城镇污水处理厂尾水中氮磷形态及光谱特征分析

Forms of Nitrogen and Phosphorus and Spectral Characteristics in Effluent from Municipal Wastewater Treatment Plants

为了进一步探究污水厂尾水排放对受纳水体的潜在影响,选取巢湖流域采用3种典型处理工艺(氧化沟、SBR、A^(2)/O工艺)的7座污水厂为研究对象,分析了尾水中氮、磷的形态及水体中溶解性有机质(DOM)的光谱特征。结果表明,不同工艺对TN、TP、COD等指标均具有很好的去除效果且无明显差异。尾水中颗粒态总氮(PN)占比在13.4%以下,主要以溶解态总氮(DTN)形式存在,其中溶解态无机氮(DIN)占比高于溶解态有机氮(DON)。尾水中颗粒态总磷(PP)占比在10.1%~66.7%,磷主要以溶解态总磷(DTP)形式存在,其中溶解态无机磷(DIP)占比在60%以上。DOM的三维荧光光谱显示,不同工艺尾水中的DOM均具有4类荧光特征峰,其中腐殖酸类物质C峰与紫外区类富里酸物质A峰较为明显。根据DOM的荧光特性参数(HIX值<4、FI值>1.9、BIX值>1.0),各污水厂出水中的DOM主要为自生来源。由此表明,污水处理厂削减了大量的入河碳、氮、磷等负荷,其尾水可用于城市河道生态补水水源,实现城市污水资源再生利用。

In order to further explore the potential impact of effluent on the water environment,seven municipal wastewater treatment plants(WWTPs)with three typical treatment processes(oxidation ditch process,SBR process and A^(2)/O process)in Chaohu Lake basin were selected as the research object and the form of nitrogen and phosphorus and dissolved organic matter(DOM)spectral characteristics in the effluent were investigated.The results indicated that the WWTPs showed excellent removal effect of basic water quality indicators(TN,TP and COD),but there were no significant differences in removal performance among the three treatment processes.Dissolved total nitrogen(DTN)was the main form of nitrogen in the effluent,and particle nitrogen(PN)accounted for less than13.4%.The proportion of dissolved inorganic nitrogen(DIN)was higher than that of dissolved organic nitrogen(DON).The proportion of particle phosphorus(PP)in tail water was 10.1%-66.7%,and phosphorus mainly existed in the form of dissolved total phosphorus(DTP),among which dissolved inorganic phosphorus(DIP)accounts for the largest proportion(more than 60%).By analyzing the three-dimensional fluorescence spectroscopy of DOM,it was found that different processes had four kinds of fluorescence characteristic peaks,and the humic acid group(C peak)and the ultraviolet group ferric acid group(A peak)were more obvious.According to the fluorescence characteristic parameters of DOM(HIX value<4,FI value>1.9,BIX value>1.0),the main source of DOM in the effluent from investigated WWTPs was the self-generated source.The above results indicate that the WWTPs have reduced a large number of carbon,nitrogen,phosphorus and other biogenic elements load into the river,and their effluent can be used as ecological water supply source of urban rivers to realize the recycling of urban sewage resources.