合川污水处理厂TN提标问题诊断及效能分析

Diagnosis of TN Removal in Hechuan Wastewater Treatment Plant and Its Efficacy Analysis

为改善三峡库区水环境质量,合川污水处理厂在提标改造项目完工投用前,对现有Orbal氧化沟工艺的生物脱氮进行了问题诊断及效能提升。水质数据的统计分析结果显示,碳源短缺是限制生物脱氮的重要原因。为此,提出通过调控内回流比和投加外碳源(乙酸钠)来提升生物脱氮效能。结果表明,当内回流比为300%、乙酸钠投加量为2 240 kg/10~4m^3(相当于104 mg/L的COD)时,出水TN浓度可稳定在10 mg/L以下。进一步的生产性试验结果表明,在水温为14℃、进水TN为57. 2～81. 1 mg/L的条件下,控制内回流比为300%、乙酸钠投加量为1 540 kg/10~4m^3,出水TN平均值为14. 4 mg/L,可稳定达到《城镇污水处理厂污染物排放标准》(GB 18918—2002)的一级A标准。

In order to improve the quality of water environment in the Three Gorges reservoir area, the existing biological denitrification of Orbal oxidation ditch process in Hechuan Wastewater Treatment Plant was diagnosed and its efficiency was improved before operation of the upgrading and reconstruction project.The statistical analysis results of water quality data showed that the shortage of carbon sources was an important reason to limit biological nitrogen removal.So,it was proposed to enhance the biological nitrogen removal efficiency by regulating the internal reflux ratio and adding the external carbon source (sodium acetate).The results showed that the effluent TN concentration was always less than 10mg/L when the internal reflux ratio was 300% and the sodium acetate dosage was 2240kg/10^4m^3(104mg/L of COD).Further productive test results showed that,the average effluent TN was 14.4mg/L under the condition of water temperature of 14℃,influent TN of 57.2-81.1mg/L,internal reflux ratio of 300% and sodium acetate dosage of 1540kg/10^4m^3,which stably reached the first level A criteria of Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant(GB 18918-2002).