At a time when every drop of water counts in view of its scarcity, researchers of the Indian Institute of Technology (IIT), Madras, have developed a prototype that can produce green fertilizers and water from human urine.
The product, ‘Water Chakra’, works on the development of a modular on-site toilet treatment unit. It recovers about 96 per cent of phosphorus and 85 per cent of nitrogen in the form of commercial grade ammonia solution and struvite fertiliser, besides recovery of 90 per cent water, according to the researchers. The Project has won the Indian Innovation Growth Programme 2.0 award in July 2019.
Anusha Gupta, a PhD scholar at IIT Madras who led the team, said the aim was to protect valuable water assets, reduce customer’s operation costs and create new products from toilet resources (human urine) in a simplistic approach. On an average, a man flushes nearly 1 liter of water every time he urinates, which equals to nearly 2160 liters of water per year.
“The Water Chakra project aims to recover fertilizers and water from urine ,” Gupta said. “The developed prototype can be installed in large footprint areas like commercial complexes, corporate buildings, where huge amount of urine can be collected and used for processing to obtain green fertilizers and water.”
According to the researchers, the human body excretes elements that are highly essential for the production of nutrients. Urine contains of about 98 per cent of water and remaining are nutrients — nitrogen, phosphorous, and potassium — that are currently flushed into sewers.
About 22 per cent of the global phosphorus demand can be achieved through the recovery of phosphorus from human waste like urine and faeces, they said.
Explaining the product’s way of operation, Indumathi M Nambi, technical mentor at the IIT Madras, said: “Urinals are retrofitted to make water-less urinals in one of our buildings, which helps us to collect the concentrated urine that is stored in a primary storage tank in large volumes of up to 500 litres.”
“This tank is followed by a hydrolysis tank where the urine is stored for three days for rise in pH to 9-10,” Nambi said. “This hydrolyzed urine then gets pumped to the distillation column, where it gets in contact with steam generated using a steam generator.”
In this column, the technical mentor said, ammonia present in urine strips out and gets collected in the ammonia collection tank after condensing happens with the help of a condenser.
“The remaining urine goes to the electro-chemical polishing unit for the removal of the organic and pharma residues,” she said, adding that 98 per cent of the water recovered can be reused for flushing, firefighting and gardening purposes.
