混合液回流比和外碳源对反硝化脱氮效能的影响

针对某城镇污水处理厂存在垃圾渗滤液间歇性排入导致进水碳氮比值较低的问题,为确保出水总氮稳定达标,进行了混合液回流比优化调控和外碳源乙酸钠投加对反硝化脱氮效果影响的生产性试验研究。结果表明,当C/N(COD/TN)值为4.48-6.97,且混合液回流比分别为200%和300%时,对TN的平均去除率分别为50.18%和61.88%,混合液回流比调增可在一定程度上提升TN去除率,但出水TN平均浓度的降低较为有限。根据进水水质与出水硝酸盐浓度水平,以投加乙酸钠的理论计算量为基础,发现当混合液回流比为300%且乙酸钠投加量为理论投加量的1.3倍(182mg/L污水)时,反硝化脱氮效能显著提升,出水TN浓度达到一级A标准,乙酸钠药剂成本约为0.55元/m^3污水。

Effect of Mixed Liquor Recycle Ratio and External Carbon Source on Denitrification Efficiency

One wastewater treatment plant has a low C/N (COD/TN) ratio due to the intermittent landfill leachate influent. A experimental study was conducted to investigate the effect of mixed liquor recycle ratio and additional external carbon source on the removal of TN , and to reduce TN concentration in effluent to satisfy the discharge standard. When the C/N ratio was 4. 48 - 6. 97 , and the mixed liquor recycle ratio was 200% and 300%, the average removal rates of TN in effluent were 50. 18% and 61. 88%, respectively. The results indicated that the increase of the mixed liquor recycle ratio improved the removal efficiency of TN to a certain extent, but it had limited benefit to the decrease of TN average concentration in effluen仁 Based on the influent characteristics and nitrate concentration in effluent, the theoretical dosage of sodium acetate was calculated. The results showed that, with the mixed liquor recycle ratio of 300% and 1. 3 times of the theoretical dosage of sodium acetate (182 mg/L wastewater), the denitrification efficiency increased significantly and the TN in effluent had met the first level A standard specified in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant ( GB18918 - 2002). The cost of sodium acetate was about 0. 55 yuan/m^3 wastewater.