Modeling of a Surface Flow Constructed Wetland Using the HEC-RAS and QUAL2K Models: a Comparative Analysis
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GENERAL WETLAND SCIENCE
Modeling of a Surface Flow Constructed Wetland Using the HEC-RAS and QUAL2K Models: a Comparative Analysis Linpeng Xiao 1 & Zhi Chen 1 & Fayi Zhou 2 & Samia ben Hammouda 1 & Yinying Zhu 1 Received: 19 January 2020 / Accepted: 28 July 2020 # Society of Wetland Scientists 2020
Abstract To assess the performance and the impact of nutrient discharges of the wetland on the receiving river, the Hydrologic Engineering Centers River Analysis System (HEC-RAS) and the River and Stream Water Quality (QUAL2K) models are examined in this study to evaluate a constructed wetland in the City of Edmonton in Canada. According to the simulation results from the HECRAS model and the QUAL2K model, the removal efficiencies of total nitrogen (TN) by the wetland are 25.64% and 13.59%, respectively. For the total phosphorus (TP), the removal efficiencies are similar to the simulation results between the HEC-RAS model and the QUAL2K model, which are 50.00% and 50.91%, respectively. The water quality simulation results from the HECRAS model of the wetland and QUAL2K model are both acceptable compared to the on-site field data. With the analysis of the two modeling systems and comparison between their water quality simulation results, the HEC-RAS model gives better performance than the QUAL2K model for this field case. Subsequently, the validated and customized HEC-RAS model is applied for analyzing and predicting the wetland performance, water quality parameter changes and the risks of the wetland effluents on the receiving river water under wetland design scenarios. Keywords Constructed wetland . HEC-RAS model . Total nitrogen . Total phosphorus . Removal efficiencies
Introduction Constructed wetlands have been increasingly used for tertiary treatment of different types of wastewaters (Kotti et al. 2013; Butterworth et al. 2016; Huang et al. 2019). They are considered as efficient and cost-effective alternatives to conventional wastewater treatment systems (Jou et al. 2012; Schierano et al. 2018; Liu et al. 2019a; Chiavola et al. 2020). In fact, constructed wetland is flexible compared to traditional wastewater treatment systems with respect to the geometric condition. It can be designed and built based on the geographic condition of the potential construction site (He et al. 2018; Liggett et al. 2019). Unlike the traditional wastewater treatment systems, the power for aerating or mixing, or chemical additions is not required when operating the constructed wetland (Boets
* Zhi Chen [email protected] 1
Department of Building, Civil, and Environmental Engineering, Concordia University, Montreal H3G 1M8, Canada
2
Edmonton, Canada
et al. 2011; Stefanakis et al. 2019). The field case studied in this paper is a surface flow constructed wetland. And it is similar to the natural open-water wetland in appearance and treatment mechanisms due to the wastewater flowing on the surface of substrates. Most of organic contaminants in wastewater are removed by the biofilm generated by the stems and trunks of vegetatio
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