Use of Constructed Wetlands for Saline and Selenium-Contaminated Agricultural Drainage Water

Abstract

By Hannah Leibman, Environmental Engineering

Advisor: Dionysios Dionysiou

Presentation ID: 22

Abstract: The agricultural sector is a major water user in the United States, with irrigation accounting for approximately 42% of all freshwater withdrawals (118 billion gallons per day). It is estimated that 45 billion gallons of excess irrigation water drain off agricultural fields every day in the U.S. In the next 30 years, the human population and food demand will likely rise, further increasing the irrigation water demand. With the increasing demand, high cost of transportation, and dwindling supply, the local reuse of agricultural drainage water can serve as a supplementary source for irrigation. Agricultural drainage water often contains nitrates, phosphates, salts, and other soluble chemicals and have been associated with surface water eutrophication and increased salinity in surface and groundwater. However, particularly in the 17 western states, the elevated levels of salts and toxic constituents (i.e., selenium and boron) present in agricultural drainage water have restricted its direct reuse for irrigation and require treatment. Constructed wetlands have been shown to offer an alternative method to remove contaminants from agricultural drainage water. This natural treatment uses a combination of adsorption, bio assimilation, and microbial methods to remove constituents from agricultural drainage water. To optimize this technology for the removal of salts and selenium, different plants, hydraulic effects, and microorganism interactions have been studied. This research highlights the key design and operational considerations as well as future research needs for the optimization of constructed wetlands for treatment of saline and selenium-laden agricultural drainage water.