Phosphorus can be Extracted from Faecal Sludge
How close is that the world to “peak phosphorus” — that time in time when production of phosphorus will reach its maximum, and it’ll get harder to access it? The solution to the present question is crucial, as its availability influences a country’s food security.
Presence of phosphorus is essential in the soil for crop growth, and its shortfall may result in a reduction of crop yield. But the reserves of phosphate rock, the most source of the element, is fast depleting.
With an annual increase of two .3 per cent in its demand, phosphorus reserves will presumably get worn out in next 50 to 100 years, confirms a 2015 study by professors of the West Bengal State University, Kolkata.
Phosphate rocks are concentrated in Western Sahara, Morocco, China, us, Russia and West Asia. Therefore, most of the planet, including India, has got to import it. In 2018, Diammonium phosphate included 28 per cent of India’s fertiliser import. Researchers mean that the planet will reach “peak phosphorus” in 2030.
By this point, India’s population is predicted to succeed in 1.5 billion. How will we sustain food production with a shortage of such an essential element?
A valuable phosphorus resource from where an enormous reserve is often generated has been largely ignored. Human excreta are indiscriminately disposed into drains a day.
“The solid matter that humans excrete is essentially organic. It contains carbon, phosphorus and an entire lot of other nutrients. We consume these nutrients within the sort of food. Leafy vegetables, as an example, have phosphorus,” says Vijay Athreye, founding father of the FINISH Society, a non-profit that works on sanitation and waste.
“About 11% of phosphorus entering Earth systems is lost in human urine and excreta, but phosphorus and nitrogen in it are often recovered by up to about 90 per cent. If recovered, this might supply 22 per cent of the present global demand for phosphorus,” says a 2011 study on the worldwide potential of phosphorus recovery from human urine and faeces.
In one day, a person produces 30 g of carbon, 10-12 g of nitrogen (N), 2 g of phosphorus and 3g of potassium (K) through human excreta, consistent with the International Water Management Institute in Colombo. With India’s 1.3 billion population, the nation generates nearly 53 million tonnes of dry excreta per annum.
An analysis by Dutch non-profit WASTE demonstrates India generates more than 204 million tonnes of phosphorus every annum. The excreta would also comprise valuable soil nutrients like over one billion tonnes of carbon, 646 million tonnes of nitrogen, four billion tonnes of organic matter and 145 million tonnes of potassium per annum.
India has an ambitious decision to double farmers’ income by 2022. NITI Aayog has, therefore, issued a press release that India must increase its fertiliser (NPK) availability by 38 per cent or 36 million tonnes. This will be achieved if India turns into NPK self-sufficient.
Intelligent use of faecal sludge might organically improve soil quality and help farmers improve their income. Pilot projects in several parts of the country are trying to show human excreta into NPK-rich fertilisers. As an example, in Talcher, Odisha, FINISH Society found out a Sewage Treatment Plant (STP) in November 2018.
A part of the city’s faecal sludge was delivered to the STP. Faecal sludge has three to 5 per cent solids; the remainder is water. The STP separated solids from water during a wetland comprising gravel and sand. The filtered wastewater was treated and wanted to recharge groundwater. Dry sludge was extracted and mixed with dry leaves for co-composting. This takes around 3 to 4 months for the waste to compost.
The non-profit is going to be ready with the first batch of compost soon. The ultimate product is going to be tested for its nutrient and pathogen content. After this, the compost is going to be sold to farmers. When the project is entirely functional, the non-profit hopes to urge 30 to 40 tonnes compost per cycle.
In Tamil Nadu’s Nilgiri district, an identical project was started in 2018 to use recycled water for agriculture. It even assisted in treating and reusing faecal sludge as co-compost for farming. Started by Rural Development Organisation Trust, along with side FINISH and WASTE, it now sells compost at Rs 8 per kg to exchange chemical fertilisers, which costs Rs 15 per kg.
The project found a 15 per cent increase in crop yield and a 20% surge in farmers’ annual income. A lot of farmers who used the compost to grow garlic, carrot and beetroot reported that the dimensions of garlic increased and carrots and beetroot were more prosperous and shinier in colour.
Impressed with the model, Niti Aayog has written to the chief secretaries of all states to explore its prospects. Its implementation can resolve another big problem for India. When the nation became open defecation-free in October 2019, the subsequent big concern was infrastructure for faecal sludge management. Projects like those within the Nilgiris and Talcher can help create a circular economy in sanitation — safe collection, treatment and reuse of faecal sludge.
Indiscriminate use of chemical fertilisers decreases soil health by killing the microorganisms, which would nourish it. The typical organic carbon content in soil — an index for soil health — may be a low 0.3-0.4%, consistent with Indian Council of Agricultural Research. This is often well below the suitable 1-1.5 per cent.
Farmers get caught during a vicious circle once they use chemical fertilisers because it degrades soil quality, which, in turn, upsurges input use. National Academy of Agricultural Sciences states that NPK use ratio stands skewed at 6.7:2.7:1. The perfect nutrient use is 4:2:1. This is often happening more in high urea consuming states, indicating an urgent need for restoring soil nutrient balance.
India must make policy changes to extract nutrients from faecal sludge, as this may serve the twin purpose of reducing its dependency on imports for phosphorus and improve soil health, thus boosting farmers’ income.