超声联合热碱技术促进剩余污泥破解的参数优化

Optimization of combined ultrasonic and thermo-chemical pretreatment of waste activated sludge for enhanced disintegration

为了进一步提高超声联合技术破解污泥的效果,在前期双因素的研究基础上,采用3因素3水平的响应曲面法分析了热水解温度(60,70,80°C)、加碱量(0.04,0.07,0.10g/g TS)和超声能量(4000,8000,12000k J/kg TS)对污泥破解度的影响.回归分析结果表明污泥破解度与三因素之间符合三元二次方程:Y=-196.87+6.11X_1+487.53X_2+0.0039X_3-1.742X_1X_2-0.000024X_1X_3+0.0044X_2X_3-0.0398X_1~2-2488.33X_2~2-1.33×10-7X_3~2,其中X_1、X_2、X_3分别为温度、加碱量和超声能量.模型拟合度高达97.548%,表明该模型能较好地模拟超声联合热碱预处理参数和预测污泥破解度.根据模型得出最佳预处理工艺组合为:温度73.06℃,加碱量0.085g/g TS,超声能量9551k J/kg TS.最佳工艺参数下污泥破解度实测值为60.411%.经济性分析表明,超声联合热碱预处理条件下每t污泥处理费较未处理污泥降低了20.42元,在本研究条件下具有较高的经济可行性.

Optimization of combined ultrasonic and thermo-chemical disintegration of waste activated sludge was carriedout using response surface methodology(RSM)and Box–Behnken design of experiment.The combined effects ofultrasonic(4000,8000,12000kJ/kg TS),thermal(60,70,80°C)and alkaline(0.04,0.07,0.10g/g TS)pretreatments on thedisintegration degree of soluble COD(DD)were tested.By applying regression analysis,DD was fitted based on theactual value to a second order polynomial equation:Y=-196.87+6.11X1+487.53X2+0.0039X3-1.742X1X2-0.000024X1X3+0.0044X2X3-0.0398X12-2488.33X22-1.33×10-7X32,where X1,X2,and X3were temperature,alkaline dosage,and specificenergy,respectively.The coefficient of determination(R2)was as high as97.548%confirming that the model used inpredicted DD had a good fitness with experimental variables.The optimum DD achieved was60.411%at temperature of73.06°C,alkaline dosage of0.085g/g TS,and specific energy of9551kJ/kg TS.Economic evaluation showed thatcombined pretreatment reduced operating costs by￥20.42/t sludge comparing with conventional anaerobic digestionwithout pretreatments.