-
PART I INTRODUCTION
-
PART II INSTITUTIONAL AND REGULATORY FRAMEWORK
-
2.INSTITUTIONAL, POLICY, REGULATORY FRAMEWORK FOR RURAL SANITATION AND WASTEWATER MANAGEMENT
-
2.1 Overview
-
2.2.Institutional Arrangement
-
2.3.Policies and Regulations
-
2.4 Discharge Standards
-
2.5.Sources of funds
-
2.6.Typical provincial cases
-
2.7.Conclusions and recommendations
-
-
-
PART III TECHNICAL BASIS
-
3 Overview of Rural Sanitation and Wastewater Management
-
3.1 Domestic Wastewater
-
3.2 Rural Toilets in China – Source of Black Water
-
3.3 Decentralized vs. Centralized Rural Wastewater Management
-
-
4 Rural Wastewater Treatment Technology
-
4.1 Preliminary Treatment
-
4.2. Primary Treatment
-
4.3 Secondary Treatment
-
4.3.1 Attached Growth Process
-
4.3.2 Suspended growth Process
-
4.3.3 Waste Stabilization Pond
-
4.3.4 Constructed Wetlands
-
4.3.5 Subsurface Wastewater Infiltration Systems
-
-
-
5 Wastewater Treatment Process Design
-
5.1 General Design Consideration
-
5.2 Sewage Collection Alternatives
-
5.3 Wastewater Treatment Process Design
-
5.4 Water Reuse
-
5.5 Sludge Management
-
-
-
PART IV PROJECT PLANNING AND DESIGN
-
6 Project Planning and Design
-
6.1 Diagnosis for Project Villages – Initial Community Assessment
-
6.2 Establishment of Stakeholder Group
-
6.3 Assessment on Existing Conditions and Community’s Capacity
-
6.3.1 Physical Conditions Assessment
-
6.3.2 Community’s Capacity Assessment
-
-
6.4 Baseline Engineering Survey and Assessment
-
6.5 Project Feasibility Study and Environmental Impact Assessment
-
6.6 Selection of Operation Model
-
6.7 Project Cost Estimate
-
-
7 Community Participation
-
7.1 Why Need Community Participation?
-
7.2 Principles of Community Participation
-
7.3 Community Participation Activities
-
-
-
PART V PROJECT FINANCING
-
8 Financing, Subsidies, and Cost Recovery
-
8.1 Programmatic Costs
-
8.2 Project Implementation Costs
-
8.3 Project Financing
-
8.4 Subsidies
-
8.5 Cost Recovery
-
-
-
PART VI PROJECT IMPLEMENTATION AND MANAGEMENT
-
9 Procurement and Implementation
-
9.1 Procurement Principles
-
9.2 Procurement Alternatives
-
9.3 Procurement Planning
-
-
10 System Adminstration, Operation, Maintenance and Monitoring
-
10.1 Introduction
-
10.2 Management and Administration Arrangement
-
10.3 Operation and Maintenance
-
10.4 Reporting and Monitoring
-
10.5 Operator Training and Support
-
-
-
Appendix: Case Studies – Rural Wastewater Management in Zhejiang, Shanxi, and Jiangsu Province
-
1.Zhejiang Province
-
2.Shanxi Province
-
3.Jiangsu Province
-
4.Summary
-
-
REFERENCES
4.1.2 Grit Chambers
- Categories: 4.1 Preliminary Treatment
- Time of issue: 2022-04-28 18:22:16
- Views: 0
Grit Chamber
Grit chamber is a long narrow or circular tank to remove inorganic particles, such as sand, gravel, and other solid materials with greater specific gravity than those of the organic matters in wastewater. The removal is achieved through physical settlement by: (i) controlling the velocity of influent flow (horizontal flow chambers); (ii) utilizing centrifugal force in the flow vortices formed by aeration (aerated chambers); or (iii) using a mechanically induced vortex to capture grit solids (vortex chambers).
Figure 4.2 Schematic diagram of an aerated grit chamber
(Source: Tilley et al, 2014)
Grit chambers can protect the downstream equipment from abrasion and abnormal wear. The horizontal-flow grit chambers are well suited for village wastewater systems to remove sand and grit from the wastewater. The designed flow velocity in a grit chamber will enable most organic particles pass through the chamber channel and grit particles retained in the chamber.
Design Criteria:
- The grit chamber should be designed with at least two parallel channels so that one may be closed for maintenance or cleaning.
- The hydraulic residence time (HRT) should between 45 to 90 seconds, typically 60 seconds.
- The horizontal velocity should be maintained between 0.25 to 0.4 m/s, typically 0.3 m/s.
- Head loss through a downstream control section of 30 to 40% is required to create backflow conditions, typically 35%.
- The overall length of the grit chamber shall be added to reduce inlet and outlet turbulence. Typically, 25 to 50% of additional length is added at both the inlet and outlet of the grit chamber.
- The minimum depth of the chamber should be 0.5 m to provide adequate freeboard.
- The minimum width of the channels should be 0.6 m to allow for easy access and cleaning.
- The grit chamber can be covered with a steel or fiberglass cover that can be opened or removed for routine cleaning.
Operation and Maintenance:
- Required regular inspection and cleaning to avoid unpleasant odor from the degradation of accumulated materials.
The screenings shall be disposed in an environmentally sound wa