Hyderabad: A waterless urinal at the metro stations is another facility that was added. In a first of its kind initiative, the Hyderabad Metro Rail and SGP waste water managers collaborated to convert urine into safe water.
HMR to install waterless urinals at Metro Stations
This methodology not only helps converting urine to safe water, but also helps increase in the ground water levels as the treated water is directed to a soak pit through a channel. This water can also be used for plants as this does not emanate foul odor and works as good as normal water. The urine is collected in anaerobic digester, where anaerobic microbes degrade urine in absence of air and reduce stickiness and TDS i.e. Total dissolved solids. Then by gravity urine enters to activated carbon filter followed by Biofilter.
The nitrogen is used as nutrient source by plants and ammonia is taken up by microbes, then they liberate enzymes which maintain pH. The fungus and algae make thin film around grit in this system. This will also help to utilize remaining free nitrogen. Thus urine becomes odourless, colorless. The color is absorbed by thin film developed around grit and then is utilized by plants to grow. In same manner solids in urine are absorbed by thin film and utilized by plants.