CAST工艺改良对系统强化除磷性能的影响

Phosphorus removal performance of modified CAST process

传统CAST工艺广泛应用于国内各种规模城镇污水处理厂,单凭生物法难以达到城市污水排放一级A标准。采用改良的CAST工艺,在传统CAST工艺基础上引入主反应区独立的搅拌时序,并在实际规模的污水处理厂进行工程示范。通过两阶段的试验,逐步缩短曝气时间延长缺氧搅拌时间,优化聚磷菌的代谢环境,增强聚磷菌的竞争优势。经过改良后的CAST工艺TP去除率达到89.1%,较传统CAST工艺提高了22%,出水TP稳定达到一级A标准。静态试验结果表明改良后的工艺反硝化聚磷菌的比例有所增加,吸收1 mg·L-1的PO34--P需消耗1.67 mg·L-1的NO-3-N。改良后的CAST工艺的反硝化效果得到改善,出水NH+4-N和TN均达到一级A标准,并在提高出水水质的同时节省生化池电耗10.4%。

The first level A standard of the sewage discharge for phosphorus removal could not reach when only biological method is employed,such as the traditional CAST（cyclic activated sludge technology）process that has been widely used in municipal wastewater treatment plants.A modification for the traditional CAST process was made by introducing an independent stirring phase in the main reactor zone.The modified process has been demonstrated in a full-scale wastewater treatment plant.To optimize the metabolic environment for polyphosphate bacteria and to increase its competition ability,gradually the aeration time was shortened and the anoxic stirring time extended by two stage experiment.For the modified CAST process the efficiency of phosphorus removal is 89.1%,22% higher than non-modified CAST process,and the first level A standard of the sewage discharge could be steadily reached for the effluent TP.The results of static tests showed that the modification of process can increase the proportion of denitrifying polyphosphate accumulating organisms,and that the removal of 1 mg·L-1 PO3-4-P need consume of 1.67 mg·L-1 NO-3-N.So,the denitrifying performance was also improved,and the concentration of NH＋4-N and TN in effluent both could meet the first level A standard with 10.4% energy saved.