Desalination, 20 (1977) 267-277 0 Ekevier scientific Publishing Company. Amskdam - Printed in The Netherlands

!&E iE.SA.LWC AdD hECY(XUG OF ‘sUZ?ElWK~ FHlbi !llWZIU DYi3IW O~OONS WIxiG I.iEiva osbd)m

267

Department of lieiechanical Jimineering, College of B&neering ,University of tbnsoura, Egypt

SUu;BtlY

the wzstewater from the textile dyea operations was sepatzted into a concentrate stream, rich in salts and dyes, and a purified pmduct PPater stream wing reverse ommxis membranes. lPlreemembranematerlals and thzxe module cmfi#ratixxiwereuaed, namely t pol.ya~~&de (hollow fine fiber configuration ), cellulose acetate ( apLralwoundandtubularconfig- uJd&OM ) aad hyd.ZOW Zr(N)- pdJ’ZiCryk%Z ( tUbriz= COAfi&utatiOA ). The modules were tested for period8 m fmm600hourstolwrethan1ooo boura~dsractual fieldconditiona.Eefnbrane fluxandrejectionwere monitoredthro~ut theoperationandsamplesof the feedandproductwatex were analyzed chemically. 'Yhe successful operation of the B.O. equip- me&under field conditions demxstrated the applioabilityof this process *the &8alinationof dyeins wastewater.

The tot&I. process-water consumption of the textile industry in the USA VW about 125 billion gallons per year in 1972 WI . !l!bie amount is disch- argzdas n&er;ater containi&a ~bsta?Aial &u&of or&a&c end inorc;an- ic c0ntanAnant-s. The major part Of this wastewater comes fmn thediffere- nt fabric dyeing and finish& pmcessea. Part of this m.zstewater finds its way to streams and rivers without pretreatment.

Vhe concern for enviromental quality end the increasing demands which are placed on OWE water resources have resulted in a sevch for a water treatment technology capable of Separating the contaminants from ths waste- water prior to recycling it back to the dyein process. Reverse osmosis (hyperfiltration) is a eeparation process involving the filter* of swpe- 'I nded and di8SolVed contaoinant3 by forca the 7Aaatewatec under pre6sure

through semi-permeable membranes. This process has attracted the rwst att- ention because of its simplicity and low enerw consumption and because of its potential for recycling.

268 A.M. EL-NASRAR

. iiowevcr, before a decesion. to rely on the relativeiy new reverse osmos-

3s technology, could be tie, the applicability of wmercially available re- verse osmosis membrane modules for the przotical desalti uld recp~ of dyeing wastewater had to be demonstrated on pilot plant sctie.

A pilot plant was built on the site of La E'rsnce Industries in ~a ;tice, SoutbCamlina. which is a dyei.IIb mill pmtiucin& about 22,OMl yards of fabric

(mostly cotton, nylon and viscose rayon) per d2y and usint, 2tnut two million &2llo_ns of w2ter per day- mostly for dye& operations. Yhis pilot plant etu-

dy [2A ms carried out with the follow- objectives in mind x (a) establish the feasibility of recycling the product waxer and concentrated

brine in the dyeing operation. (b) obt&n operating experience with Ati- equipment under dctual. field condi-

tions.

(c) establish an economic cost estimate for a 2 &I) plant. Tha pilot plant was in operation fmmharch 1973 to July 1974 under a grant from tie U.S. -vim -tal zmtection &zncy.

33ecauae of space limit&ion , this paPer will only be concerned with the presentation and analysis of the preliminary data from the different B-0. nodules and will not touch OIA o-c&r aspects of the pilot plant px-qect.

Ninety percent of the 2 I&D total water usage at la Prance Jnd. is in the dyehouse. Tlii variety of dyes employed lead to a complex and variable waste- wster composition. The principal classes of dyestufls employed, wmpris- gy/ of the total usage are neutral pre--me tdlized. direct .ahd acid dyes fi] - Other dyes used less frequently are dispersed, basic and fiber reactive *es 121 . Daily samples were collected at rsndon times duru eacn dsy and these samples were mixed together at the end of each week to result in one composite weekly sample. Ihe results of enalysis of these wmposite samples sre shownin!Pablel .

