chuong 1_in
TRANSCRIPT
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Bi ging Thit K Kim Sot Cht Thi Rn
Phn m u:Cht thi rn(CTR) xut hin t khi con ngi c mt trn tri t. Con ngi
khai thc v s dng cc ngun ti nguyn trn tri t phc v cho i sng ca
mnh, ng thi thi ra CTR. Khi , s thi b cc cht thi t hot ng cacon ngi
khng gy ra cc vn nhim mi trng trm trng do s lng dn c cn thp.
ng thi, din tch t t nhin cn rng ln, nn kh nng ng ho CTR tt, do
khng gy tn hi n mi trng.
Khi x hi pht trin, con ngi sng tp hp thnh cc nhm, b lc, cm dn c,
th s tch ly CTR tr thnh mt trong nhng vn nghim trng i vi cuc sng
ca con ngi. Trong x hi cng nghip ngy nay, qu trnh pht sinh CTR gn lin vi
qu trnh sn xut, mi giai on ca qu trnh sn xut u to ra CTR, t khu khaithc, tuyn chn nguyn liu n khi to ra sn phm phc v ngi tiu dng. Sn phm
sau khi s dng c th ti sinh, ti ch hoc b, v cng l CTR. V th khi lng
CTR hin nay pht sinh rt ln, cng thm vo l s CTR cha c x l a vn
v CTR l 1 trong vn quan tm trong vic bo v mi trng trn ton th gii
Hnh 1.1 Dng vt liu v qu trnh pht sinh cht thi rn trong x hi cng
nghip(Ngun Qun l v x l cht thi rn Nguyn Vn Phc)
Thc phm tha v cc loi CTR khc b thi b ba bi khp ni trong cc th
trn, trn cc ng ph, trc l giao thng, cc khu t trng vv to mi trngthun li cho s sinh sn v phttrin ca cc loi gm nhm nh chut. Cc loi gm
nhm l im ta cho cc sinh vt k sinh nh b cht sinh sng v pht trin. Chng l
Vt Liu Th
Sn Xut
Ti ch v tisinh
Sn xut th cp
Ngi Tiu Dng
Thi b
Cht Thi
Cht Thi
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Bi ging Thit K Kim Sot Cht Thi Rn
nguyn nhn gy nn bnh dch hch. Do khng c k hoch qun l nn cc mm bnh
pht sinh t CTR lan truyn trm trng Chu u vo gia th k 14. Mi n th k
19, vic kim sot dch bnh nhm bo v sc khe cng ng mi c quan tm.
Ngi ta nhn thy rng CTR, nh thc phm tha phi c thu gom v tiu hy hp v
sinh th mi c th kim sot cc laigm nhm, rui, mui cng nh nguy c truynbnh.
Mi quan h gia sc khe cng ng vi vic lu tr, thu gom v vn chuyn cc
CTR khng hp l th hin r rng. C nhiu bng chng cho thy cc bi rc khng
hp v sinh, cc cn nh chut, cc ni cha thc phm tha l mi trng thun li
cho chut, rui, mui v cc vi sinh vt truyn bnh sinh sn, pht trin.
Thc t cho thy, vic qun l CTR khng hp l l mt trong nhng nguyn nhn
chnh gy nhim mi trng (t, nc, khng kh). V d: cc bi rc khng hp v
sinh gy nhim bn cc ngun nc mt, nc ngm v gy nhim khng kh (mi
hi). Kt qu nghin cu khoa hc trn th gii cho thy gn 22 cn bnh ca con ngi
pht sinh do mi trng b nhim l kt qu ca vic qun l x l CTR khng hp l.
Cc phng php ph bin nht c s dng x l CTR t u th k 20 l:
Thi b trn cc khu t trng. Thi b vo mi trng nc (sng, h, bin) Chn lp Gim thiu v t
Vn qun l CTR Vit Nam
Vit Nam, tuy dn s th ch mi chim hn 20% dn s ca c nc nhng
do c s h tng k thut qu km li t c chm sc nn tnh trng v sinh mi trng
b sa st nghim trng. Tnh hnh ng rc do thiu cc trang thit b k thut cn thit
v hiu ququn l mi trng km ang gy tr ngi cho s pht trin kinh t trong
nc v chnh sch m ca kinh t vi nc ngoi.
Qu trnh th ha Vit Nam trong nhng thp k trc y pht trin chm
vi t l th ha thuc loi thp nht so vi cc nc trong khu vc, t khi chuyn
sang nn kinh t th trng c s qun l ca nh nc , tc th ha ang c
tng nhanh hn. S gia tng dn s th trong khi cha c iu kin chun b tt v c
s vt cht gy nn nhiu hu qu v kinh t, xhi nghim trng. Kt cu h tng c sca cc th nh cp nc , thot nc , nh , giao thng th, v sinh mi trng
v.v cn yu km khng p ng c nhu cu ngy cng tng ca x hi.
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Bi ging Thit K Kim Sot Cht Thi Rn
Theo Bo co Din bin Mi trng Vit Nam nm 2004 ca World Bank, lng
cht thi pht sinh ti Vit Nam c tnh khong 15 triu tn/nm. Trong thp k ti,
tng lng CTR pht sinh c d bo s tip tc tng nhanh. Cc khu vc th chim
khong 24% dn s c nc nhng li chim hn 50% tng lng cht thi pht sinh, v
c tnh trong nhng nm ti, lng cht thi sinh hot pht sinh khong 60%, trong khicht thi cng nghip s tng 50% v cht thi c hi s tng gp 3 ln sovi hin nay.
Thnh ph H Ch Minh c din tch 2093,7 km2, dn s 6.117.251 ngi (thng
10/2004) phn b ti 24 qun huyn; ni tp trung 12 khu cng nghip, 2 khu ch xut v
1 khu cng ngh cao vi hn 800 nh my ring l, 15.000 c s sn xut va v nh, 62
bnh vin, hn 400 trung tm chuyn khoa, trung tm y t v hn800 phng khm t
nhn..., hin ang pht thi mi ngy khong 5.000 5.200 tn CTR th (bao gm
CTR sinh hot trong cc c s cng nghip v cht thi cng nghip khng nguy hi),
7001.100 tn cht thi xy dng, hn 1000 tn CTR cng nghip, trong 120 150
tn CTR nguy hi, 9 12 tn CTR y t.
Ti cc vng nng thn, cc ph thi ca sn xut nng, lm, ng nghip truyn
thng (nh thn l cy, rm r, v ht, phn gia sc...) hu ht c s dng un nu,
lm phn bn hoc chn lp. Nhng cht thi c ngun gc cng nghip, nh cht do,
nha, kim loi, d lng ho cht kh phn hy, tuy cha tr thnh vn bc xcnhng ang c xu hng tng ln nhanh chng.
Ti cc th v khu cng nghip, vic thu gom v x l CTR sinh hot, CTR
cng nghip, cht thi nguy hi ang l vn mi trng cp bch. Hin nay, Vit
Nam, nng lc thu gom CTR tt c cc th v khu cng nghip mi ch t khong
20 40%. Rc thi cha phn loi ti ngun, c thu gom ln ln v vn chuyn n
bi chn lp. Cng vic thu nht v phn loi cc ph thi c kh nng ti ch, hon ton
do nhng ngi ngho sinh sng bng ngh bi rc thc hin.
Vic ng dng cc cng ngh ti ch CTR ti s dng cn rt hn ch, cha
c t chc v quy hoch pht trin. Cc c s ti ch rc thi c quy m nh, cng
ngh lc hu, hiu qu ti ch cn thp v qu trnh hot ng cng gy nhim mi
trng. Hin ch c mt phn nh rc thi (khong 1,5 -5% tng lng rc thi) c ch
bin thnh phn bn vi sinh v cht mn vi cng ngh hp v sinh. Bin php x l
CTR hin nay ch yu l chn lp, nhng cha c bi chn lp CTR no t tiu chun
k thut v sinh mi trng. Cc bi chn lp CTR vn cn gy nhim mi trng t,
nc v khng kh do qu trnh vn hnh bi chn lp cn bt cp, vic x l nc r rc,
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Bi ging Thit K Kim Sot Cht Thi Rn
mi, v sinh mi trng km nh . Hn na hin nay qu t dnh cho cc bi chn lp
gn nh l khng c hoc khng .
Vn qun l cht thi rn Vit Nam l vn cn mi m v vy h thng
lut, cc vn bn qun l CTR cn hn ch cha theo kp vi s pht sinh CTR chng
mt nh hin nay. Hiu lc thi hnh cc vn bn quy phm php lut cn cha hiu qu.Nng lc th ch v ngun lc thc thi khung chnh sch ca Vit Nam hin ang
thiu cc cp tc nghip, v cc vn bn quy phm php lut cn cha c cng ch
thi hnh hiu qu. Cc quy nh i vi cc c s qun l cht thi, cc c s cng
nghip, cc bnh vin do B Ti nguyn v Mi trng v cc c quan b/ngnh khc
(B Y t, B Cng nghip, Cc ban qun l khu cng nghip) ban hnh cn cha c
cng ch thc thi y v cha gim st c vic thc hin hot ng qun l cht
thi do thiu nhn lc, phn cng chc nng nhim v khng r rng, vai tr ca cc c
quan chnh ph cn b chng cho v cn manh mn, hn ch trong vic iu phi gia
cc c quan. Do vy, dn n tnh trng thiu cc c ch khuyn khch i vi vic vn
hnh ng k thut cc bi chn lp, cc c s cng nghip u t cho cc h thng x l
chtthi v v th to iu kin cho vic p dng cc phng php tiu hu cht thi
r tin, khng an ton nh l thi cc bi rc l thin.
