"Journal of Hydro-environment Research","volume":null,"pages":null},"PeriodicalIF":2.4000,"publicationDate":"2021-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Hydro-environment Research","FirstCategoryId":"93","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S1570644321000393","RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, CIVIL","Score":null,"Total":0}
引用次数: 0
Abstract
This paper presents a three-dimensional CFD based hydro-environmental model that simulates fate and transport of bacteria in water bodies. The model numerically solves unsteady incompressible Reynolds-Averaged Navier-Stokes equations on a structured grid. Free-floating and particle-attached bacteria were modelled separately regarding both fate and transport. Therefore, a sediment transport model was integrated into the main model in order to model particle-attached bacteria transport. In addition, Volume of Fluid approach was implemented to capture the water surface movements. Wind effect was also considered in the modelling using shear stress on the water surface. Since stormwater reuse is the source of some public health concerns, a stormwater pond was chosen as the test case for the model. The model was applied to simulate the distribution of bacterial indicator organisms in the Inverness Stormwater Pond in Calgary, Alberta, which is a large T-shaped pond with several inlets and outlets. The bacteria distribution in the pond was simulated for three rain events that occurred in the area. In six locations of the pond the modelled bacteria distribution was compared to collected data using non-dimensional bacteria concentrations. The comparison showed good agreement and indicated that the middle of the pond, close to the surface had the lowest levels of bacteria and thus, was considered the optimal location for withdrawal for reusing pond water. Furthermore, planting a tree barrier on the north bank of the West wing of the pond was shown to mitigate bacteria transport away from the inlets into the pond body and substantially decrease the risk of contamination at the optimal water withdrawal location.
本文提出了一个基于CFD的三维水环境模型,用于模拟水体中细菌的命运和迁移。该模型在结构网格上数值求解非定常不可压缩reynolds - average Navier-Stokes方程。自由漂浮的细菌和颗粒附着的细菌分别模拟了它们的命运和运输。因此,在主模型中加入泥沙输运模型,以模拟颗粒附着细菌的输运。此外,采用流体体积法来捕捉水面运动。在利用水面剪应力进行建模时,还考虑了风的影响。由于雨水再利用是一些公共卫生问题的来源,因此选择了一个雨水池作为该模型的测试案例。将该模型应用于模拟阿尔伯塔省卡尔加里因弗内斯雨水池中细菌指示生物的分布,该池塘是一个有几个入口和出口的大型t形池塘。在该地区发生的三次降雨事件中,模拟了池塘中的细菌分布。在池塘的六个地点,模拟的细菌分布与使用无量纲细菌浓度收集的数据进行了比较。结果表明,池塘中部靠近水面的细菌含量最低,是回用池塘水的最佳取水位置。此外,在池塘西翼的北岸种植树木屏障被证明可以减少细菌从入口转移到池塘体,并大大降低最佳取水位置的污染风险。
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