The Fate of Emerging Contaminants in Reclaimed Wastewater Used for Irrigation of Agricultural Crops in Nevada
Environmental Sciences and Health
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Increased demands on water supplies, especially from agriculture in response to an ever-increasing demand for food, have increased the need to use wastewater treatment plant (WWTP) effluent. However, oftentimes, treated effluent contains emerging environmental pollutants including pharmaceuticals and personal care products. The fate of these pollutants is of great interest due to their persistence in the environment and accumulation in plants, and as a result, may pose a human health risk. This study aimed to assess the plant uptake of compounds found in the Truckee Meadows Water Reclamation Facility (TMWRF) in greenhouse and field environments. This study also assessed if biochar could be used as a soil amendment to reduce the leaching and plant uptake of compounds due to its sorption properties. In a greenhouse environment, the plant productivity and compound uptake of alfalfa and green wheatgrass were tested by irrigating plants with tap water, tap water spiked with specific compounds and treated wastewater. In addition, biochar was used as a soil amendment in half of the pots. In a field study, crops and lysimeters were tested for their uptake of compounds when grown with various biochar and nitrogen treatments. Water source treatments did not affect plant uptake of compounds in most cases. In the cases where water source had an effect, surprisingly, plants grown in tap water showed the highest uptake despite compound concentrations generally being the lowest among treatments. Soils show increased compound retention when irrigated with water spiked with higher compound concentrations, but this did not lead to greater plant uptake. Biochar was somewhat effective at increasing plant productivity, possibly due to enhanced moisture retention, but had mixed results in soil and plant compound uptake. Soil solution chemistry of soil water collected in the lysimeters was not affected by the presence of biochar in the field study. DEET was the most prevalent compound in all samples analyzed, possibly from soil being previously exposed to farmworkers. Overall, most compounds translocate through water-soil-plant systems, but reclaimed wastewater did not pose a greater threat than other types of water and compound uptake in plants was well below provided health guidelines.