Tuesday, January 13, 2015

Barc offers technology to make sewage sludge pathogen free

C Shivakumar
Chennai:

In what could be a Swacchh Bharat initiative, Bhaba Atomic Research
Centre is in talks with Chennai Metro Water to offer technology to
make the sewage sludge pathogen free besides converting it into
bio-fertilizer.

Bhabha Atomic Research Centre senior scientist (Technical Coordination
Wing) J Daniel Chellappa told Express that that the technology has
been successfully tried in Vadodara in Gujarat. Vadodara has a
population of about 2.2 million, and generates about 100 tons of dry
sludge at Sewage Treatment Plants (STP)s from 300 millions of litres
of sewage everyday.

The domestic sewage typically contains 99.9per cent water and about
0.1 per cent solid. The sludge after conventional treatment, is still
likely to contain a heavy pathogenic microbial load and needs to be
hygienised before it is applied to agricultural land, Chellappa said.

The end product in a standard sewage treatment plant is sludge which
contains about 75-80 per cent solid and rest water.  “But this sludge
after being dried contains maximum concentration of bacteria or
micro-organisms and is harmful,” he says.

He says the dried sludge from the conventional STPs can be taken in a
container and then treated by gamma rays in a safe atmosphere. “This
is akin to the baggage scanning as is being done in airport” he says.

“This kills all the pathogens and the hygienised sludge is a potential
organic manure, a rich source for soil conditioning, conservation and
restoration. This can also be upgraded as bio-fertilisers. It is safe
and enriches the soil,” said Chellappa. The bio-fertiliser through
this method has been tested by Indian council for agricultural
research (ICAR) on paddy, papaya, grapes and other crops through
Krishi Vigyan Kendra (KVK).

“A 10 kiloGray (KGy) radiation treatment plant with an initial
investment of around Rs 15 crore can treat every kilo of dry sludge
for just about Re.1” he says.

Interestingly, BARC officials have inspected a few STP sites and it is
being learnt that if Metro Water agrees to the proposal than the
operation of treating the sludge could be done at a centralized
location.

He said the dry sludge can be transported to this location for
radiation treatment, as per AERB guidelines.


He said Metro water could also earn revenue by converting the treated
sludge into bio-fertiliser. He said even the animal wastes slaughter
houses could also be treated through the process, and exported as
pet-feeds.  He said this technology can be adopted by Corporates and
PSUs under its Corporate Social Responsibility (CSR) activities, which
would qualify under the Swachh Bharat Mission

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