Monitoring The Fate Of Fluorescing Substances Recycled In Ultrafiltration Process Backwash Water

Keywords

Backwash recycling; Fluorescence; Membrane; Surface water; Ultrafiltration

Abstract

The fate of fluorescing substances during the recycling of membrane backwash water (MBWW) ahead of coagulation, flocculation and sedimentation (CFS) with ultrafiltration (UF) membranes has been investigated. Bench-scale UF membranes were used to generate MBWW from a CFS-treated surface water containing 21 mg/L dissolved organic carbon (DOC) registering a 0.95 cm-1 UV254 absorbance that had been coagulated with 100 mg/L with polyaluminum chloride. CFS settled water, when processed with UF, produced MBWW containing 9 mg/L DOC registering a 0.25 cm-1 UV254 absorbance. High performance size-exclusion chromatography using UV254 detection demonstrated an analogous UV254 reduction as measured by detector response. However, fluorescence excitation emission spectroscopy revealed that protein-like substances, known to be associated with irreversible fouling, had been concentrated in the MBWW. In order to evaluate recycling operations on overall DOC removal in a CFS-UF process, a blend of 30% MBWW with 70% of raw water was treated, resulting in an overall DOC removal of 73%. However, without MBWW recycle, the CFS-UF process removed less of the influent DOC (63%). This work suggests that MBWW recycle operations should consider possible downstream impacts of concentrated protein-like substances not previously detected, as these substances are suspected to contribute to long-term irreversible UF fouling.

Publication Date

11-1-2016

Publication Title

Journal of Water Supply: Research and Technology - AQUA

Volume

65

Issue

7

Number of Pages

541-549

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.2166/aqua.2016.031

Socpus ID

84994637480 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84994637480

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