| Summary: | 碩士 === 國立交通大學 === 環境工程系所 === 101 === The objective of present research was to evaluate a cost-effective approach on the recovery of phosphorus through struvite crystallization. Central composite design of response surface methodology (CCD-RSM) was employed to investigate the effects of Mg/Ca molar ratio, aeration index and struvite seed crystal concentration on the performance of struvite crystallization with synthetic wastewater. The results show that the PO43--P recovery efficiency and the kinetic rate constant both increased with all the three factors (Mg/Ca molar ratio, aeration index and struvite seed crystal). The Ca recovery efficiency reduced and struvite purity increase with increase in Mg/Ca molar ratio and the struvite seed crystal concentration. Although the aeration in solution had positive effect on struvite formation, but excessive aeration would cause Ca recovery efficiency to increase and make the percentage of struvite decrease in production. The maximum PO43--P recovery efficiency and the minimum Ca recovery efficiency was achieved at optimized conditions with Mg/Ca molar ratio of 2.3, aeration index of 4.77. Seed crystal concentration of 475 mg/l is enough to improve struvite purity of precipitation and shorten the crystallization time. Partial precipitated product can be reused as new seed for MAP crystallization.
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