l ^ i S n Giita - Trao d&
4 a i suf dung bun thai chufa l(im loai nang 0e
„9san xuat gach Ichdng nung tren co sor on djnh hoa ran bang xi mang va polyacrylamit
O GS.TS. N G U Y I N VAN KHOI, ThS. TRAN VU T > ^ G , ThS. HOANG THj PHUONG, CN. NGUYEN VAN MANH Vidn Hda hgc, Vien Han Lam Khoa hgc vd Cdng nghd Vidt Nam
ThS. PHAN MINH TAN Trudng Dai hgc Cdng nghidp Vidt Tri
A
nh hudng eda hdm luang bun thai ddn tinh chdt gach be tdng va ham luang kim loai ndng bi thdi nhidm khdi gach da dupe nghiSn cdu. Cifdng dg udn vd eudng dp nen eua ede mdu gach dupe xae dinh sau 10, 28 va 90 ngay ddng ran. Kei qua nghien cdu cho thd'y, khi hdm lugng bun thay the edt trong gach tdng td10 - 50% thi cudng dp udn vd cudng dp ndn eua edc mdu gach giam. Tieu chuan TCVN 9239:2012 dupe sddyng dd xae dinh lupng kim loai ndng bf rtia trdi khdi edc mdu gach. Kei qua cho thdy, ham lupng kim loai ndng bi rua trdi khdi mdu gach ed chdd polyme Id thap hon so vdi mdu khdng chda polyme vd thd'p hon gIdS han cho phep theo tidu chudn QCVN 07: 2009/BTNMT.Lupng bun thai hang ndm khdng ngCmg gia tdng do qua trinh dd ttij hda vd CNH. Hau het edc kim loai ndng nguy hai (Zn, Pb, Cr, Ni, Hg, Cd, Sn va Va) deu dupe tim thd'y trong bun thai vdi ham lupng tUdng dd'i cao, gap nhidu lan gidi ban cho phep [1].
Khi thai bo tuy tien bun thai vdo mdi tnidng, kim loai ndng se de dang phat tdn sang mdi trudng dat, nUdc mdt vd nUdc ngam. Day Id mdi nguy hilm tiem tang ddi vdi sQc khoe cOa con ngudi eung nhu be sinh thai tu nhien. Kim loai ndng thudng tdn tai frong bun dudi 5 dang: dang ion; dang lien ket cacbonate; dang lien ket trong hode Idp phO ben ngoai khdi (hat)
ran vdi sat oxyt vd mangan oxyt;
dang lien kdt trong cdc phQe chat hifu CO; dang tro, ben, giu trong
cau trOc cae hat khodng, khdng bj giai phdng trong dieu kidn tU nhien [2].
Toi nguyen vd Moi traong | Ky 2-Thing 8/2015 ^J
Vide sQ dung xi mdng c d djnh bun thai la mdt giai phap dupe dp dung p h i bien trong thdi gian gan day. Joan [3] vd cdng s u dd tidn hanh nghien cCru anh hudng cOa gach khdng nung tQ bOn thai den mdi trQdng, mQc dp thdi nhiem vd ddc tfnh cOa kim loai ndng. Kdt qua cho thay, bun cd t h i dupc sQ dung d l san xudt gach khdng nung vdi hdm iQdng tQ 5 de'n 2 5 % khdi lupng. Trdn ed sQ nghien cQu Cfng dung cOa bun thai. Wells [4] vd cdng sU dd nghien cQu tiem ndng sQ dung bun khd nhU phu gia trong bd tdng. Bun thai dUpc say khd d l giam hdm I m va tdch cac vi sinh vdt. K i t qua cho thay, cudng dd nen cOa be tdng gian khi tdng ham lupng bun. Khi ham IUdng bOn trong bd tdng cao hon 10%
thi thdi gian ddng ran tdng va tfnh chat co ly giam dang k l . Tuy nhien, cac nghien cQu tren ehi dCmg lai b vide c d dinh bun thai bang xi mdng, khdng de cap ddn mQc dp thdi nhiem cOa kim loai ndng ra mdi trudng. Viec thdm polyme vdo bun thai trudc khi ddng ran d l tdng hidu qua c d dinh kim loai ndng do polyme cd kha ndng tao phQc vdi nhidu kim loai ndng.
