生物接触氧化技术处理二级出水中的氨氮

On the bio-contact oxidation process with the secondary effluent and its nitrogen removing performance and efficiency

采用生物接触氧化技术,以污水处理厂二级出水为处理对象,研究工艺的生物降解过程及脱氮效果,并分析了影响NH3-N去除效果的几种因素。实验结果表明,水力停留时间3h,进水COD80mg/L,进水NH3-N15mg/L的情况下,生物接触氧化技术能有效去除二级出水中的NH3-N,平均去除率为47.6%,出水满足GB/T18920—2002《城市污水再生利用城市杂用水水质》中的洗车、清扫的要求。

This paper aims to present its study findings on the bio- contact oxidation urban sewage treating process and its bio-degradation performance in nitrogen-removing effect with the secondary effluent. Analyzing the chief factors affecting the treating performance of ammonia, such as pH, HRT, the concentration of original COD and the concentration of original ammonia, the paper has also given a detailed discussion over the reusability of miscellaneous domestic sewage. The results of its study show that under the conditions of HRT = 3 h with original COD = 80 mg/L and original ammonia = 15 mg/L, the ammonia-removing efficiency can be made to reach as high as 47.6% . At the same time, the treatment effluent can also be made in conformity to the State Reclamation and Recycling Standard for Urban Pnblic and Home Sewage. That is to say, the processed secondary effluent can be made good enough for toilet flushing, cleaning or car washing. Moreover, ammonia-removing efficiency is expected to get further improved if HRT is used, for HRT helps to enhance the removal efficiency of ammonia. Besides, since PH also tends to affect the removing efficiency of ammonia, the paper has also made a careful analysis, finding that the optimal range of pH for ammonia removal is 7.0 -7.7. It has also detected that the removal efficiency of ammonia would lower quickly when the pH value is less than 7.0. However, the removal efficiency is likely to be mended to a noticeable extent if pH value comes back to 7.2 again. This indicates that lower pH value would restrain the microbial vitality of nitrobacteria instead of poisoning it. The above results also show that the average removing efficiency of ammonia decreases slightly with the increase of concentration of original COD. Therefore it can be inferred that little effect would be produced by enhancing the concentration of original COD on the average removing efficiency of ammonia if it is at lower concentration. In contrast, the concentration of original ammonia has greater effect on the ammonia-removal. With its concentration being enhanced, the removing efficiency of ammonia proves to get noticeably declining, which indicates that it would be impossible for higher ammonia load to make nitro-bacteria gain enough inorganic carbon. Thus, the above results help to draw a conclusion that the process of biological contact oxidation is favorable for raising the efficiency of the secondary effluent, which implies wide application promises in the field of miscellaneous waste water recycling.