The country generates about half a million tonnes of sludge, including 0.12 million of fecal waste, daily – with not more than 30% being treated before it is dumped into water bodies. Untreated sludge contaminates water bodies and degrades the soil. Even municipal bodies in mega cities such as Delhi and Mumbai can treat only half of the sludge generated, and the rest is dumped into water bodies directly.
Municipal bodies have adopted sewage treatment plants (STPs) to deal with sludge, but many of them have not been able to deal with it efficiently. “We can make STPs more effective through the use of this technology,” said Lalit Varshney in a presentation to Planning Commission deputy chairperson Montek Singh Ahluwalia recently. “The quality of compost generated is also very good, as it is a rich source of organic carbon for soil conditioning.”
The technology, termed the ‘sludge hygienisation research irradiator’, uses ionising radiation to convert liquid sludge into compost that has to be dried before being used as an organic fertiliser. The radiation is used to eliminate bacteria and also reduce the foul smell to a large extent. It also succeeds in partly ridding the waste of toxic chemicals.
The biggest advantage of this technology, however, is its low cost. Through it, sludge generated by around a million people can be converted into compost at a cost of Rs. 5.6 crore – also covering the capital cost of the technology. The life span of the plant is around 30 years, Varshney said.
Though Planning Commission officials said they would recommend the system to municipal bodies that face sludge-treatment problems, but raised safety issues over the use of radiation.