Nhn thc ca cng ng v bo v mi trng v an ton sc khe lin quan ticng tc thu gom, x l v qun l CTR vn cn ang trnh thp. Vic b ba bi
CTR xung cc knh rch gy mt v sinh, e da nghim trng n nguy c suy thoi
mi trng nc ngm.Cn tng cng cng tc truyn thng, gio dc trong cc bc
hc v vai tr ca qun l CTR trong x hi
Chin lc quc gia v qun l cht thi rn
Mc tiu ca Chnh ph l phn u ti nm 2050, tt c cc loi cht thi rn
pht sinh u c thu gom, ti s dng, ti ch v x l trit bng nhng cng ngh
tin tin, thn thin vi mi trng v hn ch khi lng cht thi rn phi chn lp n
mc thp nht. thc hin mc tiu ny, ngy 17/12/2009, Th tng Chnh ph
ban hnh Quyt nh 2149/Q-TTg ph duyt Chin lc quc gia v qun l tng hp
cht thi rn n nm 2025, tm nhn n nm 2050 c vi quan im qun l tng
hp cht thi rn l trch nhim chung ca ton x hi
Theo , vic qun l cht thi rn s thc hin nguyn tc "ngi gy nhim
phi tr tin". C th, qun l cht thi rn phi c thc hin theo phng thc tng
hp, nhm phng nga, gim thiu pht sinh cht thi ti ngun l nhim v u tin hng
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Bi ging Thit K Kim Sot Cht Thi Rn
u, tng cng ti s dng, ti ch gim khi lng cht thi phi chn lp. T chc,
c nhn pht sinh cht thi, gy nhim, suy thoi mi trng c trch nhim ng gp
kinh ph, khc phc, bi thng thit hi.
Chin lc cng t ra mc tiu n nm 2025, 100% cc th c cng trnh ti
ch cht thi rn thc hin phn loi ti h gia nh; 100% tng lng cht thi rn sinhhot th, 100% tng lng cht thi rn cng nghip khng nguy hi v nguy hi, 90%
tng lng cht thi rn xy dng th v 90% lng cht thi rn pht sinh ti cc
im dn c nng thn c thu gom v x l m bo mi trng. Lng ti nilon s
dng ti cc siu th v trung tm thng mi s gim 85% so vi nm 2010. Gii php
quan trng t c cc mc tiu trn l phi phng nga v gim thiu pht sinh cht
thi rn; thc y phn loi cht thi rn ti ngun; y mnh thu gom v vn chuyn
cht thi rn; tng cng ti s dng, ti ch cht thi...
c quy hoch chin lc nhm qun l cht thi rn, Chnh ph ch o s lp
v thc hin quy hoch xy dng khu lin hp x l cht thi rn cho cc vng kinh t
ca c nc. Tt c cc tnh, thnh ph trong c nc s lp v thc hin quy hoch qun
l cht thi rn; trong , xy dng v thc hin quy hoch xy dng khu x l cht thi
rn ti tn phng, x. ng thi, xy dng cc gii php v hon thin h thng vn bn
php lut v c ch chnh sch v qun l cht thi rn; thit lp c s d liu v h thngquan trc d liu v cht thi rn ton quc; thc y nghin cu khoa hc v mt bin
php ht sc quan trng l tuyn truyn, gio dc nng cao nhn thc cng ng v bo
v mi trng. Xy dng v thc hin cc chin dch truyn thng nng cao nhn thc
cng ng, khuyn khch tham gia vo cc hot ng phn loi ti ngun, gim thiu, ti
ch ti s dng cht thi rn, hn ch s dng ti nilon, khng rc ba bi...
a gio dc mi trng vo cc cp hc; thc hin cc hot ng th im, cc
sng kin gip qun l cht thi rn tt hn. Theo k hoch, t nay n nm 2025 s c
10 chng trnh thc hin chin lc quc gia v qun l tng hp cht thi rn c
hon thnh. Qu ti ch cht thi rn cng s c thnh lp nhm h tr cho cc hot
ng gim thiu v ti ch cht thi rn. ng thi, huy ng mi ngun vn u t cho
cng tc qun l cht thi rn, tm kim h tr t cc ngun vn ODA...
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Bi ging Thit K Kim Sot Cht Thi Rn
CHNG 1.
KHI QUT CHUNG V CHT THI RN
1.1 S b ngun pht sinh cht thi rn
Trong Ngh nh ca Chnh ph v qun l cht thi rn s 59/2007/N -CP nu
rcht thi rn l cht thi th rn, c thi ra t qu trnh sn xut,kinh doanh, dch
v, sinh hot hoc cc hot ng khc. Cht thi rn baogm cht thi rn thng thng
v cht thi rn nguy hi.
Cht thi rn pht sinh t nhiu ngun khc nhau, cn c vo c im cht thi
c th phn chia thnh 3 nhm ln: Cht thi th, cng nghip v cht thi nguy hi.
Ngun thi carc thi th rt kh qun l ti cc ni t trng (open area), bi v ti
cc v tr ny s pht sinh cc ngun cht thi l mt qu trnh pht tn.
Cht thi nguy hi thng pht sinh ti cc khu cng nghip, do nhng thng
tin v ngun gc pht sinh v c tnh cc cht thi nguy hi ca cc loi hnh cng
nghip khc nhau l rt cn thit. Cc hin tng nh chy trn, r r cc loi ho cht
cn phi c bit ch , bi v chi ph thu gom v x l cc cht thi nguy hi b chy
trn rt ton km. V d, cht thi nguy hi b hp ph bi cc vt liu d ngm nc nh
rm r, v dung dch ho cht b thm vo trong t th phi o bi t x l. Lcny, cc cht thi nguy hi bao gm cc thnh phn cht lng chy trn, cht hp ph
(rm, r), v c t b nhim.
Ngun pht sinh cht thi rn nh sau:
- T khu dn c:Bao gm cc khu dn c tp trung, nhng h dn c tchri. Ngun rc thi ch yu l: thc phm d tha, thu tinh, g, nha, cao su,... cn
c mt s cht thi nguy hi
- T cc ng thng mi:Quy hng, nh hng, ch, vn phng c quan,khch sn,...Cc ngun thi c thnh phn tng t nh i vi cc khu dn c (thc
phm, giy, catton,..)
- Cc c quan, cng s: Trng hc, bnh vin, cc c quan hnh chnh:lng rc thi tng t nh i vi rc thi dn c v cc hot ng thng mi
nhng khi lng t hn.
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Bi ging Thit K Kim Sot Cht Thi Rn
- T xy dng:Xy dng mi nh ca, cu cng, sa cha ng x, d bcc cng trnh c. Cht thi mang c trng ring trong xy dng: st thp vn, gch
v, cc si, b tng, cc vi va, xi mng, cc dng c khng dng na
- Dch v cng cng ca cc th: V sinh ng x, pht quan, chnh tucc cng vin, bi bin v cc hot ng khc,... Rc thi bao gm c rc, rc thi t
vic trang tr ng ph.
- Cc qu trnhx l nc thi: T qu trnh x l nc thi, nc rc, ccqu trnh x l trong cng nghip. Ngun thi l bn, lm phn compost,...
- T cc hot ng sn xut cng nghip:Bao gm cht thi pht sinh tcc hot ng sn xut cng nghip v tiu th cng, qu trnh t nhin liu, bao b
ng gi sn phm,... Ngun cht thi bao gm mt phn t sinh hot ca nhn vin
lm vic.
- T cc hot ng sn xut nng nghip:Ngun cht thi ch yu t cccnh ng sau ma v, cc trang tri, cc vn cy,... Rc thi ch yu thc phm d
tha, phn gia sc, rc nng nghip, cc cht thi ra t trng trt, t qu trnh thu
hoch sn phm, ch bin cc sn phm nng nghip.
Ngun gc ban u ca cht thi rn (CTR): sn phm hng ha v cc ph phmt vt liu rn.
Ngun cht thi rn th cp: chu trnh sinh trng v phn r t nhin ca thc
vt, chim mt t l nht nh trong dng cht thi.
CTR th c c trng bi cc sn phm tng i nh, s lng ln, v
vng i c ch ngn. N c to ra bi cc hot ng thng thng trong cuc sng
hng ngy
CTR dng khi ln (bulky waste) thng c kch thc ln, nhng c to ra
vi s lng tng i nh v vng i sn phm kh di.
CTR dng khi ln thng c to ra bi cc trng hp t khi xy ra nh vic
loi b mt gh bnh hay mt t lnh, lp li mi nh, ph hy mt tanh, hoc lm li
mt ng. Thnh phn ca CTR dng khi ln thng bin i nhiu hn thnh phn
CTR th.
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Bi ging Thit K Kim Sot Cht Thi Rn
Tm li, cc ngun chnh to ra CT th v CT dng khi ln: t nh dn, khu
bun bn thng mi, cc cng s, nhng phn ln CT dng khi ln li c to ra t
cc cng trng XD hay t vic ph d nh.
1.2 Khi lng cht thi rn
Khi lng c cho l thng s quan trng nht trong qun l cht thi rn. Khi
lng xc nh quy m v s lng thit b yu cu qun l cht thi rn. Khi lng
cht thi rn c th c biu th bng n v th tch (m3) hoc bng n v trng lng
(tn).u im ca vic o khi lng theo trng lng ch khng phi theo th tch l
ch trng lng thng khng thay i i vi mt tp hp cho trc ca cc vt b loi
b, trong khi th tch li bin i rt nhiu.
Khi lng cht thi rn thng c biu th bng kg trn u ngi trn ngy
cc dng cht thi cc vng khc nhau c th c so snh.
Khi lng ny c biu th bng cng thc sau:
Pcd = 1000T/365P (1.1)
Trong : Pcd: kilogam trn ngi trn ngy
T: khi lng tn CT c to ra trong mt nm, gm c CTR sinh
hot khu dn c v CTR sinh hot khu thng mi, c quan
P: dn s trong vng to ra cht thi
S lng thng k t cc tnh, thnh ph, nm 2004 cho thy lng cht thi rn
bnh qun khong 0,9n 1,2kg/ ngi.ngy cc th ln v mt s th nh dao
ng t 0,5 n 0,65kg/ngi.ngy. n nm 2008, con s ny tng ln
1,45kg/ngi/ngy cc th.
Khi lng cht thi th chim gn 50% trn tng s cht thi rn tan quc.
Kt qu nghin cu v lng pht sinh cht thi rn cc th cho thy, tng lng rc
thi sinh hot pht sinh t th c xu hng tng u, trung bnh t 10-16% mi nm.
