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This article in JEQ

  1. Vol. 43 No. 3, p. 1043-1049
     
    Received: June 24, 2013
    Published: June 24, 2014


    * Corresponding author(s): Christina.Osterballe@eng.au.dk
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doi:10.2134/jeq2013.06.0247

Effect of Livestock Slurry Ozonation and Separation on pH, Particles, and Phosphate

  1. Christina Ø. Pedersen *a,
  2. Maibritt Hjortha and
  3. Nicholas J. Hutchingsb
  1. a Dep. of Engineering, Aarhus Univ., Blichers Allé 20, Postbox 50, 8830 Tjele, Denmark
    b Dep. of Agroecology, Aarhus Univ., Blichers Allé 20, Postbox 50, 8830 Tjele Denmark

Abstract

Applying slurry to arable land as fertilizer increases the risk of phosphorus (P) runoff and thereby increases the risk of eutrophication. Solid–liquid separation can reduce the excess application of P, and this study focused on the use of ozonation as an alternative chemical pretreatment for separation to improve P separation efficiency. Sow and cattle slurries were separated by screw press and flocculation+filtration. The screw press and flocculation liquid fractions and raw slurries were treated with no ozone or with low-, medium-, or high-ozone doses and then separated by centrifugation. The pH, particle size distribution, dry matter, and dissolved phosphate (PO4) concentrations were measured. For separations without ozonation, pH increased by 0.15 to 0.87 pH units, and correlation analysis showed that the dissolved PO4 concentration decreased with increasing pH and particle removal efficiency. During ozonation, pH increased, and a shift in particle size distribution in the liquid fraction combined with an improved dry matter separation indicated particle aggregation. Ozonation thus affected the parameters found to affect dissolved PO4 separation, and at the highest ozone dose, dissolved PO4 separation efficiency increased by 7 to 81%. An ozonation pretreatment may therefore promote removal of dissolved PO4 from the liquid fraction during separation.

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