Potential Membrane Based Treatment of Triethylene Glycol Wastewater from Gas Separation Plant

Paul Jacob, Romchat Rattanaoudom, Pimchanok Khachonbuna, Nattawut Piyaprachakorn, Gamgarn Thummadetsak, Chettiyapan Visvanathan



In gas separation plant, triethylene glycol (TEG) is used in gas dehydration process. This in turn generates large volumes of two wastewater streams containing TEG in a range of 0.1-10% (by volume). TEG is a natural disinfectant, hence at higher concentrations it cannot be sent to a conventional effluent treatment. Thus this study was aimed to assess other alternative methods by utilizing two nanofiltration (NF) membranes (NF-TS40 and NF-TS80) and two reverse osmosis (RO) membranes (RO-ACM5 and RO-NTR759) for treating synthetic and real TEG wastewater. With the synthetic wastewater, RO-ACM5 and RO-NTR759 membranes presented highest TEG removal at 5% initial TEG concentration with 89.12% and 95.74% of TEG rejection and initial permeate flux of 2.57 L/m2·h·bar and 0.89 L/m2·h·bar, respectively. However, with real wastewaters, a pre-treatment using microfiltration and ultra filtration was found to be a necessary step to remove contaminants, especially suspended solid (SS) and oil and grease (O&G) before NF and RO application. The pre-treatment system was able to remove 86-98% and 88-90% of SS and O&G, respectively. But a flux reduction of 10-70% in NF and RO systems was observed, as compared to synthetic wastewater. Hence, membrane based treatment was proven effective for low TEG wastewater concentrations of 0.1 to 5% only.

Keywords: Triethylene glycol; reverse osmosis; nanofiltration; membrane; polarization; natural gas