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Bi ging Thit K Kim Sot Cht Thi Rn
Hnh 1.2 Thnh phn cht thi rn ton quc nm 2008 v xu hng thay i thi
gian ti (Ngun: Trung tm nghin cu v quy hoch mi trng th - nng thn, B
Xy Dng 2010)
Thnh phn cht thi th rt a dng t cht thi hu c (rc sinh hot t h
dn, ch, khu thng mi), cc cht do, thy tinh(chai, l) n cht thi rn xy dng
(xem bng 1.1)
T l phn trm cc cht c trong rc thi khng n nh, rt bin ng theo mi
a im thu gom rc, ph thuc vo mc sng v phong cch tiu dung ca nhn dn mi th. Tnh trung bnh, t l thnh phn cc cht hu c chim 45%-60% tng lng
cht thi; t l thnh phn nilng, cht do chim t 6-16% m trung bnh ca rc thi
t 46%-52%.
Bng 1.1 Thnh phn cht thi rn th (TPHCM)
Phn loi bc 1 Phn loi bc 2 V d
1.Giy Giy loi tr bo v tp ch Giy photocopy
Bo
Tp ch v cc loi c in n khc Cc t ri qung co
Giy ba c lp sn gn sng Ba c ph sp
Giy ba khng c lp sn gn sng Hp ng dy
Giy ba dung ng cht lnghoc c nhiu lp
T lt tr em
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Bi ging Thit K Kim Sot Cht Thi Rn
2. Cht do PET Chai nc khong
HDPE
LDPE
PVC
Khc Phim nh
a thnh phn Nha ABS
3. Hu c Xc gia sc, gia cm
Cht thi t qu trnh lm vn: l
cy, c v cc cht thi khc t qu
trnh ct ta
Thc phm
Phn gia sc, gia cm
Ph thi t cc nng sn
Vi v cc sn phm dt may
Sm, lp v cc sn phm cao su
Da
G Bao b g, pallet, mt ca
4. Kim loi en St
Bao b thic V lon
5. Kim loi mu Kim loi mu
Bao b nhm V lon
V chai bia, nc gii kht
Chai thy tinh trong
Chai thy tinh mu
Knh
7. Xy dng Gch ngi
B tng
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Bi ging Thit K Kim Sot Cht Thi Rn
t
Cc sn phm khc trong xy dng
8. Khc, nguy hitim tng
Cc cht thi nguy hi dng tronggia nh
Sn, cc bao b cha ha chtgia dng
Tro
Cht thi y t
Cht thi cng nghip
Khc
Ngun Qun l cht thi rn-cht thi nguy hi Ths V nh Long-Nm 2008
1.3 Tc ng n mi trng
CTR dng khi ln cng c kh nng lm suy gim cht lng mi trng v mt
m quan, lm mt khng gian c gi tr v lm nhim mi trng. N c th gy ra mi
nguy him chyn.CTR th cn l mt ngun vt liu th sn xut trong nh my,
lm nhin liu, lm vt liu ph trong nng nghip. Thch thc c bn trong qun l
CTR l phi gim thiu ti a cc tc ng c hi tim tng trong khi lm ti a ha
s phc hi CTR nh l mt ngun nguyn vt liu c gi v hu ch.
CTR c th lm suy thoi cht lng mi trng v mt thm m theo hai cch
sau y:
Th nht, nguyn liu cht thi m khng c cch ly mt cch hp l vimi trng (v d rc ri ba bi trn ph v mnh vn, mnh v trn mt
vng t trng) nhn chung l kh coi.
Th hai l cc phng tin, thit b qun l CTR th thng khng a nhn,v d nh cc bi rc thi trong vng ng bng, ni c mt dn c
cao v cc thit b t rc li t vng phi cng nghip.
Bi rc thng chim mt khong khng gian ln, vic gim lng pht thi cht
rn, ti ch, ti s dng, lm phn vi sinh v t rc, tt c u gp phn lm gim lng
t yu cu cho mt bi rc.t m c s dng chnlp rc thng kh c s
dng cho cc mc ch khc.Cc bi rc tip nhn cht thi rn th khng c x l
thng thm nc v s lng ng theo thi gian. Cc bi rc nh th s to ra kh metan
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Bi ging Thit K Kim Sot Cht Thi Rn
l mt cht kh gy chy n v cc cht kh khc trong vng 20 nm hoc lu hn na khi
cc bi rc ny ngng tip nhn rc.D cht thi trong mt bi rc c x l hay khng
c x l, nhn chung bi rc khng c th c canh tc li. R cy s ph hy lp t
khng thm c ph ln bi rc ng ca nhm lm gim lng nc r rc.
Ngun rc thi t cc h gia nh thng l cc loi thc phm chim t l cao
trong ton b khi lng rc thi ra. Kh hu nhit i nng m v ma nhiu nc ta
l iu kin thun li cho cc thnh phn hu c phn hy, thc y nhanh qu trnh ln
men, thi ra v to nn mi kh chu cho con ngi. Cc cht kh pht ra t qu trnh
ny thng l H2S, NH3, CH4, SO2, CO2. Thng thng th cc vn v mi nng nht
xy ra khi cht thi b thi ra nhanh, tiu th xy sn c v gy ra trng thi ym kh.
CTR dng khi ln thng khng gy ra cc vn v mi v n cha cc vt cht nhc th phn hy nhanh. Nhng CTR th thng gy ra cc mi b phn i, thm ch
khi c bao ph bng mt lp t ti trong mt bi rc.
Cc thit b t rc thng ngn nga c mi. phn vi sinh (compost) thng
gi c cht hu c nhng vn khng gy ra mi. Tuy nhin, qu trnh phn compost
yu cu k thut cn thn gim ti a vic to mi trong khi .
Bn cnh vic to mi, CTR c th cn gy ra cc dng nhim khc: Nc r rc
cha cc cht c lm nhim nc ngm v nc mt. Cc sn phm c hi, c tnh
n mn c sinh ra trong qu trnh t phi c ngn nga khng cho pht thi vo
bu kh quyn.
Mt chng trnh qun l CTR cng nn tm kim cc ngun li thu c t CTR
bao gm: ti ch, phn compost, t trc tip i i vi thu hi nng lng, ch bin
cht thi to ra nng lng v thu hi kh gas t bi rc lm nhin liu.
1.4. Cc ctnh ca cht thi rn
1.4.1 Tnh cht vt l ca cht thi rn
Nhng tnh cht vt l quan trng nht ca cht thi rn l khi lng ring,
m,kch thc, s cp phi ht, kh nng gi m thc t v xp ca cht thi rn.
1.4.1.1 Khi lng ring
Khi lng ring ca cht thi rn c nhngha l trng lng ca mt n v
vtcht tnh trn 1 n v th tch cht thi (kg/m3). Bi v khi lng ring ca cht thi
rn thay i tu thuc vo nhng trng thi ca chng nh: xp, cha trong cc t hng
cha container, khng nn, nn nn khi bo co d liu v khi lng hay th tch cht
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Bi ging Thit K Kim Sot Cht Thi Rn
thi rn, gi tr khi lng ring phi ch thch trng thi (khi lng ring) ca cc mu
rc mt cch r rng v d liu khi lng ring rt cn thit c s dng c lng
tng khi lng v th tch rc cn phi qun l.
Khi lng ring thay i ph thuc vo nhiu yu t nh: v tr a l, ma trong
nm,thi gian lu gi cht thi. Do cn phi thn trng khi la chn gi tr thit k.Khi lng ring ca cht thi th dao ng trong khong 180 400 kg/m3, in hnh
khong 300 kg/m3.
Phng php xc nh khi lng ring ca cht thi rn
Mu cht thi rn c s dng xc nh khi lng ring c th tch khong
500 lt sau khi xo trn u bng k thut mt phn t. Cc bc tin hnh nh sau:
1. nh mu cht thi rn vo thng th nghim c th tch bit (tt nht l
thng c th tch 100 lt) cho n khi cht thi y n ming thng.
2. Nng thng ln cch mt sn khong 30 cm v th ri t do xung 4 ln.
3. nh mu cht thi rn vo thng th nghim b vo cht thi nn
xung.
4. Cn v ghi khi lng ca c v thng th nghim v cht thi rn.
5. Tr khi lng cn c trn cho khi lng ca v thng th nghim thu
c khi lng ca cht thi rn th nghim.6. Chia khi lng cht thi rncho th tch ca thng th nghim thu c khi
lng ring ca cht thi rn.
7. Lp li th nghim t nht 2 ln v ly gi tr khi lng ring trung bnh.
1.4.1.2. m
m ca cht thi rn c biu din bng mt trong 2 phng php sau:
Phng php khi lng t v phng php khi lng kh.
Theo phng php khi lng t: m tnh theo khi lng t ca vtliu l phn trm khi lng t ca vt liu.
Theo phng php khi lng kh: m tnh theo khi lng kh ca vtliu l phn trm khi lng kh vt liu.
Phng php khi lng t c s dng ph bin trong lnh vc qun l cht
thi rn.
m theo phng php khi lng t c tnh nh sau:
a= {(wd )/ w} x 100 (1.2)
Trong : a: m, % khi lng
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Bi ging Thit K Kim Sot Cht Thi Rn
W: khi lng mu ban u, kg
d: khi lng mu sau khi sy kh 1050C, kg
Bng 1.2. m ca cc thnh phn trong cht thi rn th
Thnh phn % khi lng m (% khi lng)
Cht hu c
Thc phm tha
Giy
Giy carton
Nha
Vi vn
Cao su
Da
Cht thi trong vn
G
Cht v c
Thy tinh
Can thic
Nhm
Kim loi khc
Bi, tro,
9,0
34,0
6,0
7,0
2,0
0,5
0,5
18,5
2,0
8,0
6,0
0,5
3,0
3,0
70
6
5
2
10
2
10
60
20
2
3
2
3
8
Ngun: ISWM, McGraw-Hill 1993
1.4.1.3 Kch thc v cp phi ht
Kch thc v cp phi ht ca cc thnh phn trong cht thi rn ng vai tr rt
quan trng trong vic tnh ton v thit k cc phng tin c kh nh: thu hi vt liu,
c bit l s dng cc sng lc phn loi bng my hoc phn chia loi bng phng
php t tnh. Kch thc ca tng thnh phn cht thi c th xc nh bng mt hoc
nhiu phng php nh sau:
SC = l (2-2) (1.3)
SC = (l + w)/2 (1.4)
SC = (l + w + h)/3 (1.5)
SC = (l x w)1/2 (1.6)
SC = (l x w x h)1/3 (1.7)
Trong : SC : kch thc ca cc thnh phn
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Bi ging Thit K Kim Sot Cht Thi Rn
l : chiu di, (mm)
w : chiu rng, (mm)
h : chiu cao, (mm)
Khi s dng cc phng php khc nhau th kt qu s c s sai lch. Do tu
thuc vo hnh dng kch thc ca cht thi m chng ta chn phng php o lngcho ph hp.
