| Summary: | 碩士 === 朝陽科技大學 === 環境工程與管理系碩士班 === 101 === This objective of this study is to recovery phosphorus concentrate from the public sewage treatment plant. First, use of artificial synthetic wastewater for calcium phosphate metastable zone defined in laboratory trials to assessment. Based on the results of metastable zone study, calcium phosphate crystallization was tarried in the laboratory, to identify optimal conditions of calcium phosphate crystallization, include hydraulic retention time, pH and Ca/P molar ratio. The pilot test for calcium phosphate crystallization evaluate is accordance with laboratory trials results.
Calcium phosphate crystals in the laboratory trials showed that, the PO43--P concentration of 50 mg / L, the pH value of 8.6, Ca / P molar ratio of 1.75 was the best operational conditions, The crystal and removal efficiencies were about 55-60% and 60% respectively. The dewatering filtrate in this condition has the same efficiency. The pilot test for calcium phosphate crystallization showed that, the PO43--P concentration of 25-30 mg/L and, pH 9.0, the average crystal ratio was 52.0%. when the PO43--P concentration increased to 100 mg / L, the average ratio of crystallization and removal were 75.0 and 83.7% respectively. Comparative of PO43-- P 25 and 100 mg/L of the crystalline product base on XRD analysis, the crystals of PO43--P 100 mg/L showed more obvious polymorph. Moreover, the moisture content of crystal pellet was of 6-10%, and the crystal morphology were Ca5(PO4)3(OH) and CaHPO4‧2H2O of compelx calcium phosphate product. ICP analysis shows that only slight Cr、Cu and Zn metal in the crystal pellet.
|
|---|
