• K H O A H Q C C O N G N G H f •
NGHIEN CIFU SIF DUNG CAC HQP C H A T C L O Ofi XLF LY COD TRONG NU'QC R I RAC BAI RAC KIEU KY, HA NQI
TS VC DU"C TOAN Khoa Moi tnrdng, Trudng B^i hgc Thuy Lgi
DirONG V A N T U Y E N
Cong ty Co Phan Ky thupt Cong Ngh$ ECOTEK
Tom tat: Bai chon ldp (BCL) rac Kieu Ky hdt ddu vgn hdnh hogt dgng tit ndm 1999 va hi$n nay da dong bdi. Nuac ri rac tgi BCL Kieu Ky co thong s6 COD vd dg mdu cao do thdnh phdn 6 nhiem chil yeu la lignin, hgp chdt humic, fulvic vd cdc chdt hihi ca bin. Cdc hgp chdt do dugc sir dung de nghiin cuu xu ly COD vd mau trong nuac ri rac BCL rac Kieu Ky gdm co Ch, CIO2 vd FeCh. Kit qud nghien cuu cho thdy hi?u sudt xit ly COD vd do mdu khd cao. Hiiu sudt xu ly cao nhdt doi vai COD va do mdu Idn lugt la 90,2% vd 98,6%. Hieu sudt loai bo COD vd dg mdu phu thugc vdo nong dg khdc nhau cua cdc tdc nhdn oxy hoa.
Tir khoa: nudc ri rdc, xii Iy COD, oxy hda, d o hoat tinh.
Abstract: Research on the used of chlorine compounds to cod removal in kieu ky landfill leachate, Hanoi
Kieu Ky landfill has started operation since 1999 and nowaday, it was closed. The leachate in BCL Kieu Ky has high COD and color due to the main pollution component are lignin, humic, fulvic compound and persistent organic pollutants. Chlorine compounds are used to study the treatment of COD and color in Kieu Ky garbage leachate including CI2, CIO2 and FeClj. The obtain results show that efficiency of COD and color removal are very high. The highest removal efficiency for COD and color density are 90.2% and 98.6%, respectively. Removal efficiency of COD and color depending on different concentrations of oxidation agent.
Keywords: leachate wastewater, COD removal, oxidation, active chlorine.
1. M d D A U khd Idn (> 10.000 mg/L) vd ty 1? BOD5/COD >
Chdn ldp rac thdi la qua trinh sii dung phd 0,5. Khi thdi gian van hdnh cua BCL rdc tdng, biln trong xii ly chdt thai rdn dd thi. Nudc ri rdc qud trinh phan hiiy cdc h^p chit hihi co phdn Idn phat sinh tir bai chdn ldp (BCL) cd khd ndng chuyin thanh CH4 vd CO2, d i n ddn COD gidm.
chiia lugng Ion cdc chdt hiiu co dpc hai khd COD tai cdc BCL rdc cd thdi gian van hdnh Idn phan hiiy sinh hpc (Persistent Toxic Subtances, hon 10 ndm thudng cd gid tri < 4.000 mg/L va ti PTS) cdc chit gay mui va cd mau dam. Neu 1? BOD5/COD < 0,1 [5, 6, 13]. Cac phucmg phdp khdng dupc xii ly trudc khi thai ra mdi trudng, xii ly sinh hpc bi han c h i bdi cdc chit hiiu co cdc PTS se gay d nhiem mdi tnrdng nghiem bdn vd ddc cd trong nudc ri rdc. Cdc phuong trpng [2, 6]. Nudc ri rdc thudng cd ndng dp chdt phdp xii ly khdc nhu tuydn ndi, keo ty, Idng d nhilm cao vd thudng xuySn thay ddi theo thdi thudng cho hi^u suat xii ly thip. Cdc phuong gian phan hiiy. Thdng thudng nudc ri rdc ciia phap xu ly cdng nghp mdng Ipc va h i p phu bdng cac bdi chdn lip tre (1-5 ndm) cd nong dp COD than boat tinh laii cd chi phi vdn hanh cao [2],
TAP C H I T A I NGUYEN Nl/<5CS(5 1-2019 15
• KHOA HQC CONG NGHf • Hien nay cdc qud trinh xii Iy oxy hda nang cao
(Advance Oxidation Process, AOPs) dang dupc quan tdm nghien cuu trong Imh vuc xu ly nudc ri rac. Nhilu nghien ciiu cho thdy qud trinh xu ly Fenton cho hi§u suit xu ly COD dat 70% ddi vdi ngudn nudc ri rdc da qua xii ly sinh hpc [10].
