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Hollow fibre ultrafiltration membranes for water filtration
ENT DEVELOPMENTS IN MEMBRANES Nanofiltration membrane system developed for industrial applications Israel-based Membrane Pr odu ct s Kiryat Weizmann Ltd h as devloped a range of nan ofiltrati on mem brane systems for differ ent industrial applicati on s. One such system can cont inuou sly recover dissolved low molecula r weight ph arm aceu ticals fro m organic solvents origi nating from solvent ex t raction and preparative high pressure liquid chroma tography processes. Th e o rga nic solvents are pu rified for re use, which thus closes t he product ion cycle and eli m in ates high energy and transp ort costs of solvent evaporati on technique s. One of t he uniq ue features of the nanofiltrati on s p ir a l wo u n d m em branes used in t his system , is t heir stability in organic solvents . The membranes can operate at low te mperatu res , thus ma int a in ing t h e sta b ili ty of th ermally sens itive comp ound s
whi ch ca n otherwise be negatively affecte d by evaporation. Th e nan ofiltration m embr an e system can also be used t o recover 95% of cau sti c sod a and acid s from CIP was h waters from da iri es, wh ile removin g over 90 % of th e contaminants. The recovered ca ust ic is complet ely clear a nd can be reused co n ti n uo u sly. By u s in g th e membrane system, t he dairy eliminates its caust ic and acid sewer dis charge. This compact system has already been in stalled for one year in industrial applicatio ns Australia and Israel. New installat ions are now bein g initiated in t he US and in Europe. M emb r a n e Pr oducts Ki r y a t Weizma n n Ltd, PO Box 138 , Rehouot 76 10 1 Israe l. Tel: + 972 840 755 7, fax: + 9 72 84 07556.
US Filter develops advanced ion exchange membrane for use with Ion pure COl United States Filter Corp orat ion ann ounced recently th e introducti on of a n a dva nced io n exc ha nge mem bra ne for use with its Ionp u re COl (cont inu ou s deionization) product line. The polyethyl ene-based ion exc hange me mbrane exhibits better chemical resistance, p ro vides longer membrane life, is tem perat ure resistant and essent ially imperm eable to water,
and ena bles t he CDI syste m to produ ce co ns istent, high-purity wate r (u p to 18 Megohm-em r es is ti vi t y) . Th is a d van ced membran e is now available for bot h the industrial and lab ora tory COl product lines . US Filter Corp or a ti on, 46 69 Shep her d Trail, PO Bo x 560, Ro ckford, IL 61I05-0560, USA. Tel: + 1 815 8 77 304 1, f ax: + 1 8 15877 0172.
Hollow fibre ultrafiltration membranes for water filtration A range of hollow fibre mod ules equ ippe d wit h organic mem bra nes, for us e in cross flow ult rafil trat ion systems , has been an nou nced by Miribe l, Francebased Tech-Sep . Flosep hollow fibre modul es offer a number of ad van tages, such as more comp act equipmen t, lower ene rgy cons umption , use of a cellulose ester polymer particularly su ited t o water t reatment, a nd use of a polysulfon e po lymer for process applications. Flosep hollow fibre ultrafilt rati on membranes have a pore size d iamet er of around 0.01 urn guarant eeing the complete removal of algae, bacteria, viruses, colloids , susp ended matter an d organic molecules, regardless of t heir conce nt ra t ion. The quality of wa ter out p ut is th erefore consiste ntly high. Th e risk of m icrobia l reFlltratlon & Separation
J une 1995
growth in wate r supply networks ca n be eliminate d usin g t his tec hnology. Ultrafiltrat ion can be used for mains supplies , or for na tu ral sources su ch as sp rings , aq u ifers, ri vers a nd lakes. The Flosep systems are suitable for a wide ra nge of applicatio ns, inclu din g in t he food a nd bevera ge, p harmaceuti ca l and che mica l industries, as well as for pre-t reatme nt before reverse os mosis or ion ex chan ge in t he treatment of wa ter, or for post-treat ment uses. Tech-Sep, 5 Chem in du PiUon , Saint-Mauri ce de Beynost, B P 34 7, F-01703 Miribel Cedex , Fran ce. Tel: + 33 7201 2727, fox: + 33 7225 8899. Rh iin e-Poul en c Chemicals Ltd , Po leac re Lan e , Wo o d l e t , S tockport, Che s hi re SK6 1PQ, UK Tel: +44 16 1 9 10 1556 , fax: + 44 161 910 1554.
