Emerging investigator series : control of membrane fouling by dissolved algal organic matter using pre-oxidation with coagulation as seawater pretreatment

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journal

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Original languageEnglish
Pages (from-to)935-944
Journal / PublicationEnvironmental Science: Water Research and Technology
Volume6
Issue number4
Online published27 Jan 2020
Publication statusPublished - 1 Apr 2020

Abstract

Marine algae produce organic matter, namely algal organic matter (AOM), especially during a harmful algal bloom. AOM has been recognised as a key cause for the formation of organic fouling on membranes in seawater desalination applications. In this study, pre-oxidation of AOM by potassium permanganate (KMnO4) and sodium hypochlorite (NaOCl) was investigated. In addition, ferric (Fe3+) and alum (Al3+) coagulants were used for subsequent coagulation. Two different operational modes, conventional coagulation–flocculation–sedimentation (CFS) and coagulation–flocculation-dissolved air flotation (CF-DAF) processes, were used to evaluate pretreatment performance using synthetic AOM with an initial dissolved organic carbon (DOC) of around 4.8 mg C L−1 (turbidity ≈ 4.47 NTU, pH ≈ 8). Pre-oxidation with coagulation removed more AOM, compared to oxidation or coagulation alone. The removal of DOC by NaOCl–Fe3+ is relatively high when compared to other combinations of oxidant and coagulant because of in situ ferrate (Fe6+) generation, which was detected by the ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid))-ultraviolet visible (UV-vis) method. Pre-oxidation with 1.5 mg L−1 NaOCl followed by coagulation with 2.5–3.0 mg L−1 Fe3+ achieved a maximum DOC removal of 65–76% during the CFS treatment; while, the DOC removal could further increase up to 83–85% by introducing CF-DAF. Particularly, the NaOCl–Fe3+ treatment generated 1.31 mg L−1 of in situ ferrate (Fe6+). Finally, pre-oxidation and coagulation coupled with DAF successfully reduced fouling and lowered flux decline in a microfiltration (MF) membrane. Non-invasive optical coherence tomography (OCT) was performed to monitor the fouling development on the MF membrane before and after pretreatment.

Citation Format(s)

Emerging investigator series : control of membrane fouling by dissolved algal organic matter using pre-oxidation with coagulation as seawater pretreatment. / Deka, Bhaskar Jyoti; Guo, Jiaxin; Jeong, Sanghyun; Kumar, Manish; An, Alicia Kyoungjin.

In: Environmental Science: Water Research and Technology, Vol. 6, No. 4, 01.04.2020, p. 935-944.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journal