Cong Nghe Xu Ly Nc Thai Trong Che Bien Thuy San

8/4/2019 Cong Nghe Xu Ly Nc Thai Trong Che Bien Thuy San

1/21

TRNG I HC NGOI THNG

B MN HP TC U T QUC T

CHUYN GIAO CNG NGH

CC PHNG PHP X L NC THI

TRONG NGNH CH BIN THY SN

Ngy 24 thng 02 nm 2008


2/21

Ging vin hng dn: inh Hong Minh

Nhm sinh vin thc hin:

Nhm:Chicken Run

Lp: Anh3_CK2

Thnh vin nhm:

1. Nguyn Thi Bnh

2. ng Th Dn

3. Nh Hng Giang

4. Phm Th Thu H

5. Nguyn Thu Hng (1987)

6. L Thu Hin

7. L Th Hng Hoa

8. L Phng Tho

Sbd 04

Sbd 11

Sbd 14

Sbd 15

Sbd 16

Sbd 21

Sbd 20

Sbd 29


3/21

BNG CH VIT TT

DOB: Biochemical Oxygen Demand- Nhu cu xy ho.

COD: Chemical Oxygen Demand- Nhu cu xy ho hc

DO: Dissolved Oxygen- xy ho tan.

LL: Lu lng.

N: Nit.

P: Phtpho

SS: Suspended Solid- Cht rn l lng.

UASB: Upflow Anaerobic Sludge Blanket- H thng m bn k

kh dng ln


4/21

M u

Ch bin thu sn l ngnh kinh t quan trng v

c tc tng trng nhanh nc ta.Theo s liu ca cc

Thng k thnh ph H Ch Minh (1998), sn lng thu hi

sn nm 1998 l 1676000 tn, trong c 540000 tn do

nui trng thu sn. Khong 24,3% s lng ny (400000 tn)

c ch bin xut khu v phn cn li c tiu th

th trung ni a di dng ti sng hoc qua ch bin.

Ga tr xut khu thu sn ca c nc gia tng t 109 triu

USD nm 1986 ln 205 triu nm 1990 v t khong 670

triu USD nm 1996. T nm 1996, hng chc nh my ch

bin mi c xy dng , ch yu tp trung cc tnh pha

Nam, gii quyt cng n vic lm cho ngi lao ng, nng

cao gi tr xut khu ca sn phm. Bn cnh nhng li ch

do ngnh cng nghip ch bin thu sn em li th y

cng l ngnh sn xut gy nhim nng n cho mitrung, c bit l mi trng nc. Mt khc cc c s ch

bin li tp trung ch yu ven bin.Trong mt s cng

on ca dy chuyn sn xut, do khng nc ngt nn

phi dng nc mn, v vy nc thi ca cc c s ny t


5/21

nhiu b nhim mn. Do x l nc thi ch bin thu

sn l vn mang tnh cp thit cn c u t nghin

cu v a vo ng dng.

gp phn tm hiu kh nng x l nc thi ch

bin thu sn bng phng php sinh hc trong iu kin

ca Vit Nam, chng ti xin gii thiu ti:Cc phng

php x l nc thi trong ngnh ch bin thu sn vi cc

ni dung sau:

1. i tng v l do nghin cu

2. Tnh hnh nhim nc thi ni chung v

nhim cht hu c ni ring

3. nhim mi trng do ngnh ch bin thu sn

4. Cc phng php x l nc thi

4.1.Phng php c hc

4.2.Phng php ho l

4.3. Phng php ho hc

4.4. Phng php sinh hc

4.4.1. Phng php hiu kh

4.4.2. Phng php k kh

5. im mnh im yu ca cng ngh la chn

6. Gii php pht trin cng ngh trong khu vc


6/21

1. i t ng v l do chn ti

i tng nghin cu l nc thi ch bin thu sn b

nhim mn, chng ti chn ti ny v nhng l do

sau:

+ Th nht, Vit Nam l nc c ngnh Thu sn

ngy cng pht trin cho nn nhu cu x l nc thi ngnh

ny t ra l rt cp thit.

+ Th hai, nc thi loi ny c hm lng COD, N, P

cao i hi phi qua x l truc khi tin hnh x l hiu

kh.

+ Th ba nhiu nh my ch bin thu hi sn ven

bin do thiu nc ngt nn s dng mt phn nc mn

cho qu trnh ch bin.


