设计总说明：本设计所涉及的某污水处理厂位于上海西区，废水主要来自该地区周围居民区的生活污水，污水量为4万m3/d，CODcr：360mg/L、BOD5：170mg/L、SS：190mg/L、NH3-N：35mg/L、TN：60mg/L、TP：6.0mg/L。57351

经过对各生物法处理工艺的研究比较，确定采用A2/O工艺，达到脱氮除磷、降解有机物的目的。

A2/O工艺可以具有同时脱氮除磷的功能，A2/O工艺是通过厌氧、缺氧、好氧三种不同的环境条件和不同种类微生物菌群的有机配合，达到去除有机物、脱氮、除磷的功能。

在设计中，通过格栅截流较大的悬浮物或漂浮物；利用曝气沉砂池进行预曝气加速砂粒的沉淀，达到泥沙和有机物分开的目的；倒置A2/O生物反应池主要是在缺氧池和厌氧池中利用厌氧除磷菌在厌氧缺氧环境下脱氮除磷，在好氧池中氧气由池内的微孔曝气机产生，从而达到既降解废水中的有机污染物，又达到脱氮除磷的目的；二沉池的主要作用是泥水分离，确保污水处理系统的出水水质；污泥浓缩池的主要作用就是降低剩余污泥的含水率，减少污泥的体积，方便后续处理。

根据确定的工艺流程，本设计通过对构筑物(包括格栅、曝气式沉砂池、A2/O生物反应池、二沉池、紫外线消毒池和污泥浓缩池)主要尺寸的设计计算、水力损失及管路计算，完成了设计工艺说明、工艺流程图（含高层布置）、厂区平面布置图和主体构筑物单体图。

在设计中废水经水泵一次提升后，靠重力流完成污水的全工艺处理，避免污水的反复提升，以节约动力消耗，降低废水处理费用，方便操作管理。

本设计具有技术上可行、经济上合理的效果。投资费用为2012.53万元，运行费用846.8万元/年。每吨水处理费用为0.58元。本设计具有总投资少，运行稳定、处理效果好，工艺简单，占地面积省，二次污染少等优点确保废水达标排放。

废水经处理后，预计可以达到《城镇污水处理厂污染物排放标准》（GB8978-2002）中的一级B标准，即：CODcr ≤60 mg/L；BOD5 ≤20mg/L；SS ≤20mg/L；NH3-N≤8mg/L；TN ≤20mg/L；TP ≤1.5mg/L，每年削减向环境排放的COD为4380吨。达到消除污染、实现保护环境、造福人类的目的。

毕业论文关键词： 废水处理；A2/O工艺；生物法；脱氮除磷

A2/O Process Design for A Sewage Treatment Plant

General information of the design：The design involved a county sewage treatment plant is located in western district of Shanghai, its water mainly from domestic sewage in the region. The initial design plans: The amount of sewage is 40000 m3/ d. The indicator of waste water quality standard is CODcr: 360mg/L、BOD5: 170mg/L、SS: 190mg/L、NH3-N: 35mg/L、TN: 60mg/L、TP: 6.0mg/L.

By comparing the research of several biology treating processes, the design uses the anaerobic-anoxic-oxic Process to remove the nitrogen and TP.

Anaerobic-anoxic-oxic process can also complete the removal of organic matter and nitrogen and phosphorus removal capabilities. Anaerobic-anoxic-oxic process achieve for the removing function of organic matter, nitrogen and phosphorus, through the anaerobic, hypoxia, aerobic three different environmental conditions and organic cooperate for different kinds of microbe groups.

In design, through the closure of a large grid suspended solids or floating debris; aerated grit chamber is to use aeration to separate the silt and organic matter to speed up the sand in the sediment, in order to achieve grit objectives; upside-down anaerobic-anoxic-oxic bioreactor is removal nitrogen and phosphorus by anaerobic bacteria in the anoxic environment in the anoxic tank and anaerobic, and used produced gas of the aeration equipment in the aerobic tank, to efficient of organic pollutants in wastewater and to achieve the purpose of remove nitrogen and phosphorus in the same time; general secondary sedimentation tank's main role is to release mud from water,to ensure the water quality of sewage treatment systems; sludge thickener main role is to reduce the remaining pollution soil moisture content, reducing the volume of sludge to facilitate the follow-up treatment.