School of Water and Environment, Chang'an University, Yanta Road #126, Yanta District, Xi'an, 710054, People's Republic of China.
Key Laboratory of Subsurface Hydrology and Ecology in Arid Areas, Ministry of Education, Xi'an, 710054, People's Republic of China.
Environ Sci Pollut Res Int. 2020 Aug;27(23):29239-29247. doi: 10.1007/s11356-020-09293-z. Epub 2020 May 21.
Harmful algal blooms (HABs) are a growing problem worldwide, damaging human and ecosystem health. In this study, a novel buoyant-bead flotation (BBF) method using chitosan-coated fly ash cenospheres (CFACs) was developed to remove HABs in freshwater. To achieve a high removal efficiency of harmful algae (Chlorella vulgaris, Scenedesmus quadricauda, and Microcystis aeruginosa), this study investigated the effects of chitosan/fly ash ratios in CFAC composite, CFAC concentration, flotation time, and pH values on the microalgae removal. The optimized ratio of CFACs is 0.1:12, and the optimized CFAC concentration is 0.3-0.7 g L. However, the lower or higher ratios (0.1:4, 0.1:8, 0.1:16) result in microalgae reaching a zero-point charge too late or early, which failed to effectively remove HABs with an appropriate coal fly ash dosage. An optimized removal efficiency of 98.50% for Microcystis aeruginosa was reached at pH of 6.0. The optimized efficiency of Scenedesmus quadricauda and Chlorella vulgaris was 99.37% and 91.63%, respectively, at pH of 8.0. At neutral pH conditions, the surface charge of microalgae cells and CFACs are different, promoting aggregate formation. When CFACs were used to remove microalgae, aggregate size significantly influenced removal efficiency. Meanwhile, at the optimized pH and concentration, the removal efficiency of all three algal species exceeded 90.00% in 5 min. The study highlights an efficient and inexpensive method for removing HABs and obtains the optimized operational conditions.
有害藻华（HABs）是全球日益严重的问题，对人类和生态系统健康造成损害。本研究开发了一种使用壳聚糖包覆粉煤灰空心微珠（CFACs）的新型浮选矿浆浮选（BBF）方法，用于去除淡水中的 HABs。为了实现对有害藻类（普通小球藻、四尾栅藻和铜绿微囊藻）的高去除效率，本研究考察了 CFAC 复合壳聚糖/粉煤灰比、CFAC 浓度、浮选时间和 pH 值对微藻去除的影响。CFACs 的最佳比例为 0.1:12，最佳 CFAC 浓度为 0.3-0.7 g/L。然而，较低或较高的比例（0.1:4、0.1:8、0.1:16）导致微藻达到零电荷点过晚或过早，无法用适当的粉煤灰剂量有效地去除 HABs。在 pH 值为 6.0 时，铜绿微囊藻的最佳去除效率达到 98.50%。在 pH 值为 8.0 时，四尾栅藻和普通小球藻的最佳去除效率分别为 99.37%和 91.63%。在中性 pH 条件下，微藻细胞和 CFACs 的表面电荷不同，促进了聚集物的形成。当 CFACs 用于去除微藻时，聚集物的大小显著影响去除效率。同时，在优化的 pH 值和浓度下，三种藻的去除效率均在 5 min 内超过 90.00%。本研究强调了一种去除 HABs 的高效且廉价的方法，并获得了优化的操作条件。
