化学混凝强化去除微氧EGSB出水中的TP

Enhanced Chemical Coagulation for TP Removal from Effluent of Micro-aerobic EGSB Reactor

采用硫酸铝混凝强化去除微氧EGSB反应器出水中的TP,考察了混凝时间和沉淀时间、混凝剂投量、pH和温度等对强化除磷效果的影响,以分析微氧EGSB/化学混凝组合工艺作为生活污水再生回用工艺的可行性。结果表明,在最佳Al3+/TP值(质量比)为1.5～2.3、混凝时间为20min、沉淀时间为20min的条件下,对TP的去除率可达94.6%～96.4%,出水TP可降至0.29mg/L,达到了GB18918—2002的一级A标准,证明了微氧EGSB/化学混凝组合工艺作为生活污水再生回用工艺是可行的。硫酸铝的混凝除磷效果对pH的变化较敏感,最佳pH值范围为6.5～7.2,此时对TP的去除率可达到90.8%～92.1%;微氧EGSB反应器出水pH值为6.5～8.5,投加硫酸铝后能获得85%以上的TP去除率,出水TP最高可达0.85mg/L,因此需要适当调节pH使出水TP<0.5mg/L,以满足回用要求。硫酸铝混凝除磷的适宜温度为10～25℃,微氧EGSB反应器出水的温度满足此要求。

In order to confirm the feasibility of using the eombined proeess of micro-aerobic EGSB reactor and chemical coagulation for phosphorus removal as a domestic sewage treatment process, alumi- num sulfate was employed to enhance TP removal from the effluent of the micro-aerobic EGSB reactor, and the influenees of coagulation and precipitation times, pH, eoagulant dosage and temperature on the enhanced phosphorus removal were investigated. The results show that when the optimal mass ratio of A13＋/TP is 1.5 to 2.3, tile coagulation and precipitation times are all 20 rain, TP removal rate is 94.6% to 96.4% and the effluent TP is 0.29 rag/L, which meets the first level A criteria specified in the D/s- charge Standard of Pollutants for Municipal Wastewater Treatment Plant （ GB 18918 - 2002）. The com- bined process is feasible for domestic sewage treatment. Aluminum sulfate coagulation phosphorus removal process is very sensitive to pH, with the optimal pH of 6.5 to 7.2 at which the TP removal rate can reach 90.8% to 92.1%. But with the effluent pH of 6.5 to 8.5 for the micro-aerobic EGSB reactor, the TP removal rate is above 85 % after addition of aluminum sulfate, and the highest effluent TP concentra- tion can reach 0.85 mg/L. Therefore, in order to meet the reuse requirement, it is necessary to adjust the pH to allow the effluent TP to be less than 0.5 mg/L. The optimal temperature for the aluminum sul- fate coagulation phosphorus removal process is 10 to 25 ℃, and the temperature of the effluent from the micro-aerobic EGSB reactor meets the range.