Study on sludge finds high potential for use as fertilizer after treatment

Source: The post is based on the article “Study on sludge finds high potential for use as fertilizer after treatment” published in The Hindu on 11th May 2023

What is the News?

A study has found that the sludge found in Indian sewage treatment plants (STP), has “high potential” to be used as fertilizer.

What is Sludge?

Sludge is a thick residue found in Sewage Treatment Plants set up to treat polluted water.

They are rich in organic chemicals but are also a repository of heavy metals, industrial effluents and bacterial contaminants.

What is the government initiative to treat sludge?

National Mission for Clean Ganga is a flagship programme of the government to establish treatment facilities and prevent pollution of the Ganga River.

One of the measures under this is “Arth Ganga” (economic value from Ganga). It aims to “monetise” and reuse treated wastewater and sludge. This means converting sludge into usable products such as manure and bricks.

Classification of Treated Sludge: As per standards of the United States Environment Protection Agency, treated sludge can be classified as:

Class A sludge: It is safe to be disposed of in the open and useful as organic fertilizer.

Class B sludge: It can be used in restricted agricultural applications, with the edible parts of the crop not exposed to the sludge-mixed soil, and animals and people not coming into extensive contact.

Note: India doesn’t yet have standards classifying sludge as class A or B.

What did the study find about Sludge treatment in India?

A study by the Indian Institute of Technology (IIT), Roorkee found that most of the sludge analyzed after drying fell into the class B category. 

Hence, the study said that the sludge found in Indian sewage treatment plants (STP) has a high potential for use as fertilizer but required treatment before it could be used unrestricted on farms or as a potential biofuel.