CASS工艺改造与强化脱氮研究

Reconstruction of CASS Process and Enhanced Nitrogen Removal

合肥市某污水处理厂采用CASS工艺,结合该厂的实际运行情况进行了升级改造,并开展了强化脱氮效果的生产性试验研究。改造的主要工作是在原CASS反应池的主反应区增加3台高速推流器,同时对控制系统进行升级,将原来的非限制性曝气模式改为缺氧搅拌+曝气模式。结果表明,改造前的CASS工艺对COD和NH_4^+-N的去除效果较好,但对和TN的去除效果较差;改造后,增加的缺氧搅拌时段可以有效增强反硝化效果,在出水NH_4^+-N浓度基本达到GB18918—2002的一级A标准的基础上,使出水TN浓度降低了约4.0 mg/L,同时节省电耗约5%。

The cyclic activated sludge system （CASS） process was applied wastewater in a wastewater treatment plant （WWTP） in Hefei City. The reconstruction to treat municipal of the WWTP was implemented with the actual operation. The full-scale experiment on enhanced nitrogen removal was carried out. The main tasks of reconstruction were to add 3 high-speed plug-flow devices in main reaction zone of the original CASS and to upgrade the control system. The original non-restricted aeration mode was changed into anoxic stirring plus aeration mode. Before reconstruction, the removal efficiencies of COD and NH4 - N are good, but that of TN is poor. After reconstruction, the denitrification effect is enhanced by adding anoxic stirring period, and the effluent TN concentration is decreased by about 4.0 rag/L, while the effluent NH4 - N concentration meets the first level A criteria specified in Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant （GB 18918 -2002 ）. At the same time,the power consumption is decreased by about 5%.