Bai bao nay nghien cQu anh hudng cOa bun thai ddn tfnh chat gach khdng nung vd anh hudng cOa polyacrylamit den kha ndng c d djnh kim loai ndng trong bOn thai.
Thuc nghiem NguySn USu
Bun thai dupe lay sau cdng doan dp bun trong he thd'ng xiJf ly nudc thai d dang khd, ham I m 8 - 10%, bun sau dd dupe nghidn vdi kfch thudc 1.5 - 2.5 m m . Xi
Bang 2 . 1 . Thanh phan dOn phdi lidu san xuit gach khdng nung Ky hieu mau
Ro Rio
R20 R30 R40 R50
Ham lUdng (phan % khoi lupng) 2 0 % xi mdng, 10% mat da va 7 0 % eat 10% cat trong mau Ro 6ugc thay the bang bun 2 0 % edt trong mdu RQ dQdc thay thd bang bun 30% cdt trong mdu RQ dUde thay the bang bun 4 0 % cat trong mdu RQ dupc thay the bang bun 5 0 % cat trong mdu f ^ dUdc thay the bang bun
Bang 3 . 1 . Hdm lugng kim loai ndng trong mdu bOn khd (mg/kg) Hg
0.67 Cr 291.3
Va 410
Cd 22.6
Pb 363
Sb 21
As 423.6
Ni 892
Se 5.2 Bang 3.2. Ham lugng kim logi ndng thdi nhiem khdi mau gach ddng
rdn bdng xi mang Kim ioai
n3ng
Hg Cr Va Cd Pb Sb As Ni Se
Non Rio
0.09 3.6 9.16 0.07 10.8 O.OB 0.09 1.58 0.03
q d d nqam chiet (m R20
0.11 4.6 12.5 0.08 13.6 0.26 0.12 2.01 0.05
R30
0.18 5.2 15.4 0.12 14.2 0.89 0.45 2.36 0.07
q/i) R40
0.22 6.4 17.3 0.18 15.8 1.34 0.68 2.54 0.12
QCVN 07:
2009/BTNMT Ngi/8ng nong do nqam chiet. CJmq/l)
0.2 5 25 0.5 15 1 2 70
1 Bang 3.3. Ham lugng kim loai ndng thdi nhiem khdi mau gach ddng
rin bdng td hgp polyme-xi mdng
Kim loai nang Hq Cr Va Cd Pb Sb As Ni Se
Nonq do nq^m chi^t (mq/1)
R,o-M
0.78
-
1.02 1.35
-
0.04
- -
R20-M 0.81
_
2.05 1.56
.
0.07
-
R K - M
0.01 0.86 2.64 0.02 2.12
. .
0.12 0.01
R 4 0 - M
0.02 0.88 3.14 0.02 2.87 0,02 0.01 0.14 0.03
QCVN 07:
2009/BTNMT Ngirang nong do ngam
chiet, C,„(mg/I) 0.2
5 25 0.5 15 1 2 70
1 1 4 Toi n g u y e n y g Moi t r u d n g | Kt2-Thing8/2015
mdng Portland mdc PC40; da mat: kfch thude 0 - 5 mm; cdt sdng: kfch thude 0.14 - 5 mm;
Polyaeryamit (PAM): Khdi lupng phan to 1.5x106 g/mol, dupe che tao tai Phdng vat lieu polymer - Vien Hda hpe.
Phucmg phdp tidn hdnh Tien hdnh phdi trdn bun thai, xi mdng, edt, mat da vdi cac ty Id khde nhau (Bang 2.1) them lupng nUdc thfch hdp, sau do tien hanh tao mau. Moi mau gach cd kfch thudc 400x200x200 mm, dUpc trdn khd, sau dd them lupng nudc vQa dCi, tiep tue trdn ddu. Sau dd mdu dQpc nen bang may dp thOy Itic vdi lue nen 110 kg/cm^. Mau sau che tao dupe dudng am 3 ngay d nhiet dp mdi trudng (tudi 3 Idn/ngdy), sau do phdi khd tu nhien, sau 10, 28 va 90 ngdy mau dupe lay vd phdn tfch eac chi tieu cd ly (cudng dp nen, cudng dd udn) va xdc djnh ham lupng kim loai ndng bj thdi nhiem ra mdi trudng.