Qua trinh xu I;^ UV-Fenton cho hieu suit xu ly COD cd thi dat 80%, hieu qua xii ly mdu dat 90% [9, II]. Tuy nhien cdc phuong phdp ndy thudng cd chi phi xir ly cao, thiet bj phiic tap, khd dp dung vdo quy md cdng nghiep.
DS gdp phan vdo vi?c lam gidm thieu d nhiem mdi trudng ciia nudc ri rdc, nghien ciiu sir dung cdc chit Cio boat tinh (CI2, CIO2) ket hpp vdi chit keo tu (FeCb) de xii ly mdu vd COD khd phdn hiiy sinh hpc trong nudc ri rdc cua BCL cu.
Qua trinh nghiSn ciiu sir d\mg FeCb de xu ly COD trong nudc ri rdc dd dupc thuc hi?n bdi Lee Mao Rui va cac cdng su. Ket qua nghien cuu cho thay d lieu lupng hda chat tdi uu FeCb = 3g/L, COD ban ddu bang 2305mg/L, thdi gian phdn ling 30 phiit, cho hi|u suat xu ly COD vd mdu Idnlupt37%va84%[12].
Npi dung ciia nghien ciiu ndy bao gdm xdc dinh anh hudng cua Iilu lupng CI2, CIO2 va FeCl3 den pH, hieu suat xii ly mau vd COD trong nudc ciia BCL Kieu Ky.
2. PHirONG PHAP NGHIEN ClTU 2.1. Cff sfrly thuyet
Cdc chat PTS, lignin, humic, fulvic... cd trong nudc ri rdc la cdc chat khd phan huy sinh hpc, hda tan tdn tai d dgng ddng thi vd cd ldp dipn tich bl mdt rdt dn dinh. Cac chit nay .rit khd tham gia vao cac phdn ling oxy hda va keo tu vdi cdc tdc nhan rieng re nhu CI2, CIO2, FeCb. Khi trong nudc thdi cd mat ddng thdi ca 3 chit (CI2, CIO2, FeCIa), FeCb ddng vai trd vira Id chit xuc tac vira la chdt keo t\i. FeCU cd khd ndng Idm xuc tac cho CI2, CIO2 phdn ling oxy hda cdc chit hihi co cd trong nudc ri rdc theo phuong trinh:
FeCla
R + (CI2, CIO2) »- R* + (Cr, CIO2") CI2, CIO2 tham gia phdn ling d xy hda nhdn cdc electron ciia chdt hihi co va bi khii thdnh Cl"
, CIO2". cac chit hiiu ca sau qud trinh phdn ling bi suy gidm ldp electron be mdt vd bi oxy hda chuyin sang trang thdi mdt dn dinh R*, d tr^g thdi hi kich thich (R*) cdc chit hiiu co dl ddng tham gia vdo phdn ung keo tu vdi phen sdt FeCla. Kit qud lam tdng hipu qua xii ly COD va mdu trong nudc [1, 3,4,7, 8].
2.2. Thu-c nghifm
2.2.1. Mau nircrc thai thi nghidm Mau nudc ri rdc BCL Kidu Ky dd qua qua trinh phan huy yem khi duoc lay true tiep vao can nhua 30 lit khdng cham hda chdt bdo quan, sau dd dupc van chuyen ngay ve phdng thi nghi?m de tien hdnh phdn tich vd thi nghiem.
