* ,a

Evaluation of NS-100 I

: L' . : *k Reverse Osmosis ,A

Membrane

,

*I '- I

Laboratory and F l e l d Evaluation o f NS-100 Reverse Osmosis Membrane

American Electroplaters ' Society, Inc. Wirlter ?ark, FL

Prepared for

i f

*

Industr ia l Environmental Resewch LRb. Research Triangle Park, NC

Apr 80 l

RESEARCH REPORTING SERIES

, 3 4

5 6 7 R 9

- -- TFCWNICAL REPORT DAYA

LABORATORY AND FIELD EVALUATION OF NS-100 REVERSE OWOStS MEMBRANE

r l l 1980 Issulnq date O I O A N I Z A T I O N COOI

8. Plt llr OllMlNO On6ANIZATION nCCORT NO ~AUTHOLlt*) K.J. HcNulty U.C. Grant, 3 . R . Harland, and R.L. Goldsmith. Naldcn Dlvlslon 0' AS:ai*, 111.3..

1 BB610 --0 R-803753

Wllnlnaton. MA- 0'1887 . PRRPOCIWINO 0 1 6 A N l P A T I O N N A f A I A N 0 AOO*C*&

k r l c a n Elcctmplaters ' Society 1201 Loulsiana Avenue Winter Park, Florida 32789

yndus?rfar h v k w i " t m 7 research Lab, Of f l ce o f Research 8 Developncnt U.S. Envlmmental Pmtectlon Agency

KSPO onw A c c N A C A N O A o c

. Clnclnnati, Ohlo 45268 D SUPCLLMRWTARV WOTLS

Pro jec t Off lcer: Mary K. Stlnson (201)321-6683

Laboratory l i f e tests were conducted with 8-9 and NS-100 reverse osmosis (RO) nm: wanes t n a t l q zinc cyanide p la t ing solut ion s t 10% o f bath strength. The 8-9 nrem- ,ram was degraded by the hlgh pH o f the soltat?on uhlch was beyond tha upper pH l i m l t :pH 11) n c o m n d e d for th ls "brane. The kS-100 membrane showed l l t t l e de ter lo r r t lon In performance over the f l r s t 500 hours of opcratlon. A nduc t l on In ptrmeate f lux and u j e c t i o n a f t e r 500 hours appeared to be due to p e c l p l t a t i o n o f sa l ts whlch resulted

operatlon I n the closed loop test system and would not be expected I n actual f l t l d bperatlan. 1

F l c l d tes ts were conducted a t N e w England Plat lng Company t r ea t l r y rlnscwater fr6q :he xlnc cyanide p l a t lng opera t lon w l t A a module o f seven tubular NS-100 reverse os- msls menbrsc4-9. Conductlvlty rejections f 80196% and zlnc j t c t l ons of 96099.7%

murs o f cxpmwe t o tne r lnsmater, the membrane showed no degradation i n performonce 1s detemlned by NaCl performance tests and standard tes ts wi th a solut lon o f zinc *

:yanlde p la t i ng bath d i lu ted t o 5% o f bath strength. -A nunber o f attempts were made to fabrlcate an NS-100 splrrl-wound nadulo, but (111

nre unsuccessful. Further development w i l l be nqu l red b e f o n the NS-100 can be :anMrc la~ ly 'o f fe red I n an econmlcally a t t r r c t l v e configuratlon. - -

e r e measwed a t f l u x levels o f 0.20-0.37 ms /mZ/day (5-9 gal/t t 9 /day), Durlng 2300

RPI. rr(M# AM0 b b c U U R W T AWALI#(I 1.

OCSCRICTOM

Elect ropl a t i ng Waste Treatment flm bra nes

.8OCwtt?Wn.lbnM an010 TRRu8 c COOATt F l r l l m

Tim CyrnWt R 4 n s m te r

Reverse Osmor I s closscd-loap FMtwtent 1%

I' '

I LACORATORY AND FIELD EVALUATION OF NS-100 REVERSE OSHOSIS MEMBRANE

by

EPA-600/2-80-059 h=ll 1980

J

Kenneth 3. McNulty, Donald C. Grant, John R . Harlan4 and Robert L . Soldsmith

Walden Division of Abcor, Inc. W i lmington, Massachusetts 01887

for American Electroplaters' Society, Ioc.

Winter Park, Flor ida 32789

Grant No. R803753 1 Project Officer

INDUSTRIAL ENVIRONMNTAL RESEARCH LABORATORY OFFICE OF RESEARCH AND DEVELOPMENT

U. S. ENVIRONMNTAL PROTECTION AGENCY CINCINNATI OHIO 45268

I

Mary K. Stlrrson Industr la l Pol lut ion Control Dlvlslon

Indus tr I a1 Envl " e n t a l Research La bora tory Edlson, New Jersey 08817

i r ... d I__ __---- IL-- ".

D! SCLAIHER

Thlr report has been rcvlewed by the Industr ia l Environmental Research Laboratory-Cinclnnatl, U.S. Environmental Protect lon Agency, and approved for publicatlon. Approval does not slg?rlfy that the contents ntcessarll; i-sflect. the v i m and pol ic ies of the U.S. Envlronnnntal Ptotectlon Agency, nor i.xs ncntlon of trade n m s or camnerclal products const i tute endorsement or r e c m d a t Ion for use.