Chuin bj mau bu -xi mdng- polyme: Cac mau gach khdng nung chQa polyme dupe ky hidu RIO-M, R20-M, R30-M, R40-M, R50- M, idn iUdt Id cdc mau R^o, R20.
R30, R40, R50 trong dd ham lupng polyme trong bun la 100 mg/kg.
Cudng dp nen vd cudng dp udn cOa edc mau dUdc xdc djnh theo TCVN 6477:2011 v l gach khdng nung.
MQc dd thdi nhi^m kim loai ndng: Op thdi nhiem kim loai ndng tQ gach khdng nung dupc tien hdnh theo tilu chuin ngdm chidt TCVN 9239-2012.
Ke't quS va thdo luan Ket qua nghien cQu anh hudng cOa ham lupng bun vd thdi
Hinh 3.1. Anh hudng cOa ham lugng bOn vd thdi glan ddng r tinh chit gach khdng nung
:. Anh hudng cOa ham lugng bOn va thdi gian ddng r cudng dd udn cOa mau gach
gian ddng ran de'n eudng dp nen cOa gach khdng nung dupc trinh bdy trong Hinh 3.1.
Cudng dp nen la mdt chi tieu quan trpng anh hudng den dp bdn va kha ndng Ohg dung cOa gach khdng nung. Ket qua Hinh 3.1 eho thay cifdng dp nen cCia cde mau giam khi tdng ham lupng bun trong mau. MQc dp suy giam cQdng dp nen eOa mdu sau 90 ngdy ddng ran Id eao hdn so vdi mau 28 ngdy ddng ran. Sau 28 ngay ddng ran, cudng dp nen giam 19.4% d mau R4oVd 35.4 % vdi mdu RgQ. Sii suy giam cudng
dp nen khi tdng ham lupng bun trong mau cd the giai thfeh Id do ham lupng hCfu cd trong bun vd do dp ben ket cau hat bun ye'u hdn so vdi dp ben kdt cau hat cat.
Ket qua nghien cQu anh hQdng cOa ham lupng bun vd thdi gian ddng ran den cudng dp udn cOa mdu gach khdng nung dupc trinh bay trong Hinh 3.2.
Ket qua Hinh 3.2 cho thay cudng dp ud'n cOa tat ca eac mau giam khi tdng ham lupng bun trong mdu. Sau 28 ngay ddng ran, cudng dp udn cao
Tai nguydn vQ Mdi tradng | Ky 2-Thang 8/2015 ^ J
nhat dat dupc vdi mau R-|o va thap nhat la mlu R50. Dieu ndy dupc giai thfch Id do bd tdng ddng ran ed edu trOc dang ddng k i t cOa cac hydrat canxi silicat vd canxi hydroxit lien kdt vdi nhau bang lUe Var Der Wal, lUc ndy ed kha ndng bj phd vd khi ed tac dung cOa ngoai iQc, hinh thdnh len cdc vet ndrt td vi lam giam tfnh chat cd hpe cOa hon hdp be tdng. Khi cd mat cOa cac hat bun cd ket eau yeu hdn so vdi cat, thi cae vet nQt te vi nay se cd xu hudng tdng, do dd tfnh chdt CO ly cOa gach khdng nung giam khi tdng hdm lupng bun trong mau.
Ket qua phdn tfch qua trinh thdi nhiem kim loai ndng trong miiu bOn ban dau, mau bun ddng rdn bdng xi mdng vd mau bCin ddng rin bing hSn hpp xi mdng- polyme dupc trinh bdy trong Bang 3.1 - 3.3.
Theo ket qua phdn tfch dd thdi nhiem cOa mau bun khd ban ddu (Bang 3.1), nhidu kim loai ndng dope phdt hien vdi hdm lupng cao. Hdm liidng kim loai ndng bj thdi nhiem khoi mdu gach ddng rdn bang xi mdng (Bang 3.2) thap hdn so vdi mau bun ban diu. Oieu nay cd t h i dupe giai thfch la do qud trinh I n djnh ndy diia trdn su hinh thdnh canxi silicat hydrat (CaO.SiO2.nH2O), ettringite hydrate (3CaO.Al203.
