title: Phosphorus removal by an 'active' slag filter-a decade of full scale experience.
abstract: Active filters, which facilitate phosphorus (P) removal via precipitation and/or adsorption, offer a promising 'appropriate technology' for upgrading small wastewater treatment systems. Research on active filters for P removal using steel slag material has been conducted in laboratories across the world, however, field experiments have been limited and long-term data is practically non-existent. This paper presents a decade of experience on P removal by active slag filters at a full-scale treatment plant. During 1993-1994 the filter removed 77% of the total phosphorus (TP), and over the first 5 years of the filter's operation it reduced the mean effluent TP concentration to 2.3 mgl(-1). However during the sixth year of operation P removal was significantly reduced. Over the 11 years of monitoring, 22.4 tonnes of TP was removed by the filter, 19.7 tonnes of this in the first 5-year period. It was determined that the slag material maintained its maximum removal potential until reaching a P-retention ratio of 1.23 kg TP per tonne of slag. This paper provides the first long-term field data for slag filters, and shows that they can provide P removal for a half a decade before filter replacement/rejuvenation is required.
authors.affiliation: Centre for Environmental Technology and Engineering, Massey University, Private Bag 11 222, Palmerston North, New Zealand. a.n.shilton@massey.ac.nz
authors.forename: Andy N
authors.initials: AN
authors.lastname: Shilton
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Elmetri
authors.forename: Alexsandra
authors.initials: A
authors.lastname: Drizo
authors.forename: Steven
authors.initials: S
authors.lastname: Pratt
authors.forename: Richard G
authors.initials: RG
authors.lastname: Haverkamp
authors.forename: Stuart C
authors.initials: SC
authors.lastname: Bilby
mesh_terms: D000327:Adsorption; D011232:Chemical Precipitation; D005374:Filtration; D007220:Industrial Waste; D010758:Phosphorus / Q000302:isolation & purification*; D013232:Steel; D018508:Water Purification / Q000379:methods*
chemical_list: D007220:Industrial Waste; D013232:Steel; D010758:Phosphorus