Indian Railways Uses Vacuum Technology for Environmentally Friendly Prototype Carriage Toilet

Indian Railways announced that it has developed a prototype “hybrid” toilet for its passenger trains. The prototype combines vacuum technology with a biodigester to save water and dispose of waste in an environmentally friendly manner.

Vacuum technology is working tirelessly behind the scenes in many different industries to improve safety, the quality of life and the environment. Rail travel is no exception. In trains, vacuum offers a safe and efficient way to shorten response times in the braking system. Inside a passenger train, vacuum is used in bathrooms in order to dispose of human waste. In India, this was not the case until very recently. Now the first vacuum toilets are being installed in passenger compartments. But India has taken the use of vacuum one step further:  The new vacuum toilets are so-called "hybrid" systems, which combine the advantages of vacuum toilets with those of bio-toilets.

Indian Railways installed the first vacuum-biotoilet hybrid on one of its AC carriage types in late 2015 on the Dibrugarh Rajdhani Express, which connects India's capital New Delhi with the town of Dibrugarh over 2,400 km away.

According to Indian Railways, the hybrid design combines the advantages of the vacuum toilet with those of a conventional biotoilet. It claims to have developed the first toilet of its kind anywhere in the world.

The operating principle is very straightforward. A tank above the toilet delivers fresh water into a pressurizing tank, which exits under pressure through spray nozzles into the toilet bowl and is ejected into a biodigester tank. According to Indian Railways, its conventional biodigester toilets use 10-15 litres of water per flush. The vacuum-biotoilet hybrid uses about 500 ml per flush – one twentieth or less of the water required currently for a biotoilet. Once the sludge enters the biodester tank, anaerobic bacteria go to work on it, converting the waste into water and gas, which can be safely released onto the track.

The advantages are many. For one, the toilet design saves on water use, making this a highly environmentally friendly solution.

Secondly, conventional retention tanks need to be regularly emptied at the terminus. In countries such as India, where frequently the trains travel over long distances and have journey times of over 72 hours, the tank is often not able to cope with the waste produced by over 50 passengers in the carriage.

Thirdly, even if the retention tank can cope with the waste, this must be emptied at the terminus. This can overload the sewage system of some towns. A hybrid toilet dispenses with the need for ground handling facilities.

The hybrid toilet is still being put through its paces, but if trials are successful and the toilets are installed on other trains, the benefits to the environment and water use might prove to be very substantial.

Busch is a leading manufacturer of vacuum pumps and systems and provides solutions to OEMs and end customers for vacuum removal of wet waste from trains, passenger planes and ships.

Busch provides a wide range of vacuum technologies to meet the specific requirements of waste water removal. Our solutions in waste water removal are worldwide in operation. For details on specific installations, ask your local Busch sales organisation.

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