响应曲面法优化HMBR去除TN的工艺条件

采用复合式膜生物反应器HMBR处理低C/N(3-5)实际生活污水,TN含量17~45 mg/L。基于CCD响应曲面法,考察了溶解氧DO、水力停留时间HRT和污泥龄SRT的单独作用及交互作用,并建立TN去除率数学模型。结果表明,影响因子显著性顺序为HRT>SRT>DO,三者间存在一定的交互作用,但并不显著;数学模型回归性较好,预测最大TN去除率为75%,最佳条件组合为:DO=3.79 mg/L,HRT=8.84 h,SRT=33.62 d,验证实验结果TN的去除率为73%,与预测值相比偏差仅为3%。采用HMBR处理低C/N生活污水,可以满足《污水综合排放标准》(GB8978-1996)一级标准中对TN≤15 mg/L的限制要求。

Optimization of removal process conditions of TN in HMBR by response surface methodology

Hybrid membrane bioreactor (HMBR) was employed to treat the sewage with low carbon-to-nitrogen ratio, of which the total nitrogen (TN) content was 17~45 mg/L. Based on central-composite design (CCD) and response surface methodology (RSM), individual and interactive effects of dissolved oxygen (DO), hydraulic retention time (HRT) and sludge retention time (SRT) were evaluated primarily. An empirical mathematical model between TN removal rate and the above influence factors was also established. The results demonstrated that the influencing factors in the order of significance are: HRT>SRT>DO and there were interactive effects among the three, but not dramatically. A satisfactory prediction quadratic polynomial equation was derived by response surface methodology. The optimal reaction conditions with the highest TN removal rate of 75% were determined to be DO=3.79 mg/L, HRT=8.84 h and SRT=33.62 d. Using the above optimal conditions, an average TN removal rate of 73% was obtained, which agreed with the predicted value with 3% deviation. HMBR can be adopted for treatment of the sewage with low carbon-to-nitrogen ratio to meet the first discharge standard of TN≤15 mg/L in Integrated Wastewater Discharge Standard (GB8978-1996).