Utilizing acid mine drainage sludge and coal fly ash for phosphate removal from dairy wastewater

Y. R. Wang, Daniel C.W. Tsang, William E. Olds, Paul A. Weber

Research output: Journal article publicationJournal articleAcademic researchpeer-review

28 Citations (Scopus)


This study aims to investigate a new and sustainable approach for the reuse of industrial by-products from wastewater treatment. The dairy industry produces huge volumes of wastewater, characterized by high levels of phosphate that can result in eutrophication and degradation of aquatic ecosystems. This study evaluated the application of acid mine drainage (AMD) sludge, coal fly ash, and lignite as low-cost adsorbents for the removal of phosphate from dairy wastewater. Material characterization using X-ray fluorescence, X-ray diffraction, and Brunauer-Emmett-Teller surface area analysis revealed significant amounts of crystalline/amorphous Fe/Al/Si/Ca-based minerals and large surface areas of AMD sludge and fly ash. Batch adsorption isotherms were best described using the Freundlich model. The Freundlich distribution coefficients were 13.7 mg0.577L0.423g-1and 16.9 mg0.478L0.522g-1for AMD sludge and fly ash, respectively, and the nonlinearity constants suggested favourable adsorption for column applications. The breakthrough curves of fixed-bed columns, containing greater than 10 wt% of the waste materials (individual or composite blends) mixed with sand, indicated that phosphate breakthrough did not occur within 100 pore volumes while the cumulative removal was 522 and 490 mg kg-1at 10 wt% AMD sludge and 10 wt% fly ash, respectively. By contrast, lignite exhibited negligible phosphate adsorption, possibly due to small amounts of inorganic minerals suitable for phosphate complexation and limited surface area. The results suggest that both AMD sludge and fly ash were potentially effective adsorbents if employed individually at a ratio of 10 wt% or above for column application.
Original languageEnglish
Pages (from-to)3177-3182
Number of pages6
JournalEnvironmental Technology (United Kingdom)
Issue number24
Publication statusPublished - 1 Dec 2013


  • Acid mine drainage sludge
  • Coal fly ash
  • Lignite
  • Phosphate adsorption
  • Waste recycling

ASJC Scopus subject areas

  • Environmental Chemistry
  • Water Science and Technology
  • Waste Management and Disposal


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