X l nc thi cng nghip dt nhum bng qu trnh Peroxone

Nc thi cng nghip dt nhum c kim, mu v hm lng cc cht hu c, tng cht rn rt cao do s dng rt nhiu loi ha cht trong quy trnh cng ngh. Trong , mu l mt trong cc thnh phn kh x l nht. Bi bo trnh by cc kt qu nghin cu x l mu v COD kh phn hy sinh hc (COD tr) ca nc thi dt nhum khu cng nghip dt may Ph Ni (Hng Yn) bng cc qu trnh oxy ha nng cao (Advanced Oxidation Processes - AOPs) trn c s ozone l qu trnh Peroxone cp th nghim trn h thng Pilot Study t kt qu, c th nghin cu nng ln quy m sn xut thc t.

1. t vn

Nc thi cng nghip dt nhum gm c cc cht nhim chnh: Cc tp cht tch ra t vi si nh du m, cc hp cht cha nit, pectin, cc cht bi bn dnh vo si; Cc ha cht s dng trong quy trnh cng ngh nh h tinh bt, H2SO4, CH3COOH, NaOH, NaOCl, H2O2, Na2CO3, Na2SO3... cc loi thuc nhum, cc cht tr, cht ngm, cht cm mu, cht ty git. Lng ha cht s dng ty thuc loi vi, mu v ch yu i vo nc thi ca cc cng on sn xut.

Nc thi dt nhum lun dao ng rt ln v lu lng v ti lng nhim, thay i theo ma, theo loi hng sn xut v cht lng sn phm. Tuy nhin, cc c trng nhim ca nc thi cng nghip dt nhum Vit Nam gm: pH = 9,0 - 11,0; BOD = 90 - 220 mg/L; COD = 570 - 1200 mg/L; TSS = 800 - 1100 mg/L; mu= 1000- 1600 (Pt-Co).Hin nay, cng ngh x l nc thi dt nhum, v c bn qua cc bc sau: Tch rc - X l ha hc - X l ha l - X l sinh hc -Hp ph bng than hot tnh - Kh trng - X ra ngun tip nhn.

Cc phng php ha hc, ha l truyn thng x l nc thi dt nhum l trung ha iu chnh pH, ng keo t, hp ph, oxy ha. Tuy nhin, mu v mt s cht hu c kh phn hy sinh hc trong nc thi dt nhum rt kh x l, gy mu ti cho ngun tip nhn, nh hng ti qu trnh quang hp ca cc loi thy sinh, nh hng xu ti cnh quan.

Chng ti nghin cu p dng cc qu trnh oxy ha nng cao trn c s ozone x l mu v COD kh phn hy sinh hc ca nc thi dt nhum khu cng nghip dt may Ph Ni (Hng Yn) thuc Tp on Dt may Vit Nam.

2. C s nghin cu

Cn c cc thng s c trng nhim thc t ca nc thi dt nhum khu cng nghip dt may Ph Ni (Hng Yn) v Quy chun Vit Nam QCVN 13:2008/BTNMT - Quy chun k thut quc gia v nc thi ca cng nghip dt may nghin cu quy trnh x l mu v COD tr ca nc thi t kt qu tt nht.

C s khoa hc nghin cu l cc qu trnh oxy ha nng cao v ng dng trong cng ngh x l nc v nc thi trn th gii v Vit Nam.

Qu trnh oxy ha nng cao

Cc qu trnh oxy ha nng cao AOPs l mt trong nhng cng ngh cao c pht trin trong khong 20 nm tr li y. AOPs l nhng qu trnh phn hy oxy ha da vo cc gc t do hot ng hydroxyl *OH c to ra "in situ" ngay trong qu trnh x l.

Gc *OH l mt tc nhn oxy ha mnh nht trong cc tc nhn oxy ha t trc ti nay, c kh nng oxy ha khng la chn vi mi hp cht hu c, c nhng cht kh phn hy hoc khng phn hy sinh hc, bin chng thnh nhng hp cht v c nh CO2, H2O, cc axit v c...

Cc tc nhn oxy ha thng thng nh H2O2, O3, c th nng cao kh nng oxy ha ca chng bng cc phn ng ha hc khc nhau to gc *OH, thc hin qu trnh oxy ha gin tip thng qua gc *OH.

Di y l mt s qu trnh oxy ha nng cao c ng dng trong cng ngh x l nc v nc thi.

Qu trnh Fenton

Qu trnh Fenton (hay phn ng Fenton) l phn ng gia ion Fe2+vi H2O2 sinh ra cc gc t do *OH, cn Fe2+ b ion ha thnh Fe3+.