Thdi gian Idy mau vd tien hdnh thuc nghipm la thang 4 nam 2018.
2.2.2. Hda chat thi nghifm
- Natri clorat NaCIOj: Su dung hda chit thucmg phdm NaClOa dang tinh thi mau tring dp tinh khilt 99%, xuit xii Trung Qudc
Axit clohidric HCI: Sir dung hda chit thuong phim HCI d ^ g dung dich 32%, xudt xii Viet Nam.
- Phen sdt 3 clorua FeCb: Su dung hda chit thuang phdm FeCla dgng tmh thi mdu ndu dd dp tinh khilt 96%, xuit xii Trung Qudc.
2.2.3. Phirffng phdp phan tich Cac thdng sd cua nudc thai dupc xdc dinh theo cdc TCVN gdm:
pH xdc dinh bdng qui trinh trong TCVN 6492:2011.
COD xdc dinh bdng qui trinh trong TCVN 6491:1999.
Dp mdu xdc dinh bdng qui trinh trong TCVN 6185:2008.
2.2.4. Phirong phdp thuc nghiem Qua trinh thuc nghiem dupc thuc hipn theo cdc budc gdm:
16 TAP CHfTAl NGUYEN Nl/(3C S(5 1-2019
• K H O A H p c C O N G N G H E •
B u ^ c 1; Chuin bj cac dung dich NaClOs (ndng dp 0,5g/ml) va dung dich FeCls (ndng dp 0,lg/ml).
Birdc 2 : Didu chd Cl2vaC102
CI2 va CIO2 dupc dieu che theo phan ling sau [8];
2NaC103 + 4HC1 = 2 N a C l + 2CIO2 + CI2 + 2H2O
Dung dich sau phan ilng dupc ky hi$u la ddi, CO ndng dO CIO2 = 0,158 g/ml, CI2 = 0,083 g/ml.
Bu-dc 3 : Th\rc hipn thi nghipm
Thuc hidn thi nghidm nghien ciiu biuig thidt hi khuay phan ling Jartest. Qua trinh thuc nghiem dupc md ta trong hinh 1.
Mau nudc thai
Cac cdc 500ml
KhuSy ISOv/phiit (5 phut)
Khuay 150v/phiit (10 phit)
:E
m g ^Khuay SOv/phiit (3 phut) Dpi ling vd quan sat
X
(8 phiit)
i
Tach nudc trong cung vdi mau nudc dau vao
mang di ipc Phan tich COD, mau,
i
pH
Hinh 1. Sa do thi nghiem khdo sdt Jartest
3 . K E ; T Q U A N G H I E N C U t J VA T H A O L U A N
3.1. Ket q u a k h a o sat a n h hirdng cua iilu lu^ng FeCIa den fai^u s u i t xu* \^ C O D va mdu
Ket qud ciia qud trinh nghiSn ciiu khdo sdt dupc t h i hien trong bdng 1 vd hinh 2. Anh hudng cua Iilu luong FeCla dSn hieu suat xur ly mdu vd COD, dupc khdo sdt bdng each thay ddi Iilu luang FeCIs trong khodng tu 0,1 g/L den 0,5g/L.
Bang 1. Ket q u a thi nghifm khao sat anh h u d n g cua Iilu l u p n g FeClj d i n hifu suat
x u ly m a u vd C O D
FeCl3(g/L) 0 0,1 0,2 0,3 0,4 0,5
COD (mgflL)
850 620 475 356 313 245
Miiu (Pt-Co)
3480 2296 1281 816 433 295
pH 8,0 7,6 7,3 7,2 7 6,5
HcOD - C O D o /CODsaux*!]?
