Abstract
The current article tackles the challenge of reducing wastewater volumes generated from the gas industry. A forward osmosis (FO) pilot unit, deployed as osmotic concentration (OC) process without the draw solution (DS) recovery step, was applied as an option for volume reduction of real industrial effluents. A commercial hollow fiber (HF) FO membrane fabricated from Cellulose Triacetate (CTA) was firstly tested with synthetic feed solution (FS) to investigate the separation properties of the membrane and to identify the optimum operating conditions of the pilot unit. The pilot plant was then challenged with real industrial wastewater for an extended period of operation, primarily to assess membrane-fouling propensities and other performance parameters. Results revealed that according to the operating conditions, the CTA membrane can achieve feed recoveries between 60%–90%, at water fluxes between 2.24-1.65 L.m −2 h −1 (LMH)). The operation at 75% feed recovery was identified as the optimum condition since it showed the lowest specific solute flux (20.93 mmol L −1 ) at a water flux of 1.94 LMH. Outcomes of pilot testing with the real wastewater demonstrated operational stability for over 50 h of continuous operation. The pilot system recovered 75% of the wastewater feed at a stable flux trend with minimal flux decline. Water flux of 1.76 LMH was recorded along with reverse solute flux of 292 mmol h −1 . The water flux was observed to decline slightly by only 5.6%, which was attributed to inorganic scaling on the membrane surface where cleaning with citric acid solution demonstrated efficacy in restoring the initial flux. • The technical viability of osmotic concentration (OC) technology at a pilot scale was appraised. • The performance of a commercial CTA HF membrane was evaluated. • The role of operating conditions in the performance of the pilot unit was examined. • OC pilot unit successfully recovered 75% of real wastewater generated from the gas industry. • Stable flux was observed during 50 h of continuous operation with minimal membrane fouling.
Highlights
Significant volumes of wastewater are generated during oil and gas (O&G) operations
This study explores membrane fouling propensity and cleaning efficacy for fouling amelioration of the Osmotic Concentration (OC) process
The current study examines the feasibility of deploying the Forward osmosis (FO) technology as an OC process for reducing wastewater volumes generated from the gas field operations
Summary
Significant volumes of wastewater are generated during oil and gas (O&G) operations. Managing this wastewater has been a global environmental concern that represents a key challenge to the O&G industry (Zhao et al, 2017). Effluent disposal by deep-well injection is a common practice for O&G wastewater management This route is hindered by the limited capacity of underground formations, stringent regulations to minimize potential hazards of contaminating underground water sources due to well leakages, and high costs associated with well-drilling operations (Simpson and Lester, 2009). In all cases, the energy efficiency is constrained by the requirement to recover the DS, the current bottleneck of the process (Awad et al, 2019; Shaffer et al, 2015) If this step is obviated, the stand-alone FO membrane separation stage is close to zero energy
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