论文总字数：60606字

摘 要

本文的主要内容为某新城的雨水管网、污水管网和污水处理厂工艺的设计。排水体制采用完全分流制，雨水经管网收集排放至附近水体，污水则收集至污水厂进行统一处理。该污水厂的设计规模为25000m³/d，进水水质指标为BOD5=195mg/L，COD=390mg/L，SS=192mg/L，TN=35mg/L，NH3-N=25mg/L，TP=6mg/L，PH=6～8。出水水质指标，根据环保部门要求，需达到《城镇污水处理厂污染物排放标准》（GB18918-2002）所要求的一级A标准。

经技术经济比较分析，本文污水处理工艺采用CASS工艺，并加深度处理，工艺流程依次为：粗格栅、污水提升泵房、细格栅、沉砂池、CASS池、中间提升泵房、网格絮凝池、普通快滤池、接触消毒池和巴氏计量槽，处理出水排入河流，经进一步稀释和净化。污水处理所产生的污泥，经加药并浓缩脱水后外运处理。

本文中污水厂污染物的主要去除单元为CASS生化池。CASS反应器是由选择器和反应池组成，一般分生物选择区，缺氧区，好氧区三个反应区，在沉淀和滗水期可连续进水，有污泥回流。其运行过程为：进水搅拌（厌氧释磷）→反应（好氧降解有机物、硝化和磷吸收）→沉淀排水排泥（排泥除磷、缺氧反硝化脱氮）→闲置（再生污泥，准备进入下一周期）。CASS工艺优点：投资省，无初沉池、二沉池及大规模回流泵站；流程简单，占地小；运行灵活，成本较低，管理简单；抗冲击负荷能力较强；脱氮除磷效果较高，处理效果较好；污泥沉降性能良好。

关键词：排水管网、分流制、污水处理厂、CASS工艺

Preliminary design of drainage system in a city
Abstract

The main content of this article is storm water pipe network, sewage network and wastewater treatment plant process design of a town. Drainage system adopts a completely separate system, therefore, rainwater is collected by network and discharged into nearby water bodies,and waste water is collected into a town sewage treatment plant.Design of the size of the sewage plant is 20000m³/d, and raw water quality indicators are COD_cr 300~350mg/L, BOD₅ 120~150mg/L, NH₃-N 15 ~ 25mg/L, total nitrogen (TN) 20~35 mg/L, total phosphorus (TP) 3~8mg/L, SS 250~360mg/L, pH value 7~8.Effluent water quality indicators, according to the environmental protection departments, need to achieve an A standard "Municipal Wastewater Treatment Plant Pollutant Emission Standards" (GB18918-2002) required.

By technical and economic analysis, the paper’s sewage treatment process uses CASS process, and adds depth treatment process. It includes coarse grid, sewage pumping station, fine grating, grit chamber, CASS pool, intermediate pumping station, mesh flocculation tank, filter, ultraviolet disinfection and Pap metering tank. Treated effluent is discharged into rivers and goes through further dilution and purification. The sludge produced in sewage treatment,is concentrated and dehydrated and then transported to the outside.

In this paper, the main pollutants removal unit for wastewater treatment plant is CASS biochemical pool. CASS reactor is composed of the selector and the reaction tank, and generally divided into three reaction zones including biological selection area, anoxic zone and aerobic zone .In the period of precipitation and decanting water, the water can continue to flow in and the sludge to return. Its running process is: water stirred (anaerobic phosphorus release) → reaction (aerobic degradation of organic matter, nitrification and phosphorus absorption) → precipitation drainage sludge (sludge and phosphorus removal, anoxic denitrification) → idle (recycled sewage mud, ready to enter the next cycle). CASS process’s advantages: low investment, no primary sedimentation tank, secondary

resistance to impact load; high efficiency of nitrogen and phosphorus’ removal, better treatment effect; good sludge settling properties.

Keywords: drainage network, separate system, sewage treatment plant, CASS process

目 录

摘要 Ⅰ

第一章 概述 1

1.1设计目的 1

1.2设计基础资料 1

1.3设计内容 2

1.4设计依据 2

1.4.1国家有关方针、政策、法规 2

1.4.2图纸 3

1.5设计任务 3

第二章 排水管道设计 4

2.1设计原则 4

2.2排水体制选择 4

2.3污水厂位置确定 6

2.3.1厂址选择原则 6

2.3.2厂址选择 6

2.4污水管网设计 6

2.4.1定线方案 7

2.4.2水力计算 8

2.5雨水管网设计 12

2.5.1水力计算 12

第三章 污水处理厂设计 14

3.1污水处理厂设计规模 14

3.1.1 服务范围 14

3.1.2 污水厂设计规模 14

3.2污水处理程度的确定 15

3.2.1 进水及出水水质要求 15

3.2.2处理程度 15

3.3污水处理厂工艺流程方案 16

3.3.1 方案选择原则 16

3.3.2 方案工艺选择 17

3.4 CASS工艺污水处理构筑物计算 22

3.4.1粗格栅 22

3.4.2污水提升泵房 24

3.4.3细格栅 24

3.4.4沉砂池 26

3.4.5 CASS生物处理池 27

3.4.6 鼓风机房 36

3.4.7 中间泵房 36

3.4.8 网格絮凝池 37

3.4.9 普通快滤池 40

3.4.11 接触消毒池 47

3.4.12 巴氏计量槽 49

3.5 污泥处理构筑物的设计计算 51

3.5.1污泥脱水间 51

3.5.2贮泥池 51

3.6 污水处理厂平面及高程布置 52

3.6.1污水处理厂平面布置 52

3.6.2污水处理厂高程布置 54

致谢 60

参 考 文 献 61

第一章 概述

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