STUDY ON PHOSPHOROUS RECOVERY BY STRUVITE CRYSTALLIZATION IN EFFLUENT FROM AN ANAEROBIC MEMBRANE BIOREACTOR TREATING SWINE MANURE WASTEWATER

Precipitation similar to struvite was found in the effluent of an anaerobic membrane bioreactor treating swine manure wastewater by spontaneously reaction． The test studied the effect of different initial pH ( 8，9，10) on the precipitate composition and form in order to get struvite worthy of reuse． Results showed that: Phosphorous removal rate was 30. 8%，67. 6% and 87. 7%， respectively with initial pH of 8，9 and 10; struvite crystal with bigger size and better structure was formed during pH raised from 8 to 9; but precipitation formed at initial pH 10 was small，irregular and contained much impurities; besides，struvite was the main component of the precipitation at pH 8 and 9，but lots of calcium precipitation were formed at pH 10． Therefore，the optimal initial pH was 9 in this test for phosphorous recovery as struvite from anaerobically digested swine manure wastewater．