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Germs to gobble train stain
- Answer to embarrassing blot: waste-eater bacteria

New Delhi, Jan. 28: The three-tier 5207AB on the Gwalior-Barauni Mail is special — it’s the only passenger coach on the 62,000-km Indian Railways network that doesn’t discharge human waste on to the ground beneath.

At both ends of the coach, below the toilets, billions of bacteria locked inside stainless steel containers have been busy digesting waste, and displaying their potential to clean up a long-standing and embarrassing blot on the image of Indian rail travel.

The cocktail of waste-digesting bacteria created by defence scientists may help tackle the problem of human waste dropped by passenger coaches since toilets were installed in Indian trains in 1891.

“This holds out the promise of ending a problem of both hygiene and image,” said Krishnamurthy Shekhar, director of the Defence Research Development Establishment (DRDE) in Gwalior, where the bacterial broth was concocted more than five years ago — not for the railways, but to tackle human waste in Siachen.

At below-freezing temperatures in the high altitudes of the Siachen glacier, ordinary bacteria cannot degrade excreta, which had been piling up since India sent its soldiers there in the mid-1980s.

A DRDE research team used “cold-tolerant” bacteria from Antarctica, Siachen and elsewhere and created a mixture that degrades waste in extreme cold, as low as 5° C.

Some 80 digesters are deployed across Siachen and other high-altitude zones to prevent human waste from spoiling the pristine mountain environment, Shekhar told The Telegraph.

Last year, the Research Design and Standards Organisation in Lucknow — the research unit of the Indian Railways — asked the DRDE to build a digester for passenger carriages.

In the 400-litre-capacity stainless steel containers designed by the DRDE, bacteria digest waste, producing carbon dioxide, water and tiny amounts of methane, and leaving only a powder residue. The digester also chlorinates water that falls on the tracks.

“Only chlorinated water comes out,” said Lokendra Singh, a DRDE scientist. “The residue is pathogen-free, odour-free, and builds up so slowly that it will need to be removed only once in two years.”

Two DRDE digesters have been on trial since August 2006 in a coach on the Gwalior-Barauni Mail picked by the railways’ research unit. DRDE scientists said the digesters have worked well, but a senior official of the research centre told The Telegraph that they are still under evaluation.

“The pressure on our carriages is high,” the official said. “Long journeys, heavy passenger loads and the typical Indian diet with more roughage than western diets makes this a very complex problem,” he said.

An attempt by the railway research unit in the mid-1990s to use bacteria and enzymes procured from an international vendor was abandoned after foul smell emanated and cockroaches crawled out of the tanks into toilet rooms, sources familiar with the experiment said.

“If the bacteria cannot digest waste effectively, foul-smelling hydrogen sulphide is produced,” said Singh.

“The three-tier coach of the Gwalior-Barauni Mail will expose the digester to the harshest possible waste loads,” said Singh. “The load is expected to be much higher than on either air conditioned coaches or superfast trains.”

Officials of the DRDE and the railway research organisation will meet next month to discuss the performance of the digesters. “We’d like to expand this trial to more coaches on other trains,” Shekhar said.

The bacteria thrive in the digesters, some of them clinging to an immobilisation matrix on the walls of the containers to ensure that even with excess flushing, some bacteria remain behind to carry on the work. “We don’t have to replenish them, they multiply on their own,” Singh said.

The railway research unit official, who requested not to be named, said efforts are also under way to procure vacuum suction toilets that retain waste for removal at destinations. “Ground-handling systems need to be established at destination stations. We don’t want waste from trains to clog up sewage in cities.”

Some toilets in superfast trains such as Rajdhani have speed-regulated discharge outlets — waste drops out only when the speed of the train is greater than 35 km per hour when the train is unlikely to be at a station, the official said.

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