Objectives and Regulatory Considerations for Sludge Treatment in India

Sludge treatment serves multiple purposes, each aimed at ensuring public health, environmental safety, and operational efficiency. The key objectives include:

1. Regulatory Compliance Ensure adherence to national and local sludge management regulations, where applicable, for each facility.

   
   

2. Volume Reduction Minimise the overall volume and water content of sludge to reduce the cost and logistical burden associated with handling, transport, and disposal.
   

3. Safe and Sustainable Disposal Guarantee that treated sludge is managed in an environmentally sound manner, preventing adverse ecological and public health impacts.
   

4. Pathogen Reduction Eliminate or significantly reduce disease-causing organisms to safeguard human health, as well as protect flora and fauna.
   

5. Sludge Stabilisation Stabilise sludge to inhibit the proliferation of vectors such as rodents, flies, and birds, and to control the release of greenhouse gases.
   

6. Odour Control Reduce the presence of biodegradable organics to mitigate unpleasant odours, especially during storage or transport.
   

7. Resource Recovery and Circular Economy Support circular economy principles by converting treated sludge (referred to as “biosolids”) into beneficial by-products such as biogas, bio-fertilisers, and soil enhancers. Additionally, recover valuable nutrients such as phosphorus for reuse.
   

Current Regulatory Landscape in India

India currently lacks a dedicated regulatory framework specific to the handling, treatment, transport, utilisation, storage, and disposal of sewage sludge. Nonetheless, general environmental and waste management laws—covering municipal solid waste, hazardous waste, sewage, and air quality—have indirect implications for sludge management.

In the absence of specific national regulations, several progressive municipal corporations—including those in Delhi, Mumbai, Bangalore, Ahmedabad, and Chandigarh—have adopted international best practices. For instance, current sewage treatment plant (STP) tenders in these cities increasingly reference the United States Environmental Protection Agency (US EPA) 503 regulations, often specifying compliance with Class A biosolids standards.

Need for a National Sludge Management Framework

India urgently requires comprehensive national legislation on sludge and biosolids management. Such a framework would be essential to guide future infrastructure planning and implementation across the country. It should set clear minimum standards and requirements related to:

• Plant Approvals Separate regulatory approvals for the sewage treatment plant (STP) and sludge processing facility.
  

• Treatment Protocols Defined treatment processes (e.g., aerobic or anaerobic digestion, composting, liming, drying) including pre-treatment options.
  

• Hygienisation and Vector Control Mandatory hygienisation steps, limit values for pathogens and heavy metals, and strict controls on vectors and odour emissions.
  

• Biosolids Agronomic Product Enhancement Standards Class A product is an environmental standard and not an agronomic standard. Class A product has carbon stripped out during the biogas production stage. Therefore, it has to be augmented in quality and fortified with necessary nutrients before it becomes acceptable to the agricultural industry.
  

• Land Application Standards Specific guidelines for agricultural and landscaping use, including restrictions, if any, on use for food crops.
  

• Dewatering Requirements Standards to improve storage, reduce transport costs, and enhance the efficiency of downstream processes like drying or incineration.
  

• Landfilling Restrictions Clear rules to limit long-term storage, defining anything beyond three years as landfill disposal.
  

• Application Limits Maximum permissible application rates for biosolids on agricultural land (e.g., tonnes of dry matter per hectare) to prevent misuse.
  

• Monitoring and Reporting Periodic monitoring of heavy metal concentrations to track and manage industrial discharges entering the sewerage network.
  

• Intermediate Storage Standards Infrastructure and protocols to prevent pollution during interim storage and ensure timely final disposal.
  

• Energy and Emissions Accounting Lifecycle assessment of energy use and greenhouse gas emissions from sludge treatment to final disposal.

Recommendation for Urban Local Bodies (ULBs)

Each Urban Local Body should develop a comprehensive Sludge Master Plan, aligned with future regulatory frameworks, city-level environmental priorities, and resource recovery goals. These plans must be supported by adequate funding and political commitment to enable cities to transition towards safe, efficient, and circular sludge management systems.