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PO4 3− Removal by and Permeability of Industrial Byproducts and Minerals: Granulated Blast Furnace Slag, Cement Kiln Dust, Coconut Shell Activated Carbon, Silica Sand, and Zeolite

Agrawal, Sheela G., King, Kevin W., Fischer, Eric N., Woner, Dedra N.
Water, air, and soil pollution 2011 v.219 no.1-4 pp. 91
activated carbon, cement, coconuts, furnaces, industrial byproducts, kilns, permeability, phosphates, sand, saturated hydraulic conductivity, silica, slags, sorption isotherms, subsurface flow, surface quality, surface water, water quality, water treatment, zeolites
Excess PO4 3− from agricultural subsurface drainage and runoff degrades the overall water quality of the receiving surface waters in a cumulatively damaging process known as eutrophication. In the past 25 years, PO4 3− removal by industrial byproducts and minerals has received considerable attention because these materials are both abundant and inexpensive. In this study, the saturated falling-head hydraulic conductivity and phosphate removal capability of granulated blast furnace slag (GBFS), cement kiln dust (CKD), zeolite, silica sand, and coconut shell activated carbon (CS-AC) were assessed. GBFS, zeolite, silica sand, CS-AC, and 5:95% and 10:90% CKD/sand blends all exhibited hydraulic conductivities ≥0.001 cm/s. GBFS and the CKD/sand blends exhibited >98% PO4 3− removal while CS-AC removed 70–79% of initial PO4 3− concentrations. In contrast, silica sand and zeolite removed 21–58% of PO4 3−. The phosphate removal data for each material was modeled against the Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, and Frumkin sorption isotherms to yield insight into possible removal mechanisms. Overall, GBFS, CKD, zeolite, silica sand, and CS-AC were sufficiently permeable and removed significant amounts of PO4 3− and should be considered for use in treatment of agricultural effluent.