设计总说明：本设计所涉及的污水处理厂针对的是日处理量为3万m3/d，CODcr：420mg/L，BOD5：200mg/L，pH：6.5~8，SS：300mg/L，氨氮：20mg/L的生活污水，通过对各生物法处理污水工艺的比较，选择进行T型氧化沟处理工艺设计工作。要求污水处理后达到《城镇污水处理厂污染物排放标准（GB18918-2002）的一级B标准，使受污染的水质得到改善，消除污染，保护环境。  

 在本设计中，粗格栅可以阻挡悬浮固体，对原始进水进行第一步处理，使水泵不被其损害；进水泵房使进入污水厂的需要处理的污水与之后的构筑物有高程差，使得要被处理的污水借助重力作用能在之后处理构筑物内顺畅的流动，从而进行污水处理；集水井能够在某些的程度上调节进水，避免流量冲击对泵造成损害；配水井能够较为合理的将污水分派到T型氧化沟的三个槽中，方便其进行交替运行；旋流沉砂池是通过机械力，去调整水流的形态和速度，加快污水中砂粒的沉淀，使有机物随水流被带走；细格栅可以继续阻挡污水通过粗格栅后遗漏下来的相对比较小的固体物质；旋流沉沙池和细格栅合建可节约占地面积、减少各个构筑物之间所产生的沿程阻力损失；T型氧化沟通过交替运行可同时脱氮除磷，进一步去除悬浮物，降解有机物，且均在同一反应器中进行；污泥浓缩池主要将剩余污泥的含水率、污泥体积减少，方便之后进一步的处理。根据重力流进行一级提升。61762

本设计根据通过方案论证后选择的最适宜的工艺流程，对主要构筑物（包括粗/细格栅、集水井、旋流沉砂池、配水井、T型氧化沟、紫外线消毒间和污泥浓缩池）主要尺寸的设计计算、高程及管路计算，完成了工艺说明书、工艺流程图（含高层布置）、厂区的平面布置图和主体构筑物单体图。

本工程技术上可行、经济上合理，工程投资及处理费用低。投资费用为4981万元，运行费用为0.36元/m3

经处理后，BOD5≦20mg/ L，CODcr≦60mg/ L，SS≦20mg/ L，NH3-N≦8mg/ L，pH=6~9，满足《城镇污水处理厂污染物排放标准》（GB18918-2002）一级排放标准的B标准。经过氧化沟工艺处理之后预计每年CODcr可减排3942吨，从而使得受污染的水质得到极大的改善，消除污染，保护环境。

毕业论文关键词： 污水处理；T型氧化沟；CODcr；脱氮

Process Design of Triple Oxidation Ditch for Domestic Sewage

Design General Information：The design of the sewage treatment plant is designed to deal with the daily handling capacity of 30 thousand tons, CODcr:420mg/L, BOD5:200mg/L, pH:6.5~8, SS:300mg/L, NH3-N: 20mg/L of domestic sewage.Through the comparison of the biological treatment of sewage treatment process, the selection of triple oxidation ditch treatment process design work. After treatment to reach The Sewage Treatment Plant Pollutant Discharge Standard (GB18918-2002) the B standard of first level.

In this design, the coarse grid can intercept large suspended solids and impurities, purify water, protect pump. The water pumping station for upgrading the sewage of wastewater treatment plant, to ensure that the sewage can be smooth flow in structures of subsequent processing. The water-collecting well can regulate the  inhomogeneity of inflow，avoid traffic impact damage to the pump. The distribution well can be reasonable assign the sewage to the oxidation ditch. The rotational flow grit chamber is a sand settling device using mechanical to control flow pattern and velocity, accelerating the precipitation of sand and let organic matter flow away. Triple oxidization ditch can simultaneously remove nitrogen and phosphorus ，and further removal of suspended solids, degradation of organic compounds, are in the same reactor. The sludge thickening tank's main function is to reduce moisture content of  excess sludge, reduce the sludge volume, convenient follow-up treatment.According to the gravity flow to upgrade.