Phosphorus removal by an 'active' slag filter-a decade of full scale experience

Andy N. Shilton*, Ibrahim Elmetri, Aleksandra Drizo, Steven Pratt, Richard G. Haverkamp, Stuart C. Bilby

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

157 Citations (Scopus)


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 mg l-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.

Original languageEnglish
Pages (from-to)113-118
Number of pages6
JournalWater Research
Issue number1
Publication statusPublished - 2006


  • Active filter
  • Phosphorus
  • Ponds
  • Slag

ASJC Scopus subject areas

  • Earth-Surface Processes


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