đánh giá khả năng áp dụng mô hình nông nghiệp không chất thải tại
TRANSCRIPT
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I HC QUC GIA H NI
TRNG I HC KHOA HC T NHIN
KHOA MI TRNG
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L TH HNG NHUNG
NH GI KH NNG P DNG M HNH
NNG NGHIP KHNG CHT THI TI X GIAO LC,
HUYN GIAO THY, TNH NAM NH
LUN VN THC S KHOA HC
H NI - 2015
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I HC QUC GIA H NI
TRNG I HC KHOA HC T NHIN
KHOA MI TRNG
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L TH HNG NHUNG
NH GI KH NNG P DNG M HNH
NNG NGHIP KHNG CHT THI TI X GIAO LC,
HUYN GIAO THY, TNH NAM NH
Chuyn ngnh: Khoa hc Mi trng
M s: 60440301
LUN VN THC S KHOA HC
Ngi hng dn khoa hc: TS. Nguyn Th Hong Lin
H Ni - 2015
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LI CM N
Ti xin trn trng cm n:
TS. Nguyn Th Hong Lin, tn tnh hng dn, gip ti trong sut
qu trnh nghin cu v hon thnh lun vn thc s ny.
Cc thy c gio trong khoa Mi trng, Trng i hc KHTN - H Quc
gia H Ni gip ti hon thnh chng trnh hc v bn lun vn ny.
y ban nhn dn x Giao Lc v ngi dn x Giao Lc, huyn Giao Thy,
tnh Nam nh gip ti trong qu trnh nghin cu ti ny.
Cui cng, ti xin by t tnh cm v lng bit n chn thnh nht ti
gia nh, bn b, v ng nghip tn tnh gip , ng vin ti trong sut thi
gian qua.
Ti xin chn thnh cm n tt c nhng s gip qu bu .
H Ni, ngy thng nm 2016
Ngi thc hin
L Th Hng Nhung
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MC LC
MC LC ........................................................................................................................................ i
DANH MC CC HNH ............................................................................................................. v
DANH MC CC BNG ........................................................................................................... vi
DANH MC T VIT TT ...................................................................................................... vii
M U ......................................................................................................................................... 1
1. Tnh cp thit ca ti ......................................................................................... 1
2. Mc tiu nghin cu .............................................................................................. 2
3. Ni dung nghin cu ............................................................................................. 2
4. ngha khoa hc v thc tin ca ti ............................................................... 3
4.1. ngha khoa hc .................................................................................................... 3
4.2. ngha thc tin .................................................................................................... 3
Chng 1: TNG QUAN VN NGHIN CU ................................................................. 4
1.1. Tng quan v m hnh nng nghip khng cht thi ............................................................ 4
1.1.1. nh ngha v m hnh nng nghip khng cht thi ...................................... 4
1.1.2. Mc tiu ca m hnh khng cht thi nng nghip ....................................... 5
1.1.3. Tiu ch m hnh khng cht thi .................................................................... 5
1.2. Tng quan v cht thi nng nghip ....................................................................................... 6
1.2.1. Tng quan v cht thi chn nui .................................................................... 6
1.2.2. Tng quan v cht thi trng trt .................................................................... 7
1.3. Tng quan v cc phng php x l cht thi nng nghip ............................................... 8
1.3.1. X l cht thi chn nui ................................................................................. 8
1.3.2. X l cht thi trng trt ............................................................................... 13
1.4. Tng quan v cng ngh trng nm rm t rm r ............................................................. 14
1.4.1. Tng quan v nm rm .................................................................................. 14
1.4.1.1. c tnh sinh hc ............................................................................................ 14
1.4.1.2. c im hnh thi ......................................................................................... 15
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1.4.2. Tng quan v cng ngh trng nm rm t rm r ....................................... 16
1.4.2.1. Thi v trng nm rm .................................................................................. 16
1.4.2.2. Nguyn liu .................................................................................................... 16
1.4.2.3. Chn meo ging ............................................................................................. 16
1.4.2.4. X l nguyn liu ........................................................................................... 17
1.4.2.5. Cch cht m .................................................................................................. 17
1.4.2.6. Cch cy meo ................................................................................................. 18
1.4.2.7. Chm sc m nm cy ging ................................................................... 18
1.4.2.8. Cch thu hi nm ............................................................................................ 19
1.4.3. Cch phng tr bnh cho nm rm ............................................................... 20
1.4.3.1. Bnh sinh l .................................................................................................... 20
1.4.3.2. Bnh nhim ..................................................................................................... 20
1.5. Tng quan v khu vc nghin cu ....................................................................................... 21
1.5.1. iu kin t nhin x Giao Lc, huyn Giao Thy, tnh Nam nh ............. 21
1.5.1.1. V tri a l ...................................................................................................... 21
1.5.1.2. Hin trng s dng t ................................................................................... 23
1.5.1.3. Khi hu ............................................................................................................ 23
1.5.1.4. Thy li ........................................................................................................... 24
1.5.2. iu kin kinh t - x hi x Giao Lc, huyn Giao Thy, tnh Nam nh.. 24
1.5.2.1. Dn s ............................................................................................................. 24
1.5.2.2. Kinh t ............................................................................................................. 24
1.5.2.3. Vn ha gio dc y t .............................................................................. 25
1.5.2.4. C s h tng .................................................................................................. 26
1.6. Mt s m hnh nng nghip khng cht thi ..................................................................... 28
1.6.1. Hin trng m hnh nng nghip khng cht thi ca nc ngoi ................ 28
1.6.1.1. M hnh khng cht thi ti vng quc Anh ............................................. 28
1.6.1.2. M hnh VAC ti Trung Quc ...................................................................... 29
1.6.1.3. M hnh khng cht thi ti Fiji chu c .................................................. 29
1.6.2. Hin trng m hnh nng nghip khng cht thi ti Vit Nam .................... 30
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1.6.2.1. M hnh nng nghip khng cht thi phn compost ti Quan
Ha, Thanh Ha. .................................................................................................................... 30
1.6.2.2. M hnh chn nui khng cht thi ti Ph Th .......................................... 31
Chng 2: I TNG, PHM VI V PHNG PHP NGHIN CU ....................... 33
2.1. i tng nghin cu ............................................................................................................ 33
2.2. Phm vi nghin cu ............................................................................................................... 33
2.3. Phng php nghin cu ....................................................................................................... 33
2.3.1. Phng php thu thp s liu ........................................................................ 33
2.3.2. Phng php iu tra, kho st thc t .......................................................... 34
2.3.3. Phng php ly mu .................................................................................... 34
2.3.4. Phng php tham vn kin cng ng ..................................................... 35
2.3.5. Phng php chuyn gia ............................................................................... 36
2.3.6. Phng php k tha ..................................................................................... 36
2.3.7. Phng php thng k v x l d liu ......................................................... 36
Chng 3: KT QU NGHIN CU V THO LUN ..................................................... 37
3.1. Hin trng thu gom v x l cht thi nng nghip ti x Giao Lc, huyn Giao Thy,
tnh Nam nh ............................................................................................................................... 37
3.1.1. Hin trng cht thi nng nghip x Giao Lc .............................................. 37
3.1.2. Hin trng thu gom v x l cht thi nng nghip ti x Giao Lc ............. 39
3.1.3. nh gi nhng thun li v kh khn khi p dng m hnh nng nghip
khng cht thi ti x Giao Lc ........................................................................ 41
3.2. Cc m hnh x l cht thi nng nghip ti x Giao Lc .................................................. 43
3.2.1. iu kin p dng m hnh............................................................................ 43
3.2.2. Xy dng m hnh tng qut Vn Ao Chung Biogas ...................... 44
3.2.3. Xy dng m hnh hm biogas ................................................................... 46
3.2.3.1. Tnh ton hm biogas s dng cho h gia nh trung bnh 4 ngi c nui
b v ln ................................................................................................................................... 49
3.2.3.2. Cu to, hot ng ca b nha composite .................................................. 52
3.2.4. Xy dng m hnh x l cht thi nng nghip t ng rung .................... 55
3.2.4.1. M hnh trng nm rm trong nh cho h gia nh ..................................... 55
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3.2.4.2. X l b thi sau trng nm bng phn compost ...................................... 56
3.2.4.3. X l rm, gc r, tru ti rung bng ch phm vi sinh ............................ 59
3.3. nh gi hiu qu x l v kh nng p dng m hnh ...................................................... 59
3.3.1. nh gi hiu qu x l v kh nng p dng m hnh VACB .................... 59
3.3.1.1. p dng cho h gia nh nui ln x Giao Lc, huyn Giao Thy .. 59
3.3.1.2. Kt qu phn tch ........................................................................................... 61
3.3.2. nh gi hiu qu v kh nng p dng m hnh x l ph ph phm
trng nm .......................................................................................................... 67
3.4. xut cc bin php nng cao kh nng p dng m hnh nng nghip khng cht
thi ti x Giao Lc ....................................................................................................................... 69
KT LUN V KIN NGH ..................................................................................................... 71
KT LUN ............................................................................................................. 71
KIN NGH ............................................................................................................. 72
TI LIU THAM KHO ........................................................................................................... 73
PH LC ...................................................................................................................................... 75
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DANH MC CC HNH
Hnh 1.1: S chung ca m hnh khng cht thi .................................................. 5
Hnh 1.2: Hnh thi ca nm rm .............................................................................. 15
Hnh 1.3: V tri a l khu vc x Giao Lc vi cc x xung quanh ........................ 22
Hnh 1.4: H sinh thi tch hp hng ti khng cht thi ti Fiji ........................... 29
Hnh 1.5: M hnh phn compost ti Quan Ha, Thanh Ha ................................ 30
Hnh 3.1: Ngun gc pht sinh cht thi nng nghip trong 1 h gia nh .............. 37
Hnh 3.2: Ph phm cy la sau thu hoch ............................................................... 40
Hnh 3.3: M hnh tng qut VACB ......................................................................... 45
Hnh 3.4: 04 kiu hm xut trong lun vn ....................................................... 48
Hnh 3.5: Cu to hm biogas nha composite ........................................................ 53
Hnh 3.6: S quy trnh cng ngh x l b thi sau trng nm ........................... 57
Hnh 3.7: Cu to hm biogas composite 2,25m ...................................................... 60
Hnh 3.8: Mu sc nc thi u vo v u ra ca h thng biogas ....................... 61
Hnh 3.9: Biu th hin gi tr SS u vo, u ra ca h thng x l biogas
................................................................................................................................... 64
Hnh 3.10: Biu th hin gi tr BOD5 u vo, u ra ca h thng x l
biogas ........................................................................................................................ 64
Hnh 3.11: Biu th hin gi tr COD u vo, u ra ca h thng x l
biogas ........................................................................................................................ 64
Hnh 3.12: Biu th hin gi tr tng Nit u vo, u ra ca h thng x l
biogas ........................................................................................................................ 65
Hnh 3.13: Biu th hin gi tr tng Pht pho u vo, u ra ca h thng
x l biogas .............................................................................................................. 65
Hnh 3.14: Biu th hin gi tr Coliform u vo, u ra ca h thng x l
biogas ........................................................................................................................ 66
Hnh 3.15: S thay i pH v nhit trong qu trnh b thi sau trng nm ...... 68
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DANH MC CC BNG
Bng 1.1: Hin trng s dng t ti x Giao Lc .................................................... 23
Bng 3.1: Trung bnh lng phn thi ca vt nui trong 1 h gia nh/ngy ......... 38
Bng 3.2: So snh u nhc im gia cc kiu hm .............................................. 46
Bng 3.3: Cc kiu hm biogas c ngi dn x Giao Lc mun s dng ....... 48
Bng 3.4: c tnh v sn lng KSH ca mt s nguyn liu thng gp............. 49
Bng 3.5: Sn lng KSH tnh cho h gia nh A .................................................... 50
Bng 3.6: Lng kh sinh ra tnh cho h gia nh A ................................................. 51
Bng 3.7: Kich thc hm v lng cht thi np vo hm mi ngy .................. 61
Bng 3.8: Kch c h u ra .................................................................................... 61
Bng 3.9: Kt qu phn tich nc thi u vo, u ra t 1 ................................... 62
Bng 3.10: Kt qu phn tich nc thi u vo, u ra t 2 ................................. 62
Bng 3.11: Kt qu phn tich nc thi u vo, u ra t 3 ................................. 63
Bng 3.12: Kt qu phn tch phn compost ti 2 m hnh ...................................... 68
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DANH MC T VIT TT
BOD5 Nhu cu oxi sinh hc (Biochemical Oxygen Demand)
BVTV Bo v thc vt
CN - TTCN Cng nghip Tiu th cng nghip
COD Nhu cu oxi ha hc (Chemical Oxygen Demand)
CTR Cht thi rn
KSH Kh sinh hc
N.P.K Nit Pht pho - Kali
SS Cht rn l lng (Suspended Solid)
THCS Trung hc c s
THPT Trung hc ph thng
TNHH Trch nhim hu hn
UBND y ban nhn dn
VACB Vn Ao - Chung - Biogas
VCK Vt cht kh
VSV Vi sinh vt
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M U
1. Tnh cp thit ca ti
Ngy nay, nhim mi trng do qu trnh pht thi trong sn xut nng
nghip ang tr thnh vn ln i vi cc quc gia ang pht trin, c bit l
nc nng nghip nh Vit Nam. Vic lm dng cc loi phn bn, ha cht bo v
thc vt trong sn xut nng nghip v qu trnh x l cc ph phm, cht thi
trong trng trt, chn nui cha trit . Ho cht s dng ngy cng nhiu nhng
cc bin php lm sch mi trng ng rung, dit tr mm bnh trc khi bc
vo v sn xut mi li it c nng dn quan tm. Do vy lng phn bn v ho
cht bo v thc vt cn ng li trong t kh ln gy nhim mi trng, nh
hng ti sc khe con ngi. Bn cnh , cht thi t chn nui khng qua x l
n nh v nc thi khng qua x l x trc tip ra mi trng gy nhim
nghim trng.
