Studying the Efficiency of XAD-7HP Anionic Resin in the Extraction of Humic Acid from Surface Water

Introduction: Humic substances (HSs) are very complex and heterogeneous organic matter with high molecular weight and various functional groups, which are produced from the chemical and biological degradation of plants and animal tissues. HS can cause: colour, odour and taste problems in drinking water, biological growth in distribution systems, increase in chlorine demand for disinfection, membrane fouling and especially, formation of disinfection by-products (DBPs) after disinfection process. The aim of this study is to determine the effectiveness of XAD-7HP resin in the extraction of humic substances from raw water. Materials and Methods: In the extraction of humic substances from water samples, amberlit anionic XAD-7HP resin with a strong cationic resin AG MP50 was used, while for the determination of humic acid, a High Performance Liquid Chromatography (HPLC) system equipped to BIO SUIT SEC columns was used. Results: The average extraction efficiency for XAD-7HP was 77% and HA concentration determined in all seasons ranges from 0.15 to 0.29 mg/L in raw water. Conclusions: From the findings of this study, it can be concluded that the use of XAD-7HP is a proper and effective method for the extraction of HS and its extraction efficiency is more influenced by pH and turbidity than other parameters. It can also be deduced from this study that XAD-7HP resin was most efficient at a pH of 2 and an increase in turbidity resulted in a corresponding decrease in the efficiency of resin.