The suspension pH was measured usin

The suspension pH was measured using PHS-3C type
pH meter (Shanghai Hongyi Co. Ltd., China). The NH4
+
-NandPO4
3−
-P concentrations were analyzed according to
the Standard Methods (APHA, 1995). A definite amount
of 0.1500 g drying precipitate harvested from tests was
weighed accurately and dissolved completely in 500 ml
1+19 (V+V) hydrochloric acid (i.e., its concentration
was about 0.6 mol/L), respectively. Total P and metals
including K, Na, Ca, Ni, Mn, and Mg of the harvested
precipitate solutions were analyzed by ICP (OES Optima
5300DV, America PE, USA), and total N by TNM-1 (TOC-VCPN TN unit, Shimadzu, Japan). The minerals in the
precipitates were identified by X-ray Diffraction (XRD,
D/max-Rb, Japan).