11

4 ' \ - &',

FOREWORD .I;

When energy and ma t e r i a l resources a r e extrac ted * processed, converted and used, the related pol lut ionat impacts on our environment and even on our health of ten require that new and increasingly mare e f f i c i e n t po l lu t ion contml methods be used. The Indusi r ia l Environmental Research Laboratory- Clnclnnatl ( I E R L - C i ) assists I n developing and demonstrating new and improved methodologies that w i l l M e t these needs both e f f l c l t n t l y and economically.

fh fs report i s a product n* the above e f fo r ts . I t was undertaken t o dcmanstrate the effectiveness and e c m m l i feaslbf 1 I ty o f using reverse osmosls f o r closed-loop control o f metal f ln lsh ing r inse wastes uder actual p lant condf t lons, r e t u m t o the processing bath while pur i fy ing the wastewater f o r reuse i n the r fn l s lng operation. The resul ts of the report are o f value t o R 6 0 programs conctmed with the treatment o f wastewaters from varlous metal f lnfshlng, non-ferrous metal, steel , fqorganic, and other Industries. Further informa- t l on concernlng the subject can be obtained by contacting the Metals and fnorganfc Chmlcals Branch o f the fndustr la l Pol lut ion Control Dlvfsion.

The reverse osmosis system concentrates the chemlcals fo r

David G. Stephan 01 rector

Cinclnna t l Indus t r 1 a1 Envl ronmen ta 1 Resea r c h La bora to ry

. .

111 ,

ABS TRACT

LaboratoryJlife tests were conducted with B-9 and NS-100 redvse osmosis (RO) membranes treat ing zinc cyanide p la t ing solution a t ten percent of bath strength. which was beyond the upper pH l i m i t (pH 11 3 recomnended for t h i s mbrane. The NS-100 membrane showed l i t t l e deterioration i n performance over the f i r s t 500 hours of operation. A reduction i n permeate f l ux and re ject ion after 500 hours apDeared t o be caused by the precipitation of sa l ts that resulted from operation i n the closed loop test system and would not be expected i n actual f i e l d operat ion.

The 8-9 membrane was degraded b the high pH o f the salut{an,

A t the New England Plat ing Company, f i e l d tests were conducted t reat ing rinsewater fra the zinc cyanide p la t ing operation wi th a module of seven tubular NS-100 reverse osmosis membranes. percent and t i c rejections o f 6-99 percent were measured a t f l ux levels o f

t o the rinsewater, the wmbrane showed no degradation I n performance as determined by NaCl performance tests and standard tests wi th a solut ion of zinc cyanide p la t ing bath d i lu ted t o f i ve percent o f bath strength.

nunbcr (rf attempts were made t o fabricate a NS-100 spiral-wound module. These attempts were a l l unsuccessful, and It is concluded that a more exten- s ive development progran w l l l be requlred before th9 NS-100 membrane can be offered carmrcrclally I n an econa lca l l a t t tac t l ve configuration. Recently, a new "brant s i m i l a r t o the NS-100 h i s been developed I n a spiral-wound conf Igurat ion. fhls “brane, designated PA-300, shows p rm lse o f super- cedfng the WS-100 membrane for p la t ing waste applications.

This report was submitted I n fu l f f l lment o f Grant No. ROO3753 by the American Electroplatcrs’ Soclcty, Inc. under the sponsorshlp o f the U.S. Envirommntal Ptotectlon Agency. t o Apr!l 15, 1976 and work was completed as o f ;me 1, 1978.

Conductivity re jec t ions of 80-96

0.20-0.37 d / m s /day (5-9 g a l / f t ? /day). During 2,300 hours of exposure

Because of the hlgh cost per un i t membrane area o f tubular RO modules, a 1

This report covers the period June 1, 1975

CONTENTS

Forcra+d . . . . . . . . . . . . . . . . . . . . . . . . . . . . i ~ i

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . i v

Fiqures . . . . . . . . . . . . . . . . . . . . . . . . . . . . v i

Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . v i

Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . . v i 4

1. Inttaductlon . . . . . . . . . . . . . . . . . . . . . 1

2. Conclus!ans . . . . . . . . . . . . . . . . . . . . . 3

3. R e c m n d a t l o n s . . . . . . . . . . . . . . . . . . . . 4

4. Laboratory L l f c Tests with NS-100 and 8-9 Membranes . . 5

5. F l e l d Test of the NS-100 Membrane . . . . . . . . . . . 13

6.- Fabrlcatlon of NS-100 Spiral-iound Modules . . . . . . . 26 * I

s References . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

V

2

3

4

5

6

7

8

9

10

11

Flaw schmatlc for laboratory l l f e test system . . - . 6

k h m a t l c drawing o f a 8-9 mini-permeator . . . . . . 7

Rejectlons and p r o d u c t i v i t i e s vs. opsrating tfw f o r the dS-lo0 and 8-9 “brines . . . . . . . . . . . . 10

Abcor spl ra l wound “ b r a n e module . . . . . . . . . . 14 . Flow schematic for fleld test system . . . . . . . . . 15

Rejection for -rant! 31 a t 5% o f bath strength . . . Rejection far membrane 52 a t 5% o f bath strength . . .

18

19

Flux a t 5% o f bath strength . . . . . . . . Condoctlvfty reject ions obtained durtng stan wlth sodlun chloride . . . . . . . . . . . . Fluxes obtained during standard sodium chlor tests . . . . . . . . . . . . . . . . . . .

Rejtctlchi for “brant 33 a t 5% o f bath strength . . . 20 . . . . . . 21 .. ard tests

3 , (

r;

. . . . . 2 2 ’ ; ’

TABLES

de . . . . . 24

Pagc

1 W a n e Performance Durfng Operation on Actual Zfnc Cymlde Rinsewater . . . . . . . . . . . . . . . . . . 25

V I

. L. J

ACKNOWLEDGMENT

The authors g ra te fu l l y acknoaledge the cooperat ion o f M r . Bruce Warner, Mew England Plat ing Co., Worcester, PA f o r providing smtples o f zinc cyanide p la t ing bath f o r the laboratory l i f e teqt and fo r providing the s i t e fo r f i e l d tests of the NS-100 membrane.

