Railways needs a bug to keep toilets clean

A few years ago, a scientist from Defence Research and Development Organisation (DRDO) visited India’s research outpost in Antarctica. Fascinated by a strain of bacteria, psychrophiles, that ingest human waste and convert it to odourless water at subzero temperatures, he brought the bacteria with him to India. Scientists at DRDO used it to develop bio-toilets.

Bio-toilets were tested before being adopted by the military, which now uses them in the Siachen heights.

Around the same time, Indian Railways was being roundly criticised for creating an environmental hazard by discharging toilet waste on tracks. The environment ministry was unhappy with trains polluting lakes and rivers, as studies showed that trains crossed a large number of water bodies.
Indian Railways and DRDO thus came together to develop bio-toilets for trains. The railways had experimented with other options at considerable expense, but they had all failed.

“Somebody suggested that anti-corrosion paint was the best option to prevent corrosion of tracks and undercarriages of coaches,” said a Southern Railway official. “We spent crores on paints but they made no difference to the corrosion rate. Undercarriages needed to be replaced every four years as earlier. An official then proposed a controlled discharge.”

The controlled discharge toilet used a sophisticated system that used GPS. It collected waste in a box and discharged it automatically when a train picked up speed. The GPS system monitors if the train is over a water body or at a railway station to prevent polluting water bodies and keep terminals clean. It was considered an interim arrangement till a permanent solution was found.

“It looked good on paper but the GPS system did not work well,” the Southern Railway official said. “The toilet system often got jammed by bottles and garbage that travellers dumped in the commodes. It created a problem for rail yard workers who had to pry open toilet boxes and empty the waste into pit lines. The yards soon got polluted and posed a serious health hazard to employees.”

Controlled discharge toilets were also expensive, costing around 6 lakh per piece. Malfunctioning toilets threatened to derail train schedules especially at large terminals like Chennai, where more than 30 rakes have to be cleaned and overhauled every day. Railway staff have just six hours to make sure a rake is fit to be used. It was not possible to spend additional time to set right faulty toilets.

The railways then experimented with zero discharge toilets. They were developed by IIT-Kanpur and Research Design and Standards Organisation (RDSO) to segregate solid waste and liquid waste, recycling the liquid waste to be used for flushing. Solid waste was treated with anaerobic bacteria and stored in a box that was emptied at stations or yards. This toilet was found to be successful on a long-distance train. But sources said zero discharge toilets need more tests. “The systems provided varied results during trials,” a railway official said. “Removing solid waste from tanks was a problem. Vacuum machines are prone to technical glitches.”

Officials of RDSO had suggested in 2005 that railways switch over to vacuum toilets, which are used extensively in the West, for premium services. But it realised they would require expensive support infrastructure at stations or yards.

“We tried different options including zero discharge toilets and vacuum toilets,” said Indrajit Singh, executive director of RDSO. Railways is now cautious. “We have to consider what passengers feel about a certain type of toilet. On average, more than 80 people use three Indian style toilets in each coach of a train in less than 20 hours,” another official said. “Tests have demonstrated that bio-toilets can be used by a large number of people. We are continuing tests to see if they have any shortcomings and to see if there is any change in the behaviour of the bacteria,” an official said.

Bio-toilet treats waste with multiple levels of bacteria,
converts it to water and gas
Bacteria ingests fecal matter, turns it into slurry
When toilet is flushed,
treated waste flows to where it is converted into water and disinfected with chlorine
Water and gas goes to the lowest tray where it is filtered and expelled when the train is travelling at 30kmph
THE GOOD | Converts waste to water that, when expelled, does not corrode tracks
THE BAD | Bacteria may not work if passengers chucks things in toilets. If toilets are overused, bacteria will not be able to convert all the waste into water and gas ZERO DISCHARGE
Waste not dropped on tracks. Toilets segregate solid and liquid waste with solidliquid separators and store it in tanks. Liquid waste recycled for flushing
Separator does not need
power to operate
Microbials added to prevent decomposition. Can be stored for 10 days before being removed with vacuum machine
Liquid filtered twice to remove sediments, to tank in undercarriage of coaches, used to flush toilets
THE GOOD | Does not discharge on tracks, prevents corrosion. Water reused to flush, keep toilets clean. Toilet does not get clogged by bottles and garbage
THE BAD | Worked well during trials, but more tests needed.


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