Do , thay i theo hng sn xut gn vi bo v mi trng l bin php
bt buc thc hin mt nn sn xut nng nghip bn vng. Sn xut theo quy
trnh an ton, gn vi bo v mi trng trong trng trt, chn nui, nui trng thy
sn... ang l hng c ngnh chc nng khuyn khch p dng.
M hnh nng nghip khng cht thi l m hnh nng nghip bn vng,
trong ngi nng dn ch ng pht trin cc m hnh trng trt chn nui,
gii quyt rc thi nng nghip ca mnh m khng cn ph thuc vo nh cung
cp dch v. Trong m hnh ny, cht thi ca hot ng ny li l u vo ca
hot ng kia, kt hp vi mt s k thut xanh, m hnh nng nghip khng cht
thi em li nng sut cao v li nhun ln cng nh s ch ng hon ton cho
ngi nng dn. Tn dng ngun cht thi sinh hot hu c t nng nghip v
sinh hot lm biogas l gii php hu ch v khng ch to ra c sn phm
phn bn hu c c li cho cy trng, m cn cung cp lng khi t nht nh
phc v cho gia nh, tit kim c chi phi cng nh l lng phn bn ha hc,
gim c nhim mi trng.
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X Giao Lc thuc huyn Giao Thy, tnh Nam nh l mt x thun nng
nn ngi dn ch yu l lm nng nghip. Cht thi nng nghip y ch yu
gm cc cht trong trng trt v chn nui. Cht thi ny khng c x l trit ,
mt phn c ra cc knh mng, mt phn em t vi khi lng kh ln v
ph bin, dn n nhim mi trng nghim trng, nh hng n cng ng dn
c, gia tng gnh nng bnh tt.
Cng vi s pht trin khng ngng ca nn kinh t t nc, kinh t
nng thn ti x Giao Lc cng ang trong giai on chuyn mnh pht trin.
S pht trin to sc p khng nh i vi mi trng. Vic nghin cu,
nh gi v xut mt m hnh p dng ph hp, c tnh khoa hc v ng dng
cao cho x Giao Lc l cn thit. V vy ti: nh gi kh nng p dng
m hnh nng nghip khng cht thi ti x Giao Lc, huyn Giao Thy, tnh
Nam nh c la chn nghin cu.
2. Mc tiu nghin cu
Gp phn bo v mi trng nng thn thng qua hot ng tn thu v ch
bin cht thi nng nghip tr thnh phn bn theo m hnh nng nghip khng
cht thi (p dng ti x Giao Lc, huyn Giao thy, tnh Nam nh).
3. Ni dung nghin cu
- Tng quan, phn tich, nh gi v h thng ho cc ni dung lin quan
n s dng m hnh nng nghip khng cht thi trn th gii, trong khu vc v ti
Vit Nam.
- nh gi thc trng pht thi v qun l cht thi nng nghip ti x Giao
Lc, huyn Giao Thu, tnh Nam nh.
- Nghin cu, nh gi v xc nh c cc yu t nh hng n hiu qu
v cht lng qun l v s dng m hnh nng nghip khng cht thi ti vng
nng thn hin nay. Nghin cu in hnh ti x Giao Lc, huyn Giao Thu, tnh
Nam nh.
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4. ngha khoa hc v thc tin ca ti
4.1. ngha khoa hc
Lun vn nghin cu cc lun c l thuyt v thc tin v p dng m hnh
nng nghip khng cht thi, cc yu t nh hng n cht lng v hiu qu qun
l ca m hnh, trn c s phn tich ny xut c cc gii php s dng v x
l hp l cht thi nng nghip ti x Giao Lc, huyn Giao Thy, tnh Nam nh.
4.2. ngha thc tin
M hnh x l cht thi nng nghip trong lun vn c th s dng l ti liu
tham kho cho cc nh qun l a phng, gp phn nng cao hiu qu cc hot
ng qun l cht thi trng trt v chn nui ca x Giao Lc, huyn Giao Thy,
tnh Nam nh.
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Chng 1
TNG QUAN VN NGHIN CU
1.1. Tng quan v m hnh nng nghip khng cht thi
1.1.1. nh ngha v m hnh nng nghip khng cht thi
Khi nim Khng cht thi y khng phi l s khng (0) tuyt i
trong phn tch, m l khng tn ti dng thi c kh nng gy ra nhim mi
trng. Khng cht thi l mt khi nim hp nht nhng cng ngh hin hu
hng ti loi tr cht thi. Khng cht thi hng ti mc tiu khng to ra cht
thi bng phng chm tng cng ti a ti ch, gim thiu cht thi, hn ch tiu
th v bo m kh nng ti s dng, sa cha hay quay vng tr li vo t nhin
hay th trng ca sn phm to ra. [19]
M hnh nng nghip khng cht thi l m hnh nng nghip bn vng.
Trong m hnh ny, cht thi ca nhm ny li l u vo ca nhm kia, kt hp vi
mt s k thut xanh, m hnh nng nghip khng cht thi em li nng sut cao
v li nhun cho ngi nng dn.
M hnh khng cht thi l mt cch tip cn h thng ton din hng ti
nhng thay i trn quy m rng ln thng qua x hi theo con ng dng vt
cht, kt qu l khng cht thi. M hnh khng cht thi bao hm c nhng gii
php cui ng ng vi nhng khuyn khch chuyn i cht thi theo hng ti
sinh v ti to ti nguyn cng nh loi tr cht thi ti ngun.
M hnh khng cht thi da trn nguyn l ti thit k h thng nng
nghip mt chiu hin ti thnh h thng khp kn m phng theo nhng chu trnh
t nhin hon ho nhm gip cng ng t c mt nn kinh t pht trin n nh
v cung cp phng cch t cung ng y . [19]
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1.1.2. Mc tiu ca m hnh khng cht thi nng nghip
Mc tiu m hnh khng cht thi th hin nhu cu mt h thng x hi/nng
nghip khp kn. Cht thi l du hiu ca tnh khng hiu qu. Do , pht thi
bng khng c xem xt, nh gi hiu sut s dng ti nguyn 100% gm nng
lng, nguyn vt liu, nhn cng:
- Khng c cht thi v cht thi nguy hi;
- Khng cht thi vo mi trng: khng khi, nc, t;
- Khng cht thi trong qu trnh sn xut. Khng cht thi trong vng i sn
phm: t khu vn chuyn, s dng, kt thc thi b.
- Khng c t:
+ Gim thiu ri ro cho thin nhin;
+ Khng c t trong cht thi nguy hi. [19]
1.1.3. Tiu ch m hnh khng cht thi
Hnh 1.1: S chung ca m hnh khng cht thi [19]
- Tit kim tin bc
- y mnh vic ngn nga nhim: thit k v mi trng, ti s dng
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- y mnh vic thu hi cht thi: ti ch, phn bn
- nh hng cho vic bo tn ti nguyn v nng lng
- Loi tr nhim
- To ra nhng vic lm mi:
+ Qun l cht thi tr thnh qun l ngun ti nguyn
+ Sn xut nhiu sn phm t nhng vt liu c thu hi [19]
1.2. Tng quan v cht thi nng nghip
1.2.1. Tng quan v cht thi chn nui
a) nh ngha v cht thi chn nui
Cht thi chn nui l cht thi pht sinh trong qu trnh chn nui nh phn,
nc tiu, xc xc vtCht thi trong chn nui c chia lm ba loi: cht thi
rn, cht thi lng v cht thi kh. Trong cht thi chn nui c nhiu cc cht hu
c, v c, vi sinh vt v trng k sinh trng c th gy bnh cho ng vt v con
ngi.
b) Ngun gc pht sinh cht thi chn nui
Cht thi rn bao gm ch yu l phn, xc xc vt cht, thc n d tha ca
vt nui, vt liu lt chung v cc cht thi khc, m t 50% - 83% v t l
NPK cao.
Cht thi lng (nc thi) c m cao hn, trung bnh khong 93% - 98%
gm phn ln l nc thi ca vt nui, nc ra chung v phn phn lng ha tan.
Cht thi kh l cc loi khi sinh ra trong qu trnh chn nui, qu trnh phn
hy ca cc cht hu c dng rn v lng.
c) Phn loi cht thi chn nui
- Cht thi rn: Phn v nc tiu gia sc; xc sc vt cht; thc n d tha,
vt liu lt chung v cc cht thi.
- Cht thi lng: Trong cc loi cht thi ca chn nui, cht thi lng l
loi cht thi c khi lng ln nht. c bit khi lng nc thi ra chung c
ha chung vi nc tiu ca gia sc v nc tm gia sc. y cng l loi cht thi
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kh qun l, kh s dng. Mt khc, nc thi chn nui c nh hng rt ln n
mi trng nhng ngi chn nui it n vic x l n.
- Cht thi kh: Mi hi chung nui l hn hp khi c to ra bi qu
trnh phn hy k kh v hiu kh ca cc cht thi chn nui. Qu trnh thi ra cc
cht hu c trong phn, nc tiu gia sc hay thc n d tha s sinh ra cc khi c
hi, cc kh c mi hi thi kh chu. Mi hi ph thuc vo iu kin mt nui
cao, s thng thong km, nhit v m khng kh cao.
1.2.2. Tng quan v cht thi trng trt
Cht thi trng trt l cht thi pht sinh trong qu trnh trng trt nh thc
vt cht, l cnh, c, rm, r, tru, cm, li ng, thn ng
Vo nhng ngy thu hoch, lng rm, r,... v cc ph phm nng
nghip khc pht sinh nhiu v chim thnh phn ch yu trong cht thi rn
nng nghip. Vi khong 7,5 triu hecta t trng la nc ta, hng nm lng
rm r thi ra ln ti 76 triu tn. [2]
Ngoi ra, trong hot ng trng trt, tnh trng s dng ha cht trong nng
nghip nh phn bn ha hc, thuc bo v thc vt ang din ra trn lan, thiu
kim sot. Do , cc CTR nh chai l, bao b ng ha cht bo v thc vt, v
bnh phun ha cht: thuc tr su; thuc tr nm; thuc tr chut; thuc tr bnh;
thuc tr c tng ln ng k v khng th kim sot.
Theo s liu thng k ca Tng cc Mi trng, Tng cc Thng k, Tng
cc Hi quan t nm 2000 n nm 2005, mi nm Vit Nam s dng khong
35.000 n 37.000 tn ho cht bo v thc vt, n nm 2006, tng t bin ln ti
71.345 tn v n nm 2008 tng ln xp x 110.000 tn. Thng thng, lng
bao b chim khong 10% so vi lng thuc tiu th, nh vy nm 2008 thi ra
mi trng 11.000 tn bao b cc loi. [2]
Lng phn bn ho hc s dng nc ta, bnh qun 80 - 90 kg/ha (cho la
l 150 - 180kg/ha). Vic s dng phn bn cng pht sinh cc bao b, ti cha ng.
Nm 2008, tng lng phn bn v c cc loi c s dng 2,4 triu tn/nm. Nh
vy mi nm thi ra mi trng khong 240 tn thi lng bao b cc loi. [2]
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8
Theo tinh ton, bnh qun nng dn nc ta hin nay s dng khong 125kg
m nguyn cht v 80 kg ln nguyn cht cho mi ha canh tc. Kt qu tnh ton
ca cc nh khoa hc cho thy cc cy trng mi ch hp thu it hn 30%, 70% cn
li tan trong nc, ngm vo t v gy nhim mi trng, tn d trong nng sn,
pht thi khi nh kinh v lng phi u t cho nng dn. [2]
Kt qu nh gi ca cc nh khoa hc cng cho thy, b con nng dn s
dng trung bnh khong 8,7 kg thuc bo v thc vt cho mi ha canh tc. Theo
nghin cu ca Vin Bo v thc vt, t l bm dnh vo bao b trung bnh l 1,85%
v c thi ra mi trng cng vi bao b gy nhim mi trng v nh
hng nghim trng n sc khe nng dn nh lm gim a dng sinh hc, tn d
trong nng sn v gy mt s cc bnh nan y cho b con nng dn. a s vng
sn xut nng nghip, vic thu gom, x l cht thi bao b, chai l thuc bo v thc
vt cn nhiu hn ch nn lm trm trng hn nhim mi trng v sc khe
b con nng dn. [2]
1.3. Tng quan v cc phng php x l cht thi nng nghip
1.3.1. X l cht thi chn nui
Cht thi chn nui c bit l phn v nc tiu gia sc sau khi c thi
ra th kh nng nhim cn thp, kh nng ny ch tng khi phn v nc tiu
gia sc c lu trong mi trng bn ngoi. Do gii quyt kp thi vn
nhim th chng ta cn phi qun l v x l cht thi chn nui ngay t lc
mi thi ra mi trng bng mt s bin php nh: thu gom, vn chuyn, lu tr
v x l.