Closed-loop polyolefin resin degassing A pai r of closed-loop, mem brane syste ms for se pa rating monomer s and othe r hyd rocarbons from nitrogen during polyolefin r esi n de ga ssi ng were lau nched at t he recen t PetroChe mica l Exposition in Housto n. The Va porSep syste ms for polyolefin resin de gas sin g from Memb ran e Tech nology & Research, offer resin producers a new appro ach to dealing with t he vent from dega ssing op erations . By recover ing va lua ble mo nom er, hydrocarbon s such as hexane, and nitrogen that would ot herwise be lost, resi n producers ca n save o n raw ma te rials cost s as th ey expand produ ctio n ca pac ity. An im p ort a nt source of waste in polyole fin manufactu re occurs when t he solid polymer resin is pur ged with nit rogen to re mo ve unreact ed mon om er and ot her hydr oca rbon s, such as hexane. The vent from this degassing ope ra t ion is typically flared to elimi na te emissions of hazardous air pollutants. VaporSep syst ems for p olyolefin resin degassing, however , provid e a recovery alte rnative to high-cost flaring. In one design option, th e Va p o r Sep sy s te m r e covers 95 - 99 % of th e hexa ne from a purge st rea m consist ing primarily of hex an e and nitrogen . The syste m offers several ben efits to resin pro du cers by recover ing t he nitrogen and recycling it t o th e degassing operation; capturin g th e hexane, whi ch is a hazard ou s air pollutant ; an d conse rving nat ural gas by avoid ing t he need to fla re th e purge ven t. Bas ed on t he value of re covered raw ma teria ls, th e syste m pays for itself in ju st
ove r one yea r of co nti nuo us ope ra tion, according t o MTH. In another design option . th e Vapo rSep syste m for polyolefin resin degas sing recover s valuab le mono mer (p ro pylene or et hylene) from nit rogen. The residue from t he fir st mem brane va po ur separation un it. which is 90 - 95 % nitrogen , is recycled to th e degassing operation. The permeate fro m the seco nd membrane vap our sepa r atio n unit , w hi c h i s 90 - 95 % monomer, is sent for purificat ion and reuse as feed st ock in the polymer prod uct ion process. As well as recovering bot h mon omer and nit rogen, it also conserves natural gas by elimina ting t he ne ed for flaring. Wit h t he tightening market for olefins, t hese syste ms a re cla imed to come at a good time for resin producers facing ris ing costs for raw mater ials an d t he need to ex pand or debott len eck curre nt ope ra t ions . The closed-loop syste ms for polyolefin resin degas sing rely on a p roprietary, mem bran eba sed gas se para t ion techn ology called VaporSep, develop ed by MTR with funding from th e US Department of En ergy a nd EPA. The key to th e va po ur se paration process is an organic-selective membrane t hat is lO-I OO t imes mor e perm ea ble to orga nic va p ou rs that to air. Th e tech nology has been spotlighted in a variety of technical j ourn a ls in th e la st year, including Fil tration & Separation (in May 1994) . M em b1'a ne T'e ch n o l oqu & R es ea r ch In c , 1.'3 60 Willow Road , Menlo Park, CA 94025 , USA. Tel: + 1 4 15 328 2228 , fax: + I 4 15 328 6580.
