Oxidation treatment of algae-laden water may cause cells rupture and emission of intracellular organics, thus restricting its further popularization. As a moderate oxidant, calcium sulfite could be slowly released in the liquid phase, thus exhibiting a potential to maintain the cells integrity. To this end, calcium sulfite oxidation activated by ferrous iron was proposed integrated with ultrafiltration (UF) for removal of Microcystis aeruginosa , Chlorella vulgaris and Scenedesmus quadricauda . The organic pollutants were significantly eliminated, and the repulsion between algal cells was obviously weakened. Through fluorescent components extraction and molecular weights distribution analyses, the degradation of fluorescent substances and the generation of micromolecular organics were verified. Moreover, the algal cells were dramatically agglomerated and formed larger flocs under the premise of maintaining high cell integrity. The terminal normalized flux was ascended from 0.048–0.072 to 0.711–0.956, and the fouling resistances were extraordinarily decreased. Due to the distinctive spiny structure and minimal electrostatic repulsion, Scenedesmus quadricauda was easier to form flocs, and its fouling was more readily mitigated. The fouling mechanism was remarkably altered through postponing the formation of cake filtration. The membrane interface characteristics including microstructures and functional groups firmly proved the fouling control efficiency. The reactive oxygen species (i.e., SO 4 •− and 1 O 2 ) generated through the principal reactions and Fe–Ca composite flocs played dominant roles in alleviating membrane fouling. Overall, the proposed pretreatment exhibits a brilliant application potential for enhancing UF in algal removal.
Junren Zhu,Wei Ding,Zhenzhen Jiang,Ting Peng,Xintao Tan
Remediating persistent organic contaminants in near-neutral aquatic environments remains a challenge for conventional homogeneous Fe(II,III)-mediated sulfate radical-based advanced oxidation processes (SR-AOPs), which typically require acidic pH or generate hazardous byproducts. This study introduces an electro-activated sulfite process (Fe-EC/S(IV)) employing sacrificial iron electrodes to overcome these limitations. Continuous anodic Fe 2+ release sustains active FeHSO 3 + complexes, enabling efficient S(IV) activation at pH 4−6. Mechanistic analysis identifies SO 4 •− as the dominant oxidant, formed via inner-sphere electron transfer within FeHSO 3 + complexes, followed by aerobic chain reactions (SO 3 •− → SO 5 •− → SO 4 •− ). The system achieves rapid oxcarbazepine degradation (pseudo-first-order constant, k obs = 1.15 min −1 ), representing a 57.5-fold kinetic enhancement over standalone Fe-EC at pH 6. Notably, the process intrinsically suppresses the carcinogenic BrO 3 − formation (<1 μg L −1 ) through the S(IV)-mediated reductive quenching of bromine intermediates, substantially outperforming Fe-EC/peroxomonosulfate systems (11.3 μg L −1 BrO 3 − ). Demonstrating >70% removal in natural waters without pH adjustment or added electrolytes, and broad-spectrum efficacy (77.9–91.7%) across contaminant classes, this electrochemically sustained process offers a novel AOP paradigm integrating the radical-based oxidation with inherent byproduct control for complex water remediation scenarios.
危险品化学品经营许可证（带存储）