Influence of bulk concentration on the organisation of molecules at a membrane surface and flux decline during reverse osmosis of an anionic surfactant

Abstract

International audienceSurfactants are extensively used in household and industrial products. Several processes exist to treat industrial wastewaters, including membrane filtration such as ultrafiltration, nanofiltration and reverse osmosis (RO). We studied fouling of RO membranes during filtration of aqueous anionic surfactant solutions under different conditions. The aim was to describe the local organisation of the surfactant at the membrane interface. To this end, the typical surfactant sodium dodecyl sulfate (SDS) and a polyamide membrane (SG, GE Water & Process Technologies) were selected. A marked surfactant mass loss was experimentally quantified and attributed to the accumulation of surfactants on the membrane surface and adsorption on the non-membrane materials in the filtration system. The concentration of surfactant in the polarisation layer compared with the SDS phase diagram, combined with contact angle measurements and flux decline analysis, enabled us to deduce a structure for the fouling. The fouling layer presented different structures according to the surfactant concentration: from a dense hydrophobic layer at very low concentration to a lamellar hexagonal phase in the gel layer at concentrations above 35 wt% in wate

Transport Models of Ammonium Nitrogen in Wastewater from Rare Earth Smelteries by Reverse Osmosis Membranes

“…Especially, the relationship between pure water flux and the operating pressure was found to be linear, and plotting J v vs. ∆p in Figure 2a yields the value of A in Equation (1) equal to 1.96 L/m 2 h bar. The determined pure water permeability of the SG membrane just falls in the A-value ranges of commercially available polyamide seawater membranes [28], but is slightly lower than the values reported in previous studies for the SG membrane (2.46 L/m 2 h bar), possibly due to different filtration configurations and operating conditions [25,26].…”

“…Commercial flat-sheet SG membranes (GE Osmonics, Minnetonka, MN, USA) with smooth surface, fouling-resistant and high retention rate against sodium chloride were used in this study, which has an effective separation area of 0.014 m 2 . The detailed information on the structure, properties, and operating parameters of the SG membrane was described elsewhere [25,26]. All membranes were equilibrated with distilled water for at least 24 h and stored in 5 ℃ prior to use.…”

A Detergent Destruction Method Used for Aerobic Treatment of Wastewater High in Detergent Content (WHD)

“…Recent survey has shown significant accumulation of the surfactants in sediments near to the discharge area of large sewage treatment plants jeopardizing the aquatic ecosystem [1]. In water reclamation plants engaging membrane technology, cummulation of detergent content on membrane surface causes fouling of the membrane filters [2]. This has adversely affected the filtration operation.…”

Depositing lignin on membrane surfaces for simultaneously upgraded reverse osmosis performances: An upscalable route

“…Among them, organic fouling is a major concern in RO technology. The adsorbed organic fouling layer can serve as a conditioning layer for microbial attachment and growth, thus leading to the formation of more troublesome biofouling …”

“…The adsorbed organic fouling layer can serve as a conditioning layer for microbial attachment and growth, thus leading to the formation of more troublesome biofouling. 5,6 Many strategies have been developed to reduce fouling on RO membranes, including the pretreatment of feed solutions with flocculants, chemical cleaning, surface modification of RO membrane, and etc. [7][8][9] However, organic foulants cannot be sufficiently removed by the pretreatment of feed solutions as trace organic compounds remain in the feed.…”