HmSu = Dp mau ban dau/dp mau sau xii ly
1 0 0 -HCOD (%)
Hinh 2. Hieu sudt xic ly COD vd mdu bang FeCh
TAPCHfTAl NGUYEN Nl/(5CS6 1-2019 17
• KHOA HQC CONG N G H $ • Ket qua tir bdng 1 va hinh 2 cho thay, khi
tdng lupng FeCb tir 0,lg/L din 0,5g/L, hipu suit xu- ly mdu tang tir 34% len 91,5%, hieu suit xir ly COD tdng tir 27% ISn 71,2%). Tdng Iilu lupng FeCls ddng nghia vdi vi?c tang chdt keo tu vdo nudc. Chat keo t\i ndy phdn ung tao ra cac hat keo duong. Cdc hat keo ndy se tuong tdc vdi cdc hgt keo dm trong nudc d dang cdc chat hiiu co gay due, chat mang mdu ldm gidm COD vd mdu trong nudc [1,4].
pH cua nudc giam dan 8 xudng 6,5 theo chilu tdng Iilu lupng FeCIs do FeCb cd tinh axit.
3.2. Kit qua khao sdt anh hudng cua lieu lupng CI2, CIO2 den hi^u suat xu ly COD va mau Ket qud cua qud trinh nghien cuu khdo sdt dupc thi hien trong bang 2 va hinh 3.
Bang 2. Ket qua thi nghifm khao sat anh hudng cua lieu lu^ng CI2, CIO2 den hif u suat
xu ly mau va COD CI2
(R/L) 0 0,08 0,16 0,25 0,33 0,42
CIO2 0 0,16 0,32 0,47 0,63 0,79
COD (msfL) 850 650 550 400 290 430
Miu (Pt-Co)
3480 2513 1967 1164 592 534
pH 8,0 7,5 6,5 6.1 5,5 4,5 HCOD(%)
Hinh 3. Hi$u suit xii ly COD va mdu bing hdn hgp Ch, ClOi
Anh hudng cua lidu lupng CI2, CIO2 ddn hi^u SU& xOt ly mau va COD dupc khao sat bang each thay ddi lidu lupng CI2 (tir 0,08 g/L din 0,42 g/L), CIO2 (tCr 0,16 g/L den 0,79 g/L) dupc the hipn trong bang 2, hinh 3. Kdt qua cho thSy, khi tang lieu lucmg CI2 va CIO2, hieu suit lo^i bd COD tang tit 23,5% len 71,2% h-ong khi hifu stxkt loai bd mau tSng tit 27,8% len 87,6%.
Khi tang lidu lupng CI2, CIO2 thi hieu qua lam giam COD va dp mau trong nudc tang len [7, 8]. Kdt qua th^c nghiem cho thSy, khi tang lidu lupng CI2 til 0,08 g/L ddn 0,33 g/L, CIO2 tir 0,16 g/L ddn 0,63 g/L thi hieu suat loji bd mau va COD tang manh. Trong khi tang lidu lupng CI2 tir 0,33 g/L ddn 0,42 g/L, CIO2 tir 0,63 g/L den 0,79 g/L, hieu suit loai bd mau va COD tang khdng dang kd. pH cua nudc giam din 8 xudng 4,5 do trong dung dich oxy hda sau phan ling dimg dd thi nghiem cdn du axit HCI.
3.3. Ket qua khao sat anh hu-dng ciia lieu lu-pug CI2, CIOj vi FeCl3 d^n htfu suit xu ly COD va mau
Anh hudng cua lieu lupng CI2, CIO2 va FeCls ddn hieu suit xu 1^ mau va COD dupc khao sat bang each thay ddi lidu lupng CI2 (tir 0,08 - 0,42 ga,), CIO2 (tir 0,16 - 0,79 g/L), FeClj (tir 0,1 - 0,4 g/L) duac thd hien f ong bang 3, hinh 4 va Wnh 5.
Ket qua cho thiy, khi tSng lidu lupng CI2 (tit 0,08 ikn 0,42 g/L), CIO2 (til 0,16 d& 0,79 g/L) v4 FeCh (ttr 0,2 ddn 0,5 g/L), pH cua nudc giam din.