V d: Tnh ton kch thc cp phi ht ca can nhm, can thic, thu tinh da
vo phng trnh 1.6
1.4.1.4. Kh nng gi nc thc t
Kh nng gi nc thc t ca cht thi rn l ton b lng nc m n c th
gi litrong mu cht thi di tc dng ca trng lc. Kh nng gi nc ca cht thi
rn l mt ch tiu quan trng trong vic tnh ton xc nh lng nc r r t bi rc.
Nc i vo mu cht thi rn vt qu kh nng gi nc s thot ra to thnh nc r
r. Kh nng gi nc thc t thay i ph thuc vo p lc nn v trng thi phn hu
ca cht thi. Kh nng gi nc ca hn hp cht thi rn (khng nn) t cc khu dn
c v thng mi dao ng trong khong 50-60%.
1.4.1.5. thm (tnh thm) ca cht thi c nn
Tnh dn nc ca cht thi c nn l mt tnh cht vt l quan trng, n schi phiv iu khin s di chuyn ca cc cht lng (nc r r, nc ngm, nc
thm) v cc kh bn trong bi rc. H s thm c tnh nh sau:
kCdK
2 (1.8)
Trong : K: h s thm, m2/s
C: hng s khng th nguyn
d: kch thc trung bnh ca cc l rng trong rc, m
: trng lng ring ca nc, kg.m2/s
: nht vn ng ca nc, Pa
k : thm ring, m2
S hng Cd2c bit nh thm ring. thm ring k = Cd2ph thuc ch
yu votnh cht ca cht thi rn bao gm: s phn b kch thc cc l rng, b mt
ring, tnh gc cnh, rng. Gi tr in hnh cho thm ring i vi cht thi rn
c nn trong bi rc nm trong khong 10-11 10-12 m2/s theo phng ng v
khong 10v 10 theo phng ngang.
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Bi ging Thit K Kim Sot Cht Thi Rn
1.4.2 Tnh cht ha hc ca cht thi rn
Thnh phn ho hc ca cc vt cht cu to nn CTR ng vai tr rt quan trng
trong vic nh gi cc phngphp; la chn phng thc x l v ti sinh cht thi. V
d: kh nng t chy vt liu rc ty thuc vo thnh phn ho hc ca CTR.
Nu CTR c s dng lm nhin liu cho qu trnh t th 4 tiu ch phn tchho hc quan trng nht l:
Phn tch gn ng s b im nng chy ca tro Phn tch cui cng (cc nguyn t chnh) Nhit tr ca cht thi rn.
Phn tch s bi vi cc thnh phn c th chy c trong cht thi rn bao
gm cc th nghim sau:
m (lng nc mt i sau khi sy 105oC trong 1 gi) Cht d chy bay hi ( khi lng mt i thm vo khi em mu cht thi
rn sy 1050C trong 1 gi t chy nhit 9500C trong l nung
kn)
C c nh (phn vt liu cn li d chy sau khi loi b cc cht bay hi) Tro (khi lng cn li sau khi t chy l h)
im nng chy ca tro
im nng chy ca tro c nh ngha l nhit t chy cht thi tro s
hnh thnh mt khi cht rn (gi l clinker) do s nu chy v kt t. Nhit nng
chy hnh thnh clinker t cht thi rn trong khong 2000 - 22000F (1100 - 12000C).
Phn tch cui cng cc thnh phn to thnh cht thi rn
Phn tch cui cng cc thnh phn cht thi ch yu xc nh phn trm (%) ca
cc nguyn t C,H,O,N,S, v tro. Trong sut qu trnh t CTR s pht sinh cc hp cht
Clor ho nn phn tch cui cng thng bao gm phn tch xc nh cc halogen.
Kt qu phn tch cui cng c s dng m t cc thnh phn ho hc ca
cht hu c trong cht thi rn. Kt qu phn tch cn ng vai tr rt quan trng trong
vic xc nh t s C/N ca cht thi c thch hp cho qu trnh chuyn ho sinh hc hay
khng.
Nhit tr ca cc thnh phn cht thi rn
Nhit tr ca cc thnh phn hu c trong thnh phn CTR th c th c xc
nh bng mt trong cc cch sau:
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Bi ging Thit K Kim Sot Cht Thi Rn
S dng ni hay l chng ct qui m ln S dng bnh o nhit tr trong phng th nghim Bng cch tnh ton nu TP ca cc nguyn t ho hc c x.nh
Do kh khn trong vic trang b l chng ct qui m ln, nn huht cc s liu
v nhit tr ca cc thnh phn hu c trong CTR th u da trn kt qu th nghim
s dng bnh o nhit tr trong phng th nghim.
Gi tr nhit to thnh khi t cht thi rn. Gi tr ny c xc nh theo cng
thc Dulng:
1.4.3 Tnh cht sinh hc ca cht thi rnCc thnh phn hu c (khng k cc thnh phn nh plastic, cao su, da) ca hu
ht CTR c phn loi v phng din sinh hc nh sau:
- Cc phn t c th ho tan trong nc nh: ng,tinh bt, amino acid v nhiu
acid hu c
- Bn cellulose: cc sn phm ngng t ca 2 ng 5 v 6 carbon
- Cellulose: sn phm ngng t ca ng glucose 6 carbon
- Du, m, v sp: l nhng ester ca alcohols v acid bo mch di
- Lignin: mt polymer cha cc vng thm vi nhm methoxyl (-OCH3)
- Lignocelluloza: hp cht do lignin v celluloza kt hp vi nhau
- Protein: cht to thnh t s kt hp chui cc amino acid
Tnh cht quan trng nht trong thnh phn hu c ca phn CTR th l hu ht
cc thnh phn hu c c th c chuyn ho sinh hc thnh kh, cc cht v c v cc
cht tr khc.S to mi hi v pht sinh rui cng lin quan n tnh d phn hy ca cc vt
liu hu c trong CTR th chng hn nh rc thc phm.
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Bi ging Thit K Kim Sot Cht Thi Rn
a. Kh nng phn hy sinh hc ca cc thnh phn hu c trong CTR: V cc
vi sinh vt c th chuyn ha giy, cht thi sn vn, cht thi thc phm v g, cht
thi ny c gi l c kh nng phn hy sinh hc.
Cc bng v sinh ch yu c th phn hy sinh hc c, tng t nh vy i
vi bng v dt may. Mt s vt liu cht thi c th phn hy sinh hc c s sn sngc chuyn ha hn so vi cc loi khc. Vt liu sn sng c chuyn ha nht l
nhng vt liu c nit cao, hm lng m cao: cht thi thc phm, v cc cht thi
xanh, nhuyn sn vn. Nhng cht thi ny c th b thi ra v tnh sn c v sinh
hc cao. Cht thi l cy nhn chung c tnh sn c v sinh hc mc trung bnh. G,
bng, len mc d c th c phn hy sinh hc u c tnh sn c v sinh hc kh thp
v c xem l khng phn hy trong khun kh qun l CTR.
Hm lng cht rn bay hi (VS), xc nh bng cch t chy CTR nhit
5500C, thng c s dng nh gi kh nng phn hy sinh hc ca phn hu c
trong CTR. Tuy nhin s dng gi tr VS m t kh nng PHSH ca phn hu c
trong CTR th khng ng bi v mt vi thnh phn hu c ca CTR rt d bay hi
nhng li km kh nng PHSH nh l giy in.
Thay vo hm lng lignin ca CTR c th c s dng c lng t l
phn d PHSH ca CTR, v c tnh ton bng cng thc sau:BF = 0,830,028LC (1.10)
Trong : BF : t l PHSH biu din trn c s VS
0,83 v 0,028 l hng s thc nghim
LC: hm lng lignin ca VS biu din bng % khi lng kh
Cc CTR vi hm lng lignin cao nh: giy in c kh nng PHSH km hn ng
k so vi cc cht thi hu c khc trong CTR th. Trong thc t cc thnh phn hu
c trong CTR thng c phn loi theo thnh phn phn hy chm v phn hu nhanh.
b. S pht sinh mi hi
Mi hi c th pht sinh khi CTR c lu gi trong khong thi gian di mt
ni gia v tr thu gom, trm trung chuyn, v ni chn lp. S pht sinh mi ti ni lu
tr c ngha rt ln, khi ti ni c kh hu nng m.
Ni mt cch c bn l s hnh thnh ca mi hi l kt qu ca qu trnh phn
hu ym kh vi s phn hu cc thnh phn hp cht hu c tm thy trong rc th.
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Bi ging Thit K Kim Sot Cht Thi Rn
V d, trong iu kin ym kh (kh), sunphat SO42- c th phn hu thnh sunfur
S2-
, v kt qu l S2-s kt hp vi H2to thnh hp cht c mi trng thi l H 2S. S
hnh thnh H2S l do kt qu ca 2 chui phn ng ho hc
Nc rc ti bi rc c mu en l do kt qu hnh thnh cc mui sulfide trong
iu kin ym kh. Nu khng c s hnh thnh cc mui sulfide th vic hnh thnh mi
hi ti BCL l mt vn nhim mi trng c tnh cht nghim trng
c. S pht trin ca ruiTrong ma h hay l trong khu vc kh hu nng m, s nhn ging v sinh sn
ca rui l vn quantrng cn quan tm ti ni lu tr CTR. Rui c th pht trin
trong thi gian 2 tun sau khi trng c sinh ra. i sng ca rui nhng t khi cn
trong trng cho n khi trng thnh c th c m t nh sau:
Trng pht trin 8-12 gi
Giai on I ca u trng (gii) 20 gi
Giai on II ca u trng 24 gi
Giai on III ca u trng 3 ngy
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Bi ging Thit K Kim Sot Cht Thi Rn
Giai on nhng 4-5 ngy
Tng cng 9-11 ngy
Giai on pht trin ca u trng trong cc thng cha rc ng vai tr rt quan
trng v chim khong 5 ngy trong s pht trin ca rui. hn ch s pht trin ca
rui th cc thng lu tr rc nn b thng rng trong thi gian ny hn ch sdi chuyn ca cc loi u trng.
