This study compared the two novel technologies "calcium phosphate fluidized-bed crystallization (FBC) process" and "adsorption" which used an amorphous iron oxide BT-1 as the adsorbent for treating an industrial wastewater with high concentration of phosphate (1,000 mg P L-1). In the adsorption process, most of phosphorus was adsorbed rapidly initially and then reached the thermodynamics equilibrium in 24 h. The phosphate adsorptive capacity of BT-1 was 2.03 mmole/g when the PO43-equilibrium concentration was conditioned at 8.23 mM. The adsorption process followed the Langmuir and Temkin adsorption isotherm. In the FBC process, the optimum pH range was wider (pH > 5.3) for the total removal of phosphate than that for crystallization (optimum pH = 5.3-5.9). The total removal efficiency and crystallization ratio of phosphate were about 90% and 60%, respectively, in the optimum pH range. The EDS analysis showed that the Ca-P crystal products had an approximate 1:1:6 molar ratio of Ca:P:O. The XRD diagrams confirmed the crystal type of FBC product in a highly phosphate concentrated system was diacalcium phosphate dehydrate (CaHPO4 2H2O, DCPD), which was different from the general calcium phosphate crystal content, hydroxyapatite (Ca5(PO4)3OH, HAP), produced by FBC process.
All Science Journal Classification (ASJC) codes