EXPERIMENTAL STUDY OF CHICKEN MANURE FERMENTATION LIQUID TREATMENT BY STRUVITE PRECIPITATION

Struvite precipitation was adopted to treat the chicken manure fermented liquid from a chicken farm in Beijing． Single factor experiments and response surface experiments were designed to obtain ammonia removal． Effect of pH，value of n ( Mg2 + ) ∶ n( PO3 － 4 ) ∶ n( NH + 4 ) ，reaction time and stirring speed on removal ratio of ammonia nitrogen were investigated． The single factor test results showed that when pH = 10. 0 ～ 10. 5，n( Mg2 + ) ∶ n( PO3 － 4 ) ∶ n( NH + 4 ) = 1. 3∶ 1. 1∶ 1，reaction time = 20 min and stirring speed = 300 r /min，the removal ratio of ammonia nitrogen reached 75. 79%． The response surface experiments results showed that when pH = 10. 57，n( Mg2 + ) ∶ n( PO3 － 4 ) ∶ n( NH + 4 ) = 1. 27 ∶ 1. 12 ∶ 1，the removal ratio of ammonia nitrogen was up to 75. 81%． The best response surface experiments refined and validated the reaction conditions． The struvite precipitate under optimal conditions were characterized with SEM and XRD，and it' s main composition is magnesium ammonium phosphate．