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Effect of Livestock Slurry Ozonation and Separation on pH, Particles, and Phosphate
Author(s) -
Pedersen Christina Ø.,
Hjorth Maibritt,
Hutchings Nicholas J.
Publication year - 2014
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2013.06.0247
Subject(s) - slurry , phosphate , livestock , chemistry , separation (statistics) , environmental chemistry , environmental science , pulp and paper industry , environmental engineering , engineering , organic chemistry , mathematics , ecology , biology , statistics
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 (PO 4 ) concentrations were measured. For separations without ozonation, pH increased by 0.15 to 0.87 pH units, and correlation analysis showed that the dissolved PO 4 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 PO 4 separation, and at the highest ozone dose, dissolved PO 4 separation efficiency increased by 7 to 81%. An ozonation pretreatment may therefore promote removal of dissolved PO 4 from the liquid fraction during separation.