Phn v nc tiu sau khi gia sc thi ra phi c thu gom v vn chuyn ra
khi chung tri chn nui cng sm cng tt trnh vy bn ra chung tri v gia
sc ng thi trnh to mi hi thi trong chung nui lm thu ht rui mui ti,
thun tin cho vic dn ra chung tri, tit kim in, nc. Ty theo tnh trng
ca phn m ta c th thu gom bng cch ht phn rn hay xt cho phn tri theo
dng chy vo nhng thi im nht nh trong ngy.
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9
Vic thu gom vn chuyn cht thi c th dng nc bm xt tri theo ng
cng thot. Hay dng thng cha (phn lng) hoc c th dng st, bao, thng xe
vn chuyn phn rn.
Ni lu tr phn phi l h cha, b lng, thng ng c y kn hay bao
kin x l chuyn bit, ni lu tr phn phi cch bit vi chung tri chn nui
trnh nh hng n sc khe gia sc.
Vic x l cht thi chn nui trong iu kin chn nui t pht nh hin nay
do khong khng gian gia khu chn nui v khu dn c cng b thu hp th mt h
thng x l cht thi chn nui phi c thit k ng tiu chun k thut v phi
c thit b s dng ph thi dng rn v lng cng on cui cng sau khi c
thi vo mi trng ty theo iu kin kinh t ca tng c s v cc h chn nui
m a vo p dng c th nh:
a) Sn xut phn bn hu c t phn gia sc (Composting)
Phng php sn xut phn bn hu c t phn gia sc c t rt lu l
phng php phn hiu khi (composting). Phng php ny c da trn qu
trnh phn hy cc cht hu c c t trong phn di tc dng ca vi sinh vt c
trong thnh phn ca phn, tnh cht v gi tr ca phn bn ph thuc vo qu trnh
phn, phng php v kiu .
Qu trnh ny gm s ph v cc hp cht khng cha N v s khong ha
cc hp cht c cha N. Chnh do s phn hy ny m thnh phn phn chung
lun b bin i, c nhiu loi khi nh: H2, CH4, CO2, NH3 v hi nc thot ra
lm cho ng phn ngy cng gim khi lng.
- Qu trnh gm c 4 giai on bin i [16]:
+ Giai on phn ti
+ Giai on phn hoi dang d
+ Giai on phn hoi
+ Giai on phn chuyn sang dng mn
- Cc cch phn:
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10
+ nng ( ti): Phn thnh tng ng sao cho ti, xp, thong kh, gi
m 50 - 60%, m ny nhit trong ng s ln cao 60 - 70oC, phn mau
hoi, dit c di, dit mm bnh nhng mt nhiu N.
+ ngui ( cht): phn c thnh ng nn cht m bo ng phn
tin hnh trong iu kin ym kh, m 50 - 60% nhit ng phn khng
ln cao qu 35oC. Trong iu kin ny CO2 thot ra km hm s hot ng ca vi
sinh vt, phn lu hoi, khng dit c mm bnh v c di nhng gi c N.
+ hn hp ( nng trc sau ngui): i vi phn chung c nhiu
rc n, ht c di, mm bnh cn ti xp 5 - 7 ngy nhit ln n 60 -
70oC, phn mau hy sau nn cht li nhit s h xung dn cn khong 35oC
hn ch mt N. Khi cn trn thm Super P gi NH3:
Ca(H2PO4) + 4NH3 + H2O 2(NH4)2HPO4 + Ca(OH)2
+ Hoc c th dng tro tru n vi phn chung khi , v tro tru c cha
SiO2 c kh nng gi NH3.
Trong qu trnh phn khng nn dng tro bp trn vi phn chung v c
th to ra cc cht kim mnh.
CaO, K2O + H2O Ca(OH)2, KOH
Nu s dng phn ny khng ng i tng s lm nh hng n s sinh
trng v sc sn xut ca cy trng v lm bin i tnh cht ca t theo chiu
hng xu [16].
Theo Nguyn Qu Mi (1997), phng php hiu khi c c im nh sau:
- Ngun phn c m va phi 56 - 83%.
- Ngun cung cp cacbon lm tng t l C/N khong 25/1. iu ny thc y
qu trnh phn hy v trnh tht thot ngun m do lm gim cc hp cht kh
cha Nit.
- Dng c cha phn phi m bo s hiu kh cho ton b khi phn.
- Cht mi: Thng thng s phn hy hon ton xy ra khong 40 60 ngy,
tng hiu qu phn v rt ngn thi gian ngi ta c th b sung cc cht hu
c tng hot ng ca cc vi sinh vt hoc b sung trc tip cc vi sinh vt khi
phn, thi gian phn c th rt ngn cn 20 - 40 ngy.
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11
- phn kch thch cc vi sinh vt hot ng lm nhit tng ng k
khong 45 - 70oC sau 4 - 5 ngy u, vo lc ny pH axit khong 4 - 4,5. Vi nhit
v pH ny cc vi sinh vt gy bnh hu ht km chu nhit d dng b tiu dit,
ngoi ra trng k sinh trng, ht c di cng b ph hy, qu trnh cn lm thot
ra mt lng ln hi nc v kh CO2 ra mi trng, s thot kh nhiu hay t cn
ph thuc vo din tich ng . Qu trnh kt thc hp cht hu c b phn hy tr
nn xp, mu nu sm, khng c mi kh ngi.
phn hiu kh l bin php s dng nhiu nht trong vic ch bin, x l
phn ng vt, l qu trnh phn hy sinh hc ca cc cht rn trong iu kin hiu
kh. Hp cht hu c sau khi x l c th dng lm phn bn mt cch an ton, t
lm nhim mi trng so vi phn ti thi ra ngoi mi trng.
phn c th c thc hin quy m cng nghip, cc tri chn nui
ln, phn sau khi c th c ng gi bn ra th trng. quy m gia nh
phng php c s dng rng ri nhm tn thu ngun phn v ur hu c sn
c lm phn bn trong vn. [16].
b) B lng
Cu to vn hnh: Nc thi c chy qua li lc 1 x 1cm hay 1,5 x 1,5
cm loi b cn ln. Sau , nc thi c cho chy vo b lng 3 ngn (thng
xy bng xi mng) c ngn 1 su 2,5 3 m, ngn th 2 su 1,2 - 1,5m v ngn 3 su
< 1m. Nc c lun chuyn theo kiu trn.
Chc nng ca b lng l gim i phn ln cc phn rn trong nc thi
nhng gii quyt khng trit cc tc nhn gy bnh trong nc thi. Trung bnh 1
m3 x l cho di 10 ln trng thnh, hoc di 50 ln con.
Yu cu vn hnh: nh k ly bn lng trong cc b (2 - 3 ln/thng) s
dng lm phn bn.
c) H sinh hc
T nhng nm 50, cc nc nh: Trung Quc, n , Thi Lan, Philippin,
M nghin cu v ng dng h sinh hc trong vic x l nc thi sinh hot v
c nc thi cng nghip. Cc qu trnh din ra trong h sinh hc tng t nh qu
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12
trnh t ra sch sng h nhng tc nhanh hn v hiu qu hn. Trong h c
nhiu loi thc vt nc, to, vi sinh vt, phiu sinh vt, nm sinh sng v pht
trin hp th cc cht nhim. Qun th ng thc vt ny ng vai tr quan trng
trong qu trnh v c ho cc hp cht hu c ca nc thi.
Nguyn tc hot ng ca h sinh hc l vi sinh vt s dng oxi t ru to
trong ha trnh quang hp cng nh oxi t khng khi oxi ha cc cht hu c v
rong to trong h li tiu th CO2, photphat v nitrat amoni sinh ra t s phn hy,
oxy ha cc cht hu c ca vi sinh vt. h hot ng bnh thng cn phi gi
pH v nhit ti u, nhit khng c thp hn 6oC.
Quy trnh ny c u im l cng ngh v vn hnh kh n gin, gi thnh
r nhng c nhc im l x l khng trit , kh thi cn mi hi, c bit cn
din tch rng x l t hiu qu.
d) Thng sc kh
Sau khi nc thi cho qua b lng, nc thi c chuyn vo mt thng
c sc kh to thnh qu trnh ln men hiu kh. Qu trnh ny lm gim lc cc
phn l lng trong nc, gim mt s vi sinh c hi. u im l thit k gn, cn
din tch vn hnh nh nhng gi thnh cao.
e) Kh mi hi chung tri
S hnh thnh kh chung nui ch yu trong qu trnh thi ra ca phn do
cc vi sinh vt gy thi, qu trnh ny ngoi NH3 v H2S cn c mt s kh trung
gian c hnh thnh gp phn vo vic to mi hi cho chung nui.
Hin nay trn th trng c rt nhiu ch phm kh mi hi trong chn
nui, cng ngy cc ch phm vi sinh c s dng nhiu trong chn nui v n kh
thn thin vi mi trng.
g) X l bng hm biogas
Nhm x l tt ngun nc thi trong chn nui, cung cp nc ti sch v
phn bn tt cho trng trt bn cnh tn dng ngun khi metan lm khi t cho
gia nh, gp phn nng cao kinh t cho nh nng.
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13
Mt trong nhng bin php x l cht thi chn nui l biogas. y
cng l phng php c s dng rng ri. Nguyn l biogas da trn s phn
hy ym kh cc hp cht hu c ca cc vi sinh vt ym kh. Hn hp kh sinh ra
gm: CH4, H2S, NH3,.. trong CH4 v CO2 l sn phm ch yu.
Hm biogas c cc u im: to ngun nng lng thp sng, si m,
chy my pht in; cht cn thi sau qu trnh ln men dng bn cho cy trng
s hn ch c vic s dng phn ho hc; ngoi ra, trong qu trnh ln men trong
iu kin k kh cc vi khun gy bnh cho con ngi c loi tr. Nh vy,
pht trin biogas khng ch gii quyt vn nng lng m cn l gii php gim
thiu nhim mi trng, gp phn bo v v nng cao sc kho cng ng dn
c, ng thi to iu kin nng cao hiu qu sn xut nng nghip.
1.3.2. X l cht thi trng trt
Ti Vit Nam mt s m hnh x l cht thi trng trt c dn hnh
thnh, sau y l mt s v d:
a) S dng rm trng nm
c th x l cht thi trng trt th ngi ta s dng rm trng nm.
Tn dng ngun rm r sn c t cc v la trong nm, nhiu nng dn trin
khai trng nm rm va em li hiu qu kinh t ng thi x l c cht thi
trng trt.
b) S dng rm, thn cy u phng chua lm thc n cho tru b
Ngoi ra ngi ta cn x l cht thi trng trt bng cch s dng rm, thn
cy u phng chua lm thc n cho tru b. Rm la sau khi thu hoch thng
c phi kh d tr. y l loi thc n truyn thng ca tru b cc vng nng
nghip ca nc ta. Loi thc n ny c hm lng x cao (36-42%), hm lng
protein thp (3-5%) v hm lng m rt thp (1-2%), vitamin v cc cht khong
ngho nn. T l tiu ho vt cht kh ca rm thp (30-40%) do vch t bo rm
b lignin ho cao. Bnh thng khi cho n t do tru b c th n ti a lng rm
kh bng khong 2% th trng. Khi dng rm lm thc n cho tru b nn b sung
thm r mt ng, ur (nu khng x l), c xanh hay cc ph phm khc d ln
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14
men nhm ti u ho hot ng ca vi sinh vt d c. Nu trc khi cho n rm
c kim ho th t l tiu ho v lng thu nhn c tng ln nhiu. Rm la
cng c th kim ho ti ngay sau khi thu hoch bo qun lu di m khng
cn phi kh. X l rm la ti gip bo qun dinh dng v ci thin cht lng
c tt hn, gim c cng phi kh rm. [17]
c) Sn xut than sinh hc ci to t t rm r
Thay v t rm r trn lan gy nhim mi trng, b con nng dn c
th thu gom rm r sn xut than sinh hc lm cht ci to t, va gim pht
thi kh nh knh va gi c hm lng cacbon t rm r.
Cng ngh t than sinh hc t rm r c Vin Mi trng Nng
nghip pht trin ng dng thnh cng ti mt s tnh. Nguyn l sn xut than
sinh hc l t iu kin ym khi to nhit lng cao, gi li hm lng
cacbon bn vng bn trong t ci thin ph t, tng hot tnh vi sinh vt
trong t v nng cao nng sut cy trng.
d) X l rm r thnh phn hu c bng ch phm sinh hc
Phng php x l rm r bng ch phm sinh hc thnh phn bn hu c
phc v sn xut c tin hnh da trn nguyn tc b sung cc chng ging vi
sinh vt phn gii hu c c kh nng phn gii nhanh v trit rm, r sau thu
hoch thnh phn bn hu c vi sinh giu dinh dng, l sn phm tuyt i an
ton vi ngi v ng vt.
