基于正交实验的A^2/O工艺运行方式优化

OPTIMIZATION FOR OPERATION OF A^2/O PROCESS BASED ON ORTHOGNAL EXPERIMENT

采用GPS-X软件构建了南方某城市污水处理厂A^2/O工艺数学模型,并对模型参数进行调整,通过静态模拟和动态模拟验证了该模型的可靠性。以A^2/O工艺对TN、TP的去除效果为考察指标,利用所建立的模型对A^2/O工艺运行中的混合液回流比(MLR)、污泥回流比(RAS)、好氧池溶解氧(DO)、系统SRT进行了单因素分析和正交试验分析。单因素试验结果表明:当DO为1.5 mg/L,MLR为400%,RAS为110%,系统SRT为22 d时,TN去除效果最佳;当DO为1.1 mg/L,MLR为150%,RAS为60%,系统SRT为12 d时,TP去除效果最好。由正交试验结果可知:MLR对TN、TP去除效果影响显著;RAS对TP去除效果影响显著。A^2/O工艺脱氮除磷的最佳运行参数为:MLR为350%,RAS为90%,DO为1.2 mg/L,系统SRT为20 d。在此条件下,出水TN浓度能达到GB 18918—2002《城镇污水处理厂污染物排放标准》的一级A标准要求。

GPS-X software was used to develop a mathematical simulation model of A^2/O process in a WWTP in South China.Parameters of the model were calibrated,and the reliability of the model was validated through static and dynamic simulation.Based on this model, single-factor and orthogonal experiments were designed with four factors including mixed liquor recirculation（MLR）,returned activated sludge（RAS）,dissolved oxygen（DO）,sludge retention time（SRT）,with the removal effect of TN and TP as the indexes. The result of single-factor experiments showed that the denitrification was best when DO,MLR,RAS and SRT was 1. 5 mg/L,400%,110% and 22 d,respectively; the best dephosphorization was achieved when DO,MLR,RAS and SRT was 1. 1 mg/L,150%,60% and 12 d,respectively. The orthogonal experiments showed that the removal rate of TN was significantly affected by MLR; the removal rate of TP was significantly affected by RAS. The best condition of the A^2/O process was as follows： MLR,RAS,DO,SRT were 350%,90%,1. 2 mg/L,20 d,respectively. In this condition,TN in effluent could meet the first level A criteria specified in Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants（GB 18918—2002）.