化工学院 优秀毕业设计—日处理35000m3水质净化厂工艺设计.doc

2010届本科生毕业设计 PAGE VII 日处理35000m3水质净化厂工艺设计 摘 要 我国水体污染主要来自两方面，一是工业发展超标排放工业废水，二是城市化中由于城市污水排放和集中处理设施严重缺乏，大量生活污水未经处理直接进入水体造成环境污染。 本设计根据要求处理水量35000m3/d的城市生活污水及水质要求，即脱氮和除磷后达到二级水处理标准。本设计选取已运行稳定有效的CASS工艺处理城市生活污水。 在预处理阶段，污水流经格栅以除去其中较大的杂质，以免影响后续处理设施的正常运行。随后污水经提升泵提升后通过细格栅，再流入曝气沉砂池去除较大的无机颗粒，这样将会提高污泥中有机物的密度，以上是污水的物理除磷过程。 CASS是众多活性污泥法中的一种。CASS工艺流程短，构筑物和设备少，不设初沉池，同时其不设调节池和单独的二沉池，污泥自动回流，投资省，能耗??，占地少，管理简便。处理效果稳定可靠，其BOD5和SS去除率均在90％-95％或更高，COD的去除率也在85％以上，并且硝化和脱氮作用明显。 关键词：城市生活污水 活性污泥法 CASS The Craft Design Of 35,000m3/d Sewage Treatment Plant ABSTRACT Sewage in China mainly comes from two main aspects: the industrial sewage and the municipal, the aquicolous environment was polluted due to plenty of raw waste water discharge into the river. This is a design about the sewage treatment plant. According to the primitive data of the design and demanding for water quality, namely require the denitrification and phosphorus removal to reach the second class discharge standard. CASS craft is chosed. In preliminary treatment, the original water enters coarse screening in order to remove heavy solides and floatable material, in case that it influences the working of the following treatment and the pipeline. And then wastewater is promoted into the medium screening by pump, after that it enters the aerated grit chamber. It is used to remove bigger inorganic sand of heavy density, by this way, the density of organic material in mud can be improved. The above-mentioned sewage disposal is the physical disposal stage. It is one of activated sludge treatment. The craft process is short, and it has lesser structures and equipments, do not establish the primary sedimentation tank, and there are no regulating tank and secondary sedimentation tank. The activated sludge can reflux automatic, so it could be in an low standard of investment, consume, floor space, eassier for manage. This treatment is stable and reliable, its BOD5 and SS removal rate are all in 90%-95% or higher. More than 85% COD can be