Synergistic effect of potassium ferrate and ferrous iron for improving ultrafiltration performance in algae-laden water treatment

Yonghui Han; Jinlong Wang; Daliang Xu; Jialin Song; Hesong Wang; Xuewu Zhu; Xinsheng Luo; Liu Yang; Guibai Li; Heng Liang

doi:10.1016/j.watres.2023.120362

Synergistic effect of potassium ferrate and ferrous iron for improving ultrafiltration performance in algae-laden water treatment

Water Res. 2023 Sep 1:243:120362. doi: 10.1016/j.watres.2023.120362. Epub 2023 Jul 15.

Authors

Affiliations

¹ National Engineering Research Centre for Bioenergy, Harbin Institute of Technology, Harbin 150090, China; State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China.
² School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan 250101, China.
³ National Engineering Research Centre for Bioenergy, Harbin Institute of Technology, Harbin 150090, China; State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China. Electronic address: hitliangheng@163.com.

PMID: 37517148
DOI: 10.1016/j.watres.2023.120362

Abstract

The application of ultrafiltration (UF) technology in algae-laden water is limited due to the serious membrane fouling caused by algal foulants. Herein, a Ferrate/FeSO₄(Fe(VI)/Fe(II)) pretreatment was proposed aiming to improve the performance of UF. The results showed that the synergistic of Fe(VI) and Fe(II) significantly increased the zeta potential of Microcystis aeruginosa, which enhanced the agglomerative tendency of algal foulants, and the particle size of flocs remarkably increased due to the in-situ generated Fe(III). Results from dissolved organic carbon (DOC), UV₂₅₄, K⁺, and fluorescent spectra indicated that the introduction of Fe(II) avoided the excessive oxidation of Fe(VI) to algal cells and reduced the production of intracellular organic matter (IOM), while the strong coagulation efficiency of in-situ Fe(III) further enhanced the removal effect of algal organics. Meanwhile, the molecular weight distribution showed that macromolecular organics were decomposed into low molecular matters under Fe(VI) oxidation, while the Fe(VI)/Fe(II) process reduced the formation of small molecular matters compared with single Fe(VI) pretreatment. The algal-source fouling was efficaciously mitigated under the optimal experimental condition, the terminal membrane flux could be increased from 0.16 to 0.62, while reversible and irreversible fouling decreased by 67.1% and 64.1%, respectively. Modeling analysis demonstrated that the Fe(VI)/Fe(II) process altered the fouling mechanism by delaying the formation of cake filtration. Membrane interface characterization further indicated that large size algal flocs form a loose cake layer and reduce the deposition of algal pollutants on the membrane surface. The Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory confirmed that the hydrophobic adsorption between the algal foulant and the membrane was weakened, thus relieving the membrane fouling. Overall, this strategy can be considered for application in improving the UF performance and mitigating algal-source membrane fouling.

Keywords: Algae-laden water; In-situ Fe(III); Membrane fouling; Pretreatment; Ultrafiltration.

MeSH terms

Ferric Compounds
Ferrous Compounds
Iron
Membranes, Artificial
Ultrafiltration*
Water Purification* / methods

Substances

potassium ferrate
Ferric Compounds
Membranes, Artificial
Iron
Ferrous Compounds