改良型Carrousel氧化沟工艺生物脱氮优化研究

Optimization of Biological Nitrogen Removal in Modified Carrousel Oxidation Ditch Process

为解决采用改良型Carrousel氧化沟工艺的某污水厂出水TN与NH_4^+-N浓度高的问题,经现场试验对SRT、HRT和DO等工艺参数进行了优化调整。通过问题诊断,发现系统SRT过长、HRT短及好氧区DO浓度低是导致脱氮效果差的直接原因;工艺优化结果表明,将系统的SRT、HRT和好氧区DO浓度分别控制在18 d、16 h和2.5~3.0 mg/L时系统的脱氮效果提升较大,此时出水TN、NH_4^+-N的平均浓度分别为12.6和3.3 mg/L,去除率分别为78%和91%,且出水BOD5、COD与SS等指标均达到了《城镇污水处理厂污染物排放标准》(GB 18918—2002)的一级A标准。

The parameters including SRT, HRT and DO concentration were optimized through scale experiments, to solve the high concentrations of TN and NH4 ＋- N in the effluent of a modified Car- rousel oxidation ditch process in a wastewater treatment plant. The diagnosis results indicated that long SRT, short HRT and low DO concentration were the direct causes of the poor denitrification. The process optimization results showed that the system achieved higher nitrogen removal efficiency when the SRT, HRT and DO concentration were controlled at 18 d, 16 h, and 2.5 -3.0 mg/L, respectively. The aver- age concentrations of TN and NH4＋ - N in the effluent were 12.6 mg/L and 3.3 mg/L, and the removal rates were 78% and 91% , respectively. Additionally, the effluent BODs, COD and SS all met the first level A criteria in Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant （GB 18918- 2002 ）.