晋中市污水水质及低C／N值进水反硝化特征

Wastewater Quality of Jinzhong City and Denitrification Characteristics of Influent with Low C/N Ratio

针对城市污水处理厂出水总氮浓度超标和低C/N值(C/N值<4)的现象,以晋中市某污水处理厂为研究对象,深入分析其污染物指标分布概率和污水水质特征。采用间歇式反硝化试验,对比了以沉砂池、初沉池出水为进水的反硝化过程中,对NO_3^--N及COD的去除效果,并用动力学方法分析两种进水反硝化特征的差异。试验结果表明,沉砂池出水和初沉池出水的反硝化过程均可分为快速反应期、减速反应期和慢速反应期。碳氮比较低条件下,反硝化过程呈一级动力学反应。取消初沉池后,对NO_3^--N的去除率可提高9%,颗粒性有机物碳源(CODSS)可起到增加外碳源的作用。同时表明,取消初沉池为反硝化微生物提供颗粒性有机碳源的工艺思路合理可行,对实际城市污水处理具有指导意义和应用价值。

To deal with the high concentration of TN and low C/N ratio （ lower than 4） in the ef- fluent from wastewater treatment plants, a wastewater treatment plant in Jinzhong City was selected to an- alyze the distribution probability of contaminant indexes and the characteristics of wastewater quality. The removal efficieneies of NO3 - N and COD during denitrification with the effluents from the grit chamber and primary sedimentation tank as influent were compared through batch denitrification tests. The differ- ences in denitrification characteristics between the two influents were analyzed using kinetics method. The results showed that the denitrification processes using the effluents from the grit chamber and primary sed- imentation tank could both be divided into three stages, namely rapid reaction stage, deceleration reac- tion stage and slow reaction stage. Under the condition of insufficient C/N ratio, the denitrification process followed first-order kinetics reaction. After eliminating the primary sedimentation tank, the re- moval rate of NO3- - N could be increased by 9%, and CODss had positive impact as adding external car-bon source. It is feasible to eliminate the primary sedimentation tank to provide organic suspended matter for denitrifying microorganisms, and it has a better guiding significance and practical value for urban sew- age treatment.