3CaS04.32H20) va monosulphate (3CaO.Al203.CaS04.12H20) trong chat nen, do cd kha ndng phan dmg hydrat hda cOa xi mdng Portland, vd do dd kim loai ndng ca ve mat vat ly hay hda hpc ddu dupe ed djnh trong cdc vat lidu ndn, giam kha ndng that thoat ra mdi tnidng. Hdm tupng kim loai ndng thdi nhiem khoi mau tdng
khi tdng ham lupng bOn. Cu t h i , hdm IQdng cOa Va, Cd, As, Ni va Se trong mau R40 thap hdn gidi han eho phep theo QCVN 07:
2009/BTNMT. Tuy nhidn, ham lupng eae kim loai Hg, Cr, Pb va Sb vln cao hon gidi ban cho phep theo tieu chuan QCVN 07:
2009/BTNMT
Kdt qua trong Bang 3.3 cho thdy, khi ham lupng bun thap.
nhidu kim loai khdng phat hien.
Ham IUdng kim loai thdi nhidm tQ mau R40-M deu thd'p hdn gidi ban eho phep nhieu lan. Vdy, cd t h i thay rang polyme cd vai trd Idm tdng tfnh I n djnh cOa kim loai ndng trong t l hpp ddng ran.
Oieu nay cd t h i giai thfch Id do polyme cd kha ndng tao phQc vdi cac ion kim loai, do dd kim loai dUde cd djnh trong to hdp ddng ran. Vat lieu thu du'pc than thien vdi mdi trudng. Vay, bang cdng nghe hda ran bun thai bang xi mang ket hpp vdi poly- me cd djnh kim loai ndng, nguy CO thdi nhiem kim loai ndng tQ bun thai nguy hai dd dupc giai quyet triet d l .
Ket luan
Nghidn cQu dd cap den anh hudng cOa ham lupng bun thai den tfnh chd't gach khdng nung va hidu qua cddjnh kim loai ndng bang polyme vd xi mdng.
Thanh phan cOa bun Id mdt yeu td quan trpng anh hudng ddn chat lupng gach khdng nung.
Cudng dp nen vd cudng dp udn dupe xdc dinh sau 10, 28 vd 90 ngdy ddng ran. Ket qua«ho thay, khi ham lupng bOn tdng thi cUdng dp nen vd cudng dp uon tUdng dfng giam. Vdi mlu gach R40 eho tfnh chdt cd ly phu hpp vdi tieu chuin TCVN 6477:2011, cd
cudng dp nen bang 7.83 MPa vdi mde gach M7 5 {cudng dp nen tieu chuan bang 7.5 MPa).
Hdm lupng kim loai ndng thdi nhiem dupe xac djnh theo tieu chuin TCVN 9239:2012.
Ket qua cho thay ham lupng kim loai ndng thdi nhiem cda mau chQa polyme thdp hon mau khdng chQa polyme. Ham lUdng kim loai ndng thdi nhilm khoi mau chQa polyme la rat thd'p, thap hdn gidi han cho phep theo tieu ehuin QCVN 07:2009/
BTNMT
Tai lieu tham khSo [1]. C. Nllsson, H. Dahlstr#m, (2005), "Treatment and Disposal Methods for Wastewater Sludge in the Area of Beijing, China,"
Master Thesis. Published. Lund University.
[2]. M. H. Al-Malack, N. S, Abuzaid, A. Bukhari, and M.
H. Essa, (2002 ),
"Characterization, utilization, and disposal of municipal sludge:
the state of the ari," The Arabian Journal for Science and Engineering, Volume 27, Number 1B.
[3]. Joan, A.C. and VC.
Lazaro,(2012), Environmental effects of using clay bricks pro- duced with sewage sludge:
Leachability and toxicity studies.
J. Waste Manage. 32 (6): 1202- 1208.
[4]. Vails, S.. A. Yague, E.
Vazquez and F. Albareda, (2005), Durability of concrete with addi- tion of dry sludge from waste water treatment plants. Cement Concrete Res., 35: 1064-1073.
[5]. Tieu ehuin qudc gia TCVN 9239:2012 - Chat thii rin - quy trinh chiit ddc tinh.m 16 Tgl nguygn yg M6i traong [ Ky2-Thang8/2015