Table 1 Characteristics of waste stream

Avera@

CODSPP"' 160 880 303 ~D,&'pm

$ 125 46

TWPpm 168

zlCa.lihitY,Ppm 7.6 6.;; 90

Hardness. pm 2: 80 ,': !lWal 80lids.pPel 640 1280 935 Volatile solids,ppm 460 780 Dis&olvedsolids, ppm 6:; 1195 881 Suspended solids.ppm 135 Color @t-Co units) 350" 1660 !l?urbidity(l?TIJ)

7;;

z 120

Conductivity bmho/cm) 39.4

2160 129

KIESALTINGOF @ASTEUATER FROM TEXTILES 269

*i!iie pilot plant

Characteristics of ~323te

ws noused in a fabricated . _-. ed protection from directi sun.SiLine ane rainXa3.i. It containea Wio ti.3. loops: tie precast membrane 1%~ sud the dynamic iilemin-ane loop; Mgzre 1 . The precast filerdorane loop uss designed to accormdate trle tore@ main types of module configurations commercially available; i.e.

a- spira3. Kound confi@.ration b- tubuler configuration a- hollow fine fiber confi@ration

yne &zau&c membrane loop ue.s desi@ed to test dyne&&cally fotmd %tlf,- polyacrylste membrsne zxnUl.es.

Peed, p~duct and concentrate storzze tanks were provided kjacent to the pilot plant site. Zhe raw uraszev,ater feed was introduced ini.o tile pilot plant eitner iron a 2Oca;tion ckmnstrearrr of i* 4000 ballon WWL~W~TR~I 3,3ixua sunp, or directly from a dyehoiie drain discharbinb the ciyea wsstewater of five dye be&s.

A schematic of We precast nenbrane loop is S~ORXA iu Fi@re;; . khe wsstewater coliected in the two 6oL+ &%.kon feed tanks is transfered by &rav- ty to a 55- edZOn &.astic *t3nk via 2 course ~caeerx <fO me3a) -t&i.& retains

larae suspended particles. This knk. wntzins 2 c0gx3er coolint, corl to liuit the maximum feed temperature to 95" F which is hi&nest safe ogeratin& temp- erature. 'ihe feed is pressurized usin& 2 nxd.tis~e centrifiyal hump capable of delivering 13 &pm at 4UU psi;;. herore enterin& tne modules, the feed passes through a prefiltration unit. Yne filtered feed then entoxs the rsdu- les where it is separatsd knto prociuct water and concentrated brine. rartof tie concen$rated brine can be recircuiatetl back k, ti;e pump suc-cion.

Sufficient instrumentation was iucluded to permit monitor- of flow rat- es, pressure drops and feed temperG%tWe- Zresstire and temperature cut-off switches are incorporated in the loop t&a protect tne unit from o?eratinr, st

excessive pressure or tfSper2ture-

the +J~~C ~e&x~e loop contzi-ns a hi&-pressure multi-sta(ie centrUw+ pump with a capacity of 20 gpm at 1~~Pai& xi. wni&.ns also a tube-in-tube

heat excwer for controlling trle temperature of tte feed enter- tile b-c

270 A.M. EL-NASHAR

membrane nodules. The only prefiltration use& in tlna loop was a co-e (40 mesh) screen located above the feed tank to protect the unit from larezv particulates suspended in the feed.

GeneraLi, o_yerating and initial pexformsnce data of four of the iaodufee used ore Qven in %sble 2 . %!ne Universal oil Ezwducts spird wonnd unit

'fable 2 eta 0;‘ trc .c.odulei! used Leneral lsta : i&nufsctnrar ii.0.P. Lmiel Configuration

hembrane hateri _ az! kmbrane &zez(ft )

_)'

=mP* (P ) Flow iIate(&Pmj pz Filtration Bate of Start Bate of Ikst Completion

ODexx%tinr; llours

Gitisl Yerformance Flux (&pd/ft.aq.) Conductivity &ejection 5.

HaCl GoncenLration in feed

Pressure (psi&J

Yemp- (F )

kcst~use 4-291

!i!ubular (interiii)

C.A. Y-25

300 & 450 S-94 3-6

5-2-8.0

12%73 WV74

lW9

m Yont Sela.3

+9t 37%1 - hollow Fine Tubular

Fiber (exte rOlyatride =?I if(lH]y)-P

1800 5

350 8s970 S-90 s&-i94 3 & 45 lo-20

6.2-s-3 4-W-P 1 LC 25 none

3/22/?3 *O/23/7 y/29/73 11/26/7

810 600

Y-3 a7

2UOO

330 00

2.0 74 YZ d?

75W 2900

3!lo \i5G b?j 86

contained three KCP&% 41Oij modules connected in series wit‘n a tot,& membrane area of 195 square feet. 1% was in operation for aL5 kxurs.

