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To protect aquatic environment and human health, determining the optimal sewage discharge standard for wastewater treatment plants (WWTPs) is important to reduce pollutant discharge into natural ecosystems. In this study, a novel quantitative assessment method combining water environment capacity (WEC) estimation and feasibility analysis was introduced for the selection of WWTP sewage discharge standard. A certain WWTP executing national Grade 1-B discharge standard in China’s southern coast was selected as a case study. First of all, pollution sources of receiving water were investigated. More than 69.0% of nutrients (nitrogen, phosphorus) came from WWTP effluent, while non-point pollution contributed 58.3% of organic pollutants. Next, the WEC of receiving water was estimated via multiple mathematical models. It was speculated that the WEC of TP may be completely depleted by 2020 if still executing national Grade 1-B discharge standard. The maximum acceptable pollutant concentration of WWTP effluent are determined with chemical oxygen demand (COD) 86.05 mg/L, total nitrogen (TN) 19.38 mg/L, ammonium (NH4+-N )4.87 mg/L, and total phosphorus (TP) 0.67 mg/L to maintain water self-purification. Finally, after further economic/technical feasibility analysis, an optimal sewage discharge standard was recommended: 40 mg COD/L, 15 mg TN/L, 4.0 mg NH4+-N/L, and 0.3 mg TP/L. [ABSTRACT FROM AUTHOR]

According to the principle of the function division of surface water, the Songhua River basin is divided into 2 primary function regions and 3 secondary function regions by divided system of two grades based on the analysis and evaluation on the water quality and quantity. According to the practical situation that the amount of water reducing and the channel becoming shallow in dry season makes the channel water amount and velocity decrease, the paper employs one-dimensional calculation model and defines model parameters rationally to calculate the water environment capacity of every function zone and get the calculation result. Based on knowing the water environment capacity of the water function region, people should carry out the optimization distribution and management of water resources, ought to improve the benefit and efficiency of water utilization, strictly control developing the industries of highly water-consuming and high-polluting, and construct a water-saving and anti-pollution society extensively. [ABSTRACT FROM AUTHOR]

Abstract: Taking a certain large water supply reservoir as example, this paper applies homa solution of lake perfect mixing attenuation model to analyze lake volume, lake staying time and degradation coefficient''s effect on water environment capacity of total nitrogen and total phosphorus. The elastic coefficients are used as sensitivity indicators to discuss the above three model parameters’ contribution rates to environmental capacity. The contribution rates of lake volume, staying time and degradation coefficient to total nitrogen capacity are respectively 36%, 29% and 35%, and the contribution rates to total phosphorus capacity are respectively 26%, 43% and 31%. The results show that the variation of model parameters can change dramatically dilution, degradation and displace capacity, and the change will affect the total environmental capacity. From the average value of elastic coefficient, each model parameter has great contribution to total nitrogen and total phosphorus environment capacity. [Copyright &y& Elsevier]

Abstract: Estimating of the water environment capacity is an important content of the assessment of regional environmental impact. This article estimates the environmental capacity of surface water of the Yellow River basin, Haihe River basin, Huaihe River basin, Jiaodong Peninsula rivers basin in Shandong based on discussing the concept of water environmental capacity and estimation methods. This article selects the appropriate water quality model and determines the appropriate parameters looking the basin divided unit as the basic unit of the water environment capacity, based on the results of the division of surface water basin and the comprehensive comparison of the multiple water quality model. Then the author calculates the water environmental capacity and gets the control unit of the water environmental capacity, the results will be visualized feedback by GIS. The study has important reference value for assessment of regional environmental and a reasonable estimate of the water environmental capacity. [ABSTRACT FROM AUTHOR]