CHAMPAIGN-URBANA, Ill. (WCIA) — Researchers at the University of Illinois have developed a cost-effective water treatment system to address agricultural runoff pollution. The innovative system combines woodchip bioreactors with a two-step biochar water-treatment module.
Certain nutrients that wash into water from agricultural fields have been shown to pollute that water and fuel harmful algal blooms. The new treatment system aims to reduce these pollutants before they enter rivers and lakes.
“Dissolved phosphorus is a major concern in farm drainage water,” said Wei Zheng, a principal research scientist in environmental chemistry at the Illinois Sustainable Technology Center (ISTC). “Like nitrogen, phosphorus promotes algal blooms in rivers or lakes that can produce toxins, block sunlight and deprive aquatic organisms of oxygen.”
The team tested their system with a one-year field trial. After analyzing the results, they found that the woodchip bioreactor reduced nitrate-nitrogen loads in farm runoff by 58%, and ammonium-nitrogen loads by 72%. The second stage of the system, a biochar-sorption channel, reduced the concentrations of dissolved phosphorus by 3-92% and total phosphorus by 20-92%, depending on seasonal flow conditions.
The system had removal costs of $90.30 per kilogram of nitrate-nitrogen removed per year and $63.90 per kilogram of dissolved reactive phosphorus removed per year. A bigger site would also lower the costs, the researchers said.
The researchers added that the used biochar would be loaded with phosphorus, and could later be reused as fertilizer to improve soil health. Zheng led the study with ISTC postdoctoral researcher Hongxu Zhou. The research was published in the Journal of Water Process Engineering.
According to WCIA.