S?he ~~estingnouse, mociel+= +291, so called tubuiax sand-lob wdule COT). aLned 18 tubes, each -c inch i.U, snd line& internally titn cei&uLose acetat, membrsnes. Thetotal mabxwe are2 for tori a wdule is 9.25 square feet, It was in operation for 1054, hours.

rPhree IJU kont hollow fine fiber b-9 mdules nere used; only tne resul./ fk-012 the first module (5 772s~ will -b2 reported here. The salt rejects hollow fibers used in these lsdules were made of s.zo%tic polyamide snd eat module contxined 1dW square feet Qf membrane area.

Fran three sejefas modules tnat were used duriiy dperation of tile Pilot plant; the results of the first will be presented hero. %is mod&e wss 6.

DESALTING OF WASTEWATER FROM TEXTILES 271

feet Ion& end 2-5 inches diameter atA containeu two -&mus t&e buudlcs ilav- ine a total sembranc area of 5 sq-e feet. A-uynGic Ls(l‘w-j-rolyacr-3lat.e membrane was formed on the exterior surface of the tuies at O& niQ;c l,atiorl- sl Laboratory prior to the transfer of the module to tne site of the piiot plant. The module was in osecation for f%J hours in th% dynamic membrae loop before bea mved.

*fne type of pre-treatment provided prior to the introduction of feed tc different lludules is shown in Table 3. 21 ‘he precast membrane nodules

I;l;lc ; rrC-tric';;ciir 0Z _-cc2 ;trc;_:

kodule ph adjust. 40 ueail screen 25p Silter 1,‘. r'ilter U.O.P. A X A

::estin&ouse X i A Du icnt X ;+ * h SelaS X

required pb feed adjustment in addition to prc-fiitration. 'lhe U.0.k. and \ie.stinghouse modules were provided with 25 I- cartri&e filters and the uu ront module with both 25~~ end l&-filters. The feed in the Qnam.i.c membrane loop did not @ through any pre-filtration except for the 4C, - nesh acreen.

xl1 reverse osmsis membrenes suffer fron the tendency to foul with arv inorganic or ora2n.k colloids present in the fetd solution. 2b'oillw czuoes a reduction in product water flow rats and quzlity -ai& reduces the eflective service life of the membranes. This results in a need to restore the perfor- msnce whenever severe deterioation nas been observed.

In order to provent oactcriel awtrl on tne memoreues vrnich may result irontheire~suce to stsgactfeed, each nodule was flushed wltil tap vatcr for a period of 5 to 1C ninutes 2fLer eacii loop shut doorm. 1ne _urec&t l!Lekll+ rant loop contained a forward ad reverse tap b;a;er ilusltii, s;stcm v*nich enabled the precast r~ckiles ta te tap water flu&led ill Loto tnc nor& orid re- verse flow directions Loiloaing each shut down.

Tt3 restore membrane _oerfoxmauce,l*~ia~l dctcrocnt \-:cre conductea Ly circulc- tim a solution conteini~ 4 ;_ biz i.2 tap water tnrou& the loop. ILiis suiuti- on having, 2 git of doout 1U was circulated at a i_'rekz=e oi 5U - 15U psi& am tit zhe h&lent possible floK rcte tmolkh tne codrue.

J&C menbrzme periozmznce wili be discussed in tems of the percent %md- uctiviiy rejection u;_ and tne _orocuct wa*er l'lu;: in units ol ,tilon per day per square foot of memurane area (&piz/ft2,. _L ,- is JelineL t2~ t!le follol.itl; equztion : C

&> = (l-

272 A.M. EL-NA!BAR

where C SolutioE.

end C are respectively the conductivity OX produot water and feed ~i&.rea 3 through 6 are hiat~grams of conductivity rejection a&

flux for the four nndules tested.

The chemical analysis of feed and product eamplea taken near the start andend ofopez&.ionof eachmodule is shownin !fable 4.

During the first 26C hours of operation of the U.O.P. unit, the flux wezj neerly constant at 9 gpd/ft* at the operating conditions shoun in Table 2. Poll~uing this period the flux dropped to 6 gpd/ft2 and was steady at this value during the rest of operation. Ansly-sia of feed samples tekeu just be- fore and just after this sharp drop in flux indicated that the batch of wast- ewaiier which was pmceased by the uuit at that time contained exceptionally ~ high values of or&enic and inorganic contaminants. Par example, the C.O.D. value just before the dmpwaa 315 ppmaudwes 795 just after; the total solids before was 1200 ppm and was 4950 after. However, this drop in flux VI= not recovered when new batches with less contaminants were pmcessed. !phe conductivity rejection ranged fmm 94 > to 98 ya throughout the test.

