Integrating UV/persulfate and deficit irrigation of recycled water: Strategy to minimize crop accumulation of trace organic contaminants and enhance crop yield

Abstract

This study investigated the combination of UV persulfate (UV/PS) treatment of recycled water and deficit irrigation to minimize pharmaceutical and personal care products (PPCPs) accumulation and improve crop quality. Lettuce, carrot, and tomato, commonly consumed raw, were cultivated in a greenhouse using PPCPs spiked recycled water, UV/PS treated recycled water, and tap water control, under irrigation rates at 60 %, 80 % and 100 % of crop evapotranspiration (ETC) rates. UV/PS removed ≥ 99 % of carbamazepine, diclofenac, and fluoxetine from spiked recycled water. Post-treatment, carbamazepine accumulation in harvested lettuce, carrot, and tomato was reduced by 96–99 %, 35–70 % and 72–93 %, respectively. Minimal accumulation of diclofenac and fluoxetine occurred in edible crops due to their existence as dissociated ions. Three edible crops exhibited distinct trends of PPCPs accumulation in response to irrigation rates. Lettuce exhibited a decreasing PPCPs accumulation with a reduced irrigation rate, which was attributed to slower transpiration. In contrast, carrot and tomato exhibited increased PPCP accumulation due to osmotic adjustment. Lettuce and carrot exhibited higher irrigation water utilization efficiency at deficit irrigation, while the opposite was observed for tomato. This study highlights the beneficial integration of UV/PS with deficit irrigation to conserve water, maintain crop yield, and minimize PPCPs accumulation.