Human waste, which is full of nutrients, can be recycled into valuable products that could promote agricultural sustainability and even better economic independence for some developing countries, says a new study.
The researchers, from the University of Illinois at Urbana-Champaign in the US, noted that cities around the world produce huge quantities of wastewater.
This water when treated becomes an option for places where crops grow close to cities, such as many parts of Africa, Asia and Europe.
However, because of its weight and relatively low nutrient content, water is challenging to transport.
These areas may benefit most from re-circulation of human-waste-derived nitrogen, potassium and phosphorus from cities and back into farm fields, said the researchers.
"We grow our crops in the field, apply nutrient-rich fertilizers, eat the crops, excrete all of the nitrogen, phosphorus and potassium and then those nutrients end up at the wastewater treatment plant," said Jeremy Guest, Professor at the varsity.
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"It is a very linear, one-directional flow of resources. Engineering a more circular nutrient cycle would create opportunities that could benefit the environment, economy and agriculture," he added.
The team's exploratory exercise examined 56 of the largest cities across six continents to assess the feasibility of human-waste-derived nutrient recirculation.
They looked at factors like transport distance, population and cropland density, crop nutrient requirements and what types of products would do best where.
"In some cities, we would need to use more advanced technology to recover a more concentrated product suitable for longer transport distances," said Guest.
"These are similar to the crystalized fertilizers that we are accustomed to and, in most cases, the technology to produce these from human waste is well established," he noted.
--IANS
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