1.4.4 S bin i tnh cht l hc, ha hc v sinh hc ca cht thi rn
Cc tnh cht ca cht thi rn c th c bin i bng cc phng php l, ha,
sinh hc. Khi thc hin qu trnh bin i th mc ch quan trng nht l mang li hiu
qu bi v s bin i cc c tnh ca cht thi rn c nh hng rt ln n k hoch
pht trin v qun l cht thi rn.
a. Bin i vt l
Phn loi cht thi rn: Qu trnh ny nhm tch ring thnh phn cht thi rn
nhm chuyn cht thi t dng hn hp thnh dng tng i ng nht thu hi cc
thnh phn c th ti sinh, ti ch. Ngoi ra c th tch nhng thnh phn cht thi nguy
hi v nhng thnh phn c kh nng ti thu hi nng lng.
Gim th tch bng c hc: Phng php nn, p thng c s dng gim
th tch cht thi, thng s dng nhng xe thu gom c lp ghp b phn p nhm lmtng khi lng rc thu gom trong mt chuyn. Nhng loi nh giy, carton, nha, lon
nhm, lon thic khi thu gom thng c ng kin gim th tch cha, chi ph x l
v vn chuyn. ng thi phng php ny cn lm tng thi hn ca cc bi chn lp
cht thi. Gim kch thc bng c hc nhm lm gim cht thi c kch thc ng nht
v nh hn kch thc ban u.
b. Bin i ha hc
Bin i ha hc nhm lm thay i thnh phn cc pha (v d t rn sang lng,
hoc rn sang kh). Mc ch l lm gim th tch v thu hi cc sn phm bini bao
gm cc phng php sau:
t: t l phn ng ha hc gia oxy v cc thnh phn hu c trong cht thi
sinh ra cc hp cht thi b oxy ha cng vi s pht sng v ta nhit.
Lng khng kh cp d m bo qu trnh t xy ra hon ton, sn phm cui
ca qu trnh t chy bao gm khng kh nng cha CO2. H2O, khng kh d v phn
khng chy cn li. Trong thc t ngoi nhng thnh phn ny cn c mt lng nh cc
kh NH3,SO2,NOx, v cc kh vi lng ty thuc vo bn cht ca cht thi.
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Bi ging Thit K Kim Sot Cht Thi Rn
Nhit phn: Hu ht cc cht hu c u khng bn vi qu trnh nung nng,
chng c th b phn hy qua cc phn ng bi nhit v ngng t trong iu kin
khng c oxy to thnh nhng sn phm dng rn, lng, kh.
Kh ha: Qu trnh ny bao gm qu trnh t chy mt phn nhin liu Cacbon
thu nguyn liu chy v kh CO, H2v mt s nguyn t hydrocacbon trong CH4
c. Chuyn ha sinh hc
Bin i sinh hc cc thnh phn hu c trong cht thi vi mc ch l lm gim
th tch v trng lng ca cht thi, sn xut phn compost, cc cht mn lm cho n
nh t, kh mtan. Cc loi vi khun, nm, men ng vai tr rt quan trng trong vic
bin i cc cht hu c. Qu trnh bin i ny xy ra trong iu kin ym kh v hiu
kh ty thuc vo s hin din ca oxy tn ti hai phng php l phn hy hiu kh v
phn hy k kh.
Qu trnh phn hy k kh: L qu trnh chuyn ha cc cht hu c trong cht
thi rn th trong iu kin k kh xy ra theo 3 bc:
Qu trnh phn hy cc hp cht c phn t lng ln thnh nhng hp cht thch
hp l ngun nng lng.
Qu trnh chuyn ha cc hp cht sinh ra t bc 1 thnh cc hp cht c nng
lng thp hn.Chuyn i cc hp cht trung gian thnh cc sn phm ring l, ch yu l CH 4
v CO2
u im
Chi phu t thp Thu hi c kh phc v cho sn xut. Trong qu trnh s tn ti mt s loi vi sinh, vi khun gy bnh v nhit
thp. Khi cht thi vi khi lng 1000 tn/ngy mi c hiu qu v kinh
t.
Nhc im
Thi gian phn hy xy ra kh lu t 4-12 thng. Kh sinh ra c mi hi v kh chu gy nh hng ti sc khe cng ng.
Qu trnh phn hy hiu kh: Qu trnh ny da vo s hot ng ca vi khun
hiu kh khi c mt ca oxy, khong hai ngy nhit tng vo khong 450C sau 6-7
ngy nhit t t 70 75% y l nhit thch hp cho vi sinh vt phn hy cht
hu c.
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Bi ging Thit K Kim Sot Cht Thi Rn
u im:
Chi ph u t thp, sn phm phn hy thp. Cht thi phn hy nhanh sau 2-4 tun. Vi sinh vt gy bnh b cht nhanh do nhit tng.
Nhc im
Chi ph x l cao K thut phc tp Trong qu trnh vn hnh cn duy tr mt s c trng trong qu trnh .
Bng 1.3 Qu trnh bin i vt l, ha hc v sinh hc ca cht thi rn
Qu trnh bin i Ph.php bin iBin i hoc thay i c bn
sn phm
L hc
- Tch loi theothnh phn
- Gim th tch- Gim kch thc
- Tch loi bng tayhoc my
- S dng lc hoc psut
- S dng lc ct,nghin hoc xay nh
- Cc thnh phn trong hn hp
cht thi th
- Gim th tch ban u
- Bin i hnh dng ban u
Ha hc
- t- S nhit phn
- Kh ha
- xy ha bng nhit- S chng ct, phnhy
- t thiu kh
- CO2, SO2, sn phm xyha khc, tro
- Kh gm hn hp kh, cndu v than
Sinh hc
- Hiu khcompost
- K kh phnhy
- K kh compost
- Bin i SH hiu kh
- Bin i SH k kh
- Bin i SH k kh
- Phn compost- CH4, CO, sn phm phnhy cn li: mn hoc bn
- CH4, CO2, rc cn liNgun Qun l cht thi rn Nguyn Vn Phc
1.5 c tnh khi lng cht thi rn
Phng php tt nht c tnh khi lng cht thi l lp t c nh cc cn
ni tiu hy cht thi v cn tng xe ti trn ng vo v c lc ra na. Nhiu ni tiu
hy CTR c lp t cc cn, nhng ti mt s bi rc th vn cn cha lp.
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Bi ging Thit K Kim Sot Cht Thi Rn
Do vic c tnh th tnh CTR trong mt xe ti ch rc hay con-ten-n ch rc
ng kn hoc ph kn l khng d dng nn th tch cn o c ghi li chnh l cng
sut ch ca cc xe ti hoc con ten n. Bi v cch c tnh ny s to nn s khuyn
khch chuyn ch rc trn cc xe ti cht y, nn s liu th tch rc c ghi li s gn
vi th tch rc thc t.
Vic biu th khi lng cht thi bng n v tn c a chung hn l bng
yard khi. Sau y l biu thc chuyn i:
M = VD/2000 (1.11)
Trong : M : khi lng cht thi rn c o bng tn
V : th tch cht thi c o bng yard khi
D : T trng cht thi c o bng pounds trn yard khi
nhng ni tiu hy rc m khng lp t cn c nh, c th s dng cn xch
tay c tnh tn cht thi ang c vn chuyn. Cc xe vn ti s c la chn v
cn, cc kt qu s c dng c tnh trng lng ton b ca dng cht thi.
S lng rc tng cng s c c tnh theo phng trnh sau :
W = T(w/t) (1.12)
Trong :
W l trng lng tng cng ca cht thi c vn chuyn n thit b/ni tiuhy rc
T : Tng s lng cc xe vn ti chuyn ch cht thi n thit b/ni tiu hy rc
w : trng lng tng cng ca cc xe vn ti c cn
t : s lngxe vn ti c cn
Cch tip cn ny thng ph hp vi nhng ni tip nhn mt lng xe vn ti
tng i n nh. Tht ng tic l t l m cc xe vn ti vn chuyn rc n ni/thit
b tiu hy lun dao ng trong ngy.
Mt cch tip cn tt hn l cn c cng nhiu xe vn ti n trong ngy cng
tt, ri theo di tng s lng xe vn ti m chuyn ch cht thi rn trong tng
gi.Trng lng trung bnh ca mt xe vn ti ring r v tng trng lng phi c
tnh ton cho tng gi, v ri tng ca tng gi c cng li thnh tng cho mt ngy.
Phng trnh 1.12 c iu chnh nh sau :
W = T1(w1/t1) + T2(w2/t2) + ..... + Tn(wn/tn ) (1.13)
W = Tng trng lng cht thi c chuyn ch ti ni/thit b tiu hy
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Bi ging Thit K Kim Sot Cht Thi Rn
T1= s lng xe vn ti chuyn ch cht thi ti ni/thit b tiu hy trong gi
u tin
T2= s lng xe vn ti chuyn ch cht thi ti ni/thit b tiu hy trong gi
th hai.
Tn= s lng xe vn ti chuyn ch cht thi ti ni/thit b tiu hy trong gicui cng ca ngy vn hnh
w1= trng lng tng cng ca cc xe vn ti trong gi u tin
w2= trng lng tng cng ca cc xe vn ti trong gi th hai
wn= trng lng tng cng ca cc xe vn ti trong gi cui cng ca ngy vn
hnh
t1= s lng xe ti c cn trong gi u tin
t2= s lng xe ti c cn trong gi th hai
tn= s lng xe ti c cn trong gi cui cng ca ngy vn hnh
Vic c tnh chnh xc ca cc kt qu v mt thng k thng phc tp khi
m t s cc xe vn ti c cn so vi cc xe cha c cn s thay i t gi ny sang
gi khc.
