BackgroundThe most critical step to control sewage pollution and recycle of wastewater is to establish sewage treatment plants and to monitor their performance. This research aims to assess the environmental impacts of effluent waters, treated by Kermanshah wastewater treatment plant (KWTP), on some physicochemical variables of the adjacent river named as Qarasou River, northwestern Iran. Several water samples were collected from different locations into KWTP and along the Qarasou River in different time intervals of April and July 2017 to assess the effect of treated waters on the environment water quality. As well, an integrated environmental change index (ΔYi) was defined to assess the degree of changes and impacts in the current status.ResultsThe analyses indicated that the values of total suspended solids (TSS), nitrate (NO3), phosphorous (P), biological oxygen demand (BOD), and chemical oxygen demand (COD) overall decreased by treatment process at effluent water compared with raw sewage amounts. Contrarily, amounts of acidity and dissolved oxygen (DO) slightly increased in effluent water due to the aeration processes during the treatment process. The environmental change index (ΔYi) was estimated between 0.04 and 0.88 with an average of 0.28 for all variables in different time intervals, indicating the lowest degree of environmental changes and higher efficiency of treating wastewater in KWTP.ConclusionsThe results concluded the efficiency for the removal TSS, NO3, BOD, and COD is estimated 80–92% during the water purification process in KWTP as an acceptable efficiency. Finally, it can be mentioned that the activated sludge process of KWTP has not any risky impacts on Qarasou River and the whole environment.

中文翻译：

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污水处理对环境理化变量的影响评价——以伊朗克尔曼沙赫污水处理厂为例

背景 控制污水污染和废水回收利用的最关键步骤是建立污水处理厂并对其性能进行监测。本研究旨在评估由 Kermanshah 废水处理厂 (KWTP) 处理的出水对伊朗西北部名为 Qarasou 河的邻近河流的一些物理化学变量的环境影响。2017 年 4 月和 7 月的不同时间段从 KWTP 和 Qarasou 河沿岸的不同位置收集了几个水样，以评估处理后的水对环境水质的影响。此外，还定义了综合环境变化指数（ΔYi）来评估当前状况的变化和影响程度。 结果分析表明，总悬浮固体（TSS）、硝酸盐（NO3）、磷（P）、与未经处理的污水量相比，生物需氧量 (BOD) 和化学需氧量 (COD) 在污水处理过程中总体下降。相反，由于处理过程中的曝气过程，流出水中的酸度和溶解氧 (DO) 量略有增加。环境变化指数（ΔYi）估计在 0.04 和 0.88 之间，不同时间段所有变量的平均值为 0.28，表明 KWTP 中环境变化程度最低，处理废水的效率较高。在 KWTP 的水净化过程中，TSS、NO3、BOD 和 COD 估计为 80-92%，作为可接受的效率。最后，