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Costanzo J.A.,University of Virginia | Ober C.A.,University of Virginia | Black R.,Dow Water and Process Solutions | Carta G.,University of Virginia | Fernandez E.J.,University of Virginia

Acute liver failure arises when potentially toxic metabolites accumulate in the bloodstream because of a breakdown in liver function. New extracorporeal systems combining membrane and adsorbent technologies are being developed to replace critical liver detoxification functions between diagnosis and transplantation. This study addresses the adsorption of representative plasma components on four different hydrophobic, polymeric adsorbents for possible use in an extracorporeal hemodialysis device. The adsorbents considered span a range of pore sizes and include both strongly hydrophobic divinylbenzene (DVB) matrices as well as a less hydrophobic acrylate matrix. Adsorption equilibrium and rate measurements were made for these matrices using human serum albumin (HSA), polyclonal human immunoglobulin G (IgG), and bilirubin (BR), as representative plasma components. Pore size was found to contribute significantly to selectivity. Results demonstrated that strongly hydrophobic materials with pore sizes that allow free access to protein-bound BR are most effective for BR removal whether they are initially clean or pre-saturated with HSA. © 2009 Elsevier Ltd. All rights reserved. Source

Majamaa K.,Dow Water and Process Solutions | Bertheas U.,Dow Microbial Control | Finlayson F.,Avista | Levy R.B.,Dow Microbial Control
Water Science and Technology: Water Supply

Sodium metabisulphite (SMBS) is the current standard preservation chemical used in RO plants during shut down. It is a cheap and efficient preservative, but its tendency to oxidize easily has several drawbacks. The use of a non-oxidizing biocide instead could solve some of the issues currently seen with the SMBS, but little has been reported about membrane compatibility and preservation efficiency in the long-term mode. Long-term membrane preservation trials have been executed with three different non-oxidizing biocides: DBNPA (2,2-dibromo-3-nitrilopropionamide), CMIT/MIT (5- chloro-2-methyl-4- isothiazolin-3-one (CMIT) and 2-methyl-4-isothiazolin-3-one (MIT), OIT (2-octyl-2Hisothiazol- 3-one) as well as SMBS as the reference chemical. The suitability of these chemicals in this application was confirmed using both new Brackish Water Reverse Osmosis (BWRO) and used membranes with various membrane chemistries (Nanofiltration (NF), BWRO, Sea Water Reverse Osmosis (SWRO)). The preservation trial with new membranes confirmed the long-term stability of the product when stored in the biocide solution while the trial with used elements is closer to realistic plant conditions and validated the efficiency of the biocide against biofouling in the long-term. These results show that the biocides can be equivalent preservatives to SMBS and that the application is economically feasible. The used active concentrations for biocides are storage time and temperature dependent and this should be taken into account when first applying them in the field. © IWA Publishing 2011. Source

Poppe G.,Dow Water and Process Solutions
Chemical Processing

Some proactive steps that can maximize life and performance for water purification and reduce overall operating costs of the RO plant are discussed. It is essential to normalize the permeate flow, feed pressure and salt passage to a standard reference point. Before starting to clean, find out the cleaning pH and temperature limits set by the membrane manufacturer and make sure the cleaning chemicals are compatible with the membranes. Once cleaning chemicals have displaced water, recycle concentrate and permeate to the cleaning tank. After the soak, recirculate the cleaning solution at a high flow rate for 30-60 minutes to flush out foulants removed from the membrane surface. Flush out the cleaning solution using RO permeate or deionized water and during the flush, the minimum temperature should be 20°C. Source

Majamaa K.,Dow Water and Process Solutions | Johnson J.E.,Dow Water and Process Solutions | Bertheas U.,Dow Microbial Control
Desalination and Water Treatment

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, wasteor 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 Desalination Publications. All rights reserved. Source

Funk C.V.,Dow Water and Process Solutions | Koreltz M.S.,Dow Water and Process Solutions | Billovits G.F.,Dow Chemical Company
Journal of Applied Polymer Science

Nylon 11 and Nylon 12 are commercially important polymers due to their unique combination of mechanical strength, chemical resistance, and processability. Products have been prepared from these polymers via thermally induced phase separation (TIPS) for many years. Nevertheless, known diluents for Nylon 11 and 12 pose specific processing problems, and it would be desirable to find a diluent that allows low processing temperatures, has a high flash point, is inexpensive, and exhibits low toxicity. This work investigated a variety of alternative diluents not previously documented in the literature. A fundamental study was also performed to determine which factors are important in selecting a diluent for preparing Nylon liquid-liquid TIPS membranes. The information gathered in this study, including phase diagrams for all feasible systems investigated, will be important in shaping future formulation work for Nylon use in microporous membranes. © 2015 Wiley Periodicals, Inc. Source

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