Application Study of URCⓇ-A Process as a Feedwater Controlling Step of UF Pretreatment in SWRO Process

Abstract

In this study, a pilot study combining UF pretreatment with URC Ⓡ -A process was carried out in SWRO desalination. From these experiments, it was confirmed that source seawater quality parameters required for SWRO desalination such as turbidity below 0.1 NTU, TOC below 1.0 mg/L, SDI below 3, algal cells below 300 cells/mL were obtained from this pilot system. In case of high turbidity such as over 40 NTU, 99.2% removal from 42.59 NTU to 0.35 NTU was obtained after URC Ⓡ -A process. In case of high algal condition, over 90% removal was achieved and turbidity below 0.4 NTU, TOC below 1.0 mg/L, algal cells below 300 cells/mL were obtained. By introducing URCⓇ-A process, TMP of UF membrane was lowered 33% than without URCⓇ-A process, after then TMP was maintained continuously at 0.4 bar. In case of high turbidity and high algal conditions, UF process operation was very stable without any bad influence, thanks to good and stable performance of URC Ⓡ -A process. After then, when, without appling URCⓇ-A, original source seawater entered the UF pretreatment, TMP was raised to about 16%. This shows that particulate matter and organic matter in source seawater can cause membrane fouling within a month. The introduction of URC Ⓡ -A process as pretreatment step enabled stable operation of UF process and the lower TMP level of 0.4 bar could be maintained continuously to increase maintenance cleaning cycle and CIP cycle. This operation mode with longer maintenance cleaning and CIP cycles can be more economical than conventional operation mode. Key words: UF (Ultra Filtration) Pretreatment, SWRO (Seawater Reverse Osmosis), URCⓇ-A, TMP (Trans-Membrane Pressure), SDI (Silting Density Index), Algae, TOC (Total Organic Carbon)