Ch phm sinh hc c s dng ph bin nht l FITO-BIOMIX-RR do
Cng ty c phn cng ngh sinh hc H Ni sn xut c cp Bng c quyn
gii php hu ich s HI-2010 ca Cc S hu tri tu - B Khoa hc v Cng ngh.
1.4. Tng quan v cng ngh trng nm rm t rm r
1.4.1. Tng quan v nm rm
1.4.1.1. c tnh sinh hc
Nm rm c tn khoa hc Volvariella volvacea gm nhiu loi khc nhau, c
loi mu xm trng, xm, xm en, kich thc ng knh cy nm ln, nh
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15
ty thuc tng loi. cc quc gia vng nhit i rt thch hp v nhit nm
rm sinh trng v pht trin. Nhit thch hp nm pht trin t 30 - 32oC;
m nguyn liu (c cht) 65 - 70%; m khng kh 80%; pH = 7, thong kh. Nm
rm s dng dinh dng cellulose trc tip t nguyn liu trng. [3]
1.4.1.2. c im hnh thi
- Bao gc (volva): Di v cao lc nh, bao ly tai nm. Khi tai nm trng
thnh, n ch cn li phn trm ly phn gc chn cung nm, bao nm l h si t
nm cha sc t melanin to ra mu en bao gc. m nht ty thuc vo nh
sng. nh sng cng nhiu th bao gc cng en.
- Cung nm: L b h si xp, xp theo kiu vng trn ng tm. Khi cn
non th mm v gin nhng khi gi x cng v kh b gy.
- M nm: Hnh nn, cng c melanin, nhng nht dn t trung tm ra ra
mp. Chu k sng: Qu trnh to thnh qu th nm rm gm 6 giai on:
+ Giai on u inh ghim
+ Giai on hnh nt nh
+ Giai on hnh nt
+ Giai on hnh trng
+ Giai on hnh chung
+ Giai on trng thnh
Hnh 1.2: Hnh thi ca nm rm [3]
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16
- Chu k sinh trng v pht trin ca nm rm rt nhanh chng. T lc trng
n khi thu hoch ch sau 10 - 12 ngy. Nhng ngy u chng nh nh ht tm c
mu trng (giai on inh ghim), 2 - 3 ngy sau ln rt nhanh bng ht ng, qu to,
qu trng (giai on hnh trng), lc trng thnh (giai on pht tn bo t) trng
ging nh mt chic d, c cu to thnh cc phn hon chnh. [3]
1.4.2. Tng quan v cng ngh trng nm rm t rm r
1.4.2.1. Thi v trng nm rm
Nu mi trng nm ln u th nn trng vo ma kh, ch ng vic ti
nc. Trng vo ma ma, m c thch hp hn, nhng khi ma lin tip lm
lnh m nm, t kh pht trin hoc lm n nm d ng. Nu nm vng k thut
trng nm rm th c th trng vo ma ma.
1.4.2.2. Nguyn liu
Chn rm r tt, em phi kh. Rm r b mc, b nhim thuc tr su, ry,
rm la b bnh mt ma, trng nm nhiu khi khng ln hoc c nm th nng sut
rt thp. Rm cn xanh khng th trng nm c. Do , rm r sau khi thu hoch
v phi c phi kh, nh ng, bo qun tt.
1.4.2.3. Chn meo ging
Mun trng nm c nng sut cao, nn t meo ni c tin nhim. Khng
ly meo nhiu ngun khng r ngun gc. Meo tt phi m bo cc ch tiu sau:
Khng b nhim bnh: Chai meo ht hoc bch meo cng c cc si nm mc
u t trn xung di, khng c khoang, m en, xanh, vng m ch c mu
trng ca t hoc c lm m mu nu , nu hng ca hu bo t.
Ging c mi thm d chu: Nu c mi chua kh chu l ging b nhim
vi khun, nm di.
Ging khng qu gi hoc qu non: Lc chun b cy meo phi coi ngy cy
ghi trn chai. Nu qu 2 tun l meo hi gi, meo gi c m so hay cy nm mc
trong chai. Mu chai ging chuyn sang vng, nu en l ging qu gi. Nu ging
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17
cha n kin y chai hoc bch nilong l ging cn non. Nn s dng ging n
kn ht y chai/ti sau 3 4 ngy. Mun lu phi bo qun nhit lnh 4
8oC ko di 30 50 ngy.
Vn chuyn ging: Vn chuyn ging phi nh nhnh, trnh va chm mnh,
dng ng chai ging nt bng quay ln pha trn. V nh khng meo ni qu
nng hoc qu nng, khng lm tut nt bng ra ngoi. Ngoi ra khng meo ni
c nhiu thuc BVTV, nn ni sch s, thong mt. Sau khi ging mang v phi
2 ngy cho ging n nh mi em i cy ging. [3]
1.4.2.4. X l nguyn liu
Tri rm ra, ti nc vi 1% cho t u rm vi (3,5kg vi ha vi 1.000
lit nc) hoc ngm trong nc vi 48 gi, sau cht thnh ng , c mi lp
rm cao 40 - 50cm th ti nc vi 1 ln cho n khi ht rm. ng thng c
b ngang 1,5m, cao 1,5m. Sau dng bao nilon hoc l da, l chui che y li
. Sau khi khong 5 - 10 ngy th c th d ra xp m trng.
Nguyn liu qu t (khi vt vi cng rm c nc chy thnh dng) cn tri
rng ra phi mi em trng. Rm r t (khi vt vi cng rm c nc chy
thnh git) l tt nht. Nu kh qu cn b sung thm nc khi o ng .
S dng nc vi lm t rm r c tc dng lm mm nguyn liu, hn
ch s pht trin ca vi khun, nm mc v lm tng pH ca mi trng nui,
thch hp cho nm pht trin. Trong thi gian , c th b sung thm ngun phn
m bng cch ti thm phn N.P.K vi liu lng khng qu 0,5% so vi nguyn
liu trc khi cht m. Khi b sung ur, nu pH thp, m cao th thng xut
hin nhiu nm di, nm gi. [3]
1.4.2.5. Cch cht m
Rm r sau khi x l, cht thnh tng lp dy 10 - 15cm, rng 50 - 60cm.
Cht khong 3 - 4 lp. Sau khi cht mi lp, ti nc v dm ln rm trn mt
m d cht, sau cy meo nm.
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18
Cng c th b rm r li thnh tng b, ng knh 10 - 15cm. Cht cc b
st nhau thnh 2 dy, mi m c chiu rng t 50 - 60cm. hai u m, cc b rm
c xp theo hnh r qut. Lp trn cht tht vo so vi lp di. [3]
1.4.2.6. Cch cy meo
Cho meo ging vo thau sch, x vn ra, cy tng nhm nh, cch nhau 15 -
20cm. Meo nm cy vo m cch ba m 5 - 10cm, khng nn cy meo st ba m
hoc qu su bn trong m v nu cy st ba, khi ti nc meo s ri ra ngoi, cn
nu cy meo su, nm mc bn trong lm cho vic thu hi gp kh khn.
Nu rm tut bng my b ri, c th dng khun cht. Sau khi , ly rm
nhi vo khun. Khun thng c lm bng g, c dng hnh thang rng 40 - 50cm,
di 60 - 120cm, cao 40cm. Tri mt lp rm dy 10 - 12cm, cy mt lp meo ging
vin xung quanh, cch mp khun 4 - 5cm. Tip tc xp 3 lp rm. Lp trn cng
(lp th 4) tri rng u khp b mt. Lng ging dng cho mi khun khong 200 -
250g. Sau mi lp cy dng tay n cht, nht l xung quanh thnh khun.
Trung bnh 1 tn rm r kh cht c 75 - 80 m nm. Sau khi cht m, cn
phi 1 - 2 nng trnh b mt m qu m t, d pht sinh nm di, mc. Sau ,
ri rm r vn xung quanh m v t va st khun va cung cp thm cht
khong cho nm, si m meo ging v kich thich t nm pht trin, sau ti
nh ln m nm.
Khi cht m cn lu b tr li i li 30 - 40cm thun tin trong vic
chm sc, thu hi nm. Nn cht m theo hng song song vi hng gi, hng
nng. [3]
1.4.2.7. Chm sc m nm cy ging
Ty thuc a im trng trong nh hay ngoi tri (sn bi, di tn cy,
ng rung,) m cch thc chm sc s khc nhau.
a) Trng trong nh
Sau 3 - 5 ngy u khng cn ti nc, nhng ngy tip theo quan st b
mt m nm thy rm r kh cn phun nh nc trc tip xung quanh. Ch phi
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19
ti nc kho, nu ti mnh (ht nc ln) d lm si nm tn thng, nh
hng ti nng sut v lc ny si nm pht trin ra tn pha ngoi thnh m.
n ngy th 7 - 8 bt u xut hin nm con (giai on ra qu), 3 - 4 ngy sau nm
ln nhanh to bng qu to, qu trng, vi gi sau nm c th s n d. Nm ra
mt dy, kich thc ln cn ti 2 - 3 lt nc cho mt ngy. Lng nc ti
mt ln rt t (0,1 lt cho 1,2 mt m/ngy). Nu ti qu nhiu nm d b thi chn
v cht ngay t lc cn nh.
b) Trng ngoi tri
ng m nm ngoi tri thng b cc t ma ln, nng nng lm h hng,
v th cn che ph thm mt lp rm r kh trn b mt m nm. Lp rm r ny
cn tt, xp theo mt chiu, ph theo kiu lp mi nh, chiu dy 4 - 5 cm. Tt c
cc b mt ca nhng m mp ngoi khu vc trng cng cn che ph bng lp
rm ph o, kim tra nu thy m nm b kh c th ti trc tip ln lp o ph
nhiu ln trong ngy, sao cho lp rm phia ngoi ca m nm khng b mt nc.
trnh ma v tin cho vic chm sc m nm, c th cm cc cc tre, hoc an
thnh chic lng cch mt m nm 10 - 15cm, pha ngoi bc mt lp nilong,
pha trn cng ph rm r kh cng tt. Nhit m nm trong nhng ngy u
khong 38 - 40oC l tt nht. Vic ti nc tng t nh vi nm trng trong nh.
Khi thu hi ht nm t 1 cn nht sch tt c cc gc nm v cy nm nh cn
st li, dng nilong ph li cho n khi nm ra th g b. Ngng 3 - 4 ngy sau
ti tr li nh ban u, tip thu t 2. Sn lng nm thu hi tp trung n 70 -
80% trong t u, t 2 cn li 15 - 25%. [3]
1.4.2.8. Cch thu hi nm
K t lc trng n khi hi ht t 1 khong 15 - 17 ngy. Nm ra r vo
ngy th 12 n 15. Sau 7 - 8 ngy ra tip t 2 v hi trong 3 - 4 ngy th kt thc
mt t nui trng (tng thi gian 25 - 30 ngy). Dn v sinh sch s, ti nc vi
3 - 4 ngy li trng t tip. Hi nm cn giai on hnh trng (trc khi nm
n d) l tt nht, m bo cht lng v nng sut cao. Trng hp nm mc tp
trung thnh cm, ta c th tch nhng cy ln hi trc, nu kh tch th hi c cm
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20
(c to, nh u hi ht). Mt ngy, hi nm 2 - 3 ln. Nhng ngy nng nng, nhit
khng kh cao, nm pht trin rt nhanh, v vy ngi hi nm phi quan st k,
khi nm hi nhn u l hi c ri. [3]
1.4.3. Cch phng tr bnh cho nm rm
Trong qu trnh trng nm rm thng gp mt s bnh, c th chia thnh 2
loi sau:
1.4.3.1. Bnh sinh l
- Nhit : Nhit nh hng rt ln n s pht trin ca t nm v tai
nm. Nu nhit thay i t ngt s lm cho nm cht hng lot.
- nh sng: nh sng rt cn giai on nm ang pht trin. giai on
ny, nu thiu nh sng, qu th c mu trng hoc xm, hm lng vitamin E gim
ng k, khng hnh thnh c sc t en, khng c vitamin D. Nu cng nh
sng qu cao c th lm nm cht hng lot.
- Nc ti: Nm ch pht trin tt, cho nng sut, cht lng khi c cung
cp y theo nhu cu. Nu tha hoc thiu nc u khng tt cho s sinh
trng, pht trin ca nm. Ngoi ra, cht lng nc cng nh hng rt ln, nu
nc c cht lng xu nh nc phn lm t nm mc chm, tha, u si t s b
cong li, tai nm b d hnh. Khi ti bng nc nhim mn, nm cng pht trin
kh khn hn. [3]
1.4.3.2. Bnh nhim
Trong qa trnh v trng, nm thng b nhim nm di v nm mc.
- Nm di: Ph bin nht l nm gi, nm di thng xut hin trc nm
rm. Nm di pht trin khi nguyn liu c m cao hn 70%, khi ti nhiu ur,
pH < 5. phng chng nm di, dng nc vi x l k nguyn liu trc khi
cht m; iu chnh m nguyn liu lc cht m (70%), hn ch ti ur, hn
ch ti nc.
- Nm mc: C mc xanh, mc cam, mc thch cao, nm trng c. Nu b nh
th phi kh mt m (mt nng), dng nc vi 0,5 - 1% ti ln ch b bnh. Nu
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21
b nhim nng th dng thuc dit nm bnh nh Benomyl 0,1%, Zineb
7% hoc Validacin 3%... tr nm thch cao th s dng thuc tm (KMnO4) s c
hiu qu cao hn.