Bang 3. Ket qua thi nghifm khao sit anh hirong ciia lieu lu-ong FeCIj va CI2, CIO2 sin
hifu suit xir Iy mau va COD FeCb
(g/L) 0 0,2 0,2
CI2 (ga^)
0 0,08 0,16
CIO2 (ga-) 0 0,16 0,32
COD (mga,)
850 450 293
Mau (Pt- Co) 3480 1710 818
pH 8 7 6,5
18 TAP C H l T A l N G U Y e N N U e c s a 1-2019
• KHOA HQC CONG NGHE •
FeClj (g/L) 0,2 0,2 0,2 0,3 0,3 0,3 0,3 0,3 0,4 0,4 0,4 0,4 0,4 0,5 0,5 0,5 0,5 0,5
Ch (g/L)
0,25 0,33 0,42 0,08 0,16 0,25 0,33 0,42 0,08 0,16 0,25 0,33 0,42 0,08 0,16 0,25 0,33 0,42
CIO2 (g/L) 0,47 0,63 0,79 0,16 0,32 0,47 0,63 0,79 0,16 0,32 0,47 0,63 0,79 0,16 0,32 0,47 0,63 0,79
COD (mg/L)
215 196 184 275 210 171 155 146 211 175 157 132 115 145 116 103 94 83
M a u (Pt- Co) 312 181 217 885 257 106 212 229 648 148 163 193 299 50 117 180 267 393
pH 6,2 5 4,5 6,7 6,2 4,5 4,2 3,6 6,5 6,0 4,5 3,5 3,2 6,2 4,5 4,0 3,5 3,0
-FeC13 = 0,2g/L - F e C 1 3 - 0 , 4 g / L
0,08.0,160,16.0,320,25.0,470,33.0,630,42.0,79
CI2.C102 (g/L)
-FeCI3 = 0,2g/L -FeCI3 = 0,4g/L
Hinh 4. Hieu sudt xu ly COD cita Ch, Cl02vdFeCh
Hinh 5. Hieu sudt xi^ ly mdu bdng hon hgp Ch. Cl02vd FeCh
Hieu sudt loai bd COD tdng manh tir 51,2%
len 90,2%. Hi?u suat loai bd mau dat 98,6% tai dilm CI2 = 0,08 (g/L), CIO2 = 0,16 (g/L), FeCh
= 0,5 (g/L).
Khi tdng tang Iilu l u ^ g CI2, CIO2 ddng nghia vdi vi?c gia tdng Cio hoat tinh trong nudc.
Cio ho^t tinh se phdn ling vdi cdc chat hftu co vd bi khii thdnh Cl', CIO2' [7, 8]. Cdc chdt him ca sau phan ling b; suy gidm ldp electron bl mat vd bi oxy hda chuyen sang trang thdi mdt dn dinh, d trang thdi nay cac chat h&u co de dang tham gia vdo cdc phan ling keo tu vdi phen sdt FeCl3 [1, 4], ket qua ldm gidm COD vd mdu trong nudc. Tuy nhien khi tdng lieu lugng CI2, CIO2 len qud cao s6 dan tdi du thiia chdt oxy hda trong nudc ldm tang dp mdu trong nudc (CIO2 cd mdu ndu dd).
Anh hudng cua FeCla, khi tang Iilu lugng FeCla ddng nghla vdi viSc gia tang chdt xiic tac va chat keo tu vdo nudc. FeCls Id mudi mang tinh axit, cd khd ndng tham gia xiic tdc cac TAPCHfTAl NGUYEN NaCfCS6 1-2019 19
• KHOA HQC CONGNGH5 • phdn ling cua CI2, CIO2, vdi cac chdt huu co cd
frong nudc thdi [3]. Ddng thdi FeClj Id ciing tham gia phdn ling keo tu vdi cdc chdt hiiu co trong nudc sau Ichi hi oxy hda bdi CI2, CIO2, kit qua lam giam COD vd mdu trong nudc.