Fe2+ + H207 -> Fe3+ + *OH + OH-GC *OH oxy ha cc cht hu c kh phn hy sinh hc, phn hy chng thnh cc cht v c hoc cc cht c phn t lng thp hn, c kh nng phn hy sinh hc.Theo phng trnh (1), phi c ion Fe2+ to ra gc *OH, trong iu kin pH thp mi tn ti ion Fe2+, hiu qu nht l pH 3, cn trong iu kin pH cao s to thnh Fe3+ v kt ta Fe(OH)3 (phng trnh 2), phn ng Fenton s xy ra rt chm.

Fe3+ + 3OH- -> Fe(OH)3 (2)

Qu trnh Peroxone

Qu trnh oxy ha ca ozone vi s c mt ca H2O2 c gi l qu trnh Peroxone hoc Perozone. S khc nhau gia qu trnh Ozone v Peroxone l qu trnh Ozone thc hin oxy ha cc cht nhim trc tip bng phn t O3 trong nc, cn qu trnh Peroxone thc hin oxy ha cht nhim gin tip thng qua gc *OH.

C ch phn ng to gc *OH t h O3/H2O2 theo phng trnh (3). H202 + 3O3 -> 2 *OH + 3O2 (3)

Phn ng (3) cho thy, qu trnh Peroxone c th tin hnh trong iu kin pH trung tnh. Hiu qu phn hy cc cht nhim hu c ca h O3/H2O2 cao hn nhiu so vi tc dng oxy ha ca O3 n v c tc nhn *OH c sinh ra trong qu trnh phn ng.

Qu trnh Cataione ng thQu trnh Catazone l qu trnh a vo h O3/H2O2 cc cht xc tc nng cao hot tnh oxy ha ca ozone.

Cht xc tc kim:

C ch to gc t do hydroxyl *OH trong mi trng nc vi cht xc tc kim OH- nh sau [4]:

H2O2 + 3O3 2*OH + 3O2 (4) Cht xc tc kim loi

Cho vo h O3/H2O2 cc lon kim loi chuyn tip c tc dng nng cao hot tnh oxy ha ca ozone.

i vi xc tc st Fe2+: Cho vo h O3/H2O2 dung dch FeSO4 s to gc *OH v to thnh Fe3+. Trong trng hp ny Fe2+ l cht tham gia phn ng v b tiu hao trong qu trnh phn ng:

H2O2 + 3O3 - 2 * OH + 3O2 (5)

i vi xc tc nhm Al3+: Cho vo h dung dch phn nhm Ab(SO4)3. C ch phn ng c th nh sau: Trong mi trng nc, Al3+ to thnh Al(OH)3 kt ta v cc bng keo ny hp ph mt phn COD v cht mu trong nc, lm nng COD cao hn trong nc. Khi c O3 kt hp vi H2O2 s to ra gc *OH v xy ra phn ng phn hy cht hu c trong nc, do trong cc bng keo c nng cht hu c rt cao nn tc phn ng tng mnh, gim nng cht hu c v tip tc qu trnh hp ph cht hu c vo bng keo v qu trnh phn hy COD v mu nc thi tip din.

Qu trnh Cataione d th Qu trnh Catazone d th l qu trnh a vo h O3/H2O2 cc cht xc tc rn l cc oxit kim loi chuyn tip hoc than hot tnh.

C ch qu trnh Cataione xc tc d thTheo Legube et ai. (1999), c ch phn ng Catazon d th c th xy ra theo 2 kh nng sau y:

+ Cht xc tc ch ng vai tr nh mt cht hp ph Me-OH, ozone v gc hydroxyl to ra t s phn huy ozon s l tc nhn oxy ha.

+ Cht xc tc c th tc dng vi c ozon v cht hu c hp ph trn b mt, ng ngha vi bn cht ca qu trnh xc tc.

La chn qu trnh AOPs thch hp x l nc thi dt nhum

Vi c trng nhim ca nc thi dt nhum l c mu cao v COD kh phn hy sinh hc, pH = 9 - 11, chng ti la chn qu trnh AOPs trn c s ozone l Peroxone nghin cu x l nc thi dt nhum.

