New Delhi: Passengers travelling in long-distance trains will soon get respite from the stench of toilets with Railways set to replace them with "odourless" bio-toilets.

With a view to provide more hygienic conditions, Railways is firming up a green initiative to manufacture 2,500 bio-toilets in the upcoming fiscal.

Unlike traditional toilets in trains where the waste is discharged on tracks, the new system will treat the same inside a tank with the help of bacteria, which will convert it into harmless gas and water.

Two expert panels appointed by Railways to suggest ways for upgradation of rail infrastructure and safety measures, have strongly recommended introducing "green toilets" in trains.

Manufacturing of these bio-toilets is likely to be mentioned in the Rail Budget 2012-13 as part of the green initiatives being undertaken by the nation's largest transporter to improve the cleanliness in rail premises.

This will not only improve the environment but also help in preventing corrosion of rail tracks, a senior Railway Ministry official said.

Estimated to cost about Rs one lakh per bio-toilet, these new age toilets will be manufactured at Kapurthala coach factory and fitted in long-route trains.

While about 50 bio-toilets will be fitted in LHB (Linke Holfmann Bush) coaches, the rest will be used in conventional coaches.

The bio-toilets are already operational in some coaches as part of a pilot project. "Some modifications are being made during the trial and now the new technology will be extended to as many trains," said the official.

The anaerobic bacteria inside the toilets consume waste material and convert it into water and gas in the bio-toilet system. The water passing through chlorine tank is discharged as clean water and the gas generated evaporates into the atmosphere.

Railways had joined hands with Defence Research and Development Organisation (DRDO) for development of bio-toilets.