南方城市污水处理厂低浓度进水水质特征分析

Characteristics of Low Concentration Influent Quality in Municipal Wastewater Treatment Plants in a Southern City

为了了解南方典型城市污水处理厂的进水水质特征,对南方某城市16座污水处理厂近8年的进水水量和水质数据进行了系统分析。结果表明,2015年1月—2023年3月,污水处理厂进水COD、SS、NH3-N、TN和TP浓度年均值整体呈上升趋势,而进水BOD5浓度年均值的变化不大,均未超过100 mg/L。以2019年污水处理厂进水水质数据为样本,BOD5、COD、SS、NH3-N、TN和TP浓度均呈正偏态分布,累积概率分布较高范围分别为40~160、100~350、50~300、6~21、15~33、1.5~6.5 mg/L。对进水指标比值进行统计分析发现,污水可生化性较好,可满足生物除磷需求,但存在反硝化碳源不足的问题,而且受到工业废水接入的影响。该市污水处理厂除进水SS均值略高于全国的统计数据外,其他指标均值均低于或接近全国的统计数据;进水浓度偏低的主要原因有生活污水浓度低,雨水、外水和工业废水的接入,化粪池对污染物的去除,污染物在排水管网中的沉积和降解等,可采取相应措施提高进水浓度,保证出水水质稳定达标。

A systematic analysis was conducted on the data pertaining to both the influent quantity and quality of 16 wastewater treatment plants(WWTPs)in a southern city over the past 8 years,so as to comprehend the characteristics of influent quality at WWTPs in southern China.From January 2015 to March 2023,the average COD,SS,NH3-N,TN and TP in influent of WWTPs exhibited a general increasing trend,while the average BOD5 in influent showed minimal interannual variation and remained below 100 mg/L.Based on the influent quality data from WWTPs in 2019,the BOD5,COD,SS,NH3-N,TN and TP concentrations were found to exhibit positive skewness,and the ranges with higher cumulative probability distribution were 40-160 mg/L,100-350 mg/L,50-300 mg/L,6-21 mg/L,15-33 mg/L,1.5-6.5 mg/L,respectively.The statistical analysis of the ratio of influent indicators indicated that the wastewater exhibited favorable biodegradability and was capable of satisfying the requirements for biological phosphorus removal.However,it faced challenges related to insufficient denitrification carbon sources and susceptibility to collected industrial wastewater.The average influent SS of WWTPs in this city slightly exceeded the national statistical data,while the averages of other indicators were lower than or close to the national statistical data.The primary factors contributing to the low influent concentration included the low concentration of domestic sewage,infiltration of rainwater and external water,mixing of industrial wastewater,pollutants removal by septic tank,as well as the deposition and degradation of pollutants in the drainage network.Corresponding measures could be implemented to enhance the influent concentration and ensure consistent effluent quality.