Synergistic mechanism of pH control by CO2 and CaO2 pre-oxidation to enhance algae dehydration

• Published in: Separation and purification technology 2025-03, Vol.355, p.129565, Article 129565
• Main Authors: Yang, Shumin, Ma, Shunjun, Wang, Xiaodong, Zhang, Yongji, Xu, Bin, Yu, Shuili, Tang, Yulin
• Format: Article
• Language: English
• Subjects: Algae dehydration; Carbon dioxide; Dissolved organic matter; Microcystis aeruginosa; Moderate peroxidation
• ISSN: 1383-5866
• DOI: 10.1016/j.seppur.2024.129565

[Display omitted] •Impact of pH adjustment on the oxidation process of CaO2.•Influence of pH on pre-oxidation-enhanced coagulation.•Efficiency and underlying mechanisms of the CO2-CaO2-PAC process in algal dewatering.•Dynamics of algal-derived organic matter throughout the treatment process. This study investigated the improvement of algal dehydration efficiency through CO2 pH adjustment and moderate pre-oxidation with CaO2 to enhance coagulation. Adjusting the pH of algal water to 6.0–9.5 with CO2 significantly affected zeta potential and photosynthesis, enhancing aluminum hydrolysis product aggregation. At pH 6.5, the composition of algal organic matter closely matched the original water, indicating minimal impact on algae and optimal cell activity. CaO2 pre-oxidation effectively reduced residual aluminum content and DOM release after coagulation. The DOM removal rate reached 44.50 % at pH 6.5, with the highest dehydration efficiency of 44.34 % and the lowest cell rupture rate of 5.55 %. Small molecular aromatic proteins decreased, while humic substances increased significantly. The chemical bonding between the EPS membrane and CaO2 improved system density and elasticity, enhancing dehydration performance. This study provides new insights and guidance for the ongoing study of pH and CaO2 enhanced algal dehydration.