Tuy nhien khi tang Iilu lugng FeCb len qud cao din tdi du thira FeCh trong nudc, ddn den pH cua nudc giam.
Ket qua ciia qud trinh nghien ciiu cho thay d ndng do hda chdt tdi uu FeCU = 0,5g/L, CI2 = 0,08g/L, CIO2 = 0,16g/L, Vi?c sii dung rieng re timg tdc nhdn cho hieu sudt xii ly COD va mau thdp hem nhieu so vdi trudng hgp sii dung ket hgp, hieu suat cua qua trinh xu ly d ndng dp hda chdt tdi uu dugc the hi?n trong bdng 4.
Bang 4. So sanh hi^u suat xu- ly COD va mdu ct nong do hoa chat toi iru
Hieu sudt xii
ly(%) HcoD Hmiu pH
FeCl3=
0,5g/L
71,2 91,5 6,5
Cl2=
0,08g/L ,C102 = 0,16g/L 23,5 27,8 7,5
FeCl3= 0,5g/L, CI2 = 0,08g/L, ClO2=0,16g/L
83 98,6
6,2 4. KET LUAN
Ket qua cua qud trinh nghien cilu cho thiy vipc su dung rieng re cac tac nhan CI2, CIO2 va FeCls cho hipu suit xil ly nudc ri rac khdng cao.
Tuy nhien khi sir dyng kdt hop, FeCls lam chit keo tu va xiic tac cho CI2, CIO2 phan ring oxy hda cac chat him ca trong nudc da cho thiy hieu qua xir ly vuot ttdi so vdi viec sil dung rieng re timg tac nhan. Hipu suit xil ly COD va mau lin lupt dat 83% va 98,6% tai didm ndng dp hda chit tdi uu FeCls = 0,5g/L, CI2 = 0,08g/L, CIO2
= 0,16g/L. Hipu suat xu ly COD tSng Idn 90,2%
khi sil dung du lidu lupng CI2 = 0,42g/L, CIO2 = 0,79g/L, tuy nhien hieu suit xu ly mau gi&n 88,7%, hipu suit xil ly mau gihn do du thira ciia CIO2 trong nudc.
TAI LlfU THAM KHAO 1. Hoang Van Hue, Trin Dllc Hj. (2002), Thodt nuac tap 2 xit ly nuac thdi. Nha xuit ban khoa hpc va ky thuat.
2. Hoang Ngoc Minh, "Nghien cuu xit ly nuac thdi chita cdc chdt hiiu ca kho phdn hiiy sinh hoc bdng cdc phucmg phdp oxy hoa ndng cao", Luan an tien sT, Trudng D^ hpc Bach Khoa Ha Ndi, Ha Npi 2012.
3. Nguydn Minh Thao. (2005), Tdng hap hieu CO, NXB Dai hpc Qudc gia Ha Ndi.
4. Trin Vto NhSn, Ngd Thi Nga. (2002), Gido trinh cong nghe xit ly nudc thai. Nha xuit ban khoa hpc va ky thu^t.
5. Calace N., Liberatori A., Petronio B.M., Pietroletti M. (2001), "Characteristics of different molecular weight fiactiora of organic matter in soil sorption of heavy mettals", Environ. Pollut.., Vol 113, No. 3,331-339.
6. Deng Y., James D. Englehardt. (2006),
"Treatment of landfill leachate by the Fenton process". Water Ress.., Vol40,3683-3694.
7. Howard AUiger. (2011), overall view of chlorine dioxide (CIO2). Frontier pharmaceutical, Inc, 10 Ponderosa Drive, Melville, New York 11747...
Nguoi phdn bi$n: TS. Nguyin Thj Thu Hien Phdn bifnxong: 12/2018
20 TAP CHdAlNGUYfNNl/dC 561-2019