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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 #430727

Research Project: Biochar Removal of Emerging Contaminants from Wastewater Effluent Irrigation Water

Location: Water Management and Conservation Research

Project Number: 2020-13000-004-02-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Aug 15, 2017
End Date: Aug 14, 2019

Objective:
Optimize a low input treatment system to remove emerging contaminants from reclaimed wastewater using biochar.

Approach:
Emerging contaminants (ECs) include pharmaceuticals, hormones, personal care products and industrial byproducts that can interfere with metabolic functions. Conventional wastewater treatment does not fully remove ECs and thus their presence is a concern when effluents are used for irrigation of crops. Municipal wastewater effluents are increasingly viewed as a potential supply source in water resources planning and thus effluent quality is a critical determinant of the potential uses of reclaimed wastewater. Effluent quality standards are particularly high when effluents are used for irrigation of fruits and vegetables for direct human consumption. Micro-irrigation systems often apply water directly onto the edible portion of the crop and thus removal of ECs from effluents used in such systems is essential for protecting human health. Biochars are products formed from pyrolysis of biomass materials that have been shown to be low-cost highly effective sorbents for a variety of organic pollutants. This project will evaluate the use of biochar for removing ECs from effluents prior to their use in micro-irrigation. Two major research phases are involved. The first phase involves selection of biochar material with high sorption potential for selected ECs. Because pyrolysis alters important adsorption related properties of the biochar (porosity, surface area, crystallinity, surface functional groups), several candidate biochar materials will be compared for their EC-sorbing properties. Batch experiments will be conducted to develop adsorption isotherms and evaluate reaction kinetics. Following selection of suitable biochar materials, the second research phase will involve experiments conducted to determine how these biochars can be added to existing off-the-shelf micro-irrigation sand filtration systems. Key experimental parameters are anticipated to include biochar size, porosity, and blending ratio. Of overriding importance will be selecting biochar materials that result in substantial EC removal during the filter residence time without significant increase in pumping cost due to increased head loss.