(503b) Improved Phosphorus Precipitation from Wastewater Using Pulsed Potential Waveform Approach

Water recycling is a part of agricultural water resource management as a result of the growing world population and the anticipated intensification of climatic variability and fluctuations in dependable water supplies. Furthermore, valuable nutrients like phosphorus that could be recovered and reused to produce food (as agricultural fertilizer) are lost to wastewaters. Struvite has demonstrated potential as a substitute supply of phosphorus for fertilizer in agriculture. Studies conducted on row crops indicate that struvite (MgNH4PO4.6H2O) is a feasible fertilizer compound when compared to conventional fertilizers. Using an alkaline electrochemical reactor with a magnesium alloy anode and a stainless steel cathode for reducing water to hydrogen gas and hydroxide, our research aims to recover struvite from wastewater. The magnesium electrode that is used to produce magnesium cations in solution and precipitate struvite becomes seriously contaminated over time with subsequent reactor batches. This raises energy requirements and lowers fertilizer recovery for struvite. This research makes use of a dynamic, pulsed voltage waveform at the magnesium electrode surface producing a stress-strain-like effect that prevents or reduces the quantity of struvite precipitate that would adhere to the electrode. When compared to a constant voltage approach, an aqueous solution of ammonium dihydrogen phosphate (NH4H2PO4, 10 mM) at a neutral pH showed a 60% increase in divalent magnesium cations and a 40% increase in phosphate recovery as struvite.