Ngoi ra, nm cn b mt s i tng khc tn cng nh: Kin, mi, cun
chiu, gin, mt g, b nhy, tuyn trng phng nga cc i tng ny th
cn x l nn t tht k trc khi trng bng cch xi xo t mt, rc thuc
phng tr nh Furadan, Mocap
Trong thi gian thu hoch, nu b cn trng ph hi, thuc khng nh
hng n nm, khng gy c hi cho ngi tiu dng, cn tr kin bng cch
phun thuc tr su (nh Regent) vo thc n kin a thich nh cm rang hay cm
da kh t thnh tng cm gc ngoi ca m kin n n v cht. [3]
1.5. Tng quan v khu vc nghin cu
1.5.1. iu kin t nhin x Giao Lc, huyn Giao Thy, tnh Nam nh
1.5.1.1. V tr a l
X Giao Lc nm phia ng Nam huyn Giao Thu, cch trung tm huyn
khong 8 km, c v tri a l nh sau:
- Pha Bc gip x Giao Thanh, x Hng Thun.
- Phia Nam gip Giao Xun v Vn Quc gia Giao Thu.
- Pha ng gip x Giao An v Giao Thanh.
- Pha Ty gip x Giao Xun, x Bnh Ha. (Hnh 1.1) [12]
X Giao Lc c hnh ch nht, chiu di 3,35 km chiu rng 2,1 km, gia x
l sng Giao Lc, hai bn b sng l hai tuyn ng trc x chy dc theo hng
bc nam, v c cc tuyn ng bao quanh. X c phn b thnh 22 xm.
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22
Hnh 1.3: V tr a l khu vc xa Giao Lc vi cc xa xung quanh [12]
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23
1.5.1.2. Hin trng s dng t
Din tch t nhin: 704,67 ha
Trong hin trng s dng t c trnh by trong Bng 1.1
Bng 1.1: Hin trng s dng t ti x Giao Lc [12]
STT Hin trng s dng t Din tch (ha) T l %
1
Nng nghip
+ Trng cy hng nm
+ Trng cy lu nm
+ Nui trng thu sn
+ Nng nghip khc
524,54
424,55
48,87
50,83
0,29
74,44
60,25
6,94
7,21
0,04
2
Phi nng nghip
+ t
+ t chuyn dng
+ Tn gio tin ngng
+ Ngha trang, ngha a
+ Sng sui v mt nc
179,26
45,44
121,01
3,04
4,21
5,56
25,44
6,45
17,17
0,43
0,60
0,79
3 Cha s dng 0,87 0,12
1.5.1.3. Kh hu
Cng nh cc tnh trong vng ng bng Bc B, x Giao Lc, tnh Nam
nh mang khi hu nhit i gi ma nng m. Nhit trung bnh trong nm t 23
24C. Thng lnh nht l cc thng 12 v 1, vi nhit trung bnh t 16 17C.
Thng 7 nng nht, nhit khong trn 29C.
Lng ma trung bnh trong nm t 1.750 1.800 mm, chia lm 2 ma r
rt: ma ma t thng 5 n thng 10, ma it ma t thng 11 n thng 2 nm sau.
S gi nng trong nm: 1.650 1.700 gi. m tng i trung bnh: 80 85%.
Mt khc, do nm trong cng vnh Bc B nn hng nm Nam nh thng
chu nh hng ca bo hoc p thp nhit i, bnh qun t 4 6 cn bo/nm.
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24
Thu triu ti vng bin Nam nh thuc loi nht triu, bin triu trung bnh t
1,6 1,7 m; ln nht l 3,31 m v nh nht l 0,11 m. [13].
1.5.1.4. Thy li
C 2 sng chnh l sng Cn Nm di 2 km v sng Nguyn Vn B di 2,3
km do Cng ty TNHH Mt thnh vin K thut cng trnh thy li Xun Thu qun
l, ch yu s dng cho tui tiu phc v sn xut.
C 16 sng cp 2 vi tng chiu di l 29 km. Trong c 7 sng ti vi
tng chiu di 15,1 km, 9 knh tiu di 13,9 km. Phn b u trn cc khu vc sn
xut, nc lu thng theo hnh thc t chy c bn p ng nhu cu ti tiu.
C 111 knh cp 3 vi tng chiu di 33,30 km. Trong knh nm trong
vng ng lc l 6 km, cn li l nm trong vng ti tiu t chy l 27,30 km.
Cng tc ti, tiu, dch v thu nng ca x do Hp tc x nng nghip ph
trch iu hnh. Hin ti ton x c 1 trm bm mi xy vi cng sut 2000m3/h.
H thng cng, p ngn c 1 cng tiu i ng qua Trung ng, 23
cng cp 2 phc v khoanh vng iu tit nc cho sn xut. [13]
1.5.2. iu kin kinh t - x hi x Giao Lc, huyn Giao Thy, tnh Nam nh
1.5.2.1. Dn s
Theo thng k nm 2013, dn s ton x l 10.536 ngi, 2.565 h, c
khong 70% dn s theo o Cng gio, c 1 nh th Gio x n thnh i ng,
1 nh th gio x Lc Nam, 1 nh cha Hng Lc t v 7 nh th gio h, gio khu
o Cng gio. Mt dn s 1.496 ngi/km2; t l tng dn s t nhin nm
2013 l 1,16%. Tng s 5.790 lao ng. Trong lao ng ngnh nng nghip,
thy sn l : 3.330 ngi. [13]
1.5.2.2. Kinh t
Giao Lc l mt x thun nng c 2.208 h lm nng nghip (86%). Din
tich t canh tc bnh qun 403m2/khu, ch yu l trng la, rau mu, cy n qu,
cy cnh, chn nui v nui trng thu sn. Chn nui tuy pht trin song ch yu
http://vi.wikipedia.org/wiki/Th%E1%BB%A7y_tri%E1%BB%81u
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25
l chn nui gia nh quy m nh. S gia tri trang tri cha nhiu. Ngnh ngh
nng thn gm c: an mc si, ngh mc, n, sn xut vt liu xy dng, ch bin
lng thc, thc phm, lm mm chp, lm vy o ci, may xut khu, nui
trng nh bt thy hi sn... ch yu t pht v pht trin chm do ph thuc rt
ln vo th trng tiu th sn phm.
- V trng trt: Nm 2013 nng sut t 117,89 t/ha, sn lng lng thc
quy thc 5.129 tn, bnh qun lng thc u ngi 486,8 kg/ngi/nm, gi tr
canh tc t trn 54 triu ng/ha.
- V chn nui: Nm 2013 tng n ln 2.200 con, n gia cm 19.100 con,
tru b 80 con.
- V thy sn: Nm 2013 tng sn lng khai thc 5.170 tn.
- Gi tr sn xut nm 2013 t 158,040 t ng (gi HH), trong :
+ Nng nghip: 72,0 %
+ CN - TTCN - Ngnh ngh NT: 10,0 %
+ Dch v: 18,0 %
- Bnh qun thu nhp: 15 triu ng/ngi/nm.
- T l h ngho: 13,56% theo tiu ch mi [13]
1.5.2.3. Vn ha gio dc y t
a) Vn ha gio dc
Hin ti ton x c 3 trng hc vi tng din tch 25.415 m2. Trong c 1
trng THCS, 1 trng tiu hc v mt trng mm non.
- Tng s gio vin l 104, trong :
+ Phn theo trng: Trng mm non 30 gio vin; Trng THCS 38 gio
vin; Trng Tiu hc 36 gio vin.
+ Phn theo trnh : i hc: 11; Cao ng: 51; Trung cp : 42.
+ tui trung bnh : 41 tui.
- Tng s hc sinh 3 trng l 2.213 em.
+ T l hc sinh tt nghip THCS, tip tc hc THPT, B tc v Trung hc
ngh l 70%.
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26
- Y t
X Giao Lc c mt trm y t x c xy dng kin c hai tng trn din
tch 400 m2 vi 15 phng lm vic cht lng tt, 9 ging bnh v c vn trng
thuc nam. Tuy nhin cc dng c trang thit b phc v khm cha bnh cha p
ng c nhu cu khm cha bnh trong giai on hin nay; nh v sinh xung
cp cn c tu sa. [13]
1.5.2.4. C s h tng
a) Giao thng
Giao Lc khng c ng quc l, tnh l i qua, khong cch t tr s
UBND x n tnh l gn nht l 2,5 km.
H thng ng giao thng trc chnh ca x c quy hoch theo 2 tuyn:
tuyn Bc Nam t gip x Hng Thun i Trung ng di 3,35 km; tuyn ng
Ty t gip x Giao An i Giao Xun di 2,1 km.
Tng h thng ng giao thng ca x c tng chiu di l 59,873 km, gm
ng trc x, lin x, ng lin xm, ng ng xm, ng ni ng.
Trong h thng giao thng ni ng hin c 14 tuyn di 16,91 km. Hin
nay giao thng ni ng ca x ch yu l ng t, cha p ng c nhu cu
phc v cho sn xut.
Nm 1992, hng ng chng trnh giao thng nng thn ca tnh, huyn
pht ng, Giao Lc tp trung xy dng cc tuyn ng giao thng ca x vi
ngun kinh phi do nhn dn ng gp. n nay nha v b tng ho c
32,863 km. ng ng xm c b tng ho t 100% so vi tng chiu di
cc tuyn ng. [13]
b) Ch Giao Lc
Nm v tr xm 22 thuc pha Ty Bc cch trung tm x 1km gn vi cc
x Hng Thun, Bnh Ha, Giao Thanh, v tr ch hp l vi din tch 1815 m2, c
bn p ng c nhu cu mua sm sinh hot, bun bn ca ngi dn. Ch c 1
dy lp tn cn mi, 1 dy xy dng t lu xung cp cn nng cp ci to trong
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27
thi gian ti, cn li l cc dy ln tm xung quanh ch, khu vc v sinh v thu
gom cht lng cn hn ch, gy nhim mi trng.
Ch khng c kh nng m rng, cn c u t nng cp hoc di chuyn
a im n ni khc. [13]
c) Bu in
Hin ti bu in x cha c im truy cp internet cng cng, ch c c
nhn s dng theo ng in thoi c nh hoc di ng.
X c 1 im phc v bu chinh vin thng (im bu in vn ha x) c 1
cn b thng trc, nh mi bng, din tch xy dng 70 m2 nm trn khun vin
khu t 100 m2, rt cht hp, cn m rng hoc xy mi [13].
d) Nh
Xut pht t nhu cu sinh hot v sn xut kinh doanh ca cc h gia nh,
Giao Lc c cc loi nh sau:
- Nh ca cc h thun nng, din tch khun vin t 700 - 1.800 m2 bao
gm nh chnh 50 - 70 m2, nh ph thng vung gc vi nh chnh din tch 30 -
50 m2, trc nh l sn rng 100 - 200 m2, ao rng t 200 - 600 m2. Cn li l vn
trng rau mu, cy n qu, nh quay nhiu hng theo a hnh tng khu, khu chn
nui c bn gn nh nn khng hp v sinh.
- Nh ca cc h kinh doanh hoc cc h mi mua t lm nh, din tch t
100 - 200 m2 bm theo 2 ng trc chnh gia x, ng gip khu vc ch Hng
Thun, khu vc gip Trung ng t 4 - 8 m thng xy theo dng nh hnh ng
va kt hp n , sinh hot v kinh doanh.
T l nh kin c v bn kin c l 85%, khng cn nh tm, dt nt. Vic
xy dng nh ca nhn dn hon ton t pht cha theo quy chun ca B xy
dng. Nhng nm gn y do kinh t pht trin nn vic xy dng nh ca
nhn dn Giao Lc c nhiu tin b hn trc, nh cao tng, nh kin c c
xy dng nhiu. [13]
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28
1.6. Mt s m hnh nng nghip khng cht thi
1.6.1. Hin trng m hnh nng nghip khng cht thi ca nc ngoi
Mt s quc gia trn th gii bt u nh gi v thit k li cc h thng
hin ti ca h y mnh vic thu hi ti nguyn v to dng mt nn kinh t s
dng nguyn liu hiu qu hn. Nhiu ngnh cng nghip hin ti phi thit k
li sn phm t tiu chun " khng cht thi " nhm p ng yu cu ca cc
quc gia m h tin hnh u t.
1.6.1.1. M hnh khng cht thi ti vng quc Anh
tng ch o l pht trin mt quy trnh s dng cht thi bng cch tch
hp nhiu c ch k thut sinh thi khc nhau nhm hp thu nng lng v cht dinh
dng cho mc ich quay vng trong quy trnh nh mt sn phm c gi tr.
M hnh ca t chc sng kin khng pht thi vng Earth Center, Anh, l
mt h thng bao gm mt nh my bia cng sut nh, mt khu trng to, trang tri
nui c nc ngt v trng cy theo phng php thy canh khp kn. Mc tiu ca
d n thit lp m hnh ny ca Zeri l nhm cung cp mt dn chng thc t v
quy trnh sn xut khng cht thi to ra mt loi cc sn phm c gi tr v gp
phn bo v mi trng sinh thi.
