Evaluation of industrial by-products and natural minerals for phosphate adsorption from subsurface drainage. Issue 6 (8th March 2019)

• Record Type: Journal Article
• Authors: Sellner, Bjorn M.; Hua, Guanghui; Ahiablame, Laurent M.; Trooien, Todd P.; Hay, Christopher H.; Kjaersgaard, Jeppe
• Is Part Of: Environmental technology. Volume 40:Issue 6(2019)
• Page Start: 756
• Page End: 767
• Publication Date: 2019-03-08
• Subjects: Phosphate -- adsorption -- steel by-products -- natural minerals -- subsurface drainage; Environmental engineering -- Periodicals; Environmental protection -- Periodicals; 628.05
• DOI: 10.1080/09593330.2017.1407364
• Languages: English
• ISSNs: 0959-3330

Abstract

ABSTRACT: Agricultural subsurface drainage has been recognized as an important pathway for phosphorus transport from soils to surface waters. Reactive permeable filters are a promising technology to remove phosphate from subsurface drainage. Three natural minerals (limestone, zeolite, and calcite) and five industrial by-products (steel slag, iron filings, and three recycled steel by-products) were evaluated for phosphate removal from subsurface drainage using batch adsorption experiments. Phosphate adsorption onto these materials was characterized by Langmuir isotherm and second-order kinetic models. The adsorption capacities increased by factors of 1.2–2.5 when temperature was increased from 5°C to 30°C. Industrial by-products exhibited phosphate adsorption capacities that were one order of magnitude higher than natural minerals. Medium-sized steel chips exhibited high phosphate adsorption capacities (1.64–3.38 mg/g) across different temperatures, pH values, organic matter concentrations, and real drainage water matrixes. The strong chemical bonds between phosphate and steel by-products prevented the release of adsorbed phosphate back to the solution. The steel by-product filter can be paired with a woodchip bioreactor for nitrate and phosphate removal. It is suggested that the phosphate filter be connected to a woodchip bioreactor after the startup phase to minimize the impact of dissolved organic matter on phosphate adsorption. The results of this study suggest that the low-cost steel by-products examined could be used as effective adsorption media for phosphate removal from subsurface drainage.