Effluent organic matter (EfOM), consisting of natural organic matter (NOM) and soluble microbial products (SMP) causes membrane fouling, taste, color, and is the precursor of disinfection by products. Therefore, EfOM removal is the most important issue in wastewater reclamation. In this study, the adsorption of Suwannee River NOM (SRNOM) and EfOM by carbon-based nanomaterials was investigated. The adsorbents were single-walled carbon nanotube (SWCNT), multi-walled carbon nanotube (MWCNT), expanded graphite (EG), and powdered activated carbon (PAC). The change of the characteristics of SRNOM and EfOM after adsorption was investigated using UV/Vis spectroscopy, fluorescence spectroscopy, and size exclusion chromatography. The adsorption capacity of SRNOM was in the order of MWCNT > PAC > SWCNT > EG, while that of EfOM was MWCNT > SWCNT > EG > PAC. The specific UV absorption at 254 nm and average molecular weight were decreased after adsorption using all adsorbents, for both SRNOM and EfOM, indicating that high molecular weight fraction of SRNOM and EfOM was preferentially adsorbed onto the adsorbents. In addition, the electron-donating groups, such as alkyl, ethyl, amino, hydroxyl and alkoxy groups, decreased as indicated by fluorescence spectroscopy. The preferential adsorption of SRNOM was the most significant when SWCNT was used, while that of EfOM was the biggest when SWCNT or EG were used. The excitation-emission map of the residual EfOM after adsorption also showed that SWCNT was efficient in SMP removal. The results in this study indicate that a pretreatment of EfOM with SWCNT, MWCNT, or EG can reduce membrane fouling via adsorption of SMP and high molecular weight fraction of EfOM.

Adsorption characteristics of natural organic matter by carbon based nanomaterials

248th National Meeting (2014)

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