The \~estinghouse module was operated at feed pressures of 300 psig and 450 psig and this explaina the rapid increase in flux whenever the pressure is increased from 300 psig to 450 psig. The decline p flux is noticeable end th.ia resulted in a decrease in flux fmm S g,/ft at the start of test to 3 gpd/ft* at the end.

The pu Pant module exhibited an initial drop in flux during the first 80 hours of operation but was steady during the rest of operation. Several I~&z" deteqpznt uashes were conducted on this module to prevent Wrflux decline and these were suocessful in achieving this aim.

me flux of the Selas module was kept at about 30 gPd/ft2 by using det- er&z& washes during the first 250 hours of operation. "!ihis flux declined to about 10 gpd/ft2 during the last operating period wren no further deterLent rashes were conducted. A decline in rejection also took place. It was evid- ent that the membrane performance could kept hi& witi frequent detertent washes.

5 successful operation of the test site under zctti field conditions demonstrated the practical apPl.icability of the LO. process for the desali- nation of dye- wastewater. 5 quality of the product water fmm eaoh mod- ule was recycled succeaafully in the dyeing proceee to replaoe tap water whi- ch demonstrated Lao that recycling of this w'mtewater ia perfectly feasible.

1. mviJ= nmental Protection Agency, In-Plsnt Control of Pollution. !rechnolo~ !Prenafer seminar Publioation No. EZA-623/3-74-004, Oct. 1974.

2. Brandon C A -El-IIesher,A.M. aud Forter.J.J.; , - 0, Wypzfiltration Pilot Plent for Textile W&&mater Eenovationns American Dyestuff Reporter, Vo1.64, No. 10, Oct. 1975.

ACKXC- 5autir wi3bee to acborledge tbeoitciL effoxtaof themsininveatigstora; IEa C.A.-n and J-J-Porter and of T..%zgent of the USEPA.

DESALTING OF WASTEWATER FROM TEXTILES 273

!Table 4 Chemical anaIysia of feed and product samples

x4ule U.O.P. ~festin&.mse

Spiral hound Tubulzr

titi& Sample i5nal Lalple I.niti;l janple Yinal Scmple

cuntsminsnt Feed Pmduct Feed Ymduct Teed kmduct Yeed 1miuct

C.O.D. PTP

225 9 380 20 265 75 145 35

B.O.D. 20 2 Dml

15 3__--

Alkalinity 110 10 150 10 - mm

&udness 60 2 - - - - Ppm

95 0.5

Totalsolid- urn

1240 15 2170 b0 1380 40 4190 270

COlOlZ ptco 135 1 fm 1 585 2 1560 45

Turbitity Fru 0.64 6.1 40 0.20 30 0.35 20 2.0

WCiUm 2.2 0.12 0.40 P?xn

4.4 0.06 3.6 Ii.10 4.2

h&zleaium PEm

5.9 0.02 13.0 0.03 5.0 0.03 11.2 0.38

Imn 0.32 0.17 PFm

0.17 0.17

sodium 14 1600 80 PI=

350 5 335 15 370

ma Bmt IiollorFiae Fiber &?%nbrane

C.O.D. 300 10 280 55 150 15 335 50 PP

. . . 90 15 36 7 7 2 25 7 PP

pm 130 10 105 20 55 20 75 30

-se 2 pm

45 10 40 5 15 2 90

Imalsollda 10650 1200 1180 200 040 1140 335 160 PB

color

Pgm Ka+pesiun 0.08 0.06 2.2 0.35

e o-7? 0.003 5.9 1.3

e-- -- 4.0 0.10 4.0 0.1

1660 198 140 44 290 55 470 175 DUII

274 A.M. EL-NASHAK

DESALTING OF WASTEWATER FROM TEXTILES 275

c; 2 R N

276 A.M. EL-NASHAR

200 300 400 limo 600 700 800 O&WiW ‘%%&I$ ( hclx%?8 )

FIGURE 3. CONDUCTIVITY REJECTION AND FLUX FOR THE DlJ PONT NODULE.

l

400 590 600 7@Q

OPEEWIW’I?yIE(~-~

FIGURE 4, CONOllCflVITY REJECTION AND FCUX FOR THE SELAS HODULE

DESALTING OF WASTEWATER FROM TEXTILES 277

%-

94- F

Oo foe 200 300 400 4-m 6Qo 700

tihTxlIG TILE ( hou?.-s )

FIGURE 5. CONDUCTIVITY REJECTION AND FLUX FOR THE UOP UNIT

i:; 2

0 100 m 800 moo ~200

100. OHsttAl~C'~ (ho== j

FIGURE 6. CONDUCTIVITY REJECTION AND FLUX FOR THE C(ESTINGHOUSE HODULE