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Journal of Environmental Quality Abstract - Waste Management

Precipitation of Liquid Swine Manure Phosphates Using Magnesium Smelting By-Products


This article in JEQ

  1. Vol. 36 No. 2, p. 557-567
    Received: May 2, 2006

    * Corresponding author(s): parentg@agr.gc.ca
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  1. Gaétan Parent *a,
  2. Gilles Bélangera,
  3. Noura Ziadia,
  4. Jean-Pierre Delandb and
  5. Jean Laperrièreb
  1. a Agriculture and Agri-Food Canada, Soils and Crops Research and Development Centre, 2560 Hochelaga Blvd., Quebec, QC, Canada G1V 2J3
    b Norsk Hydro Canada Inc., 7000 Raoul-Duchesne Blvd., Bécancour, QC, Canada G9H 2V3


Swine manure contains considerable amounts of total (P) and soluble phosphorus (PO4–P) which may increase the soil P content when applied in excess to crop requirements and, consequently, risk water eutrophication. The feasibility of using magnesium (Mg) from the by-product of electrolysis and foundries (BPEF) for the removal of P from liquid swine manure was studied by adding up to 3 g of Mg as BPEF per liter of nursery (NU) and grower-finisher (GF) swine manure in 25-L plastic buckets. Changes in P and other elements were monitored for up to 360 h. Small amounts of Mg as BPEF (0.5 and 1.0 g Mg L−1 manure) reduced the total P concentration of the liquid fraction by 70 to 95% of both manure types with respect to the control treatment of mixed raw manure. A settling period of 8 h or more was necessary to significantly reduce the liquid fraction's total P concentration for both manure types. Reduction of PO4–P varied from 96 to 100% in the liquid fractions for both manure types, which along with natural settling, explains most of the total P reduction in that fraction. The addition of BPEF did not influence the N content of manure. The low P liquid fraction can be safely applied to saturated P soils whereas the high P solid fraction offers the opportunity of transporting manure to agricultural soils deficient in P. Since N is conserved, both liquid and solid fractions could be valuable fertilizer manure by-products.

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