Wastewater irrigation beneath the water table: analytical model of crop contamination risks

Darrell W.S. Tang, Ruud P. Bartholomeus and Coen J. Ritsema

Agricultural Water Management, 2024, vol. 298, issue C

Abstract: Wastewater irrigation alleviates freshwater scarcity. However, conventional (near)surface irrigation techniques directly expose crops to contaminants. Irrigating wastewater into shallow phreatic zones to raise the water table enhances groundwater evapotranspiration, while using the vadose zone as a bioreactor that attenuates contaminants through dilution, adsorption, and biodegradation. Nevertheless, contaminants may spread across the groundwater, soil, and vegetation. In this study, we focus on the crop contamination risks, and derive a simple analytical model to estimate crop solute uptake. Although crops are not directly exposed to the irrigated wastewater, contaminants (and nutrients) may spread to the root zone. Results show that crop contamination is primarily determined by the root zone water balance, and by solute dispersion and biogeochemical reaction parameters. The model contributes towards identifying hydrogeologically and climatically suitable locations for phreatic zone wastewater irrigation, determining acceptable levels of irrigation water quality, and evaluating crop contamination hazards against the fertigative value of wastewater.

Keywords: Phreatic zone wastewater irrigation; Groundwater aquifer management; In-situ bioremediation and attenuation in soils; Root zone water balance; Analytical model; Crop and soil contamination (search for similar items in EconPapers)
Date: 2024
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Citations: View citations in EconPapers (1)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:agiwat:v:298:y:2024:i:c:s0378377424001835

DOI: 10.1016/j.agwat.2024.108848

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