1.5.1 Ly mu cht thi rn th c tnh thnh phn
V trong tt c cc s dng thng k da trn vic ly mu, th s thu mu l mtbc quan trng, mang tnh then cht c tnh thnh phn cht thi rn th. Cc
xem xt v mt nguyn tc trong vic thu mu c th hin nh sau:
Mi kg cht thi trong dng cht thi phi cmt c hi nh nhau c thhin trong cc kt qu cui cng.
S lng cc mu cng ln th chnh xc ca kt qu cng cao S thay i gia cc mu cng ln th cng nhiu mu phi c phn loi
nhm t c mt mc chnh xc cho trc.
Thi gian dnh cho vic thu mu cng ln th thi gian dnh cho vic phnloi mu li cng t i.
Cng nhiu cht thi c x l trc khi phn loi th cng kh khn v tchnh xc phn loi.
Vn c bn l thi on thu gom mu. Nhn chung, giai on mt tun c
s dng bi v hu ht cc hot ng ca con ngi v hu nh cc k hoch thu gomph thi u da trnc s mt tun. Vic ly mu trong vng mt tun i vi mi ma
trong mt nm thng c a dng hn. Ly mu vo ma xun th c bit quan trng
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Bi ging Thit K Kim Sot Cht Thi Rn
bi v cht thi sn vn c sinh ra trong thi gian ny l ln nht v vo ma ng l
nh nht, v loi cht thi cng thay i nhiu nht.
Vn c bn khc na l hoc thu gom mu cc v tr ni cht thi c to ra
hay thu gom cht thi ni/thit b tip nhn cht thi. Vic ly mu ni/thit b tip
nhn cht thi c a dng hn. Tuy nhin, thu gom mu nhng v tr to ra cht thic th cn thit trong nhng trng hp sau y:
Mc tiu u tin l m t cht thi c to ra bi mt ngun no , nhl cc loi bun bn c th.
Xc nh cc ni m cht thi c tip nhn m nhng ni ny khng cth c d bo vi tin cy cho bt k mt tun cho trc no.
Cc ni tip nhn cht thi m phn b rng khp lm cho vic ly mukh khn hn v chi ph nhiu hn cho c vic ly mu v hot ng phn
loi
Kh c th tip cn ti ni/ti thit b tip nhn cht thi. Ti ni/thit b tip nhn CTR, khng c ch dnh cho hot ng phn
loi rc
Vic ly mu cc v tr to ra CTR c th s t hn v t c gi tr hn so vi
vic ly mu ti ni/thit b tip nhn CTR. Chi ph ph thm l do cc n lc c yucu tng thm thit k cng ly mu v thi gian di chuyn lin quan n vic thu
gom cc mu.C 2 nguyn nhn c bn lm gim tnh hp l ca vic ly mu ti ni
CTR c to ra:
Th nht, cht thi c th kh thu cbi v n nm trn a phn cnhn m khng th ra vo mt cch t do c, hoc cht thi rn li
trong cc thit b nn p rc. Mt s cht thi li khng tip cn c vo
ban ngy bi v chng khng c trong cc thng cha rc ngoi tri
cho ti khi kt thc gi lm vic v chng s c ly i vo sng sm
hm sau.
Th hai, mt phn tng i cht thi c i din bi tng thng charc th li cha bit bi v tn sut thu gom v khi lng rc trung bnh
trong thng cha rc ti mi ln thu gom (pick up) th cng khng bit.
Vic la chn mt cch ngu nhin cc thng cha rc ly mu dnn vic ly mu khng ng cch nhiu thng cha ang hot ng,
cha nhiu cht thi.
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Bi ging Thit K Kim Sot Cht Thi Rn
CTR th khu dn c thng tip cn d dng ly mu t cc l ng vo
ngy thu gom. Bi v cc h dn c to ra mt khi lng rc thi tng t nhau, vic la
chn mt cch ngu nhin cc h gia nh ly mu s cho mi kg cht thi mt tn
sut tng t trong mt mu. Hn na, bi v c tnh ca CTR th nht qun t h gia
nh ny sang h gia nh khc hn l t cng s ny sang cng s khc, nn nhng thiust trong mt chng trnh ly mu CTR sinh hot nhn chung t quan trng hn nhng
thiu st trong mt chng trnh ly mu CTR thng mi (commercial). Mt chng
trnh chung ly mu CTR t cc a im to ra cht thi l khng th thc hin ci
vi Nh nc bi v cc tnh hung thay i rt ln t ni ny n ni khc, t nghin
cu ny n nghin cu khc. Sau y l cc nguyn tc chung cn tun theo:
Thu thp cc mu t nhiu lnh vc khc nhau trong vng nghin cu cngnhiu cng tt m khng lm qu ti vic ly mu trong cc lnh vc quan
trng.
Nu c th, vic thu mu t cc v tr bun bn, thng mi nn t l thunvi ln ca cc ni cha CTR v t l vi tn sut chuyn ch cht thi
(pick-up).
Thu mu t cc khu dn c c cn h ring bit v t khu chung c nn tl vi s lng ngi sng trong
Yu cu nhng ngi i thc a khng c t do lm theo mnh trongvic la chn cc v tr thu mu
Vic thu mu ti ni/thit b tip nhn CTRthng r hnvic thu mu ti cc v
tr sinh ra CTR v thng c kh nng to ra cc kt qu c gi tr. L do l v khng yu
cu vic di chuyn, i li. Cc mu m thu thp c ti ni/thit b tip nhn CTR
thng i din cho CTRang c quan tm bi v chng c la chn mt cch in
hnh t mt dy cc xe ti n l c bit cc thng s v ln m cha ng ton
b dng cht thi.Vic thu mu ti ni/thit b tip nhn CTR gm hai giai on:
La chn xe ti ly mu Thu mu t lng cht thi c x ra t cc xe ti c la chn trong
bc trc .
1.5.2 La chn mu
Cc k s mi trng thng la chn cc xe vn ti n l ngoi thc a ly
mu, nhng h c th la chn trc cc xe ti m bo chc chn rng cc tuyn thu
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Bi ging Thit K Kim Sot Cht Thi Rn
mu c th u c mt trong cc mu. Cc phng php c th thc hin c la
chn cc xe ti ngoi thc a nh sau:
- Khong thi gian khng i- To ra s ngu nhin- Phn phi gia cc ngun cht thi
Khong cch ly mu khng i c th hin nh sau:
- Tng xe ti th nh nth- Tng tn cht thi th nth- Tng mt khi cht thi th nth- Mt xe ti c sau n pht
Thu gom mt mu t mi mt xe ti th n th tng i n gin nhng li lm
cho cht thi trong mi xe ti nh hoc mt phn cc xe ti ch y ri vo tnh trng b
qu i din (overrepresented) trong cc mu.
Thu gom mt mu t xe ti cha mi tn cht thi th n th l tng nhng trong
thc t li kh khn bi v trng lng ca mi xe ti theo quan trc l khng r rng.
Thu gom mt mu t xe ti cha mi m3cht thi th n th kh thi hn bi v th
tch ca hu ht cc xe ti c th c xc nh thng qua quan trc. Tuy nhin, vic ly
mu da vo th tch xe vn chuyn c xu hng lm cho cht thi khng c nn p.Khong cch gia cc ln ly mu c da vo mt tp hp s lng cc xe vn
chuyn hoc mt tp hp khi lng cht thi s gy ra s dao ng trong nhp vn
hnh ly mu trong tng ngy lm vic ngoi thc a. S dao ng ny c th dn ti
vics dng nhn lc khng hiu quv lm chch kng k hoch ban u vch ra.
Cch tip cn ny cng gy ra tnh i din qu mc ca cht thi khi n vo thi im
mun trong ngy v khongt gia cc xe ti vn chuyn c xu hng ko di ra vo phn
cui ca ngy v bi v cc xe ti n mun thng c xu th ch khng y, c bit
nu chng li c tnh bng tn ch khng phi tnh bng m3.
Vic t c cc mu theo yu cu phn loi th tng t nh vic thu mt
mu c sau n pht v chng u c nhng nhc im nh nhau.Khong cch ly mu
mt cch ngu nhin c cng nhc im nh l khong cch ly mu khng i tng
ng cng vi mt s nhc im ph thm sau y:
- Khong cch ly mu ngu nhin s lm tng kh nng i ly mu ngoithc a i khi phi n khng ngi ri, hoc i khi phi lm thm ngoi
gi
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Bi ging Thit K Kim Sot Cht Thi Rn
- Khong cch ly mu ngu nhin s lm tng kh nng b l cc xe ti c la chn khi m c qu nhiu xe ti n mt cch ngu nhin trong
mt khong thi ngn.
Trong nhiu trng hp, vic ly mu theo ngun cht thi s lm gim ti a cc
vn i km theo cc kiu ly mu theo khong cch ny. Cc ngun cht thi m t cc mu c th c la chn bao gm cht thi th, cht thi t cc xe gong n l,
t cc tuyn thu gom c bit, t cc khu vc to ra cht thi nh khu dn c v khu
thng mi v cc ngun c th nh t khch sn, hoc t cc chung c. Nhn chung,
vic ly mu theo ngun s c ngha nu nh vic cung cp thng tin mt cch y
v khi lng cht thi t mi ngun c ly mu. Cc mu c th c thu gom t
tng ngun t l thun vi khi lng cht thi t mi ngun, hoc cc kt qu thnh
phn i vi cc ngun khc nhau c th c ly theo trng s da trn khi lng t
mi ngun.Tt nht l, ni/thit b tip nhn CTR c sn cn v mt ngn hng d liu
my tnh cha ng nhng thng tin sau y v ti lng cht thi:
trng lng thc ca cht thi, loi cht thi, loi xe vn ti chuyn ch cht thi, v loi xe gong thu gom c thu gom t th no ban u.Thng tin ny s c kt hp vi cc thng tin trong hp ng chuyn ch cht
thi trong mi th c tnh mt cch hiu qu khi lng CTR th t khu dn c
v t khu thng mi, bun bn.Cc dch v cng ch (thuc quyn qun l ca chnh
quyn thnh ph) tronng cc th thng chuyn ch CTR t cc khu dn c, cn cc
dch v t nhn thng ph trch chuyn ch cht thi rn khu bun bn, thng mi.
