前置反硝化脱氮系统外加碳源在线控制基础

以低碳氮比(C/N)生活污水为研究对象,对连续流前置反硝化生物脱氮系统外加碳源的控制方法进行了研究,从而能使出水硝酸盐和亚硝酸盐(NO_x-N)的浓度在满足出水水质标准的情况下,尽可能减少外加碳源的投加量.试验结果表明:总回流比大于2碳源不足时,增加总回流比并不能提高脱氮效率;总回流比一定,缺氧区出水NO_x^--N的浓度达到2mg/L左右时,即使碳源投加量成倍增加,TN的去除率提高不多.在对总回流比与投加碳源量的相互关系分析的基础上提出了外加碳源量的控制方案:通过使缺氧区出水NO_x^--N浓度维持在2mg/L左右来控制外加碳源的投加量,总回流比由进水TN及出水NO_x^--N浓度的标准值来确定.该控制方案既容易判断碳源投加的最佳点又能节省碳源的投加量,易于在污水处理实践中实现.

On-line Control of External Carbon Addition to Predenitrification Process

With domestic wastewater of low ratio of carbon and nitrogen(C/N), the control of external carbon dosage was studied for the predenitrification process with continuous flow. The objective is to keep the external carbon usage as low as possible while nitrate plus nitrite concentrations(NO_x^--N) of outflow under demand. The experimental results show that nitrogen removal efficiency couldn't be improved by increasing total recirculating rate with total recirculating rate more than 2 for lack of carbon source and removal efficiency of TN couldn't be largely improved by double dosage of carbon source with constant recirculating rate when NO_x^--N concentration reaches about 2mg/L. Based on the analysis of the relationship between the external carbon addition and total recirculating rate, a control method was proposed. The external carbon dosage is controlled by keeping NO_x^--N concentration of anoxic zone at the level of 2mg/L, and the total recirculating rate is determined by stated effluent NO_x^--N concentration. The control method not only can determine the reference point of carbon dosage, but also can optimize the usage of carbon addition. It is easy to be carried out in wastewater treatment plants.