Technical d i rec t ion was received throughout the progrm from the EPA Project Officer, Ms. Mary K. Stinson, and from the members o f the AmcriLan Electroplaters' Soclety Project Connittee: Mr. Charles Levy, Mr. Jack Hyner, M r . Lawrence Greenberg, M r . Joseph Conoby, O r . Robert M a t t a i r , M t . James Morse, Mr. Herbert Rondeau, and M r . George Scott. 1

v l 1

The d isch major source o techniques are p l a t i n s proccc on closed- 1000

arge o f IJSU~ r insewatcrs from metal f i n i s h i n q operations i z a f water p o l l u t i o n i n the e l w t r o p l t inq i nda~s t ry . Vwiouc

ava i l ab le f o r t r e a t i n q the r inwwate; generated i n tho e l e c t r o - s . i)urinq recent yeatr,, increased E t t e n t i c n hat been focuccd systems usad t o rec la im r inqewater from i n d i v i d u a l p l n t i n q

baths. are concentrated f u r r e t u r n t o the p l a t i n q bath. i n the process caq be reused f o r r i i i s i n q .

I n these systems, the chemicals dissolved i n the r i n w w a t c r discharge . . ,e p u r i f i o d water produced

Reverse o v " 0 i s ( R O ) i s one o f Feveral concentrat ion technrquec t h a t cdn be w e d f o r c losed- loop treatmeot of e l e c t r o p l a t i n q r insewaters. When pressur ized r insewater ( feed) i s brouqht i n coctact w i t h a smi-pcrmeabls ' membrane, water passes rhrouqh the mmbrane a t a much hiqher r a t e than the d isso lved s a l t s . The process produce5 a low c o n c e n t r a t i o ~ / h i q b volume "permeate" stream, which i s recyc led t o the r i n s i n q operation, and a h i $ . concentrat !on/low volume "concentrate" stream, which i 5 returned t o the., : . , p l a t inq bath. Membrane performance i s genera l ly Ln,3racteri zed i n t e r m P o f

r e e c t i o n ( t h e percent concentrat ion differe:ne between the feed and pecrmtlltdk' ';L-.- s reams,, both measured a t s p e c i f i e d cond i t i ons . Advantaqec and l imi tat i 'onc o f RO f o r closed-loop treatment o f c l e r t r o p l a t i n q r i x e w a t c r s have been d 1 scussed prev i ous 1 y ( 1 ) .

f l u x ( t h e f low r a t e o f permeate produced per u n i t membraric arpa) and '* 29 I

Prel iminary testr , have been conducted (1) t o assess the appl icabi 1 i!y o f t h e c a m e r c i a l l j ava i l ab le membranes ( c e l l u l o s e acetate and polyamide) K O a v a r i e t y o f d i f f e r e n t e l e c t r o p l a t i n q r insewaterr,. While the membranes were e f f e c t i v e ir concentrat ing dissolved species f o r a l l the p l a t i n o baths, membrac? l i f e was judqed t o be i n s u f f i c i e n t f o r use i n c e r t a i n -insewaters w i t h e x t r m s o f pti o r h igh oxidant (chromic ac id ) l eve l s .

Several RO f i e l d t e s t s have been conducted t o determine the appl ica- b i l i t y of RO under p r a c t i c a l condi t ions. These have included:

-- spiral-wound c e l l u l o s e acetate f o r treatment o f Watts-nickel r insewater ( 2 ) .

-- hol low f f b e r polyamlde f o r treatment o f Watts-nickel r insewater ( 3 ) .

-- hol low f l b e r polyamide f o r treatment o f copper cyanide r insewater ( 4 ) .

1

Thtsc f fc ld tcsts Indtcate that either the cel lulose rrcetate or polyamide maihrrne can be used t o t reat Uattr-nickel rinsewaters, and the economics of ? h i % m l f c r t i o n can bc qul tc Attractive. On the other hand, treatme,nt of cc\pcwr cyanldt t rnsewaters cannot t, considered a proven application S4nce. tlvrtnq one of tw f f r l d tests. the r a t e o f mcnrbrane deteriorat ion would r w u l t tn pxctrslvc cos ts f o r membrane r e p l a c m n t .

!n g r r t t r r l , previous work has indicated that “ b r a n e l i f e 1s c r i t i c a l I n detcr“ntng the appl icahl l i ty of RO t o rinsewa: c recovery, and that pH i s an Important pa rsmt t r i n mccrbrane l i f e . For the cel lulose aceta te membrane, 1 t f t i s n t n t r a l l y adequate over a pH range of 2.5-7; for ti.e polyanide mabrttne* ltfc f s generally adequatc aver a pH range o f 4-11,

the obJtctive o f the m r k covered by t h i s report was t o extend the I

r p g l l c n b l l l t y o f RO t o the h!gh-pH cybnide rinsewaters. cyanidc was sclcctcd because of i t s high pH and i t s htgh volume usage i n the p l r t l n q Industry. able aumbrrnrr, a non-comwrcial “brsnc, NS-100, was t o be tested and dtvelovul I n a spiral-wound cnnf Iguratlon for e lect rop lat l rg applications. Prevlauo tcsto wi th t h i s mclnbranc have indicated good s t a b i l i t y over a pH rawe of 1-13 ( 5 ) .

In part icular, zinc ,

Recause o f the pH l imi tat ions o f the commercial ly avai l- n

2

SECTION 2

COrrclUS 1ms

Laboratory l l f e tests indicated that the NS-100 “ b r i n e I s chmlca l l y resistant t o zlnc cyanide rlnscwater a t ten percent bath strength ( r lnscrs ter pCr 12.0-12.5). On the other hand, the performance o f the canrrncrcially available B-9 -rant deteriorated with tlnc, probably as a resul t o f chemical degradation since the ph of the test solutlon war beyond the recOlnnMded range (4-11i for t h t s d r a m .

500 hours o f @peration, was probably the resu l t o f the buildup and preclpl ta- tion o f a sparingly soluble sa l t w i th in the closed-loop test system. type o f fouling would not be anticipated In a pract ica l system.

