西安市某污水厂氧化沟工艺升级改造工程研究

Upgrading of Oxidation Ditch Process in a Wastewater Treatment Plant in Xi'an City

针对西安市污水厂出水水质执行国家一级A标准的要求,对该市某污水厂的奥贝尔氧化沟工艺进行解析,明确了出水NH_3-N与SS值偏高是限制该污水厂达标的主要因素。进一步的研究表明,氧化沟转刷曝气引起的系统内DO浓度上下分层严重以及好氧区容积严重不足是导致出水水质超标的主要原因,同时污泥沉降性能差引起出水SS超标。基于上述问题,提出将氧化沟内沟改为底部曝气、增加内沟到外沟的硝化液回流系统以及二级出水后增设滤布滤池的改造方案。系统改造后,出水NH_3-N及SS值明显降低,出水水质各项指标可稳定达到一级A标准。

According to the requirement that the effluent quality of wastewater treatment plants in Xi'an should meet the first level A criteria specified in the national discharge standards,the Orbal oxidation ditch process in a wastewater treatment plant was analyzed. It was found that the main factors affecting the effluent quality of this WWTP were the excessive concentrations of NH_3- N and SS in the effluent. Further research showed that the serious stratification of dissolved oxygen caused by brush aeration in oxidation ditch and gravely insufficient volume of aerobic zone were the major reasons,and the poor sludge settleability resulted in exceeding the limit for SS in the effluent. Based on the problem analysis,a modification plan was put forward: the aeration was performed at the bottom of the inner ditch,a nitrifying liquid return system was added between the inner ditch and the outer ditch,and a cloth media filter was added. After the upgrading,the concentrations of NH_3- N and SS in the effluent were significantly decreased,and the effluent quality of the WWTP met the first level A criteria specified in the national discharge standards.