摘要:本次毕业设计的题目为某污水处理厂设计——氧化沟工艺。主要任务是工艺流程选择及构筑物设计和计算。

　　　该污水处理厂工程，总规模达到4万吨/日。该污水厂的污水处理流程为：从泵房到沉砂池，进入氧化沟，二沉池，最后出水；污泥的流程为：从二沉池排出的剩余污泥首先进入浓缩池，进行污泥浓缩，然后进入消化池，经过消化的污泥再送至带式压滤机，进一步脱水后，运至垃圾填埋场。出水执行国家污水综合排放标准（GB8978-1996）一级标准。

　　　工艺主要特点：1）工艺流程短，构筑物和设备少，不设初沉池，调节池和单独的二沉池，污泥自动回流，投资省，能耗低，占地少，管理简便。2）处理效果稳定可靠，其BOD5和SS去除率均在90％-95％或更高。COD得去除率也在85％以上，并且硝化和脱氮作用明显。3）产生得剩余污泥量少，污泥不需小孩，性质稳定，易脱水，不会带来二次污染。4）造价低，建造快，设备事故率低，运行管理费用少。5）固液分离效率比一般二沉池高，池容小，能使整个系统再较大得流量和浓度范围内稳定运行。6）污泥回流及时，减少污泥膨胀的可能。

关键词：氧化沟工艺，二沉池，国家标准

Abstract:

　　　The sewage treatment plant project, the total amount to 40,000 tons / day. The wastewater treatment plant sewage treatment process : from the pumping station to Grit Chamber, enter oxidation ditch, two sedimentation tank, the final effluent; Sludge Process : two from the settling tank discharge of the first to reach the remaining sludge thickening tank, sludge thickening, and then enter Digester, After digestion of sludge sent to the belt filter presses, and further dehydration, transported to the landfill. Implementation of the national sewage effluent discharge standards (GB8978-1996) 1 standard.

　　　the main characteristics in pond in reaction:1)The craft process is short, the builds the thing is little with the equipments, do not establish the beginning sink the pond, regulating the pond with lone of two sink the pond, automatic reflux in dirty mire, investment province, can consume low, cover little, manage simple.2)Handle the result stability is dependable, its BOD5 does away with the rate with the SS all in 90%-95% or higher.The COD have to  away with the rate too above 85%, and the nitric turns with take off the nitrogen function obviously.3)Creation the dirty amount of mire in surplus is little, the dirty mire do not need the child, the kind is stable, easy dehydration, can't bring to pollute two time4)Build the price low, construct quick, the equipments trouble rate is low, circulating the administrative expense little.5)The liquid separates efficiency ratio general two sink the pond high, the pond permits small, can make whole system been bigger again get the discharge stabilize the movement with density scope inside.6)Dirty mire reflux on time, the possibility that reduce the dirty mire the inflation.

Key words：The craft of oxidation ditch，digestion tank，National standard