-ram fouling, &?ch was observed I n the laboratory l i f e tests r t t c r

l b l s

hour f i e l d tes t wi th a tubular MS-100 module, f l u x levels o f 0,20.-0.37 &Ing a33- / /day, conductlvity reject ions o f 80-96 percent, and z i n c re ject ions o f 96-99.7 percent, were obtained and remained stable throughout the test , There was no degradatlon of the “ m e as detemlned by a strndatd MaC1 s o l u t i a i tes t and a standard test wi th zinc cyanldt s o l u t b n d i l u t e d t o 5 percent of bat,, strength.

Attempts t o f a b t i c r t t the Nf-100 membrane i n a splral-wound conf lgurr t ion were unsuccessful. A more extensive developmnt ef for t w l l l be r q u i r e d before thc WS-100 “b ran t can be offer-ed i n an econmlcally a t t r8ct lve

I &

, a configuration for electroplat lng applications, . (

3

F -7-- ” a l a *

SECIIfM 3

.

Consldering both the l d n t n t camnrcrciallzatlon o f the PA-300 “ b r a n e In a rplral-wound conf lgurat lm srrd the s iml la r f ty o f the PA-300 t o the NS-100 In type and chemistry, tests should be conducted wlth the PA0300 “ b r a n c t o evaluate I t s performance and stability fo r treatnwrt,t o f r lnc cyanlde r lnse- waters. If the results look praising, f i e l d t e s t s should be conducted t o evaluate the performance o f spiral-wound PA-300 modules fo r treatment of actual zinc cyanide rinsewaters. (These recOmMndat ions are Implemented under €PA G r a n t Nos. R W 3 3 1 1 and R805300. Ful l resul ts will be Included I n II

the f l n a l reports for these grants).

Furthw development of tht US-100 membrane should be suspended u n t l l the PA-300 and other “brant materlals have been evaluated fo r the treatment of vwlous r!::troplat lng r inscwrt t rs.

* ‘ i

b

I:” i 1 P

4

.’ .,

. ,

I

* ’ d ’r. ,1* SECTIOCI I . i . (..

4 1 l A 8 O R A m Y LIFE TESTS W I T H 15-100 MO E-9 MMSRANFS

The objective of t h i s progrm was t o demonstrate the f t a s l b l l l t y of using RO for closed-loop treatment o f tht rlnscwattrs resul t lng from t lnc cyanldei; p la t ing operations. laboratory ? l f e tes t was conducted t o determlne whttner the du Pant B-9 polymide membrane coul be used I n the f i e l d tests. ln i t lated, the polyaride “&raw was the only canmrc la l l y avallablc m- brane that could wl thstmd a l k a l l m cmdl t lons (pH 4-11). The other comer: c i a l l y avallable lMlnbrmcs, nmely cel lu lose acetate and cellulose t r lacc- , tate, arc l imi ted t o pH values belaw about 8.0.

I n para l le l w i t h these tests, r laboratory 1I fe test was conducted with the NS-100 dcvelopclrmtrl m r a n c t o determlne if t h i s membrane could be used for the f i e l d test in the went that the 6-9 “ b r a n t was degraded by the t lnc cymfd t rlnseuatct. ’

over a pH range of 1-13 (5).

EXPER IM€NTAL PROCEDURE

1-ratory L i f e Test System

l l f e tests i s sharrn i n Figure I. A p o f i t i v e displecmwnt pun0 (Yrmay Cyclophrm Model 072) was used t o w l t h d r r r s o l u t b n from the feed tank and presswize i t t o 2.8 I I ( r a ~ psig). me f law ra te t o the modules

volune of the pug. The pur0 dlschmf, pressure wrs mersured, rnd pressure p u l s r t l m s m e dmgmccd by M w c u w l r t o r , The modules were protected u p f n s t ove r -p r t r t u r i t r t l on by r orcrsure r e l i e f valve and 8 high pressure twitch, I n rddi t lon, t b p u g wrs protected q r i n s t running dry by a law pressure switch. Feed passad through 1 IIS-1c)o tube and r 8-9 mini -pemator

tor. GarrtcMtrate and both m r t e s were returned t o the feed tank ( t9 ta l recycle) so thrt the feed concmtrr t lon would not v r ry wi th the. The feed tmqmr tu re was mersured rt the punp suction. f r k t i o n r l heat lnput from the pun0 w a s rmmved by 4 caallng c o i l plrced in the feed tmlt.

Buaure o f the high pH of zinc c,ymIde r lnsmatcr , a

Hen t h i s p r o g r a was

The NS-100 membrane has cxhlblted good s t a b l l l t y

a .$ . ’).

A sinrglff led f l o w schmr t lc of the test system used for the labor9tory

w n control led rt 0.12 mf I h r (0.S3 pp) by rdjust lng the d i s p l r c m n t

;, I n st r les , wlth the operrting pressure controlled by I back pressure regula- tt*

Y r r m M u l e s

desi9 of 4 min l -pmmrtor i s show i n Figure 2. The u t i v e port ion o f the pnw,to+ consists o f OM s t rnn l (150 f l lun@nts) of polymlde hollow fibers.

tho 8-9 galyutide “ne wrs i n the form o f (1 mlni-petmator. The

S

F I g u n 1. Flm rchcrt lc for labontory lffe t e s t system.

c

i ..

The strand i s looped as sham, and both ends are sealed in an cpaxy pot.-’. Permeate i s withdrawn f r a one end o f the f i be r strand af ter s l k i n q exposes- the open fiber ends. A normal four-inch diameter permeator contain1 about 900,OOO f i laments; so the nlni-permeator contains less than 2 x 10” o f the surface area o f a f u l l - s c a l t module.

