Simple sand-and-gravel bed systems used to dewater and dry sludge through drainage and evaporation.
Sludge drying beds integrated with plants that aid dewatering and further treatment through root-zone filtration.
Working Principle:
Sludge Drying Bed (SDB) is a shallow, rectangular structure filled with layers of graded filter media, typically comprising sand and gravel of varying sizes and thicknesses. The bed is generally open to the atmosphere and is equipped with a drainage system at the base to collect percolate or leachate. An anaerobic digester can be deployed for digestion of sludge before application on the sludge drying beds, if required. Sludge is applied evenly over the top sand layer, and water drains through the filter media by gravity. An underdrain system collects the leachate, which is then directed either to a liquid treatment facility for further treatment. In addition to percolation, surface evaporation accelerates the drying process. The dried sludge is manually removed, usually after 10–15 days, depending on local climatic conditions and sludge characteristics.
Suitability:
- Suitable for small to medium towns with moderate sludge generation.
- Ideal where land is available, and climate is warm and dry.
- Can be used where periodical sludge removal is feasible manually.
- Suitable where no skilled manpower or electricity is available.
- Can be adopted where mechanical drying is not preferred or practical.
- Effective in remote locations with basic infrastructure
Pros/Cons:
Pros: Simple to construct and operate, low capital and operating cost, no energy or mechanical equipment required, uses locally available materials
Cons: Requires manual removal of sludge periodocally, drying time depends heavily on local weather conditions, can produce odor if not properly managed, prone to clogging over time, frequent maintenance of sand layer needed
O&M requirement:
Periodic removal of dried sludge (typically every 10–15 days depending on drying time)
Regular cleaning or replacement of the sand layer to prevent clogging
Monitoring of drainage system to ensure proper leachate flow
Odor control through proper loading and timely sludge removal
Maintenance of bed leveling and weeding if any vegetation grows unintentionally
|
Parameter |
Design Value |
Unit |
|---|---|---|
|
Thickening Tank |
||
|
Desired TS in thickened sludge |
5 |
% |
|
Settling efficiency |
60 |
% |
|
Sludge retention time |
6 |
Days |
|
Operational Cycle |
||
|
Feeding phase |
3 |
days |
|
Resting phase |
2 |
days |
|
Emptying phase |
1 |
day |
|
Surface loading rate (SLR) |
30-45 |
kg TS /m²/day |
|
Up flow velocity |
0.5 |
m/hr |
|
Length to Width ratio |
3:1 |
- |
|
Height of oil and grease zone |
0.2 to 0.3 |
m |
|
Sludge Drying Bed (SDB) |
||
|
Sludge thickness |
0.25 |
m |
|
Number of beds |
10 |
Nos |
|
Days of application in a week |
5 |
Days |
|
Feeding frequency in a bed |
Once in 15 |
days |
|
Leachate/percolate from SDB |
||
|
BOD |
200 |
mg/l |
|
COD |
400 |
mg/l |
|
Hydraulic retention time |
2 |
Hours |
|
Peak hours |
4 |
Hours |
|
SS/COD ratio |
0.45 |
- |
|
De-sludging interval in Settler |
18 |
Months |
The following will be the treated sewage characteristics for the design of the FSTP-SDB:
|
Parameter |
At PGF Outlet |
At ACF+PSF Outlet |
Unit |
|---|---|---|---|
|
Effluent Characteristics |
|||
|
BOD |
< 30 |
< 10 |
mg/l |
|
COD |
< 100 |
< 50 |
mg/l |
• There is vehicular access available to the site.
• The site is fairly level ground, free of any structures, large trees requiring cutting permission, any kind of underground or overhead utilities, etc. except for small shrub's, vegetation, etc.
• The soil profile of the site involves earth work excavation in soil only, excavation involving rock blasting is not necessary.
• The site is not a low-lying area or marshy land or sewage farm, etc.
• The site is with original soil profile, without deep filling or overburden.
India’s rural sanitation sector has witnessed significant progress under the Swachh Bharat Mission Grameen (SBM-G), with increasing emphasis on sustaining Open Defecation Free (ODF) outcomes and strengthening Solid and Liquid Waste Management (SLWM) systems across villages. As rural communities continue to evolve and generate higher volumes of greywater and wastewater, there is a growing need for decentralized, cost-effective, and sustainable rural used water management solutions that are technically sound and easy to implement.
Despite the availability of various treatment technologies and management approaches, Gram Panchayats, Rural Development Departments, and implementation agencies often face challenges in selecting appropriate technologies, preparing technical designs, estimating costs, and planning site-specific interventions. The lack of standardized technical resources and easy access to implementation-ready designs further slows down the execution of rural sanitation infrastructure.
To address these challenges and support the effective implementation of rural used water management systems, WASH Institute has developed this dedicated web-based Rural Used Water Management Portal. The portal is envisioned as a comprehensive technical decision-support platform to assist states, districts, blocks, Gram Panchayats, and practitioners in planning and implementing sustainable rural sanitation infrastructure.
The portal provides a curated repository of commonly adopted rural treatment technologies and management systems, including soak pits, leach pits, waste stabilization ponds, DEWATS, drain-end treatment systems, co-treatment models, FSTPs and other decentralized greywater management solutions suitable for rural contexts. Each technology package includes standard design drawings, technical specifications, implementation guidance, and quantity estimates (BoQs) that can be readily adapted for field implementation.
The technical resources available on the portal have been prepared by experienced sector experts in alignment with CPHEEO guidelines, SBM-G operational guidelines, and established field practices. The technologies featured on the portal have been successfully implemented across multiple villages and states, ensuring their practicality, scalability, and suitability for diverse rural conditions.
By making standardized designs and implementation resources easily accessible, the portal aims to strengthen planning capacities, reduce duplication of technical efforts, improve the quality of infrastructure implementation, and accelerate the adoption of safe and sustainable rural used water management systems across India.
Importantly, the portal is designed as a dynamic and evolving knowledge platform rather than a static repository. It will continue to expand through contributions from sector practitioners, government departments, and technical institutions. Future enhancements will include state-specific schedule of rates, GIS-based planning support, case studies, operation and maintenance guidance, and real-time cost estimation tools to further support rural sanitation planning and implementation.
Local governments follow staged planning for grey water management projects — planning and project formulation, DPR preparation, tendering, construction, and operation & maintenance. This portal supports the tendering stage by providing standardized technical drawings and cost estimates.
The designs, drawings, and bills of quantities (BoQs) provided on this portal are intended for reference purposes only and cannot be used directly for construction. Validate design assumptions, adopt locally applicable Schedule of Rates, and ensure compliance with applicable national or state-level standards.