ABATING THE EFFECTS OF CALCIUM ON STRUVITE PRECIPITATION IN LIQUID DAIRY MANURE

作者：Shen Y; Ogejo J A^*; Bowers K E

来源：Transactions of the ASABE, 2011, 54(1): 325-336.

• Calcium inhibition
• Dairy manure
• EDTA
• Magnesium ammonium phosphate
• Oxalate
• Phosphorus recovery from manure
• Struvite precipitation

Phosphorus (P) can be recovered as struvite from liquid dairy manure as a way to recycle and reuse P One of the factors that can inhibit struvite precipitation is the calcium (Ca) concentration in dairy manure. This study used modeling and laboratory experiments to investigate acidification and addition of Ca sequestering compounds (ethylenediaminetetraacetic acid and oxalic acid) as means of enhancing the precipitation and recovery of struvite from dairy manure. The Visual MINTEQ model was used to determine the desirable pH of manure at which all the particulate inorganic phosphates are released into solution and predict the quantities of struvite and other minerals that can be formed. The model results were validated experimentally using synthetic liquid and dairy manure. Both the model and experimental results showed that struvite can be precipitated from dairy manure with a high calcium-to-magnesium molar ratio (Ca:Mg) of 1.46 by acidifying manure to pH 4.5, adding EDTA or oxalic acid, and then raising the pH to 7.5. Adding magnesium to lower the Ca:Mg ratio was not effective in struvite precipitation. In addition, reducing the total suspended solids concentrations supported better struvite precipitation.

• 出版日期2011-2