Trong mt s trng hp khc, chnh quyn thnh ph thng k hp ng vi dch v
chuyn ch t nhn thu gom cht thi khu dn c. Cht thi dn c v cht thi
thng mi, bun bn cng c th c phn bit bi loi xe vn chuyn m c s
dng chuyn ch cht thi.Nu ni/thit b tip nhn CTR khng c sn cn, ngi ta
c th ghi chp li V cht thi trong vic thit k k hoch ly mu nhng phi phn bit
gia cht thi c nn p v cha c nn p. Nhiu ni/thit b tip nhn CTR
nhn rt t cht thi th cha c nn p, trong khi nhng ni khc li tip nhn mt
khi lng ng k loi cht thi cha c nn p ny. Bi v tnh theo bnh qun u
ngi th cht thi dn c c to ra tng i thng nht nn c th s dng s li u
dn s phn b cc mu cht thi dn c trong s cc th nu nh khng sn c cc
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Bi ging Thit K Kim Sot Cht Thi Rn
bn ghi khi lng cn thit. i ng nhn s ngoi thc a phi phng vn cc xe vn
chuyn t nhn n ni/thit b nhn rc bit v ngun gc cht thi ch n. Thng
tin c cung cp t nhng i vn chuyn ny thng khng c y . Trong mt
vi trng hp, thng tin ny c th c b sung hoc c chnh sa trong qu trnh
phn loi mu.
1.5.3 Thu mu
Hu ht cc chng trnh ly mu bao gm c ASTM D 5231 u khng nh rng
mi mt xe ti c la chn th nn c hng dn x cht thi trong vng c
quy nh thu mu. ASTM D 5231 cng khng nh rng b mt m cht thi s c
x xung nn c dn sch s nhng trong hu ht cc nghin cu, vic ngn nga mt
mu khng cho cha mt s lng vt cht t mt khi lng cht thi khc nhau l
khng cn thit.
Vic la chn mt phng php ly mu i hi s nh gi v bn cht ca CTR
th c x t mt xe ti c nn p theo tiu chun ln b mt ca mt bi rc hoc
ln mt mt phng c lt. Cht thi c xu hng gi c hnh dng ca n vn c
khi c ch trong xe ti ch khng phi s thnh mt ng xp mm.Ti cht thi
c c th cao t 7 n 8 fit.Trong nhiu ng rc, cc ti rc b nn li vi nhau
cht n mc m rt kh khn ko vt cht ra khi ng rc. Mt s cht thi thngb tt khi nh hoc b tt sang mt pha ca ng rc, nhng cht thi xp v lng lo
ny khng nn c s dng ly mu bi v n c th c nhng c im khng i
din.Nhn chung, mt mu nn c la chn mt cch ngu nhint mi xe vn ti
c la chn nh c ch ra trong ASTM D5231. Nu nhiu mu phi c ly t
mt ng rc th nn thu gom cc mu t nhiu phn khc nhau ca ng rc.
Vn u tin l kch c mu c thu gom t mi xe vn chuyn. Ngi ta
s dng cc kch c mu khc nhau, thay i t 50lb ti ton b ng rc.
Cc mu lnc cc u im sau y:
-S bin thin ( lch chun) gia ccmu th nh hn v vy mt s mu t hn
c yu cu t c mt mc chnh xc cho trc.
-S phn b kt qu phn loi cc mu th gn vi phn b chun hn (ng
cong hnh chung)
-Phm vi ranh gii gia mu v phn cn li ca ng rc th nh hn, tng xng
vi th tch ca mu
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Bi ging Thit K Kim Sot Cht Thi Rn
B
C
DA
Cc mu nhthng c u im l thi gian phn loi mu v thu gom mu ngn
hn. Ngi ta nht tr rng kch c mu ti u khong t 200 n 300 lb (90,8 kg
136,2 kg) t cc ng CTR th bao gm:
Tp hp mt mu t hp t vt cht c ly t cc im c xc nhtrc trong ng rc (v d nh l tng gc hay l ti im gia ca mipha)
To thnh hnh nn v chia u thnh bn phn Thu gom mt mu bng gu ngom t mt im c la chn ngu
nhin
Thu gom th cng mt ct cht thi t mt v tr c la chn ngu nhin.Nhc im c bn ca cc mu t hp th ging nh nhc im ca cc mu
nh: phm vi bin ly mu ln buc nhng ngi ly mu phi a ra qu nhiu quyt
nh liu c gp cc loi cht thi trong mu khng. Mt mu t hp c xu hng l mt
mu nh gi hn l mt mu ngu nhin. Nhc im th hai ca cc mu t hp l
chng mt nhiu thi gian hn thu gom nu so snh vi mu gu (grab) hoc mu ct
(column). S bin i ca ly mu t hp l phi thu gom tng mu t nhng ng cht
thi khc nhau.
Trong bc to thnh hnh nn v chia u thnh bn phn,nhng ngi ly mu trn mt khi lng ln cht thi lm cho cc
c tnh ca n ng u hn, ri sp xp cht thi c trn vo mt ng hnh nn
v la chn ngu nhin mt phn, thng l mt phn t ca ng cht thi c trn.
Mc ch: kt hp cc u im v mt thng k ca cc mu ln vi thi gian phn
loi cc mu nh hn c gim i. Qu trnh sp xp thnh hnh nn v chia u
ng cht thi thnh 4 phn c th c lm vi c ng cht thi hoc ch vi mt phn
cht thi v c th c thc hin mt ln hoc nhiu ln nhm t c mt mu n.
ASTM D 5231 ch r mt vng nn v chia t, bt u khong 1000 lb (454 kg) cht
thi rn nhm t c mt mu khong t 200 n 300 lb (90,8 kg 136,2 kg).
To thnh hnh nn v chia t (coning and quartering) tim n nhng kh khn
nu so snh vi ly mu gu (grab) hoc ly mu ct v c nhng nhc imnh sau:
V c bn l lm tng thi gian ly mu i hi c khng gian rng C xu hng lm rch, gy cc ti rc, lm cho vic x l cht thi kh khn hn
nhiu.
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Bi ging Thit K Kim Sot Cht Thi Rn
Lm tng thi gian phn loi rc do lm ph v cc cm rc cc loi. Yu cu s dng mt my cht ti kiu ko (front-end loader) trong mt giai on
kh di. Nhiu ni/thit b tip nhn CTR c th to ra mt my cht ti kiu ko
v lun phi c ngi vn hnh trong cc giai on ngn; nhng mt vi ni/thit
b tip nhn CTR khng c th cung cp mt my cht ti kiu ko trong cc giaion di hn c yu cu cho to hnh nn v chia t.
chnh xc ca vic phn loi rc b gim i do c s tng ln v phn trm chtthi thc phm b dnh vo hoc b hp ph vo cc thnh phn cht thi khc.
Lm tng tn tht m t mu Thc y s phn tng cht thi do t trng v c ht. gim thiu kh nng
phn tng ny th mu ly phn t phi mt mt phng vi cnh thng ng v
cc im nm trung tm hnh nn. Thc t th hnh dng ny rt kh c th t
c.
u imca to hnh nn v chia t l n lm gim i s khc nhau gia cc mu
( lch chun), gim s lng mu cn phn loi. To hnh nn v chia t c cho
l hp l nu nh n lm gim lch chun b p nhng nhc im v nhng
kh khn tim tng.
Nu to hnh nn v chia t c lm mt cch hon thin v y th vic phnloi mu cui cng s tng ng vi vic phn loi ton b nn cht thi, v lch
chun c gim mt cch ng k. V s lng cc mu phi c phn loi t
c mt mc chnh xc cho trc th t l vi bnh phng lch chun, vic to
nn v chia t c th lmgim mt cch ng k s lng mu c yu cu. Tuy nhin,
lu rng cng thc hin vic to nn v chia t k lng th tng nhc im cng nh
tng kh khn tim tng lun i km theo phng php ny li cng r rt.
Mt phng php ly mu CTR thng dng hn l thu mt mu gu c s
dng mt my cht ti kiu ko. Phng php ny tng i nhanh v thng c th
c lm bi nhn lc ph trch thit b m khng can thip qu mc vo vic vn hnh
thit b thng thng. Vic ly mu bng my cht ti kiu ko s lm gim tc ng
tim tng v s thin v ca ngi ly mu thng xy ra vi cc phngphp ly mu
th cng, nhng li tim n nhng loi thin v khc nh sau:
Ging nh ly mu bng xng, vic ly mu bng my cht ti kiu ko cxu hng thun li cho cc vt th nh v c chc hn l cc vt th nh
v to. Cc vt th nh v to c xuth b y i hoc b ri xung khi m ci
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Bi ging Thit K Kim Sot Cht Thi Rn
gu ca my cht ti kiu ko c lp t, c nng ln, hoc c rt
ra.
Mt khc, vic lm gy, t cc ti cha rc khi gu ca my cht ti kiuko xm nhp su vo ng cht thi th c xu hng gii phng cc vt
cht mn, c chc khi nhng ti ny, iu lm gim tnh i din cavt cht ny trong mu.
Cc mu ly bng my cht ti kiu ko trn b mt t th thin v chtthi ri xung t nh hoc t cc pha ca ng cht thi m chng c th
khng c cc c tnh nh l cc cht thi vn cn li trong ng. Trn
cc b mt bm bi, cc mu ly bng my cht ti kiu ko trn b mt t
c th b nhim bn bi bi.
Tc ng ca nhng nhn t khng khch quan ny c th c gim i nu nh
mu c ly cn thn v i ng ly mu phi chnh sa cc ngun gy ra s khng
khch quan, v d nh cc vt th nng ri xung t gu khi n c nng ln. Trong
phng php ly mu bng my cht ti kiu ko, nhn lc ly mu c th dng cc im
ly mu khc nhau cho cc ti khc nhau m bo chc chn rng cc lp cht thi
khc nhau theo phng ng v phng ngang u c i din trong mu. C th thay
i im ly mu hoc l ngu nhin hoc l theo kiu lp li. Phm vi thin lch m cth xut pht t vic s dng cc im ly mu ging nhau cho mi ng cht thi th
khng c bit.Mt nhc im c hu ca phng php ly mu bng my cht ti
kiu ko l kh khn trong vic c tnh trng lng cc mu. Trng lng ch c th
c c tnh da trn th tch, v cc mu c th tch bng nhau li c trng lng khc
nhau.
