title: Achieving very low mercury levels in refinery wastewater by membrane filtration.
abstract: Microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) membranes were evaluated for their ability to achieve the world's most stringent Hg discharge criterion (<1.3ng/L) in an oil refinery's wastewater. The membrane processes were operated at three different pressures to demonstrate the potential for each membrane technology to achieve the targeted effluent mercury concentrations. The presence of mercury in the particulate form in the refinery wastewater makes the use of MF and UF membrane technologies more attractive in achieving very low mercury levels in the treated wastewater. Both NF and RO were also able to meet the target mercury concentration at lower operating pressures (20.7bar). However, higher operating pressures (≥34.5bar) had a significant effect on NF and RO flux and fouling rates, as well as on permeate quality. SEM images of the membranes showed that pore blockage and narrowing were the dominant fouling mechanisms for the MF membrane while surface coverage was the dominant fouling mechanism for the other membranes. The correlation between mercury concentration and particle size distribution was also investigated to understand mercury removal mechanisms by membrane filtration. The mean particle diameter decreased with filtration from 1.1±0.0μm to 0.74±0.2μm after UF.
authors.affiliation: Argonne National Laboratory, Energy Systems Division, 9700 S. Cass Avenue, Argonne, IL 60439, USA.
authors.forename: Meltem
authors.initials: M
authors.lastname: Urgun-Demirtas
authors.forename: Paul L
authors.initials: PL
authors.lastname: Benda
authors.forename: Patricia S
authors.initials: PS
authors.lastname: Gillenwater
authors.forename: M Cristina
authors.initials: MC
authors.lastname: Negri
authors.forename: Hui
authors.initials: H
authors.lastname: Xiong
authors.forename: Seth W
authors.initials: SW
authors.lastname: Snyder
mesh_terms: D019652:Extraction and Processing Industry; D005374:Filtration / Q000295:instrumentation / Q000379:methods; D007220:Industrial Waste; D008567:Membranes, Artificial; D008628:Mercury / Q000302:isolation & purification*; D010578:Petroleum; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000295:instrumentation / Q000379:methods
chemical_list: D007220:Industrial Waste; D008567:Membranes, Artificial; D010578:Petroleum; D014874:Water Pollutants, Chemical; D008628:Mercury