Date of Graduation
5-2026
Document Type
Thesis
Degree Name
Bachelor of Science in Biological Engineering
Degree Level
Undergraduate
Department
Biological and Agricultural Engineering
Advisor/Mentor
Dr. Brian Haggard
Committee Member
Dr. Bradley Austin
Second Committee Member
Dr. Yiting Xiao
Abstract
Nonpoint source pollution from agricultural landscapes contributes to freshwater eutrophication, with legacy phosphorus (P) in soils potentially driving soluble reactive phosphorus (SRP) losses to surface waters. The objectives of this study were to evaluate SRP adsorption by dried water treatment residuals (WTRs) produced by Beaver Water District, quantify reductions in soil SRP release across increasing WTR application rates, and compare dried WTR performance to prior WTR studies.
Dried WTRs (~98% solids) were assessed using batch sorption experiments and soil core incubations. Phosphorus sorption was measured by mixing WTRs with CaCl2 solutions containing increasing SRP concentrations and fitting results to a Langmuir isotherm. Soil cores were treated with WTRs at rates of 0, 440, 2200, 4400, or 8800 kg ha⁻¹ and flooded with 1 L of water. Soluble reactive phosphorus (SRP) concentrations in overlying water were measured over 24-hour incubations to calculate SRP release rates, typically using the first 8 hours of data.
Dried WTRs showed a Langmuir-estimated P sorption capacity at 100,000 mg kg⁻¹, which was greater than values reported for fresh or centrifuged WTRs from the same drinking water facility, and on the high end in the literature. Application of dried WTRs to soil cores reduced soil SRP release, where SRP release rates decreased with increasing dried WTR application rates. The greatest reduction occurred at application rates of 2200 kg ha⁻¹ and greater. Dried WTRs effectively adsorbed SRP and reduced soil P release, suggesting that dried WTR application might be an effective management option for legacy P in soils. When compared to prior studies, dried WTRs showed greater phosphorus sorption capacity than most reported WTR materials except liquid WTRs, suggesting strong potential as an improved management option.
Keywords
water treatment residuals; phosphorus sorption; soluble reactive phosphorus; legacy phosphorus; agricultural soils; eutrophication
Citation
McKay, K. B. (2026). Dried Water Treatment Residuals Might be an Option to Reduce Soluble Reactive Phosphorus Release from Soils. Biological and Agricultural Engineering Undergraduate Honors Theses Retrieved from https://scholarworks.uark.edu/baeguht/110
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Biochemistry Commons, Bioresource and Agricultural Engineering Commons, Environmental Engineering Commons, Environmental Microbiology and Microbial Ecology Commons, Other Civil and Environmental Engineering Commons, Water Resources Engineering Commons
