REUSE & DISPOSAL
The faecal sludge treatment system generates two key end products with opportunities for safe reuse and resource recovery. Proper management of these products closes the sanitation loop and creates value from waste.
End Products
1. Biosolids
Dried sludge from planted drying beds or sludge drying beds. Rich in nitrogen, carbon, and phosphorus—valuable nutrients for agriculture.
Nutrient Content:
- Nitrogen (N): Important for plant growth
- Phosphorus (P): Essential for root development
- Carbon: Improves soil structure
- Organic matter: Enhances water retention
Quality Standards:
Biosolids must meet pathogen reduction and quality standards before reuse. Proper drying (minimum 6-12 months in PDB) significantly reduces pathogens.
2. Treated Water
Liquid fraction collected in storage tank after treatment. Can be reused for non-potable applications after meeting quality parameters.
Quality Parameters:
- BOD: < 30 mg/L (typical for reuse)
- COD: < 100 mg/L
- TSS: < 50 mg/L
- pH: 6.5 - 8.5
- Fecal coliforms: As per reuse category
Treatment Requirements:
May require polishing treatment (maturation ponds, constructed wetlands) depending on intended reuse application.
Reuse Options
Biosolids Reuse
Soil Conditioner
Primary reuse option. Dried biosolids are applied to agricultural land to improve soil fertility and structure. Rich organic matter enhances water retention and nutrient availability.
Composting
Biosolids can be co-composted with green waste or agricultural residues to produce high-quality compost for sale or distribution to farmers.
Fuel Production
Dried biosolids can be processed into briquettes for use as fuel in industries (brick kilns, cement plants) after proper treatment.
Landfill Disposal
If reuse is not feasible, stabilized biosolids can be disposed at designated landfill sites following proper protocols.
Treated Water Reuse
Agricultural Irrigation
Treated water can irrigate crops (non-food or food crops depending on treatment level). Provides water and nutrients to plants.
Green Belts & Plantations
Watering tree plantations, avenue trees, and green belts along roads or within the treatment facility premises.
Gardening & Landscaping
Non-edible plants, lawns, and decorative landscaping in parks, institutions, and public spaces.
Groundwater Recharge
Where appropriate, treated water can contribute to groundwater recharge through percolation or injection wells.
Implementation Considerations
Quality Monitoring
Regular testing of biosolids and treated water to ensure they meet quality standards for intended reuse applications.
Market Linkages
Establish connections with farmers, nurseries, and industries that can utilize biosolids and treated water. Create awareness about benefits.
Storage Facilities
Adequate covered storage for biosolids until sale/distribution. Water storage tanks with appropriate capacity for treated effluent.
Record Keeping
Maintain records of quantities produced, quality test results, and end-users for accountability and continuous improvement.
Closing the Loop
Safe reuse of treatment products transforms waste into resources, reducing environmental impact while providing economic benefits. This circular approach is essential for sustainable sanitation systems.