Researchers from the University of Wollongong in Australia have designed a system that captures phosphorus from sewage waste, reports Chemical & Engineering News.
Scientists predict that over the next few decades phosphorus will become more and more scarce as the demand for agricultural fertilizer depletes geological reserves. Meanwhile, phosphorus-laced runoff from farms and other wastewater that finds its way into waterways is harmful for fish. The research could help with both problems, the publication reports.
The process described by Ming Xie, Long D. Nghiem, William E. Price and Menachem Elimelech uses a combined osmosis-distillation process to deliver clean water. Traditional methods for extracting phosphorus from wastewater involve pumping chemicals into the wastewater in an effort to pull out a mineral called struvite that contains phosphorus. However, the amount of chemicals needed to pull out agriculturally usable amounts of struvite often make the recovery process economically unviable.
To bring down the cost, the researchers adapted a process they recently designed for extracting freshwater from wastewater. The new process reduces the amount of chemicals needed for struvite extraction. The system has two parts that work in tandem: one to extract struvite, the other to extract freshwater.
The forward osmosis method requires 2.4 g of struvite per liter of incoming wastewater. It requires less than one-sixtieth of the MgCl2 and one-fifteenth of the NaOH compared to the traditional methods, Chemical & Engineering News says.
In November, Siemens Water Technologies made its magnetite ballasted CoMag System, which was already helping municipalities to increase water and wastewater treatment plant clarification, available for industrial water and wastewater treatment applications.
The CoMag System removes contaminants by reducing total phosphorus, total suspended solids, turbidity, color, pathogens and metals far below conventional treatment, the company says. The system enables designers and plant operators with space constraints to economically expand treatment capacity and limit the footprint of planned facilities.