Ba dng cht thi c cng nhn a vo p dng nh sau:
+ Cht thi rn: Ng cc qua s dng Trng nm Composting
Ci to t.
+ Dng thi lng: Dng thi nng Thu hi nhit Sn xut to Nui
c nc ngt Canh tc thy canh.
+ Kh thi: S dng cho canh tc thy canh.
B tr cc hng mc: Tng din tch mt bng cn c khong 150m2. Tt
nht m hnh c b tr trn sn i vi hng n gi Ty Nam. Din tch cn
cho tng hng mc nh sau: Khu sn xut bia: 30m2; Khu nui to: 10m2; Khu nui
c: 50m2; Khu thy canh: 40m2.
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29
c tinh lng sn phm: Bia: 10 thng/tun; C: 50m2 vi 30kg/m2/nm
1,8 tn/nm; Nm: 20/30% khi lng cht nn. [19]
1.6.1.2. M hnh VAC ti Trung Quc
Ti Trung Quc, vt v ln c nui gn mt h nc. Cht thi t cc vt
nui ny s c thu vo h, gp phn gia tng mc sinh trng ca thy sinh
vt trong h. C trong h c c ngun thc n di do t cc loi thy sinh ny
s pht trin tt. Nc trong h vi hm lng dinh dng cao s c s dng cho
mc ich ti tiu nng nghip. Tn tich nng nghip s l thc n cho gia cm, to
thnh mt vng hu nh khp kin. [19]
1.6.1.3. M hnh khng cht thi ti Fiji chu c
Ti Montfort Boys Town (Fiji chu c), h thng c m rng bao gm
c vic sn xut nm t b ru bia. Qua ligno-cellulose trong b thi ban u
b phn hy, b thi sau c th c s dng lm thc n cho ln. Cht thi t
chn nui ln c ln men k khi sn sinh metan vi mc ich cung cp nng
lng. To sinh trng thnh cc mng trn h nhm tn dng ht hm lng dinh
dng cao c th c thu hoch lm thc n cho gia sc.
Hnh 1.4: H sinh thi tch hp hng ti khng cht thi ti Fiji [19]
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30
1.6.2. Hin trng m hnh nng nghip khng cht thi ti Vit Nam
1.6.2.1. M hnh nng nghip khng cht thi phn compost ti Quan Ha,
Thanh Ha.
Nhng loi cy di lm phn xanh, kt hp vi cc nguyn liu nh mn ca
tre, than tre, ph bng vi khng dt toptex to phn compost. phn compost
khng nhng dit tr mm bnh m thnh phn compost u nhit cn to iu kin
cho cc vi khun hu ich sinh si v khi pht trin s lng th cc vi khun ny
s dit tr mm bnh. Khong 3 tn rc c th cho ra 1 tn thnh phm. Dng phn
compost ny bn cho cy trng em li nng sut cao. M hnh s dng phn
v nc tiu ca ln nui u trng rui BSF, cn nc tiu nui bo tm.
Thc n nui ln chinh l nhng loi cy trng nh rau mung, rau lang, khoai
nc (c bn bng phn compost), u trng rui (BSF) c nu bng bp khi
ha, giun cng l ngun thc n cho g. Bn cnh , bo tm lm ngun cung
cp thc n cho ln v g. [7]
Hnh 1.5: M hnh phn compost ti Quan Ha, Thanh Ha [7]
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31
Ngun cung cp u trng rui BSF n nh bng thng rc sinh hc. Bin
php ny cho php x l ti a 60 kg phn/ngy v to ra 10 kg u trng BSF. D
lng ca u trng rui BSF (ch yu l xenlulo) li rt thch hp lm thc n cho
giun . Phn giun lm mi trng trng cy rt tt v gim c lng phn
bn ng k.
X l cht thi sinh hot cng l vn c quan tm. Phn s c u
trng rui BSF phn hy, nc tiu c tch ra dng cho b nui bo. Ngoi ra m
hnh cn s dng tro bp kh mi hi trong chn nui v phn. [7]
1.6.2.2. M hnh chn nui khng cht thi ti Ph Th
Chn nui theo quy m trang tri ang pht trin nhanh, mnh vng nng
thn trn a bn tnh Ph Th, to cng n vic lm cho nhiu lao ng v mang
li hiu qu kinh t cao, gp phn xo i gim ngho ti a phng. Tuy nhin,
tnh trng nhim mi trng do ngun cht thi chn nui gy ra ngy cng
nghim trng lm nh hng ti khng khi, t v nc v tim n nguy c gy ra
bnh dch cho ngi v cc vt nui khc, ng thi nh hng ln ti cht lng
cuc sng ca ngi dn. gii quyt vn trn, Trung tm Khuyn nng tnh
Ph Th xy dng thnh cng m hnh chn nui ln tht kt hp x l cht thi
chn nui bng cht n chung sinh hc ti cc h chn nui ln tht thuc Vn
Lung, th x Ph Th. [18]
Qua nh gi ca Trung tm khuyn nng, sau 3 thng th nghim m hnh
gip gim ti 60% sc lao ng (do vic khng phi dn phn ln), tit kim ti
80% nc v sinh chung tri v 10% thc n. c bit p dng bin php ny,
chung tri chn nui khng c cht thi ra mi trng v khng c mi hi thi, t
l sng ca vt nui u t 100%, hiu qu kinh t cao hn so vi chn nui thng
thng khong 40.000 ng/con/3 thng nui; ng thi nng cao sc khng
chng li bnh tt v nng cao cht lng tht ca vt nui. [18]
Nguyn liu s dng ch yu l mn ca (tr mt s loi g c nh g lim)
hoc cc cht liu "tr" nh tru, mn da, v lc, li ng nghin..... lm gi th
cho vi sinh vt phn gii cht thi ln men. Nguyn liu m bo c cc iu
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32
kin nh thm nc tt, khng mn, n hi tt, xp khng b nn. Sau phun ch
phm vi sinh vt ln mt nn m lt. Hin nay, ch phm vi sinh vt ang c s
dng rng ri lm m lt ln men l ch phm vi sinh s phn gii phn, nc
tiu sinh trng pht trin v lm gim nhim do cht thi gip lm gim c
ng k mi hi thi, rui mui. c bit, protein vi sinh vt to ra trong mn ca
ca n lt s tr thnh thc n sinh thi cho vt nui. Khi c phn gii, cc cht
dinh dng trong phn vt nui s chuyn ha thnh protein ca vi sinh vt c li.
Cc vi sinh vt c li s thc y qu trnh tiu ha ca vt nui c tt hn, nh
m hiu qu s dng thc n ca vt nui tng, phn ngay t lc c vt nui
thi ra ngoi bt hi. [18]
T m hnh ti x Vn Lung khng nh vic p dng cng ngh chn
nui khng cht thi mang li hiu qu r rt. N khng ch gip ngi chn
nui gii quyt c vn nhim mi trng, tit kim chi ph trong chn nui,
cho hiu qu kinh t cao m cn to ra sn phm sch, p ng nhu cu ngy cng
cao ca ngi tiu dng. M hnh ny, cng gip b con nng dn trong x nhn
thc c tm quan trng ca vic x l nhim mi trng trong qu trnh sn
xut, c trch nhim hn trong vic bo v mi trng trong chn nui, nht l chn
nui tp trung, quy m ln. T thc t cho thy, vic m rng m hnh chn nui
khng cht thi rt cn c nhn rng khng ch x Vn Lung m ti nhiu a
phng khc, nhm gp phn thc y lnh vc chn nui pht trin v gim thiu
nhim mi trng nng nghip, nng thn. [18]
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33
Chng 2
I TNG, PHM VI V PHNG PHP
NGHIN CU
2.1. i tng nghin cu
i tng c lun vn la chn nghin cu l cht thi nng nghip ti x
Giao Lc, huyn Giao Thy, tnh Nam nh vi vic nghin cu, nh gi cc yu
t tc ng n hiu qu v cht lng qun l, s dng m hnh v xut m
hnh nng nghip khng cht thi thich hp.
2.2. Phm vi nghin cu
- Phm vi v ni dung nghin cu: Xc lp c s khoa hc cho m hnh nng
nghip khng cht thi s dng cho cc h gia nh.
- Phm vi v khng gian nghin cu: x Giao Lc, huyn Giao Thy, tnh
Nam nh.
2.3. Phng php nghin cu
2.3.1. Phng php thu thp s liu
- Thu thp s liu v cht thi nng nghip thng ngy ca cc h gia nh.
- Thu thp s liu v cng tc thu gom, vn chuyn v x l cc loi cht thi
nng nghip.
- Thu thp cc s liu v iu kin kinh t, x hi, gio dc, mi trng, k
hoch pht trin kinh t x hi ca x Giao Lc.
- Thu thp, tm hiu v m hnh nng nghip khng cht thi hin nay ti nc
ngoi v Vit Nam.
-
34
2.3.2. Phng php iu tra, kho st thc t
Tin hnh pht 50 phiu iu tra cho 50 h gia nh trong x, ng thi
tin hnh kho st thc t xc nh cc vn nghin cu.
Theo iu tra trn a bn x, th hu ht cc h gia nh chn nui tru,
ln (3- 20 con) tp trung vo 09 xm: xm 1; 2; 5; 6; 7; 8; 9; 10; 12. Cc xm
11; 16; 17; 18; 19; 22 (06 xm) ch yu l nm theo dc trc ng x nn phn
ln l kinh doanh nh, ch nui g, vt s lng nh. Cn li mt s xm (07
xm) cng khng chn nui ln m ch chn nui nh. V vy, lun vn pht
phiu iu tra cho 50 h ca 7 xm trn l in hnh trong x.
Theo iu tra trn a bn ton x c 62 h chn nui tru b, 135 h chn
nui ln (trung bnh mi h nui 6 - 20 con ln). Gia nh nui ln nht l 1 con
tru, 10 ln v g hoc h gia nh khng nui tru th nui ln nht 20 con ln.
Nh vy, lun vn a ra m hnh VACB p dng cho h gia nh 4 ngi c 1
con tru hoc b, 10 con ln v 20 con g l gia nh in hnh trong x.
2.3.3. Phng php ly mu
a) Ly mu v bo qun mu nc thi t hm biogas
Cc mu nc thi c ly trong 3 t ti cc hm biogas vo cc ngy:
20/3/2015 (t 1), 3/4/2015 (t 2) v 17/4/2015 (t 3). Mi t tin hnh ly 02
mu bao gm 01 mu nc thi u vo v 01 mu nc thi u ra. Cc mu nc
thi c ly theo TCVN 5999:1995.
Mu nc thi u vo c ly ti cng thi ca chung nui vo thi im
di ra chung (trong cc khong thi gian t 7g00 8g00). Mu nc thi u
vo c ly h lc u vo, lc ang ra chung.
Mu nc thi u ra c ly h lc u ra sau biogas, cng lc ly
mu u vo.
Mu c cha trong chai nha PET c bo qun lnh trong qu trnh vn
chuyn v lu gi trong t lnh phng th nghim.
-
35
Mu c phn tch ngay sau khi a v phng phn tch Vin ha hc
Cng nghip Vit Nam, s 2 Phm Ng Lo, H Ni.
b) Phng php phn tch mu
Cc thng s phn tch bao gm: nhit , pH, cht rn l lng (SS), Vt
cht kh, BOD5 (nhu cu oxi sinh hc), COD (nhu cu oxi ha hc), tng nit, tng
photpho, coliform.
- Phn tch nhit
Nhit mu nc thi u vo v u ra c o bng my o nhit
hiu Thermo Orion.
- pH
pH o bng my o pH hiu Thermo Orion. Trc khi o pH mu nc,
pH my c chun bng dung dch chun c gi tr pH = 7, sau o trc tip
ti v tr ly mu.
- Kh gas
Tng lng gas sinh ra: Tin hnh o bng ti d tr. Sau 24h o chiu
di ti lu tr 1 ln. Kt qu c o trong 3 ngy lin tip. S dng my ht
kh ht gas t hm cho vo ti d tr bng nilon di 3 m, ng knh 0,8m.
Tnh kt qu: Vgastt = *R2*l/n (m3/ngy)
Trong :
- R: Bn kinh hnh trn ca ti d tr
- l: chiu di ti d tr khi cng trong 24h
- n: s ngy o
So snh hiu sut sinh gas thc t so vi l thuyt c tnh theo Bng 3.4
Vgaslt = Hiu sut sinh khi x lng thi hng ngy (m3/ngy)
2.3.4. Phng php tham vn kin cng ng
Gp mt, phng vn hoc t chc cc bui hp nh trong cng ng
chia s thng tin v kinh nghim trong lnh vc chn nui; v xut, la chn
-
36
cc phng thc k thut ph hp cho m hnh chn nui khng cht thi ti a
phng.
2.3.5. Phng php chuyn gia
Phng vn, xin kin cc chuyn gia trong lnh vc nng nghip, mi
trng v cc vn lin quan n m hnh nng nghip khng cht thi.
Xin kin ca ThS L Th Thanh Thy Vin Mi trng Nng nghip v
lnh vc x l biogas v x l ph ph phm trng trt.
