Characterization and management aspects of total organic carbon in reverse osmosis concentrate: Comparison of full-scale industrial water production plants under different source water

초록

Reverse osmosis is a key technology for producing high-purity industrial water; however, it generates reverse osmosis concentrate (ROC) that poses significant treatment challenges. This study investigated the impact of source water characteristics (surface water vs. domestic wastewater effluent) on the composition and treatability of ROC from two full-scale industrial water production plants (IWPPs). Advanced organic matter characterization techniques, including specific ultraviolet absorbance at 254 nm, fluorescence excitation-emission matrix spectroscopy, and liquid chromatography-organic carbon detection, revealed that despite similar total organic carbon (TOC) concentrations (similar to 49.5 mg/L) in both ROCs, their organic matter characteristics showed noticeable differences. These compositional differences significantly influenced biological treatment performance: a sequencing batch reactor treating surface water-derived ROC achieved 42.3% TOC removal, whereas a biofilm process treating wastewater effluent-derived ROC achieved only 17.2% removal. Ion exchange resin, evaluated as a post-treatment option, demonstrated effective dissolved organic carbon removal of up to 56.2% at an empty bed contact time of 30 min, with preferential removal of humic substances and aromatic compounds. The findings indicate that source water characteristics can significantly influence ROC composition and subsequent treatment performance, although plant-specific operational conditions may also contribute to the observed differences. These findings highlight the importance of considering source-water characteristics when designing treatment strategies for ROC management under increasingly stringent TOC-based discharge regulations.

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