Every time you flush, life-giving nutrients are wasted. But one of the core substances produced by our body’s waterworks is also killing wildlife.
Let’s start with the positive. Sort of. According to researchers at the University of Surrey, urine contains a wealth of good things — like nitrogen, phosphorus, and potassium — which are being flushed down the toilet, rather than saved, stored and used to feed plants.
But by using osmosis, the UK academic team was able to recover high levels of these substances from wastewater supplies, whilst using much less energy than traditional sewage systems and treatment processes. If scaled up, this method could reduce pressure on infrastructure at a time when Britain’s water network is in urgent need of upgrading. And it could significantly cut reliance on existing forms of fertiliser which are linked to environmental degradation, offering an alternative to ecologically damaging urea which can be produced domestically. This is particularly useful given the supply chain collapse caused by the Iran war, and how much fertiliser currently comes from the Middle East.
‘It is strange to say, but it has the added benefit of being true – our pee is an underutilised resource,’ said Dr. Siddharth Gadkari, Lecturer in Chemical Process Engineering at the University of Surrey and lead author of the study. ‘Even though it contains the key nutrients we need for agriculture, we currently treat it as waste. Our research shows that with the right treatment approach, we can recover these nutrients efficiently while reducing the energy demands of wastewater treatment.’
Meanwhile, a separate group of experts working on an unrelated project have found evidence that urea — a colourless, odourless compound produced by the liver to convert ammonia into a soluble form for excretion in urine — can lead to extreme water quality loss in the Canadian Prairies. The substance is widely used in fertilisers worldwide.
Led by researchers at the University of Manitoba, Canada, and the University of Regina, Italy, the scientists added urea to farm ponds in a bid to simulate the impact of agricultural fertilisation. Algae growth increased by 10 fold compared to other damaged ecosystems not exposed to urea. The presence of these excess microscopic plants led to rapid draining of essential oxygen from water, triggering a sharp rise in species die-off. Agricultural areas of China, the US, and many other countries are therefore vulnerable to this because of the fertiliser they use, particularly in places where natural wetlands, which would act filter and stop farmland runoff from entering rivers and lakes, are being or have been drained.
‘Our findings help explain why surface waters around the world are experiencing rapid oxygen loss that kills fish, increases toxin exposure, and intensifies harmful algal blooms, pushing freshwaters to an ecological tipping point,’ said Dr. Cale Gushulak, lead author of the research paper and an assistant professor at the University of Manitoba.
‘Two-thirds of the world’s population is supported by urea and other nitrogen fertilizers—so we cannot, and should not, stop its use,’ Gushulak added. ‘However, if the fertilizer is lost from the soils, and ends up degrading surface water, then everyone loses.’
Image: Boudewijn Huysmans / Unsplash
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