Dow Water & Process Solutions
Dow Water & Process Solutions
Funk C.V.,Dow Water & Process Solutions |
Billovits G.F.,Dow Chemical Company |
Koreltz M.S.,Dow Water & Process Solutions |
Dooley J.,Dow Chemical Company |
Chiou N.-R.,Dow Chemical Company
Journal of Applied Polymer Science | Year: 2017
Nylon 11 and Nylon 12 have been studied for many years for the purpose of fabricating microporous films. Unfortunately, these polymers have somewhat unique properties that prevent the films from exhibiting porous surfaces when their solutions undergo thermally induced phase separation by quenching in water. Without surface pores, these films have limited utility as water purification membranes. In this work, application of high temperature diluent coatings to the surface prior to quenching is shown to enable the formation of surface porosity in Nylon 11 and Nylon 12 films. Furthermore, the pore sizes achieved are suitable for ultrafiltration applications. Following successful lab-scale coating experiments, the effects of coating thickness, temperature, and solvent type on surface morphology are demonstrated over five film extrusion trials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44695. © 2017 Wiley Periodicals, Inc.
Majamaa K.,Dow Water & Process Solutions |
Johnson J.E.,Dow Water & Process Solutions |
Bertheas U.,Dow Microbial Control
Desalination and Water Treatment | Year: 2012
Exposure to water containing micro-organisms causes biofouling on reverse osmosis (RO) membranes as they adhere, multiply and produce extracellular polymeric substances (ESP) which form biofilm on the surface of the membrane. As micro-organisms are present in virtually every water system, biofouling is one the most commonly encountered fouling types in large and small scale RO installations treating surface, waste- or seawater. Biofouling control is significantly improved when multiple methods are combined in an integrated approach and prevention methods employed in the RO stage itself are applied. In this study the impact of new membrane chemistry, feed spacer thickness and the use of non-oxidative biocide upon to the rate of biofouling in RO systems was investigated using a pilot-scale experiment involving small membrane elements subject to a high-fouling feed and autopsy-based analysis of membrane foulant loading and composition. The results were as follows: (1) The benefit of using the newest development in the family of fouling resistant (FR) membranes, DOW FILMTEC™ BW30XFR, was validated with side-by-side operation where lower rate of flux loss was observed when compared to the current industry standard membrane, BW30. (2) Thicker feed spacers provided reduced pressure drop and reduced rate of pressure drop increase during episodes of fouling. Overall organic foulant loading and bacterial counts were found to be reduced on membrane used in combination with thicker spacers. (3) The clear benefit of DBNPA dosing was observed with both shock and continuous dosing regimes. The benefit was most visible in the evolution of Δp as the treated elements operated at significantly lower Δp. Autopsy based results verified significantly lower organic fouling loading on the biocide treated element. These results point to the value of the studied factors–membrane chemistry, feed spacer configuration, and biocide dosing–for use with high-fouling feeds. The suggested route is to combine the components for use as an integrated strategy to solve biofouling. Combining a FR membrane with a thick feed spacer is preferred whenever a high potential for biofouling is seen. The use of targeted biocides in the pretreatment section will further result in improved fouling prevention and ensure long-term trouble free operation, maximizing the membrane lifetime and minimizing the operational expenses of the treatment system. © 2012, Copyright Desalination Publications.
Gilabert-Oriol G.,Dow Water & Process Solutions |
Hassan M.,Dow Water & Process Solutions |
Dewisme J.,Dow Water & Process Solutions |
Garcia-Molina V.,Dow Water & Process Solutions |
Busch M.,Dow Water & Process Solutions
Desalination and Water Treatment | Year: 2015
This paper discusses the feasibility of using reverse osmosis concentrate to backwash ultrafiltration membranes in the seawater reverse osmosis desalination space. Brine is produced through DOW FILMTEC™ reverse osmosis elements and it backwashed every 90 min to DOW™ ultrafiltration membranes. A side-by-side validation is done for 15 d using two parallel ultrafiltration and reverse osmosis integrated systems. One line uses brine for backwashing, while the other uses conventional filtrated water. The optimization is proven to have the same cleaning efficiency than the conventional backwashing methods and no precipitation is observed in the fibers. An additional validation period that uses reverse osmosis brine during backwashes and only two backwash steps is also carried out successfully. These steps are the previously identified backwash top with air scour and forward flush. Fibers also show an excellent integrity after the whole experimental period. A model is built in order to analyze the backwash efficiency of the optimized conditions and the transmembrane pressure increases during the filtration cycle. The results show the same fouling tendency for the line operating with brine and the line operating with filtrated water. The efficiency of the ultrafiltration process is improved from 88 to 98% thanks to this optimization together with the previous researches. This represents filtrating 96 min extra per day and a reduction of 100% in the filtrated water used during backwashes. The chemical equivalent concentration is also optimized from 0.28 to 0.06 mg/L NaClO thanks to the adjustment of the chemically enhanced backwash frequency. This accounts for a 7.1% savings in the ultrafiltration step and for a 1.2% savings in the whole desalination process. © 2014 Balaban Desalination Publications. All rights reserved.
Massons-Gassol G.,Rovira i Virgili University |
Massons-Gassol G.,Dow Chemical Company |
Gilabert-Oriol G.,Dow Chemical Company |
Garcia-Valls R.,Rovira i Virgili University |
And 3 more authors.
Desalination and Water Treatment | Year: 2016
This paper discusses the steps followed to establish an accelerated reverse osmosis membrane biofouling test protocol. Easily bioassimilable nutrients were dosed into water from the Ebro River which was fed into a membrane flat cell pilot plant. The membrane biofouling results were determined by measuring adenosine triphosphate and total organic carbon extracted from the exposed membrane and feed spacer. This strategy was chosen because the equipment does not have pressure drop measurement capability and the observed change in flux or salt rejection was not significant under the testing conditions. The duration of the experiment was set to 3 d to enable rapid screening of different membrane types, yet enable a smooth evolution of biofilm. This study determined that achieving a similar amount of biofouling in each of the three cells was very sensitive to the level of bioassimilable nutrients were dosed to the water. For the Ebro River water, 0.2 mg/L of carbon, 0.04 mg/L of nitrogen, and 0.02 mg/L of phosphorous was determined to provide the best result. © 2016 Balaban Desalination Publications. All rights reserved.
PubMed | Dow Water & Process Solutions
Type: Journal Article | Journal: Water science and technology : a journal of the International Association on Water Pollution Research | Year: 2011
Nanofiltration (NF) is an attractive technology for potable and industrial water treatment because NF operates between ultrafiltration (UF) and reverse osmosis (RO) membranes. NF is designed to remove a high percentage of organic contaminants (humic acids, pesticides, color bodies) while passing a medium to high percentage of salt. Compared to UF membranes, the NF product water quality is significantly better; compared to comparable RO treatment systems NF systems require lower operating pressures. Due to these features, NF is increasingly used in a broad range of water treatment applications. The general applications include softening, as well as color, organics and micro-organism removal. DOW FILMTEC NF270-400 is one the most frequently used elements in water treatment and this paper presents examples of three recent NF270-400 installations in Europe. The first two plants, Eupen and Stembert, are located in Belgium and produce potable water from surface water. The third one is a Scandinavian plant which purifies groundwater for a brewery and soft drink production. The presented operation results prove NF to be a highly competitive technique for low cost water treatment.