Improvement of UF/NF/RO Membrane Performance Through the Use of Innovative Coatings
The reuse of produced and flowback waters from oil and gas production is an expensive process, and often, these waters are reinjected into the ground at a significant cost. Water purification via membrane technology offers an energy efficient and inexpensive alternative to reinjection.
Albert Lee, Siriat Kasemset, Daniel J. Miller, Bryan D. McCloskey, Dr. Benny D. Freeman, Dr. Mukul M. Sharma
Gas Technology Institute (GTI)
Research Partnership to Secure Energy for America (RPSEA)
Improve UF/NF/RO membrane performance through the use of innovative coatings
Barnett and Appalachian Shale Water Management and Reuse Technologies
RPSEA Report No: 08122-05.03
The challenge in using membrane technology for produced water purification lies in fouling. Fouling is the build-up of particulate matter on the membrane either externally or internally which eventually inhibits its activity. Unlike regular seawater or brackish water, produced water contains many particulates, such as emulsified oils and organics, which aggressively foul the membrane.
Polydopamine (PDOPA) was found to be an effective anti-fouling surface coating for UF, NF, and RO membranes for produced water purification. The deposition of PDOPA improved the permeate flux for all types of membranes studied during simulated oil/water emulsion filtration. For UF membranes, additional grafting by using poly(ethylene glycol) (PEG) further enhanced the fouling resistance. Energy savings were estimated for the PDOPA-modified UF and RO membranes in oil/water emulsion filtration by comparing power required per permeate volume. With the same amount of energy provided by the pump, the modified RO membrane produced 1.27 times more permeate volume than unmodified RO membrane after 1 hour oil/water emulsion filtration. The modified UF membrane permeate volume increased by a factor of 2.35 after 1 hour of oil/water emulsion filtration. By translating these benefits for industrial membrane applications, PDOPA modification is estimated to provide savings for 30% of the capital and 40-80% of the operating costs. Based upon the first year of study, the evaluation of PDOPA-coated membrane modules in the field is recommended for Barnett Shale flowback water reclamation.