Oregon wastewater tech taps irrigation and fertilisation

The three-year project arose from the desire to reduce the amount of chemical fertiliser and freshwater used in farming. With food systems becoming more stretched on both the supply and demand side, alternative methods of agriculture – particularly irrigation – will be increasingly needed.  

“Agricultural activity accounts for 70 per cent of all available freshwater,” said project lead Xue Jin, assistant professor of environmental engineering at Oregon. “Worldwide, demand for food production continues to grow along with the population. As droughts become more frequent and severe, there is a critical need for effective treatment technologies that provide safe reclaimed water for agricultural irrigation.”

Supported by $750,000 from the US Department of Agriculture, the Oregon team developed a two-stage, hybrid membrane filtration technology compatible with the discharge produced by anaerobic digesters. In the first stage, an electrically charged membrane attracts ions including ammonium, phosphorus and potassium and concentrates them into a fertiliser-rich brine. In the second stage, a forward-osmosis membrane removes contaminants such as bacteria, and the bacteria-free water is then recombined with the brine to produce a nutrient-enhanced solution that can be used on crops.