Phenol/chloroform alternative for high recovery of enzyme-free nucleic acids Millipore recently lau nch ed its Ult rafree-MC Probi nd cent rifugal filt er devices for fast an d si mple rem oval of enzymes from up to 500 III of react ion mixture cont a ining double-stranded nu cleic ac ids. This device incorporates a polyvinylidene ( PVDF) membrane, whi ch exhibits preferentia l binding of prot ein over doub le-stran de d DNA. Ultrafree -MC Probind is an efficien t an d effective altern ative to ph enol/chloroform ex traction of DNA solution s for removal of potentially contaminating enzymes. The procedur e is rapid and easy-to -use . On cent rifugat io n, the enzyme is imm obilised on t he PVDF mem bra ne, and th e restricted pro-
te in-free DNA can be recovered fro m the microcentrifu ge tube in less t han 30 s. The method is non-toxic, so t here is no den aturation of th e nucl eic aci ds an d no specia l waste dispo sal issues. Less sa mple man ip u lati on is re q u ire d wit h th ese devices. t he re by p rovidi ng in cr ea sed yields of nucleic acids beca use of better sepa rati on between prote in and DNA. Mi llip ore Corp ora tion , 80 A shby Road, PO Box 9125, Bedford , MA 01730-9125, USA. Tel: + 1 617 275 92 00, Fax: + I 617 2 75 5550. Millipore SA, 39 Route In dus trielle de la Hardt , F-67120 Molsheim, Fran ce. Tel: + 33 8838 9000, Fa.r: + 338838 9193. 515
whi ch ca n otherwise be negatively affecte d by evaporation. Th e nan ofiltration m embr an e system can also be used t o recover 95% of cau sti c sod a and acid s from CIP was h waters from da iri es, wh ile removin g over 90 % of th e contaminants. The recovered ca ust ic is complet ely clear a nd can be reused co n ti n uo u sly. By u s in g th e membrane system, t he dairy eliminates its caust ic and acid sewer dis charge. This compact system has already been in stalled for one year in industrial applicatio ns Australia and Israel. New installat ions are now bein g initiated in t he US and in Europe. M emb r a n e Pr oducts Ki r y a t Weizma n n Ltd, PO Box 138 , Rehouot 76 10 1 Israe l. Tel: + 972 840 755 7, fax: + 9 72 84 07556.
US Filter develops advanced ion exchange membrane for use with Ion pure COl United States Filter Corp orat ion ann ounced recently th e introducti on of a n a dva nced io n exc ha nge mem bra ne for use with its Ionp u re COl (cont inu ou s deionization) product line. The polyethyl ene-based ion exc hange me mbrane exhibits better chemical resistance, p ro vides longer membrane life, is tem perat ure resistant and essent ially imperm eable to water,
and ena bles t he CDI syste m to produ ce co ns istent, high-purity wate r (u p to 18 Megohm-em r es is ti vi t y) . Th is a d van ced membran e is now available for bot h the industrial and lab ora tory COl product lines . US Filter Corp or a ti on, 46 69 Shep her d Trail, PO Bo x 560, Ro ckford, IL 61I05-0560, USA. Tel: + 1 815 8 77 304 1, f ax: + 1 8 15877 0172.
Hollow fibre ultrafiltration membranes for water filtration A range of hollow fibre mod ules equ ippe d wit h organic mem bra nes, for us e in cross flow ult rafil trat ion systems , has been an nou nced by Miribe l, Francebased Tech-Sep . Flosep hollow fibre modul es offer a number of ad van tages, such as more comp act equipmen t, lower ene rgy cons umption , use of a cellulose ester polymer particularly su ited t o water t reatment, a nd use of a polysulfon e po lymer for process applications. Flosep hollow fibre ultrafilt rati on membranes have a pore size d iamet er of around 0.01 urn guarant eeing the complete removal of algae, bacteria, viruses, colloids , susp ended matter an d organic molecules, regardless of t heir conce nt ra t ion. The quality of wa ter out p ut is th erefore consiste ntly high. Th e risk of m icrobia l reFlltratlon & Separation
J une 1995
growth in wate r supply networks ca n be eliminate d usin g t his tec hnology. Ultrafiltrat ion can be used for mains supplies , or for na tu ral sources su ch as sp rings , aq u ifers, ri vers a nd lakes. The Flosep systems are suitable for a wide ra nge of applicatio ns, inclu din g in t he food a nd bevera ge, p harmaceuti ca l and che mica l industries, as well as for pre-t reatme nt before reverse os mosis or ion ex chan ge in t he treatment of wa ter, or for post-treat ment uses. Tech-Sep, 5 Chem in du PiUon , Saint-Mauri ce de Beynost, B P 34 7, F-01703 Miribel Cedex , Fran ce. Tel: + 33 7201 2727, fox: + 33 7225 8899. Rh iin e-Poul en c Chemicals Ltd , Po leac re Lan e , Wo o d l e t , S tockport, Che s hi re SK6 1PQ, UK Tel: +44 16 1 9 10 1556 , fax: + 44 161 910 1554.
