Pilot-scale study on the reverse osmosis treatment of oil sands tailings pond water: Impact of pretreatment on process performance

• This pilot study investigated the use of reverse osmosis (RO) to treat recycle water.
• The impact of different pretreatments on the RO performance was studied.
• RO permeate fluxes normalized to 25 °C of 31 to 52 L/m2·h were recorded.
• The two configurations resulted in low total dissolved solids and dissolved sodium.
• Clean-in-place procedures were not required for both treatment configurations.

The oil sands industry has recently focused on both reducing their freshwater usage and maximizing the reuse of process water. This study is one of the few pilot-scale investigations reporting the ability of reverse osmosis (RO) to treat recycle water (RCW) from an oil sands facility. Two distinct treatment trains were assessed to evaluate the impacts of pretreatments on the RO performance. Treatment train 1 consisted of coagulant addition, ceramic ultrafiltration (CUF), antiscalant, and a single-pass RO system operated at natural pH, while the treatment train 2 included softening, coagulant addition, CUF system, weak acid cation ion exchange, antiscalant addition, and an RO system operated at alkaline pH. RO permeate fluxes normalized to 25 °C of approximately 31–39 L/m2·h at 72% recovery and 38–52 L/m2·h at 85% recovery were recorded for treatment trains 1 and 2, respectively. At these conditions, the two treatment trains resulted in total dissolved solids lower than 18 mg/L, while the dissolved sodium concentrations were below 7 mg/L. During the pilot tests, clean-in-place procedures were not required for both treatment configurations, highlighting the effectiveness of the pretreatment steps to reduce the RO membrane foulants.