两级AO工艺处理黑水研究

STUDY ON TREATMENT OF BLACKWATER USING TWO-STAGE AO PROCESS

黑水的COD和氮磷浓度高,常规处理工艺停留时间长、碳源利用率低。本研究在小试条件下采用两级AO工艺处理模拟黑水,考察了不同有机负荷以及体积回流比、SRT等对于系统脱氮除磷效果的影响,探讨该工艺对各项污染物的去除特性。结果表明,在HRT=21.4 h、外体积回流比为100%、内体积回流比为250%,SRT=10 d时,出水COD为60 mg/L,NH3-N和TN质量浓度分别达到7.0、17.2 mg/L以下,达到(GB 18918-2002)一级B标准;但出水的TP质量浓度为3～4 mg/L,仍需化学辅助除磷。两级AO工艺中的不同区段在污染物去除过程中发挥着不同的作用,延长第二级AO池的停留时间和增大内回流比,是增强该系统脱氮除磷的有效方式。

The conventional blackwater treatment processes need a long hydraulic retention time（HRT） and have a low carbon utilization ratio,due to the high concentrations of nitrogen and phosphorus in blackwater.In this study,two-stage AO process was adopted to treat simulative blackwater,the influence of different organic loading,reflux ratio and sludge retention time（SRT） on nitrogen and phosphorus removal were investigated,and the pollutants removal characteristics of the process was discussed.The results show that,under the conditions of HRT is 21.4 h,sludge recycle ratio is 100%,reflux ratio is 250%,and SRT is 10 d,the concentration of COD,NH3-N and TN is respectively below 60 mg/L,7.0 mg/L and 17.2 mg/L,which can up to the discharging standards for Chinese urban WWTPs（GB 18918-2002） first class B.However,the concentration of TP in the effluent was 3～4 mg/L,where phosphorus was still need to remove by chemical method.As different stages in the two-stage AO process played different roles in the pollutants removal,extending the HRT in the second stage and increasing the reflux ratio are both effective measures to improve nitrogen and phosphorus removal.