Mt phng php ly mu CTR t ph bin hn l thu gom th cng mt ct cht
thi rn hp t mt v tr c la chn ngu nhin trn b mt ng cht thi, ko di t
y n nh ng cht thi. Phng php ny c nhng u im nh sau:
khng yu cu bt c thit b nng no thi gian ly mu tng i ngn Do cc lp khc nhau trong ng cht thi theo phng ngang u c ly
mu, nn cc mu s i din nhiu hn so vi phng php ly mu bng
gu s dng mt my cht ti kiu ko. Tuy nhin, lu rng cc ng cht
thi cng b phn tng pha trc ra pha sau, v cc mu ly theo ct
khng i din cho cc lp khc nhau theo phng ng.
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Bi ging Thit K Kim Sot Cht Thi Rn
Nhc im chnh ca phng php ly mu theo ct l ch vic ly cht thi
bng th cng t pha b nn cht ca ng cht thi th rt kh khn v nguy c b cc
vt thng ct v chch t vic ko cc cht thi l ln.
Trong s nhiu quy trnh ly mu lai ghp m kt hp cc c im ca 4 quy
trnh chung ny, c hai quy trnh kh l thch hp vi s lu c th.Th nht, trong quy trnh ly mu c ch r ASTM D 5231, mt my cht
ti kiu ko c th loi b t nht l 454 kg(1000lb) vt cht dc theo ton b mt pha
ca ng cht thi; sau ng cht thi s c xo trn, to nn v chia t to ra
mt mu nng t 90,8 n 136 kg (t 200 n 300 lb). So snh vi phng php ly mu
bng gu c s dng mt my cht ti kiu ko, phng php ATSM c u im l to ra
cc mu mang tnh i din cho cht thi tt hn, nhng li c nhc im l lm tng
thi gian ly mu.
Trong mt quy trnh ly mu lai ghp th hai, mt my cht ti kiu ko lm ti
mt khi lng nh cht thi t mt im c la chn ngu nhin hoc t mt ct
trong ng cht thi, v mu c thu th cng t ng cht thi c lm ti ln.
Phng php ny th an ton hn phng php ly mu theo ct th cng v kim
sot c trng lng ca mu nhiu hn l ly mu bng my cht ti kiu ko. Phng
php ny ch yu trnh c cc thin lch tim n ca ly mu bng my cht ti kiuko nhng li c xu hng thin lch do ngi ly mu.
1.5.4 Phn loi v cn mu cht thi rn th
Trong hu ht cc trng hp, vic phn loi CTR nn c xem nh l mt hot
ng cng nghip ch khng phi l mt ng.cu trong phng th nghim. Trong khi
chnh xc l rt cn thit th vic o chnh xc ph hp li l ounces ch khng phi l
gam hay hay l mg. Nu c nht nh i hi c mt mc chnh xc cao qu th s lm
chm li qu trnh phn loi, gim s lng mu c th c phn lo i.
Ln lt, s gim ny s lm gim chnh xc thng k ca kt qu. Trong case
m mt hot ng yu cu mt mc chnh xc l 10% th khng chnh xc l 1%
khng c cho l quan trng lm.Cc nguyn l v hot ng cng nghip ng dng
cho phn loi CTR bao gm gim thiu ti a s di chuyn ca cng nhn, duy tr s
thoi mi v khch l cng nhn.
a.Ly mu cht thi rn th phn tch trong phng th nghim
t c cc kt qu th nghim c ngha i vi CTR th th kh khn.
Cc ngun kh khn c bn l:
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Bi ging Thit K Kim Sot Cht Thi Rn
s c mt ca nhiu loi vt th khc nhau trong CTR th v kch c ln ca cc vt th ny.
Thu gom cc mu nh nhng mang tnh i din t mt ng ng nht cc vt
th nh (v d nh ng go) th d dng hn t mt ng cc vt th ln khng ng
nht. Cc ngun kh khn th cp trong ly mu CTR th bao gm s phn b khngng u ca m v cc quy trnh th nghim khng trc sau nh mt. Thnh phn
ca CTR khng mang tnh cht ng nht. vic xc nh thnh phn ca cc cht thi
khng phi l cng vic n gin.
Cng vic kh khn nht trong vic thit k v vn hnh h thng qun l CTR l
d on c thnh phn ca cht thi trong hin ti v tng lai . Mt cch xc nh
n gin nht hin nay vn p dng l phng php mt phn t.
Trnh t tin hnh nh sau:
1. Mu CTR ban u c ly t khu vc ng.cu c khi lng khong 100-250kg. ng rc ti mt ni c lp ring bit, xo trn u bng cch
vun thnh ng hnh cn nhiu ln. Khi mu trn u ng nht chia
hnh cn lm 4 phn bng nhau.
2. Kt hp 2 phn cho nhau v tip tc trn u thnh 1 ng hnh cn. Tiptc thc hin bc trn cho n khi t c mu th nghim c khi lngkhong 20-30kg phn tch thnh phn.
3. Mu rc s c phn loi th cng, bng tay. Mi thnh phn s c tvo mi khay tng ng. Sau em cn cc khay v ghi khi lng ca
cc thnh phn. c s liu cc thnhphn chnh xc, cc mu thu thp
nn theo tng ma trong nm
b.Quy trnh th nghim (labortory procedure)
Vn c bn l kch c cc mu ln nh th no c gi ti phng th
nghim. Cu tr li i vi vn ny ph thuc vo cc quy trnh c s dng bi
phng th nghim. Mt quy trnh th nghim thng mi gm cc bc sau:
Mt phn vt cht ca mu c gi ti phng th nghim s c cn, lm kh,v c cn li xc nh hm lng m. Yu t gii hn g. on ny ca
quy trnh thng l ln ca l sy kh trong phng TN.
Mt phn vt cht kh c nghin thnh ht t 1/8 n 1/4 in. Mt phn vt cht t 1/8 n 1/4 in c nghin mn thnh bt, cng nh cng tt.
i vi nha do, phi thm vo kh trc khi nghin lm cho n gin hn.
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Bi ging Thit K Kim Sot Cht Thi Rn
Nhn chung, th nghim trong phng th nghim mt cch thc s c thc hintrn 0,5 n 3 gam vt cht c nghin mn, ph thuc vo loi th nghim, thit
b c th v quy trnh th nghim.
Nhng s thay i v quy trnh ny nh sau:
Huht cc phng th nghim khng c thit b nghin cc vt cht v c nhthy tinh v kim loi. Trong th nghim chy, vt cht ny b loi khi mu trc
khi nghin ri cn v ghi chp li nh l tro. i vi th nghim kim loi, cc vt
th kim loi c th b ct ra tng mnh bng tay hoc khoan to ra cc l nh
th nghim. Thy tinh v gm s thng b nghin.
Nhiu phng th nghim khng c cc thit b nghin mn v vy vic thc hincc th nghim trn vt cht tng i to, th.
Thm vo vic s dng cc phng php khc nhau chun b cht thi cho th
nghim, cc phng TN cng s dng cc phng php th nghim khc nhau. Vn
thc s khng phi l ln ca mu ln nh th no th c gi ti phng TN m l
i ng nhn s phng TN v ngoi thc a nn chia s nhim v l: lm gim cc mu
ti 1 hoc 2 gam
i vi cc mc ch thc hnh, khi lng ti a c gi ti phng th nghim nn l
khi lng m phng th nghim c chun b dn ra v trn ln trong vic chun b la chn vt cht c lm kh. Khi lng ti thiu nn l khi lng m phng th
nghim c chun b lm kh v nghin nh. Cc mu t hp lm th nghim ch
yu c tch ly trong cc ti nha ng rc ri ng hp vn chuyn.
Mt phng php khc l tch ly cc mu trong cc thng nha 5l c np y. Cc
thng nha th t hn nhiu so vi cc ti nha nhng c mt vi u im sau y:
Cc thng nha v np ca chng th d dng dn nhn v cc nhn thd dng c.
Cc np, chng ch c nhc ln ch khi vt cht c thm vo thng,ngn nga c tn tht m trong giai on ly mu hiu qu.
Vt cht ca mu c th c nn li trong cc thng nha nu n cy xung xung quanh ra bn trong.
c.Xem xt v s dng cc kt qu th nghim
Cc quy trnh, th tc th nghim khng hon chnh v cc li xy ra khi thc hin cc
quy trnh cng nh trong tnh ton v ghi chp cc kt qu l ph bin. Xem xt li
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Bi ging Thit K Kim Sot Cht Thi Rn
cc kt qu nhn c t mt phng TN thy chng c ngha hay khng l mt
vic rt quan trng.
Vic kim tra ny kh d dng i vi cht thi c tnh chy bi v nhiu ngi
c bit v cc c tnh gy chy ca CTR v cc vt cht thnh phn ca n. Nhn
bit cc kt qu th nghim b li i vi kim loi th kh khn hn nhiu so vi cccht hu c c hi. Sau y l cc hng dn ng dng nh gi tnh hp l,
ng n ca kt qu th nghim i vi cc c tnh gy chy trn c s kh:
cc kt qu trn c s kh i vi giy, cht thi sn vn, nha, g, v cc loibng v sinh c th tiu hy c nn gn vi kt qu ca cc vt cht k trn,
phi chp nhn s thay i ln hn trong cc kt qu n l i vi cht thi thcphm, dt/cao su/da, bi qung v cc cht t khc do s bin i v mt ha hc
ca nhng loi ny
trong s cc loi giy, ch c nhng loi vi t l giy bng cao nh l tp ch vcc th qung co nn c gi tr tro ln hn 10% mt cch ng k.
Phng th nghim nn t nguyn kim tra s tnh ton ny v lm nhc li th
nghim nu nh cc tnh ton khng phi l nguyn nhn ca vn . Nghin vn cc vt
cht khng u, dng khi ln nh cc ng g d nh trc khi chn lp