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Potential of STP sludge in Ganga River cleanup efforts


The sludge from Indian sewage treatment plants (STPs) is significant in treating polluted water from the Ganga River. A recent study highlights the potential of this sludge as a fertilizer and biofuel.


GS III: Environment and Ecology

Dimensions of the Article:

  1. Details
  2. What is Sludge?
  3. Main Findings from the study
  4. About Project Arth Ganga


  • The National Mission for Clean Ganga is an initiative aimed at preventing pollution and rejuvenating the Ganga River.
  • The initiative ‘Arth Ganga’ has been introduced as part of this mission to derive livelihood opportunities from the river rejuvenation program.
  • The primary objective of this initiative is to monetize and reuse treated wastewater and sludge, which are byproducts of sewage treatment plants.

What is Sludge?

  • Sludge is the thick residue generated during wastewater treatment.
  • It is the semi-solid material left after separating and treating the liquid portion of the sewage.
  • The composition of sludge varies depending on the source and treatment processes used.
  • It can contain organic compounds, nutrients, microorganisms, as well as contaminants such as heavy metals, industrial pollutants, and pathogens.
Treatment and Classification:
  • Treatment and processing of sludge can yield organic fertilizers, biogas, or construction materials.
  • Contaminants in sludge require careful handling to avoid negative impacts on water bodies and agricultural land.
  • The United States Environment Protection Agency classifies sludge as Class A or Class B based on their safety for disposal and use.
    • Class A sludge is safe for open disposal and serves as organic fertilizer.
    • Class B sludge can be used in restricted agricultural applications, with precautions to avoid exposure of edible parts of crops to sludge-mixed soil and to limit contact with animals and people.
Sludge Disposal in India:
  • India does not have established standards for classifying sludge as Class A or B.
  • Contractors under the Namami Ganga Mission are assigned land for sludge disposal.
  • Inadequate treatment of sludge by these contractors leads to its release into rivers and local water sources during rainfall.
  • Data on the chemical characteristics of sludge is essential to incentivize private players to treat and dispose of sludge properly.

Main Findings from the study:

  • The majority of the analyzed dried sludge belongs to the class B category.
  • Nitrogen and phosphorus levels in the sludge exceed India’s fertilizer standards, while potassium levels are lower than recommended.
  • Total organic carbon content in the sludge is higher than recommended, but heavy metal contamination and pathogen levels surpass fertilizer standards.
  • The calorific value of sludge ranges from 1,000-3,500 kcal/kg, which is lower than Indian coal.
Recommendations for Improving Sludge Quality:
  • Storage of sludge for at least three months is suggested to kill pathogens.
  • Blending sludge with cattle manure, husk, or local soil can help reduce heavy metal content.
  • However, these measures would still classify the sludge as class B.
  • Converting the sludge into class A would require more extensive treatment.

About Project Arth Ganga

  • PM Modi first introduced the concept during the first National Ganga Council meeting in Kanpur in 2019, where he urged for a shift from Namami Gange, the Union Government’s flagship project to clean the Ganga, to the model of Arth Ganga.
  • The latter focuses on the sustainable development of the Ganga and its surrounding areas, by focusing on economic activities related to the river.
  • At its core, the Arth Ganga model seeks to use economics to bridge people with the river.
  • The project has been assisted by the World Bank.
Features of the project:

Under Arth Ganga, the government is working on six verticals.

  1. Zero Budget Natural Farming, which involves chemical-free farming on 10 km on either side of the river, and the promotion of cow dung as fertiliser through the GOBARdhan scheme.
  2. The Monetization and Reuse of Sludge & Wastewater, which seeks to reuse treated water for irrigation, industries and revenue generation for Urban Local Bodies (ULBs).
  3. Arth Ganga will also involve Livelihood Generation Opportunities, by creating haats where people can sell local products, medicinal plants and ayurveda.
  4. To increase public participation by increasing synergies between the stakeholders involved with the river.
  5. The model also wants to promote the cultural heritage and tourism of Ganga and its surroundings, through boat tourism, adventure sports and by conducting yoga activities.
  6. The model seeks to promote institutional building by empowering local administration for improved water governance.
Significance of the project
  • The project is a holistic viewpoint of the Ganga rejuvenation project which seeks to promote sustainable livelihood of the population in this area.
  • Inland Waterways being the most important part of the Arth Ganga project, will create huge economic activities while focusing on inclusive and sustainable livelihood.
  • Trade and market access benefits, local community economic growth, and passenger convenience all have a big impact.
  • According to the World Bank, this project’s infrastructure-related operations will lead to the creation of 100–150 direct jobs per industry.
  • The Arth Ganga project will also ensure large scale skills enhancement and public/private sector capability development.
  • The ease of transportation and doing business will have a huge impact on the farmers especially horticulture farmers in the region.

-Source: The Hindu

March 2024