The NS-100 "brant i s frrtncd by t reat ing a polysulfone “ b r a n e support wi th a solut ion o f P E I (polyethylenimlne) i n water, d solut ion o f TDI (2.4- t o l y l m e diisacyanate) i n hexane, and heat curing t c cross-link the P t i . Before reaction wi th the P E I and 101, the polysulfone “ b r a n e i s essenttal ly an u l t r a f i l t r a t i o n “ b r a n t capable o f removing suspended sol ids and macro- ’

molecules. The PfI/TDI/heat-ci~re treatment causes a s k i n t o form 4t the ’

membrane surface that i s capable o f re ject ing smaller molecules and dissolved salts. ingrcgnatcd ffberglass tube 12.7 mn (0.5 in) I n diameter and 0.61 . . mm (2.0 .\

‘ C The NS-lo0 mnbrane i s supported on the In te r i o r w a l l of an epoxy-

f t ) long. “3 . Perfomance Parameters ,$ \ ‘ 4

. I

’ L

Product i v i t y - - The product iv i ty of a given module i s the r a t e a t which permeate i s ’‘

produced under specific conditions. Productivi ty I s dependent on tempera- twe. pressure, and feed concentration a t the membrane surface. Mere s l l g h t variat ions i n the operating conditions occurred, he measured productfvfty o f

(noma1 operating condit!ons for the du Pont module) using data from the du Pont Technical Information Manual. unt t Wcrt)rane area. 4,

the mini-permcator was corrected t o 2.8 x lo6 N/m !! (400 psig) and 25’C i

- , , . Flux i s defined as product iv i ty per .\ +;*&’

Conversion-- $$ n e conversion i s the rrti:, o f Oermeate flaw t o feed f law. For a module. ;

4

operating a t near-zero conversion (as were both modules I n the life test) , the concmtrationx o f the feed and concentrate s t r e a s are nearly the sm. Thus, the concentration on the feed/concentrate side of the membrane i s very nearly the s m c as the feed concentration. On the other hand, a module operated a t high conversion w i l l produce a concentrate stream having a hlgher concmtratlan than the feed strtm. I n t h l s case, the average concentratton on the feed/conccntratt side of the membrane w i l l be substantial ly higher thm the feed concentration, For two modules operated a t the same pressure. temperature, and feed concentration, the f lux w i l l be lower for the module operated a t the higher conversion, since f l u x decreases with increasing average concentrat ion on the feed/cmcentrate stde of the membrane.

Reject ton-

vented from passing through the membrane. The re ject ion depends on the mer- +

a t h g pressure, the conversion, and the feed concentratlon, and 1s defined by:

ne re ject ion (r) measures the degtcc to whlch p l r t i n g s a l t s are pre-

. ”

100 CCf - Cpl r =

C f

where Cf * feed concentration (conduct i v l t y ) Cp penmate conccntratjon (corrductIvity).

Opeat Ing Condi t Ions

snsplc of zinc cyanide p la t ing bath from New England Plat ing Company t o ten percent o f bath strength (volumetric basis).

The fed solut ion used i n the l i f e tests was prepared by d l l u t i n g a

The nominal bath canpositlon i s g i v m belaw:

r lnc (as metal)

f ree cyanide

C W S t I C 75.0 g/1 (10 or/gal)

carbonate

br i ght ener

15.0 g / l (2.0 o r l ga l )

19.5 g / l (1.6 o r l ga l )

50-60 g/1 (7-8 or/gal) avg

0.sx ( vo l )

The test systcn was operated continuously on the zinc cyanide feed solution, except during inturrupt ions for maintenance and Hac1 performance tests. ' ? I 1

9

L

. .

.I '

;. .

F l q u n 3. ReJectlarts and p n d u c t l v l t l r s vs. o p e r a f l n g - t l m for the NS-100 and 8-9 mnbrrnas.

10

* 1- 1 E

1 I

r

1

i a1 ‘value . 4

I i Dtlghtenlng agent,’ the product lvt ty ..rcrecrxxl almost t o (C), but dropped a f t e r treatment with a PEI solut ion (0).

t s i n

The pvoductlvl ty for the 8-9 decrcrscd r g l d l y t o about ont- third of I t s l n l t t r l v r l w md gpcrttd t o be l t ve l l ng o f f unt l l about 500 havrs. A r g l d decllne In product iv i ty was again observed between 500 and 600 hours rrd between (500 md 700 hours. Only -st improvcnrcnts I n pro- duc t i v l t y were obtrlned a f te r c lemlng and PT-8 treatment.

but there ru r s u b s t r r t l r l decline In re ject lon bet” 500 and 600 hours a d between 660 and 700 hours. This declfne corresponds exactly with the product lv l ty decline discussed rbave. CI t r i c wid cleanlng and PEI treatment restwed the reJection of the NS-100 t o I t s i n t t t a l value.

fhc re ject lon for the 8-9 decreased subs tmt la l l y over the l l f t test and could not be restored by c l t r l c acid cleaning or Pf-8 treatment. Even over the f i r s t 506 hows, d w e the re ject ion for the WS-lo0 raa lned constant, the re ject ion for the 8-9 d c ~ t l w subs tmt l r l l y .

Om of the aost s t r l k l ng fertures o f t h a t dat8 I s the difference in wnbtme perfornmce k f 6 W md after 500 hews o f operstlng the. Appar- ently, some type of “brmt f w l l n g occurred af ter 500 hours. The cleanlng s o l u t l m (two percent c l t r l c acid rt pH 4) wrs selected t o rerrrove Iron hybraxlde prec lp l t r te , th lch could have resulted from cor~osion of stainless steel c-ts In the test system. Hawcver, l f this were the foulant, pedwnrnca should hwe decllned grrdually from the beginning o f the l i f e test. A a w e o r t l s t u t o r y exglmrtlon I s that s w const l tmnt In the fed bullds t@ t o I t s s o l u b l l l t y l l i l t over the f i r s t 500 hours of operrtton md, tRe?&ter, earrtlnues t o fou l the ncmbrme by prec lp l t r t ion, This hypothesis I s supported by the presence of (I pree ip i t r te i n the feed t m k that was qu l tc wldent rttu 720 b r s and my have started t o accumulrte rt about 500 hours. The feed solut ion was m r l y n d for c&rbCMrtes, with the thought that tRe dissolut ion of cd could Imrerse the crrbarrrte level m d cwsc preci- p f t r t i o n of II $q fhe m r l y s l s shoued that Wr2CO3 was carrslderrbl k~ar i t s sot i 1 i y l i m i t ; however, p m i p i t r t i o n of stme less so lu i le cwbonrte s p c l a t cnrnot be ruled out.

