An optimized CaO2-functionalized alginate bead for simultaneous and efficient removal of phosphorous and harmful cyanobacteria

• Published in: The Science of the total environment 2022-02, Vol.806, p.150382-150382, Article 150382
• Main Authors: Chen, Zhihao, Chen, Meiqing, Koh, Kok Yuen, Neo, Wenyang, Ong, Choon Nam, Chen, J. Paul
• Format: Article
• Language: English
• Subjects: Harmful algal blooms; Hydrogel bead; In-suit synthesis; Metal peroxide; Phosphate adsorption; Slow release
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.150382

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. [Display omitted] •Simultaneous phosphate and algae removal could be obtained.•H2O2 could be slowly released by the synthesized material.•P removal was effective in a pH range of 3.0–10.0 with a negligible Ca2+ release.•CaO2-functionalized beads could be efficiently used in realistic algae-laden water.•Effectiveness of CaO2-functionalized beads for algae removal could last for 170 d.