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Sludge to Fertilizer


Source: TH


Context: A recent study conducted by the Indian Institute of Technology (IIT)-Roorkee has found that the sludge from sewage treatment plants (STP) in India, which is rich in organic chemicals, has “high potential” for use as fertilizer.


About sludge:

Topic Information
Definition Sludge is the thick residue that remains after the treatment of sewage or wastewater in a sewage treatment plant.


Composition Sludge is rich in organic chemicals, heavy metals, industrial effluents and bacterial contaminants.
Treatment The sludge needs to be stored for at least three months to kill pathogens and blended with cattle manure and husk or local soil to reduce the heavy metal content.
Government Initiative National Mission for Clean Ganga (NMCC) has launched “Arth Ganga” to monetise and reuse treated wastewater and sludge by converting it into usable products such as manure and bricks.
Classification As per the United States Environment Protection Agency standards, treated sludge can be classified as Class A and Class B. India does not yet have such standards.
Class A Vs Class B sludge Class A sludge can be disposed of in the open and used as organic fertilizer without any safety concerns.


On the other hand, Class B sludge can only be used in restricted agricultural applications where edible parts of the crop are not exposed to the sludge-mixed soil, and people or animals do not come into extensive contact.