If the hypothesis i s correct that the total-recycle nada o f operation multed i n m a c m u l a t i m of spvrlngly soluble sa l t , the d r t r beyond 500 haun, spcnrtlng t i m e would not be c h n r t u l s t i e o f e r n e perfommce cmdrr u t u r l agaratlng candlt ims. Evm if the bath were saturated wi th this salt, t)n drag-out would be d i lu ted tn the rinse n d canccntrrted i n the RO

ratwrtlm. Hance, the spn lng ly soluble s r l t would not &ccY’ lete I n the nwrsr o m l s systm as lt d m durlnq t o t r l recycle.

Based on the f l r s t 500 how8 of agmrtian, ths decline l n both f l u x md m j u t l o n for the 8-9 I s too r rp ld t o W e thls “ n o ecmomtcrlly rttru- tlw far tlm cymlde ncowry . fhlr camlus lm 1s supported by tk resul ts of s t r t l c tests canducted by du P a t . In these tests the polymtde hollow flbu w u sorlod In (I t f M cymlde ralutlm 8t tm pnmt of bath rtrangth.

7Rc reJection for the RS-100 was very stable over the f i r s t 500 hours,

G

. b

s

Y

’ ,

.,

.I

r y s t r t o only rbaut ten Wcmt e? bath strength, thrt 18, ten percent of . ‘

* &

11

12

. I

SECTION V

F I E L D TEST OF THE MS-100 MEMBRANE

ATTEMPTS TU FABRICATE AM NS-100 SPIRAL-WOUOND MOOULE

Following the laboratory l i f e tests wi th the 8-9 dni-permeator and the a

WS-100 tubular “ b r a n e i t was decided that the most meaningful f l e l d test would be one conducted with the NS-100 membrane In the spiral-wound conf igur-

Since attempts t o fabricate a NS-100 splral-wound module were unsuccess- ‘5 fu?, tt W I S decided t o proceed with f i e l d test lng the WS-100 “ b a n e i n the tubular configuration. I t was reasoned that these tests would I l l u s t r a t e the pevformence of the membrane over an extended period of exposure t o rinsewater under actual f i e l d conditions. development of a splral-wound module would be warranted,

EXPER IWNTAL PROCEDURE

tubular Nf-100 “brant! i s sham In f igure 5 , Feed was pumped from the r i n s e ’ t m k by I booster pmp (Uorthlngton M e 1 0-520) and f i l t e r e d through a 304nicran m d a 1-micron cartr idge filter arrenged I n series. The pressure *

If these tests were successful* fur ther

A flow schcmatfc of the reverse osmosis system used t o f i e l d test the

13

i ..

Figure 4. Abcor spiral-wound " b r a n t module.

- 7

0 .

-*u- . - . . .

t

1,

* ? .

a

I 11

L

0 c

B c u,

. *. ,

15

L.

of thc r l l t e r d f t v d um then increased t o the desired operating pressure of

( V w w i y Cyc laphrm Model 072). rrrumulator located or. !he pump d i r harqe.

prrmratc t t r csn from the tubular NS-100 module flowed d i rec t l y t a the plant w a s t k a t e r treatment systan. The concentrate stream passed through a back Irwrrurc requlator, which r d 5 used t o control the operating pressure. Mast nf the coiccntratc ttrtmn was returned t o the suction side of the booster p c m while a w a l l port ion (suf f ic ient t o y ie ld a 90 percent conversion) was Dlcd thrnuqh 4 ron t ro l valve to the plant wastewater system. I

4 7 I IO6 N/m 5 ( 6 0 psiq) by d posi t ive displacement diaphragm pump

t n w r i w with (I f l m t d t c of 2.5 m s /day (0.45 gpm) i n each tube. The

Pressure pulsations were dampened by an The membrane tubes were connected

Prcs%urc% wcre mcasiwtd hefore and af ter the cartr idge f i l t e r s , t o dctcmlr,e when rcplacmnnt ;cecessary, and before and a f t e r the reverse o w " r modulr t o dettwnirc the ~ p e r a t i n g pressure and pressure drop along thp tirhrs. Thc s y i t t m ~ 4 % prottc:ed from over-pressurization by a preswre

reed and canrcn!, a t ? flow rates were measured using flow meters, while

rrl t r f valve. 4 % ?

< 1 . the pcrmcate flow '*ate from each individual tube was measured by the "bucket

and rtopwrtch" terhnfquc. Fwd, concentrate, and permeate samples were taken , t

' . pcrtadirrlly f o r malys is . Smples were analyzed for z inc, t o ta l solids, pH, k , and ronduct I v l t y u5:nq the following analyt ical methods: 6.2.

f a

s; 11; * . P a r m t r r Met hod Procedure

2 4nt Atomic abrorpt ion 301A*

Totdl %ol!ds lvaporat ion-grav lmetr i c 208A.

FH Met er read 1 ng 424.

Condirc t i v i t y Meter readinq 205*

fhr nMnhrane module cnnslcted of seven tubular NS-100 membranes arranged i n crertcr. Each tube had a d fmnter o 12.7 nun 0.5 in), a length of 0.61 mm

arc# 0.17 J ) . the m0c)u'Ic: four tuhct of Type I "b rane cast on a 4-mil-thick polysulfone bnck4nq, and t h r w tuhc: of Type J, cast on 8-mil-thick polysulfone backing.