2.3.6. Phng php k tha
Thng qua cc kt qu nghin cu trc ca Vin Mi trng v Nng
nghip la chn v ng dng cc cng ngh vo cc m hnh x l cht thi
a ra cc bin php nhm hn ch nhim mi trng, nng cao cht lng sn
phm u ra.
2.3.7. Phng php thng k v x l d liu
Sau khi thu thp iu tra x hi, cc thng tin t liu s c thng k,
phn loi theo tng phn x l cc d liu bng phn mm Excel, lc thng
tin nhm phc v cho vic tng hp bo co.
-
37
Chng 3
KT QU NGHIN CU V THO LUN
3.1. Hin trng thu gom v x l cht thi nng nghip ti xa Giao Lc, huyn
Giao Thy, tnh Nam nh
3.1.1. Hin trng cht thi nng nghip x Giao Lc
Cht thi nng nghip l cht thi pht sinh t cc hot ng sn xut nng
nghip nh: trng trt, chn nui, thu hoch, bo qun v s ch nng sn.
Rc thi chn nui ch yu l phn gia sc, gia cm. Con vt nui ch yu l
ln, vt, g. Chn nui tuy pht trin song ch yu l chn nui gia nh quy m
nh. S trang tri cha nhiu.
Hnh 3.1: Ngun gc pht sinh cht thi nng nghip trong 1 h gia nh
Vi din tch trng la ti x l 400 ha, nng sut t bnh qun 117,89 t/ha.
Nh vy, cht thi rm r ca x Giao Lc nm 2013 c tinh t hn 5.000 tn
rm r ti/nm, tng ng khong 2.000 tn rm r kh/nm v 1.000 tn tru
sau khi st go [13].
Cht thi nng
nghip pht
sinh trong h
gia nh
Trng trt (thc vt
cht, l cnh, c)
Thu hoch nng sn
(rm, r, tru, cm,
li ng)
Chn nui (phn gia
sc, gia cm, ng
vt cht)
Bo v ng, thc vt
(chai l ng thuc
BVTV, tr su, dit cn
trng)
Qu trnh bn phn,
kich thich tng
trng ( bao b
ng...)
Th y (chai l ng
thuc th y, dng c
tim m...)
Git m ng vt
-
38
Theo s liu iu tra t 50 h gia nh lm nng c nui tru, b, ln hoc
vt quy m ln, khng bun bn ( c th p dng lm m hnh biogas), trong 50
h c:
- 17 h nui tru hoc b (1 con hoc 2 con)
- 42 h nui g vt s lng nh (
-
39
Cht thi sinh hot y ch yu l cht hu c, bao b, ti nilong. Cht thi
rn hu c (thc n tha, rau c qu hng) hu ht c ngi dn tn dng nui
gia sc, gia cm nn lng pht sinh ra ngoi mi trng tng i t. Ngoi ra do
ngi dn bit thu gom kim loi, giy bo bn, v th khi lng ca cc
nhm ny l khng cao.
3.1.2. Hin trng thu gom v x l cht thi nng nghip ti x Giao Lc
Cng nh giai on trc, hin ti qu trnh x l rc thi cng nh thu gom
rc thi ti nng thn vn ch yu tp trung ti h gia nh. Rc thi c th ti ch
c ph hp vi iu kin nng thn c tn dng mt cch ti a. Nhng rc
thi cn li khng tn dng c thng b vt ra vn hoc ti nhng a im
cng cng thiu s qun l ca chnh quyn (nh cc khu vc gip danh gia cc
lng, x ).
a) Rc thi sinh hot, cht thi chn nui
Theo kt qu iu tra t 50 h gia nh th c 50 h c hi u tr li rc
thi hu c d phn hy l ch yu v hu nh khng phn loi rc.
Trong 50 h gia nh th c 37 h gia nh s dng ti nilong hoc bao ti
ng rc, 13 h cn li th ng rc bng thng ng v c n ngy rc th
rc trc tip ra l ng.
Theo phiu iu tra th hu ht cc h gia nh u dng thc n tha lm
thc n cho gia sc, gia cm. Gc rau, hay rc ngoi vn (l cy, hoa qu hng...)
cng c ngi dn b. Phn ngi, phn gia sc c a v 1 h thu gom,
khi y th em ti rau vn, hoc thi trc tip ra mng cnh nh. Phn gia
cm th hu nh khng thu gom, m tri theo nc ma ra knh mng.
b) Cht thi trng trt
Cc kt qu t phiu iu tra thc t cho thy trung bnh c 1 tn thc sn
phm thu hoch c s c khong 1 tn ph phm rm, r tng ng. Ty loi
la, t l tru trong thc chim trung bnh tng ng khong 20% tng trng
lng. Nh vy, trung bnh 1 tn thc sau khi xay xt, thu c khong 200 kg
tru ph phm.
-
40
Trc y rm r thng lm nguyn liu un nu. Nhng hin nay, do
ngi dn s dng nhiu cht t khc nh gas, than nn rm r sau khi thu hoch
phn ln c em t ly tro lm phn bn hay vt b ba bi ra ao, knh mng
... Rm c thu gom nh ng v s dng vo mc ich chinh l un nu, cng
vi phn chung lm phn bn, cho tru b n, lt chung cho m, tro dng
bn rung, rm ca la np dng lm chi, mt s ni lm thc n cho tru b...
Tru thu c t cc c s xay xt thc, lng ny rt ln. Mt phn, lng
tru ny thng c ngi dn xin v, em t m to thnh than (t cng
mt b rm va phi ri tru vo cho chy m qua m) bn lt cho rung
la v bn cho cy trng trong vn nh. Mt phn khc, tru thng c thu gom
lt chung cho chung g, vt. Ch mt phn nh th c ngi dn cht ng
ri em b (theo kho st ti 50 nh th ch 4/50 nh b).
Hnh 3.2: Ph phm cy la sau thu hoch
La
Gt la
Xn la
u bng la
Tut la
Thc
Xay xt
Go Tru
Rm
R
Phi kh
t
t S dng cho
mc ich khc
100%
80% 20%
8%
92%
-
41
Theo nh phng vn trc tip ngi dn th bao b thuc bo v thc vt s
c b cng cc loi rc khc. Cn cc bao ti ng s c ngi dn tn
dng ng rc thi.
3.1.3. nh gi nhng thun li v kh khn khi p dng m hnh nng nghip
khng cht thi ti x Giao Lc
a) Thun li
Qua kho st bc u, cc ch h u nhn thc r vai tr ca VAC. VAC
l mt trong nhng h sinh thi bn vng - tim nng pht trin kinh t v c kh
nng p ng nhu cu ca con ngi bi s dng cc ngun nng lng an ton,
tit kim v ti ch. VAC tr thnh mt m hnh quan trng v hiu qu xa
i ngho. Tuy nhin, m hnh VACB vn cn mi v cha c p dng rng ri
ti y. Phong tro khai hoang, phc ha nhm khai thc hp l ngun lc con
ngi v ngun ti nguyn thin nhin tim nng bng p dng m hnh VACB
ang gp phn quan trng vo Chng trnh pht trin kinh t chung trong c nc.
Kt qu nhn c t iu tra mt s vng thc hin thi im VAC (D n
an ninh lng thc h gia nh HFS/UNICEF) cho thy vic ci thin tiu chun
dinh dng theo cc ch n ung trong cc gia nh nh sau: C tng 3,14 ln;
Tht (g, ln, b,...) tng 2,40 ln; Trng (g, vt) tng 2,90 ln; Tri cy tng 3,14
ln v c bit VAC c th ng gp hiu qu gim t l tr em suy dinh dng.
[9]
Cc nghin cu cho thy: nhiu x ca vng ng bng sng Hng, thu
nhp t cc hot ng VAC ca nhiu gia nh nng dn t ti 70% tng thu
nhp v t 3-5 ln cao hn (v i khi mi ln cao hn) so vi sn xut t trng
la 2 v/ nm trong cng mt din tch.[10]
Thc t kho st, cc h gia nh x cng lm theo m hnh VAC, c
kt hp nhng cha trit . Cc h c trng cy, th c, nui ln g, trng rau, tuy
nhin, rc thi t vn vn em thi b ch khng tn dng ht nui c, nui gia
sc. Phn gia sc gia cm ra knh mng ch khng tn dng
-
42
Khi gii thiu v m hnh VAC kt hp m hnh Biogas, cc ch h u rt
phn khi v vic xy dng cng trnh KSH khng ch gip m bo mi trng
chn nui, tng sn lng vt nui m cn mang li hiu qu kinh t thit thc nh
s dng KSH thay th in, gas cng nghip, ci, tru..., bnh qun gip tit kim
c t 200.000 300.000 chi phi trong 1 thng mua nhin liu sinh hot. [10].
Ngoi ra, li th ca ngi dn x Giao Lc l sng ch yu bng ngh trng
la, sn phm ph (rm, r) t qu trnh trng la l rt ln (2.000 tn rm r
kh/nm), cho nn vic a m hnh trng nm rm s tn dng c ph phm cy
la sau thu hoch, to ra sn phm mi, ph hp vi lao ng nng thn v khai
thc li th nhn ri trong khi ch ma thu hoch sau. Nu s rm r ny c s
dng vo nui trng nm rm th s to ra mt khi lng sn phm nm rm v
cng to ln. Ph liu rm r c x l sau khi dng nui trng nm rm cn l
ngun phn hu c bn trc tip cho ng rung, gp phn gim tnh trng nhim
mi trng do t rm r hoc rm r t phn hu trn cc b rung, l ng.
Do nm rm c th trng quanh nm, chi phi u t thp, yu cu k thut khng
phc tp, thu hi vn nhanh nn tt c cc h gia nh, c bit l nhng h gia nh
ngho cng c th p dng c.
b) Kh khn
Tuy nhin, vn cn kh khn trong pht trin KSH l do nhn thc ca ngi
dn, vi thi quen s dng nng lng t cc nguyn liu truyn thng nh in,
than, ci, vn ng ngi dn s dng mt loi nng lng mi l rt kh.
Trong khi trnh dn tr ca ngi dn nng thn cn cha cao, s dng hm
biogas an ton rt cn c ngi hng dn. Mt kh khn na l vn vn cho
xy dng hm biogas. Mun s dng KSH th phi xy hm, chi phi trung bnh
xy hm biogas hin nay khong 5 - 9 triu ng, y l mt khon tin kh ln i
vi ngi nng dn.
Thc t khi kho st ti x Giao Lc, c 34% s h gia nh (17/50 h) chp
nhn xy dng hm vi mc chi ph 5-7 triu ng, 18% s h (9/50 h) chp
-
43
nhn xy dng hm vi mc phi khong 3 - 5 triu ng. Cn li cc h chp
nhn mc phi trn 7 triu (24/50 h).
Nguyn nhn mt phn l do chi phi u t xy dng hm cn cao so vi
thu nhp ca ngi nng dn nn h cn d dt trong vic u t. Mt phn khc l
mt s h trong x p dng m hnh ny v cho kt qu tt nn cc h dn xung
quanh cng mun p dng.
3.2. Cc m hnh x l cht thi nng nghip ti xa Giao Lc
3.2.1. iu kin p dng m hnh
M hnh VAC l mt m hnh thm canh sinh hc cao, trong cc hot
ng trng trt, nui trng thy sn v chn nui gia sc gia cm l cc hot ng
chnh v c nhng mi quan h mt thit v khng khit nhau. M hnh ny tn
ti rt lu ti cc vng nng thn Vit Nam v c th thc hin ti bt c gia nh
no. Ty thuc vo iu kin a phng v cc khu vc, cc h thng VAC sinh
hc c th bao gm tt c 3 thnh phn V, A, C hoc ch c 2 thnh phn nh VA,
CV hoc AC. Tuy nhin, vi m hnh VACB M hnh kt hp hm biogas ch
c th p dng i vi nhng h gia nh chn nui ln, chn nui tru b hoc gia
cm s lng khng qu ln. (ph hp vi cc h gia nh ti x nui tm 20 con
ln, 1 con tru v di 50 con g, vt).
Theo iu tra trn a bn ton x c 62 h chn nui tru b, 135 h chn
nui ln (trung bnh mi h nui 6 - 20 con ln), c 13 nh nui vt thnh tri ln
(trn 300 con vt) cn li cc nh khc (89%) l c nui g vt s lng nh trong
gia nh. Vi s lng h chn nui s l ngun cung cp KSH ng k. Nu
vic xy dng v vn hnh tt cc cng trnh, b con nng dn s tn dng c
lng KSH trn gp phn tit kim ng k trong nu nng v sinh hot gia nh
khi gi gas, inlin tc tng. Mt im ng quan tm khc l m hnh v
ang tng bc gp phn gim thiu nhim mi trng theo tiu ch xy dng
nng thn mi.
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44
Tuy nhin, thc t kho st hu ht cc h chn nui cha bit tn dng trit
ngun cht thi chn nui. Phn ln cht thi chn nui cha c s dng hiu
qu, c n 26,11% cht thi chn nui b b, khng nhng gy mi hi kh
chu, mt m quan mi trng m cn lm ly lan dch bnh nguy him. Do ,
vic pht trin xy dng m hnh hm biogas l mt vic lm v cng thit thc.
Cn trng nm t rm r th c th p dng c cho tt c cc h gia nh.
