科研之友
微信
新浪微博
Facebook
分享链接
摘要
Removal of excess P from pig manure can be accomplished by the precipitation reaction to form struvite (MgNH4PO4 center dot 6 H2O). However, recovery is limited by the concentration of dissolved phosphorus, in form PO4-P, as it is typically only about 10% of total phosphate in liquid pig manure. To increase P recovery, manure can be stored anaerobically to increase acidity, which has been to shown to produce higher concentrations of PO4-P.. However, manures from different farms can vary markedly in chemical properties and this technique may not be effective in all cases. This experiment investigated chemical changes from anaerobic fermentation of manures collected from several commercial pig operations in Manitoba. Fresh manures were placed in triplicate stirred anaerobic digesters and monitored daily for pH and analyzed for total solids, volatile solids (VS), alkalinity, volatile fatty acids (VFA), dissolved and total nutrients (P, Mg, and Ca) on days 0, 4, 8, and 12. Under identical storage conditions, manures displayed different pH and PO4-P responses, varying from almost no response to a significant drop in pH with corresponding increase in dissolved PO4-P and Mg. Manure pH and PO4-P concentration were negatively correlated in all manures (-0.63 to -0.98). Through comparison with these and other manures, a relationship was found between manure alkalinity buffering and the acid forming effects of VS, expressed as mg/L of total alkalinity to g/L VS. Manures with low alkalinity/VS ratios became acidic during anaerobic fermentation and consequently increased in PO4-P concentration. Both VS and alkalinity are easily performed analyses and the ratio could be used to predict the suitability of a manure to release PO4-P during anaerobic storage, which increases the total recoverable P by struvite precipitation.
- 出版日期2016