( ? f t ) , bnd crurfacc a r r a of 0.024 m ! (0.?6 f t 1 ), (tubular module t o t a l Two d l f fc rcn t types of NS-100 "b rane were insta;led In

'

M r a n c performance was dctcnnincd by pcriodi:al l y interrupt Ing the field tpcrt and canductinq a t o ta l recycle test wi th a standard solut ion a t r t m d r r d npcrrtlnq condltianc. Thc standard solut ion was contained !n an auni l iary teed tank and, a f ter drainlnq and flushing the system, feed was

rcturncd t o the trnk (5cc FIqurc 1). , '- ! * withdrawn trom tht a u r i l i r r y tank and both concentrate and permeate were

' C . A t steady r t a t e , the f lux of each tube .. ,

.$tmdard Method far the fxaminatlon of Water and Wastewater, 14th ad,, W r t c r n Puhlic Hce l t l , Assoclat ion, Uashlngtan D.C. 1976.

16

was measured and smples of feed and ptrmcate were obtained t o determine the re ject ion for each tube. returned t o operation on the actual zinc cyanide rinsewater.

Following the test, the system was drained and

Stsndsrd performance tests were conducted with two di f ferCnt solutions: E 1,500 ppm Mac1 solution, and a solutfon o f the actual zinc cyanide p la t ing bath df luted to ffve per cnt f bath strength. Duri these testz .ire system was operated a t 4.2 x los N/v? (600 oslg), 25°C ( 7 7 ’ 7 , and 2.5 mj/day/tube ( 0 . 4 gpn/tube) feed ra te .

during operation on the actual rinsewater are d i f f i c u l t t o interpret since

Since feed concentrat icn affects both f lux and re ject ion, data obtained a t d i f f e w n t feed concentrat ions cannot be d i r e c t l y compared t o detQrmine whether the f l u x and reject ion remain stable wi th t ime. T h i s problem, varyinq feed concentration, i s obviated by using the standard zinc cyanide solut ion and t o t a l recycle operation.

RESUtTS AM0 OlSCUSSIOrr

Results o f previous f i e l d tests have sham that performance data obtained”

there i s no way t o control the concentrstfon o f the feed t o the RO sfitem, ‘ . * *,u

I

I

During the tests, the module wi th seven tubu a r membranes was exposed t o . I * t i nc cyanide rinsewaters for 2,300 hours, n i t h an actual operating t i m e of * .

. \ * I.

1,300 hours. The shorter operat ing t inre re f l ec ts uncontrol lable system interruptions a t the s i t e , as well as minor mechanical problems that mafnly occurred during the f i r s t 1,OOO hours of “ b r a n e exposure. and solute reject ions f o r both types o f “ b r a n e showed l i t t l e decline i n performance throuqhout the test. The T y p e 3 membranes (8-mil backin ) displayed higher reject ions than the Type I membranes (4-mil backing 4 , prcsumsbly because of the improved physical properties. data for the lype J “ w a n e s are presented.

The reject ions obtained during standard tests wi th zinc cyanide :*Fse- waters (p la t ing bath d i lu ted t o f ive percent o f bath strength) f o r the three Type 3 tubular membrane assemblitz are presented i n Figures 6 through 8, Each f igure presents the reject ion data obtained f o r one o f the three Type 3 tubes test&. The reject ions were excellent. They appeared t o increase during the f i r s t 1,500 hours, then rmafned constant or decreased s l f g h t l y during the remainder o f the tes t . Conductivity reject ions were 80-96 per- cent, t o t a l sol ids reject ions 87-96 percent, and zinc re ject font 96-99.7 percent.

t

’ $

’ ^ , Permeate fluxes

V ” . * /

Accordingly, anly

i

3

I Fluxes obtained during the tests a t f i v e percent of bath strength were Th y re presented i n Figure 9, which indicates f lux

The conductivfty reject ions obtained with 1,500 ppm NaCl solutions are The reject ion appeared t o decrease with time, but t h i s

also very stable. levels of 0.20-0.37 m 5 s /m /day.

g i v m i n Figure 10. i s believed t o have resulted from an ion exchange or adsorption phenomenon occurring when the “branes were i n contact with the highly alkal ine zinc cyanide rinsewaters. r y s t n on a 10,ooO ppm NaCl solut ion fo r 170 hours and again measuring the

fhfs hypothesis was substant iated by operating the

W.8

m c 0 T.t.1 Sell&

FIgurr 6. Rejection for “brine 31 a t 5% o f bath strength.

19

--

If

Figure 9. Flux a t 5 1 o f bath s t n n g t h .

m -

a *E a

F i p n IO. conductivity re&ctlons obtalnd during stadad tests with sodim chloride.

cmduct iv l t y re ject ion wlth a 1,560 p p Wac1 solution. It was f e l t that by

exchange that had occurred could be reversed. This was Indeed the case, as

t % \

~b s' b operating the system a t a high sa l t concentration, the adsorption or Ion '8%.

; \ the reJectiorr fo r a l l three membranes Increased a f t e r t h l s treatment (closed s m l s , Figure 10). Perhaps further recovery o f Wac1 re ject ion n ight be '

achfeved by operating the s y s t a wfth higher s a l t concentratfons f o r a lOnger period o f t ime.

Flux levels remained stable during the tests except f o r an apparent increase af ter an elapsed exposure tlnc of 1,600 hours (Figure 11). This may Indicate "b ran t degradation, but It l s more l i k e l y t o be connected wlth *

saae other phmarmnon slnce no other data Indicate degradatlon o f the 1~111- brute.

rinsewaters Indlcate high fluxes rejections, as shown i n Table 1. Mabrane f luxes were 0.25-0.41 d/ /day; conductlvl ty reject lons were 76-94 percent; t o t a l sol ids reject ions were 85-87 percent; and zinc rejec- t lont were 95.5-99.3 percent. It should be noted that although the system was operated a t 90 percent water recovery, concentratlons i n the membrane loop w e only 2-4 times those I n the feed because o f the low reject lons .of

* a < ' t ) . ,

" ' 5 * the Type I mabrmts.