Closed-loop polyolefin resin degassing A pai r of closed-loop, mem brane syste ms for se pa rating monomer s and othe r hyd rocarbons from nitrogen during polyolefin r esi n de ga ssi ng were lau nched at t he recen t PetroChe mica l Exposition in Housto n. The Va porSep syste ms for polyolefin resin de gas sin g from Memb ran e Tech nology & Research, offer resin producers a new appro ach to dealing with t he vent from dega ssing op erations . By recover ing va lua ble mo nom er, hydrocarbon s such as hexane, and nitrogen that would ot herwise be lost, resi n producers ca n save o n raw ma te rials cost s as th ey expand produ ctio n ca pac ity. An im p ort a nt source of waste in polyole fin manufactu re occurs when t he solid polymer resin is pur ged with nit rogen to re mo ve unreact ed mon om er and ot her hydr oca rbon s, such as hexane. The vent from this degassing ope ra t ion is typically flared to elimi na te emissions of hazardous air pollutants. VaporSep syst ems for p olyolefin resin degassing, however , provid e a recovery alte rnative to high-cost flaring. In one design option, th e Va p o r Sep sy s te m r e covers 95 - 99 % of th e hexa ne from a purge st rea m consist ing primarily of hex an e and nitrogen . The syste m offers several ben efits to resin pro du cers by recover ing t he nitrogen and recycling it t o th e degassing operation; capturin g th e hexane, whi ch is a hazard ou s air pollutant ; an d conse rving nat ural gas by avoid ing t he need to fla re th e purge ven t. Bas ed on t he value of re covered raw ma teria ls, th e syste m pays for itself in ju st
ove r one yea r of co nti nuo us ope ra tion, according t o MTH. In another design option . th e Vapo rSep syste m for polyolefin resin degas sing recover s valuab le mono mer (p ro pylene or et hylene) from nit rogen. The residue from t he fir st mem brane va po ur separation un it. which is 90 - 95 % nitrogen , is recycled to th e degassing operation. The permeate fro m the seco nd membrane vap our sepa r atio n unit , w hi c h i s 90 - 95 % monomer, is sent for purificat ion and reuse as feed st ock in the polymer prod uct ion process. As well as recovering bot h mon omer and nit rogen, it also conserves natural gas by elimina ting t he ne ed for flaring. Wit h t he tightening market for olefins, t hese syste ms a re cla imed to come at a good time for resin producers facing ris ing costs for raw mater ials an d t he need to ex pand or debott len eck curre nt ope ra t ions . The closed-loop syste ms for polyolefin resin degas sing rely on a p roprietary, mem bran eba sed gas se para t ion techn ology called VaporSep, develop ed by MTR with funding from th e US Department of En ergy a nd EPA. The key to th e va po ur se paration process is an organic-selective membrane t hat is lO-I OO t imes mor e perm ea ble to orga nic va p ou rs that to air. Th e tech nology has been spotlighted in a variety of technical j ourn a ls in th e la st year, including Fil tration & Separation (in May 1994) . M em b1'a ne T'e ch n o l oqu & R es ea r ch In c , 1.'3 60 Willow Road , Menlo Park, CA 94025 , USA. Tel: + 1 4 15 328 2228 , fax: + I 4 15 328 6580.
Phenol/chloroform alternative for high recovery of enzyme-free nucleic acids Millipore recently lau nch ed its Ult rafree-MC Probi nd cent rifugal filt er devices for fast an d si mple rem oval of enzymes from up to 500 III of react ion mixture cont a ining double-stranded nu cleic ac ids. This device incorporates a polyvinylidene ( PVDF) membrane, whi ch exhibits preferentia l binding of prot ein over doub le-stran de d DNA. Ultrafree -MC Probind is an efficien t an d effective altern ative to ph enol/chloroform ex traction of DNA solution s for removal of potentially contaminating enzymes. The procedur e is rapid and easy-to -use . On cent rifugat io n, the enzyme is imm obilised on t he PVDF mem bra ne, and th e restricted pro-
te in-free DNA can be recovered fro m the microcentrifu ge tube in less t han 30 s. The method is non-toxic, so t here is no den aturation of th e nucl eic aci ds an d no specia l waste dispo sal issues. Less sa mple man ip u lati on is re q u ire d wit h th ese devices. t he re by p rovidi ng in cr ea sed yields of nucleic acids beca use of better sepa rati on between prote in and DNA. Mi llip ore Corp ora tion , 80 A shby Road, PO Box 9125, Bedford , MA 01730-9125, USA. Tel: + 1 617 275 92 00, Fax: + I 617 2 75 5550. Millipore SA, 39 Route In dus trielle de la Hardt , F-67120 Molsheim, Fran ce. Tel: + 33 8838 9000, Fa.r: + 338838 9193. 515