The Development Cell of the Indian Railways has come up with a prototype 'Hybrid Vacuum Toilet' that consumes around 500 ml of water for a flush.
According to Indian Railways, the advanced loo is a first of-its-kind to have been developed and built by any railway system in the world.
The newly-launched system, deployed as a pilot in a coach of Dibrugarh Rajdhani, is way ahead performance-wise, as a conventional toilet or biotoilet uses 10–15 liters of water per flush.
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'prototype' loo consists of a custom-designed vacuum toilet adapted from a commercially available vacuum toilet present in aircraft, which evacuates its discharge into a biodigester tank. Modifications have been made in the standard flushing protocol of a vacuum toilet so as to create a water seal and additional post flush cycles.
As in a bio-toilet, the biodigester tank present in the prototype is fitted underneath the coach and contains anaerobic bacteria that converts human faecal matter into water and small amount of gases before discharging the same on the ground/track.
"Water is a very precious natural resource. Therefore, this innovation shall save water to the tune of at least 1/20th of the quantity that is used in the current design of biotoilets/conventional toilets," Indian Railways said in a statement.
Across the world, Railways had built vacuum toilets that have retention (very large) tanks fitted underneath the passenger coaches to hold all the human waste. During the journey, these tanks are evacuated at terminal stations, from where, there is rapid discharge of human waste of an entire train into their respective sewer systems.
This process, however, is nearly impossible in the domestic scenario, as Indian Railways' trains traverse the length and breadth of the country with journey times as long as 72 hours and generally over 50 passengers for every coach.
Further, they require installation of stationary facilities for evacuation of these holding tanks. The city municipal corporations at cities where these ground-handling facilities are to be created have to be taken into confidence to allow one-shot rapid discharge of human waste of an entire train into their sewer systems.