".I

indicated rdtquate f lux a d re ject ion and no degradatlon f o r the Type 3 ':* W d r n e s .

.

Data obtalned while the system was operating on actual zinc cysnlde , D

2 I

*

Results of the 2,300-hour f i e l d t e s t wl th the tubular WS-100 module . ' i ,' I

It is, therefore, concluded that the NS-lo0 "brim can be usedl f o r the treatment of zinc cyrnlde rinsewaters. ' *

23

i

3 N s \ a

0.6 I

0.6

0. b

-

0.2 1

Figure 11. Fluxes obtalncd during standard s o d l u chlorlde tests.

.. ..

25

Y

SECTION 6

FABRICATION Or: WS-100 SPIRAL-UWND NOOULES

Following the successful f i e l d tests wi th the NS-100 membrane In tubular configuration, fur ther e f fo r t s were dlrected toward fabr icat ing an NS-100 spiral-wound module. 4

The preparation o f WS-100 spiral-wound membrane modules based on fona- t i o n procedures developed for tubular conf iguratlons required adaptations, In . two main areas: h

1, the casting of a continuous f l a t s h e t po1ysuWone substrate on i ’

c lo th backing (rather than the casting o f discrete tubular SeCtlons)

2. thc formation of the RS-100 u l t ra th in “brant on the f l a t sheet po 1 ysu 1 f one subs tr a t e.

A f l a t sheet o f polysulfone, 0.91 m wide by 92 m long, was cast, and two

. .

“ . I

. basic approaches t o the formation o f the WS-lo0 spiral-wound module were attempted. the 115-100 skin was famed In s i tu . In the second approach, the 15-100 u l t ra th in was foraed on t‘he polysulfore substrate md then the wllrbrme was uwnd i n to a sp i ra l module. One module using the f l r s t approach m d four modules using the second approrch were frbrlcated. The best per- fommcc c h a u t 1 t i c s obtalntd during a stmdard 1,500 /1 Wac1 tes t were

attempts It was concluded that the additional development r q u i r e d t o fabr l - cate a workable WS-lob spiral-wound mdule was bcyond the resources available t o t h i s progrm,

Although ca rw+c~a l l ra t~ac r of a spiral-wound WS-100 module does not rp~nrt Iminent, the F lu id Systcn Dlvlsian of Univeral 011 Products, Inc. (fan Diccga, CA) has recently dcveloped a s in i la Immbrmc, designated PA-300, I n a spiral-wound configuration. This IMIIOrme module should be c a r w r c i a l l j r v r i l e b l e I n the near future nd may ell superctdc the WS-lob as the most p r a i s i n g new fo r treatment af zinc cyanide nd other clutroplat+f ‘pg rinsewaters. Tests belng conducted a t the Yaldm Division of Abcor, Inc.,’ under a sepwatc €PA grant, lnd lc r te excellent ycrfommce cha6tcter lst ics*, fo r P A - m flat-sheet “brmes during exposure t o rinc cyanide rlnsewaters. Dated an these tests md the resul ts presented i n Sections 1 and 5 for the 113-100 “ n e (given i t s s im i la r i t y t o the PA-300). f i e l d test inq of a spiral-wound PA-300 “ n e on zinc cyanide rinsewater I s rccmmndcd. Such a f i e l d test I s belng conducted under a separate €PA grant; resul ts w l l l be ’

published I n a separate report.

*

I n the f i r s t rpproeh, a polysulfone module was wound and then .*

a f l ux o f 0.33 &&,day and a re ject ion o f 60 percent, Fa 7 lowing these

$, -

26

1.

2.

3.

4.

5.

6.

REFERENCES r’

b ‘ 6

Dannclly, R.6.. R.L. (;oldsmith, K.J. kRul ty , D.C. G r a n t , and N. fan.; 1976. Treatment of electroplat ing wastes by reverse osmsls. E P f i W / P - .’, 76-261, U.S. Environnmrtrl Protection Agency, Cinclnnati, Ohio. 96 pp‘, .

6olocnb, A. 1973. Application of reverse osmosis t o electroplat lng wa%te’ * treatment, P a r t 111. Plat lng 60(5):482-486. 1977.

WMulty, K.J., R.L. (;oldsmith, and A . Z . 6011an. 1977. Reverse o f i e l d test : treatment o f Ma t t s n lcke l r lnsc waters. EPA-600/2-7 -039, U.S. E n v i r c ” t r 1 Protection Agency, Clncinnatl, Ohlo. 29 pp. .

Wulty, K.J., R.L 6o ldu l th , A.Z. bllm, S. Hortlan, and 0. 1977. Revest o m x i s f i e l d test : treatment o f copper cyan1 waters, €PA-600-2-77-170, U.S. Envlromental Protect Ion A6e nrti, Ohio. 89 pp. *

_I

i

TSiS .

Rorelle, L.T., 3.E. Culotte, C.V. Kapp, md K.E. Coblan. 1973. NS-1 ’

membranes: p o t m t l r I l y e f fec t i ve new m r r n e s tor treatment of washi ter ’ fn space cabins. Mm Paper 73-ERAS-19. A X , New York, N.Y. 5 ppI . ~ 3 .

Zakak, A., P, Hoover, A.Z. 6o l lm, and R,L. 6oldsmith. 1975. Developrant .? of I low-cost tubular reverse osmr l s module for me-pass scb water tksal t tng. U.S. martmnt o f In ter lor , Off ice of saline Mater, 09 Contract No. 14-30-3251.

I , ‘tp

.. *

8‘8

Y

27