An optimized CaO2-functionalized alginate bead for simultaneous and efficient removal of phosphorous and harmful cyanobacteria
2022
Chen, Zhihao | Chen, Meiqing | Koh, Kok Yuen | Neo, Wenyang | Ong, Choon Nam | Chen, J Paul
Simultaneous removal of phosphorus (P) and algae is important to mitigate eutrophication, however, it is rather challenging in remediation of harmful algal blooms (HABs)-contaminated water. In this study, a wet alginate bead functionalized by CaO₂ particle formed layer by layer was prepared with an in-situ method and optimized to remove phosphorous and inhibit algae growth. The stable H₂O₂ release with a concentration level of 0.06 mM was observed for a period of 26 d. The content of peroxy groups (-O-O-) in the optimal bead was 0.44 mmol·g⁻¹ through permanganate-based titration study. For solution with an initial phosphorous concentration of 10 mg·L⁻¹, the removal was around 97% in pH 3.0–10.0. XRD, SEM, and XPS studies and kinetic modelings showed that removal of phosphorus was mainly due to formation of insoluble Ca-P compounds in the bead. The CaO₂-functionalized bead inhibited algae growth with an effect lasting over 170 d, which was much better than liquid H₂O₂ and Ca(OH)₂ bead; the phosphorous removal with an efficiency of about 70% was simultaneously obtained. Furthermore, the bead demonstrated to be effective in removing algae in the realistic water from a reservoir. In summary, this study shows that the CaO₂-functionalized material is promising for simultaneous removal of phosphorous and management of HABs.
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