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ARS Home » Pacific West Area » Maricopa, Arizona » U.S. Arid Land Agricultural Research Center » Water Management and Conservation Research » Research » Research Project #441621

Research Project: Increased Water Security through Safe Reuse of Reclaimed Water

Location: Water Management and Conservation Research

Project Number: 2020-13000-005-000-D
Project Type: In-House Appropriated

Start Date: Jan 3, 2022
End Date: Jan 2, 2027

The long-term objective of this project is to provide science-based data to ensure that treated municipal wastewater used for irrigation poses minimal threat to people and the environment. Specifically, during the next five years the project will focus on the following objectives. Objective 1: Determine the processes that govern the environmental fate and transport of emerging contaminants and other constituents found in treated wastewater used for irrigation to provide a research basis for potential regulation of these constituents. Sub-objective 1.A: Determine the effect of temperature on the sorption, fate, and transport of pharmaceuticals in soil. Sub-objective 1.B: Determine the effects of long-term wastewater irrigation on soil contaminant concentration and the soil microbiome. Sub-objective 1.C: Optimize removal of pharmaceuticals from water. Objective 2: Develop and optimize low input treatment systems to reduce emerging contaminants and nutrients found in degraded waters to increase water resources used for food production.

Objective 1 will seek to Increase water supplies available for irrigation and managed aquifer recharge through safely reusing treated wastewater. The effect of temperature and season on the environmental fate and transport of contaminants of emerging concern (CEC) found in reclaimed wastewater will be characterized and quantified. Ten different pharmaceuticals that have a range of pKa’s from (4.0 – 16.0) will be evaluated in the lab by batch sorption and column flow through experiments using soils from the Southwest US. Experiments will be conducted at 10° C, 25° C, and 40° C. Pharmaceutical mobility will be evaluated and compared to seasonal soil temperatures to determine seasonal variability in soil transport. A set of paired stormwater recharge basins, one that receives wastewater inputs and one that does not, will be sampled for pharmaceutical analysis. Results from lab experiments and the paired basins will be used to model the potential for stormwater retention basins to contaminate groundwater with pharmaceuticals found in the wastewater used for irrigation. These results will be used to provide management guidance for stormwater retention basins. Finally, biochar pyrolyzed from walnut shells and cotton gin waste will be evaluated as a treatment method for removing pharmaceuticals from wastewater. Biochar pretreatments will include untreated, acid treated, and base treated prior to pyrolysis. Lab scale columns will be constructed and water containing pharmaceuticals will be passed through biochar filter columns. Removal efficiency and capacity will be calculated, and sorption mechanisms elucidated. Objective 2 Will be a modeling exercise to determine the potential for using reclaimed wastewater as a supplemental irrigation source in rainfed agricultural systems. The volume of produced wastewater in regions of the Midwest will be spatially matched to potential crop needs. Crop irrigation needs will be modeled using historical weather data and then spatially matched to wastewater availability. Results will be used to determine potential yield loss related to reduced rainfall due to short term spatial and temporal drought. Yield recovery will be related to available water and distance water needs to be transported.