Abstract
Excess nutrient input to water bodies frequently results in algal blooms and development of oxygen deficient conditions. Mining or metallurgical by-products can potentially be utilised as filtration media within water treatment systems such as constructed wetlands, permeable reactive barriers, or drain liners. These materials may offer a cost-effective solution for the removal of nutrients and dissolved organic carbon (DOC) from natural waters. This study investigated steel-making, alumina refining (red mud and red sand) and heavy mineral processing by-products, as well as the low-cost mineral-based material calcined magnesia, in laboratory column trials. Influent water and column effluents were analysed for pH and flow rate, alkalinity, nutrient species and DOC, and a range of major cations and anions. In general, by-products with high Ca or Mg, and to a lesser extent those with high Fe content, were well-suited to nutrient and DOC removal from water. Of the individual materials examined, the heavy mineral processing residue neutralised used acid (NUA) exhibited the highest sorption capacity for P, and removed the greatest proportions of all N species and DOC from influent water. In general, NUA and mixtures containing NUA, particularly those with calcined magnesia or red mud/red sand were the most effective in removing nutrients and DOC from influent water. Post-treatment effluents from columns containing NUA and NUA/steel-making by-product, NUA/red sand and NUA/calcined magnesia mixtures exhibited large reductions in DOC, P and N concentrations and exhibited a shift in nutrient ratios away from potential N- and Si-limitation and towards potential P-limitation. If employed as part of a large-scale water treatment scheme, use of these mining and metallurgical by-products for nutrient removal could result in reduced algal biomass and improved water quality. Identification and effective implementation of mining by-products or blends thereof in constructed wetlands or other intervention structures to augment nutrient and DOC retention has considerable potential as an aquatic ecosystem management tool.
Original language | English |
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Pages (from-to) | 2705-2717 |
Journal | Water Research |
Volume | 46 |
Issue number | 8 |
DOIs | |
Publication status | Published - 15 May 2012 |
MoE publication type | A1 Journal article-refereed |
Funding
The authors gratefully acknowledge Iluka Resources Ltd. , HIsmelt Operations Pty Limited and the Western Australian Government for support provided through the Water Foundation and the Department of Water. Mr. Mark Raven, CSIRO Land and Water, Adelaide, is thanked for XRF and XRD analyses and expert interpretation. Appendix
Keywords
- By-product
- Dissolved organic carbon
- Eutrophication
- Nutrient
- Water treatment