3. Tin hnh th nghim

a. Chun b th nghim

Nc thi u vo th nghim ly ti b iu ha trm x l nc thi khu cng nghip dt may ca Tp on Dt - May Vit Nam ti Ph Ni (Hng Yn).

b. Ha cht

Ha cht keo t PAC cng nghip, cht tr keo t: Polymer A101, Polymer c cng nghip. Phn nhm Al2(S04)3.18H20 cng nghip lm cht keo t v xc tc ong th. FeSO4.7H2O tinh khit lm cht xc tc ng th. H2O2 cng nghip nng 55%. H2SO4; NaOH tinh khit dng pha ch dung dch iu chnh pH.

c. Thit b th nghim

+ H thng thit b th nghim Pilot Study x l nc thi kh phn hy sinh hc bng cc qu trnh oxy ha nng cao trn c s ozone cng sut 2 x 8gO3/h do Vin Khoa hc v Cng ngh mi trng (HBK H Ni) ch to.

d. Phng php v thit b phn tch

Phn tch kt qu th nghim ti phng th nghim Nghin cu v pht trin cng ngh mi trng -Vin Khoa hc v Cng ngh Mi trng (HBK H Ni). pH xc nh theo TCVN 6492:1999, thit b o pH meter - USA; COD xc nh theo TCVN 6491:1999, thit b DRB 200 - USA; mu xc nh theo TCVN 6185:1996, thit b Quang ph k UV - vis Perkin Elmer.

e. Trnh t qu trnh th nghim

+ X l s b nc thi dt nhum bng qu trnh keo t

Keo t nc thi dt nhum bng PAC v Polymer C vi ch nh sau:

+ Th tch mu keo t : 20 lt + Nng cht keo t: 5 gPAC/L + Nng cht tr keo t: 3 ml Polymer C/L + Thi gian lng: 2 h.

Sau khi bng keo t lng hon ton v phn lp, tch ly nc trong sau keo t x l bc oxy ha bng Peroxone v Catazone. Ly mu nc thi trc v sau keo t, bo qun phn tch.

+ Th nghim x l nc thi dt nhum sau keo t bng qu trnh Peroxone

X l nc thi dt nhum sau keo t bng qu trnh Peroxone trn thit b Pilot Study vi ch nh sau:

+ X l bng ozone n: H O3 + X l bng Peroxone: H O3/H2O2 4. Kt qu v tho lun + Theo Quy chun Vit Nam QCVN 13:2008 - Quy chun k thut quc gia v nc thi cng nghip dt may nh sau: v ch tiu mu: Ct A: 20 (Pt - Co) i vi c s mi, 50 (Pt - Co) i vi c s ang hot ng; Ct B: 150 (Pt - Co). V ch tiu COD: Ct A: 50 mg/L; Ct B: 150mg/L.

Ghi ch: Ct A quy nh gi tr cc thng s nhim cho php thi vo cc ngun nc dng cho mc ch cp nc sinh hot. Ct B quy nh gi tr cc thng s nhim cho php thi vo cc ngun nc khng dng cho mc ch cp nc sinh hot.

Kt qu x l bng qu trnh Peroxone trn Pilot Study t yu cu v ch tiu mu theo Ct A. i vi ch tiu COD, phi x l bng cc qu trnh sinh hc t Quy chun, qu trnh Peroxone c th l qu trnh x l cui cng hoc trc qu trnh hp ph bng than hot tnh.

+ Khi x l bng ozone n (O3) khng x l c mu, ch gim COD trung bnh khong 15 - 18%.

+ X l bng h Peroxone (h O3/H2O2) c hiu qu trong khong nng H2O2 t 250 - 500 mg/L. X l mu t 90 - 99%, x l COD t 39 - 80%. Khi tng nng H2O2 u vo t 250 mg/L ln 500 mg/L th hiu qu x l tng. Tuy nhin, khng nn tng nng H2O2 qu cao v s c ch vic sinh ra cc gc t do *OH, lm gim hiu qu qu trnh theo c ch *OH + H2O2 H2O + *HO2 [4].

+ Nc thi dt nhum sau x l loi c mu gn nh tuyt i (>99%), iu khng nh u th ca qu trnh Peroxone v hiu qu x l mu ca thuc nhum.

+ i vi x l nc thi dt nhum bng qu trnh Peroxone (h O3/H2O2) c hiu qu hn nhiu so vi x l bng ozone n v qu trnh Peroxone hiu qu to ra do tc dng oxy ha ca gc *OH v c O3, trong khi x l bng ozone n ch c tc dng oxy ha ca O3.

5. Kt lun

+ Trc khi x l nc thi cng nghip dt nhum bng cc qu trnh Peroxone phi keo t tin x l nc thi th loi b cc cht rn l lng, bn v loi b mt phn COD ha tan, gim ti cho qu trnh oxy ha nng cao.