Do rm r nhiu nn c th trng nm theo quy m h gia nh hoc theo quy m
hp tc x. Nm c th trng c quanh nm, tuy nhin ty theo iu kin thi tit
m ngi dn c th p dng cc bin php khc nhau khc phc tnh trng bt li.
C th cht rm nhiu ni nh: t rung, trong vn cy, xung quanh nh,c
th trn nn t, gch, xi mng trn k, ngay c trong nh, trong bc nylon.
3.2.2. Xy dng m hnh tng qut Vn Ao Chung Biogas
VACB l nhng ch u ca 4 t Vn - Ao - Chung - Biogas. VACB
cung cp thc n cho con ngi v cng cung cp qua li cho nhau:
- Vn cung cp rau, c ti cho con ngi, rau c hng cho gia sc, gia
cm hay cho c (dng cho C v A). Cc cht thi nng nghip nh rm r, cnh cy
kh c tn dng lm thc n cho gia sc, gia cm, lt chung vo ma
ng hay lm compost (phn rc bn ngc li cho V).
- Ao cung cp thc n cho con ngi (c, tp, hn, c...), cung cp bo tm
lm thc n cho gia sc, gia cm. Cc loi cht thi v cc th khc t A nh
bo, khoai nc c th dng lm thc n cho C. Bn ao sau mi ln no vt c th
dng bn cho cy hay chung vi rm, r lm phn cho V.
- Chung gm cc loi gia sc, gia cm, cung cp tht cho con ngi. Phn,
nc tiu ca gia sc, gia cm c a vo h thng biogas bn cho V, a vo
ao nui c. Nu thiu c th b sung thm mt s loi bo, l cy vo h thng
biogas.
- Phn, nc tiu ngi cng c a vo h thng biogas.
- H thng biogas l h thng ln men hm kin nn khng c rui nhng
v trnh nhim. N cung cp khi lm cht t phc v cho con ngi. B thi
-
45
c bn cho cy trng, la, hoa mu... v lm thc n cho ng vt trong ao hoc
nui giun lm thc n cho c hoc cho gia cm.
Hnh 3.3: M hnh tng qut VACB
Theo kt qu nghin cu ca Vin Nng nghip Vit Nam th thnh phn
amoniac ca phn hu c c men trong 30 ngy mt hm biogas tng
19,3% v thnh phn photphat hu ich tng ln 31,8%. Theo thc nghim, phn
c trong cc hm biogas lm tng nng sut ng 28% v la nc l 10%. Nu
dng nc thi t hm biogas ngm ht ging th s lng ht ging ny mm s
tng cao hn hn so vi cc ht ging khng c ngm phn. B thi ca biogas
c lng v c khi s dng bn cy u cho nng sut tng, it su bnh. Tc
dng ci to t ca phn biogas cng th hin r sau 2-3 nm sau. B thi cng
c lm thc n cho c, cc cht dinh dng kch thch s pht trin ca c v
thc vt ph du. Do vy, sn lng tng ng k.
Ao Chung
Ngi Vn
Biogas
Bo tm
C,
tp,
c,
hn
Rau, c, qu, hoa mu, go
Rau
c
hng,
r
cy
Phn,
nc
tiu
Phn,
nc
tiu Kh sinh
hc Nc tiu
B
thi
B
thi
Trng nm Rm, r
Nm
phn compost
B thi
Rm, r, tru
Phn
hu
c
-
46
Cc thn cy, l cy v cc cht thi khc u l nhng vt liu tt cho vic
sn xut biogas. Ngi nng dn c th tch tr vt liu ny a vo hm khi
khng c phn gia sc.
Kh biogas lm cht t va gim chi ph sinh hot, va khng gy nhim
mi trng. Kh biogas ngoi vic un nu thc n cho con ngi cn un nu
ru hoc un nu thc n cho gia sc, gia cm v vy lng kh sinh ra trong 1
ngy s c tn dng ht, khng gy d tha.
Rm r ngoi ng c tn dng nui trng nm, tng thu nhp cho
ngi dn. B thi sau trng nm hoc rm r, tru c th compost (c b sung
ch phm vi sinh) bn trc tip ngoi vn, ng rung, tng nng sut cy
trng, gim thiu lng phn bn ha hc v thuc bo v thc vt.
3.2.3. Xy dng m hnh hm biogas
Lun vn xut 04 kiu hm biogas cng vi cc thun li, kh khn khi
p dng m hnh nh sau:
Mi kiu hm biogas c 1 chi phi u t ban u khc nhau vi cng th
tch: Chi ph xy dng cao nht ti thi im ny l kiu hm np tri ni v
hm nha compostie, hm ch nht ci tin v sau cng l ti plastic.
Bng 3.2: So snh u nhc im gia cc kiu hm [6]
Kiu hm
biogas u im Nhc im
Hm np
tri ni
- p sut kh n nh
- Ph hp hm ln
- D s dng
- Chi ph cao
- Khng lm vng xa xi
ho lnh, do khng c np hm
bng kim loi.
- i hi bo dng thng
xuyn
- Tng i nhy cm vi
thay i nhit , khng ph
hp cho vng ni.
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47
Hm
nha
composite
- Thun li cho vn chuyn, d
dng cho vic thay th sa cha
- p lc kh n nh, din tch mt
bng ph hp.
- Nhanh c gas ch 7 15 ngy,
hiu sut sinh kh cao
- p lc kh gas cao v t iu p
kh gas, gas tha b t ng x kh
m khng cn van an ton.
- C kh nng t ph vng
- Vn hnh n gin, thi gian s
dng t 15 n 20 nm
- Chi ph cao
- Dung tch nh, khng lp
c cho trang tri nui ln.
- bn va p km, tuy
nhin xy chm di t nn
khng nh hng.
Hm ch
nht ci
tin
Vi mt trn v mt di b
tng kin c v xung quanh xy
bng gch th 2 l v va, khng
cho thm nc v thot kh.
- Nm chm di t
- Tn it t
- Gi thnh r
- D xy dng
- p sut kh gas sinh ra thp
- Phi dng ti cha kh v my
ht kh khi s dng.
- Cn pha long lng cht thi
thi vo
- D b ln, nt v, d b d kh
khng khc phc c
Ti
- Chi phi u t thp
- o v tr nng, thch hp vi
vng c nc ngm cao.
- Rt d hng
- Cn sa cha thng xuyn,
v bin php bo v
- p sut kh thp, khng thch
hp cho chiu sng bng biogas
- Tui th thp, nht l khi
hm b nng chiu trc tip
(di 2 nm)
- Nhy cm vi thay i nhit
mi trng
- i hi din tch b mt ln
- Ch ph hp cho nhng h
chn nui vi s lng nh.
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48
Hm np tri ni
Hm nha composite
Hm ch nht ci tin Ti plastic
Hnh 3.4: 04 kiu hm xut trong lun vn [6]
Vi nhng u nhc im nh trn, kt qu iu tra trn 50 h c nui tru
b v ln cho thy, cc h gia nh c la chn c th c trnh by nh sau:
Bng 3.3: Cc kiu hm biogas c ngi dn x Giao Lc mun s dng
Kiu hm S lng
Hm np tri ni 03
Hm composite 21
Hm ch nht ci tin 17
Ti 09
Tng 50
Ngun: Tng hp phiu iu tra
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49
a s chn m hnh hm nha compostie vi gi thnh cao nhng bn, t
phi bo tr v t gy hu qu nh ti . Mt khc, ti x cng c mt s h s
dng hm biogas composite cho kt qu tt nn ngi dn cng thy yn tm v
mun s dng loi ny. Vi nhng u, nhc im trn, kt hp vi iu kin t
nhin ca vng th ti cng khuyn khich ngi dn nn s dng m hnh hm
nha composite.
3.2.3.1. Tnh ton hm biogas s dng cho h gia nh trung bnh 4 ngi c nui
b v ln
Cc thng s ban u lm c s tnh ton:
- Hiu sut sinh kh ca cht thi, Y (l/kg/ngy).
- Lng cht thi np hng ngy, Md (kg/ngy).
- T l pha long, N (l/kg).
- Thi gian lu, RT (ngy).
- H s tr kh, K.
Cc thng s cn tnh:
- Lng nguyn liu (cht thi + nc) np hng ngy, Sd (l/ngy).
- Th tch phn gii, Vd (m3)
- Cng sut sinh kh ca cng trnh, G (m3/ngy).
- Th tch tr kh, Vg (m3).
- Th tch hm , Vc (m3).
a) Hiu sut sinh kh ca cht thi nguyn liu, Y (l/kg/ngy)
Bng 3.4: c tnh v sn lng KSH ca mt s nguyn liu thng gp [14]
Loi nguyn
liu
Lng thi
hng ngy
(kg/con)
Hm lng
cht kh (%)
T l C/N Hiu sut
sinh kh
(lt/kg/ngy)
Phn b 15 20 18 20 24 25 15 32
Phn tru 18 25 16 18 24 25 15 32
Phn ln 1,2 4,0 24 33 12 13 40 60
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50
Phn gia cm 0,02 0,05 25 50 5 15 50 60
Phn ngi 0,18 0,34 20 34 2,9 10 60 70
b) Lng cht thi np hng ngy, Md (kg/ngy)
Tnh trung bnh vi 1 h gia nh A: c 4 ngi, nui nhiu nht 1 con tru
hoc b, 10 con ln v khong 20 con g th lng khi sinh ra nh sau:
Bng 3.5: Sn lng KSH tnh cho h gia nh A
Loi nguyn liu S lng
(con)
Lng thi hng
ngy (kg/con)
Lng thi hng
ngy (kg)
Phn b (tru) 1 15 25 15 25
Phn ln 10 1,2 4,0 12 40
Phn gia cm 20 0,02 0,05 0,4 1,0
Phn ngi 4 0,18 0,34 0,72 1,36
Tng 28,12 67,4
Vy, Md = 67,4 kg/ngy
c) T l pha long, N (l/kg)
i vi cc loi cht thi ca ln v tru b, khi thit k thng thng ngi
ta chn t l pha long l 1lit nc/1kg cht thi. Vy, N = 1 lt/kg
d) Thi gian lu, RT (ngy)
Thi gian lu l thi gian nguyn liu nm trong thit b phn gii. y l
khong thi gian dch phn gii sn sinh ra KSH. i vi ch np lin tc,
nguyn liu c b sung hng ngy. Khi mt lng nguyn liu mi np vo, n
s chim ch ca nguyn liu c v y dn nguyn liu c v pha li ra. Thi
gian lu chinh bng thi gian nguyn liu chy qua thit b t li vo ti li ra.
Trong iu kin Vit Nam, Tiu chun ngnh 10 TCN 97 - 2006 quy nh thi
gian lu i vi cht thi ng vt min Bc Vit Nam ma ng l t 10 -15oC,
thi gian lu l RT = 55 ngy.
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51
e) H s tch tr kh, K
Chn theo thi gian cn tch gi kh lu nht trong ngy.
Thng thng cc h dn ch s dng un nu, thp sng hng ngy. Nh
vy, ch cn tr khi ban m (10 gi), K = 10/24 = 0,4.
f) Lng nguyn liu np hng ngy, Sd (l/ngy)
Lng nguyn liu np hng ngy bng lng cht thi np hng ngy cng
thm vi lng nc pha long. V cht thi c t trng xp x bng 1 nn c th coi
th tch ca cht thi bng khi lng ca n. Do :
Sd = (1+N) Md = (1 + 1) x 67,4 = 134,8
=> Sd = 134,8 (lt/ngy)
g) Th tch phn gii, Vd (m3)
Vd = Sd RT / 1000 = 134,8 x 55/1000 7,4 m3
=> Vd = 7,4 m3
h) Cng sut sinh kh ca cng trnh (m3/ngy)
G = Md x Y/ 1000
Bng 3.6: Lng kh sinh ra tnh cho h gia nh A
Loi nguyn
liu
S lng
(con)
Lng thi hng
ngy (kg) Kh sinh ra (lt/ngy)
Phn b (tru) 1 15 25 15 32
Phn ln 10 12 40 480 2400
Phn gia cm 20 0,4 1,0 20 60
Phn ngi 4 0,72 1,36 43,2 95,2
Tng 21,9 46,9 558 2.587
Vy, G = 2,6 m3/ngy
i) Th tch tr kh, Vg (m3)
Th tch tr khi c tnh theo cng sut ca cng trnh v h s tr kh (K)
Vg = G x K = 2,6 x 0,4 = 1,04
=> Vg = 1 (m3)
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52
k) Th tch hm Vc (m3)
Th tch hu hiu ca hm phi bng th tch kh cn tr:
Vc = Vg = 1 (m3)
Nh vy, hm cn kich thc ti thiu l : V = Vd + Vc + i (i l khong trng
khi lu thng, i t chn)
V = 7,4 + 1 + i = 8,4 + i (m3)
y, lun vn chn i = 0,6 m3. Vy cn thit k hm c kich thc nh
nht l 9 m3 cho h gia nh 4 ngi.
Nh vy, ty gia nh c nui it con vt hn m kich thc hm c th nh
hn hoc ln hn.
3.2.3.2. Cu to, hot ng ca b nha composite
a) Cu to
y l loi bn b c sn c ch to bng vt liu composite, ct thy
tinh, si