title: Nutrient and trace-metal removal by Bauxsol pellets in wastewater treatment.
abstract: In this study, Bauxsol pellets packed in PVC columns were used to remove nutrients and trace-metals from municipal wastewater during a 6 months field trial. Bauxsol pellet columns showed a high phosphate removal rate via precipitation of PO(4)(3-) with Ca(2+) and Mg(2+) ions: at 90% in the 1st month; at 80% from the second to fifth months; and at 60% in the sixth month. Pellet bound total phosphorus and Colwell phosphorus were 7.3 g/kg and 2 g/kg and are about 20 times the concentrations found in most fertile soils. Trace-metals in effluents were bound, probably irreversibly under the columns' environmental conditions, to the Bauxsol minerals that have high surface area to volume ratios and high charge to mass ratios. Experimental results showed a complex nitrogen cycle operating within the Bauxsol pellet columns including anoxic nitrification, denitrification, and anammox processes. Although a transient pH spike, associated with the release of unreacted CaO from the cement binder used in the pellets, was observed, this may be readily corrected through post-treatment pH adjustment. Hence, the geochemistry of Bauxsol pellets can effectively remove and bind nutrients and trace-metals during wastewater treatment, and further research may show that saturated spent pellets can be used as fertilizer.
authors.affiliation: School of Environmental Science and Management, Southern Cross University, PO Box 157, Lismore, New South Wales 2480, Australia.
authors.forename: Laure M
authors.initials: LM
authors.lastname: Despland
authors.forename: Malcolm W
authors.initials: MW
authors.lastname: Clark
authors.forename: Tony
authors.initials: T
authors.lastname: Vancov
authors.forename: Dirk
authors.initials: D
authors.lastname: Erler
authors.forename: Michel
authors.initials: M
authors.lastname: Aragno
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry*; D004553:Electric Conductivity; D006863:Hydrogen-Ion Concentration; D019216:Metals, Heavy / Q000032:analysis / Q000737:chemistry*; D009584:Nitrogen / Q000032:analysis / Q000737:chemistry*; D010710:Phosphates / Q000032:analysis / Q000737:chemistry*; D013696:Temperature; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D019216:Metals, Heavy; D010710:Phosphates; D014874:Water Pollutants, Chemical; D000537:Aluminum Oxide; D009584:Nitrogen