+ Kt qu x l COD tr v mu nc thi dt nhum trn h thng thit b Pilot Study bng cc qu trnh Peroxone t yu cu ca QCVN 13:2008 v cc ch tiu mu. Cn phi x l COD bng qu trnh sinh hc t quy chun. quy m th nghim cho kt qu tt nhng cn nghin cu thm c th p dng quy m ln hn.

+ Cht oxy ha l ozone c sn xut ti ch, khng phi vn chuyn v lu gi. Cc qu trnh ny tin hnh c hiu qu trong iu kin mi trng c pH = 7 - 9.+ Hn ch khi p dng cc qu trnh oxy ha nng cao trn c s ozone l thit b to ozone c gi t, c bit l cc thit b cng sut ln, phi nhp ngoi nn kh khn trong cng tc sa cha khi c s c h hng thit b. Do , vic nghin cu ng dng cc qu trnh oxy ha nng cao trn c s ozone x l nc thi cng nghip dt nhum phi xem xt iu kin v k thut v ti chnh.+ Cn c nghin cu ng dng qu trnh Catazone ng th so snh hiu qu vi qu trnh Peroxone. Qu trnh Catazone ng th vi cht xc tc nhm Al3+ v st Fe2+ s c hiu qu kp l "oxy ha/ keo t" nn chc chn hiu qu s cao hn khi x l nc thi dt nhum bng qu trnh Peroxone.

TI LIU THAM KHO

1. L Vn Ct - C s ha hc v k thut x l nc. Nh xut bn Thanh Nin, 1999;

2. L Vn Ct - X l nc thi giu hp cht nit v pht pho - Nh xut bn Khoa hc t nhin v Cng ngh. H Ni, 2007;

3. Nguyn Vn Phc, V Ch Cng - Nghin cu nng cao hiu qu x l COD kh phn huy sinh hc trong nc rc bng phn ng Fenton - Tp ch Pht trin Khoa hc v Cng ngh, tp 10, s 01-2010.

4. Trn Mnh Tr, Trn Mnh Trung - Cc qu trnh oxi hoa nng cao trong x l nc v nc thi - C s khoa hc v ng dng - Nh xut bn Khoa hc v k thut, 2005.

5. Trn Vn Nhn, Ng Th Nga - Gio trnh Cng ngh x l nc thi. Nh xut bn Khoa hc v k thut. H Ni, 1999.

6. Abdo, M.S.E., Shaban, H., Bader, M.S.H (1988). Decoloiation by ozone of direct dyes in presence of some catatysts. J. Environ. Sci. Health A23, 697.

7. Adel Al-Kdasi, Azni Idris, Katayon Saed, Chuah Teong Guan. Treatment of textile wastewater by advanced Oxidation Processes - A review. Global Nest: the Int. J. Voi 6, No 3, pp 222-230, 2004.

8. Advanced Phisico - chemical Treatment Processes. Edited by Lawrence K. Wang, Yung - Tse Hung, Nazih K. Shammas. Hummana Press, 2006;

9. Craig w. Jones - Applications o/Hydrogen Peroxide and Derivatives. The Royal Society of Chemistry, 1999.10. Melike Yalili Kilic, Kadir Kestioglu and Taner Yonar - Landyill leachate treatment by the combination of physicochemical methods with adsorption process - Biological Environmental Science, 2007, 1(1), 37 - 43.

11. Simon Parson (2004) - Advanced Oxidation Processes for Water and Wastewater Treatment, IWA Publishng, Alliance House, London, UK.

12. Univeritat de Barcelona - Fenton and UV-vis based advanced oxidation processes in wastewater treatment: Degradation, mineralization and biodegradability enhancement. Mguel Rodriguez, Barcelona, April, 2003.DYE-TEXTILE WASTEWATER TREATMENT BY PEROXONE PROCESS

Nguyn Ngoc Lan, Hoang Ngoc Minh, Duong Thi Thuy Linh

Institute of Environmental Science and Technology Hanoi Universitv o/Science and Technology.

Dye-textile industry wastwater contains high alkality, colour, high on centration of organics, high total suspend solid because of many chemicals used in technology. In there, colour and COD non-biodegadability are most difficult to eliminate.This paper shows the results of studying on elimination of colour and COD non-biodegradability of dye - textile vvastvvater of Textile Industrial Zone Pho Noi (Hung Yn) by Advanced Oxidation Processes (AOPs) based n ozonation - Peroxone process with Pilot Study, It may be studied to lager scale for production.Nguyn Ngc Ln, Hong Minh Ngc, Dng Th Thy Linh

Vin Khoa hc v Cng ngh Mi trng i hc Bch khoa H Ni

Theo TCMT 09/2011