7/21

2. Tnh hnh nhim n c ni chung v

nhim cht hu c ni ring Vit Nam

Trong nhng nm gn y, tc pht trin kinh

t ni chung v cng nghip ni ring nc ta ang gia

tng ng k, cc vn v nhim mi trng cng v

th m gia tng, c bit l nhim mi trng nc. Cc

tc nhn gy nhim quan trng l cc cht hu c (d

phn hu v kh phn hu), kim loi nng v cc ho

cht c hi nh ch, thu ngn, asen, clo, phenol,, d l-

ng thuc bo v thc vt, vi khun gy bnh v cc chtv c nh H2S, NH4+, SO2-

Mc nhim c bit nghim trng i vi cc thnh

ph ln, ni tp trung dn c ng c, c nhiu nh my,

x nghip. Theo s liu thng k, ti H Ni cc sng, h,

knh, rch vi din tch 723 ha hng ngy phi tip nhn

300-400 nghn m3 nc thi sinh hot, nc thi cng nghipv nc thi t cc bnh vin khng qua x l, trong lng

nc thi cng nghip t 85-90 nghn m3. Kt qu o c

xc nh ti 40 c s H Ni cho thy lng nc thi trong

mt ngy m l 21.982 m3 v khng qua x l trc khi i

vo h thng dn nc ca thnh ph do gy nhim

nng cc sng bao quanh H Ni nh: Kim Ngu, T Lch,lm nh hng xu n sc kho nhn dn trong thnh ph

v cc vng xung quanh H Ni.

nhim cht thi hu c l mt trong nhng nguyn

nhn chnh gy nn tnh trng nhim nc. Cc cht


8/21

hu c ch yn c bt ngun t cng nghip ch bin

thc phm nh: cc nh my ch bin nng, lm, thu

snTuy nhin thnh phn nc thi mi nh my l khc

nhau v ph thuc vo chng loi sn phm, cng nghs dng v qui m sn xut.

3. nhim mi tr ng do ngnh ch bin

thu sn

Theo bo co ca B Thu sn (1998), lng nc

thi trung bnh t mt tn sn phm l 15m3, trong khi

sn lng thu sn nm 1998 l 1676000 tn. Ngun nc

thi ny c nhu cu oxy sinh ho BOD5 trung bnh 1250-

1800 mg/l, COD khong 1600-2300 mg/l v giu cc cht

dinh dng vi hm lng nit tng cng t 70-120 mg/l.

Ngun nc thi bt ngun t cc cng on sn xut nh:

+ S ch nguyn liu bao gm ra m, r

ng.

+ Qa trnh hp luc.

+ Qa trnh ngm thu sn.

+ Cng on ra thit b.

Lng nhim gy ra do ngnh ch bin

thu sn v cc ngnh khc c trnh by trong bng 1.

+ Qu trnh ngm thu sn

+ Cng on ra thit b.


9/21

Lng nhim gy ra do ngnh ch bin thu sn v cc ngnh

khc c trnh by trong bng 1

Bng 1. Thnh phn v nng cc cht nhim t cng ngh thc

phm

Ngnh cng ngipLu lng

m3/ngy

Lng nhim kg/ngy

SS BOD TKN

Ch bin hi sn 18.900 4.200 28.400 1.700

Bt giy v giy 49.200 54.900 104.800 340

Bt khoai m 47.100 30.600 590.000 -

Dt v nhum 32.500 5.600 17.300 -

Nc gii kht 15.600 4.400 19.000 630

Ch bin tht 6.400 4.000 13.300 1.020

Ngnh ng 5.520 6.900 32.000 72

Rau qu ng hp 3.700 520 2.700 70S liu bng 1 cho thy ngnh ch bin hi sn l mt trong nhng

ngnh cng nghip gy nhim nhiu nht cho mi trng c bit l mi

trng nc. Nc thi ch bin thu sn cha cht hu c v cht dinh

dng (N,P) cao, to iu kin cho cc vi sinh vt gy bnh pht trin nh:

vi khun thng hn, t, l, siu vi trng gan v mt s loi nm gy bnh

cho da, ng thi lm tng lng to trong nc (hin tng ph dng-

eutrophy). Loi nc thi ny c nguy c gy nhim trm trng cho mi

trng xung quanh nu khng c x l ng mc. Ngoi ra nc thi ch

bin thu sn cn cha du m sinh ra t qu trnh ch bin c c nhiu du.

Mt c im quan trng khc l hu ht cc nh my ch bin thu sn


10/21

nm ven bin, ngoi tr thnh ph H Ch Minh, nn u thiu nc ngt

ch bin. V vy mt s nh my dng trc tip nc bin cho mt s

cng on trong qu trnh ch bin nh x , m x v ra nguyn liu. Do

lng nc thi ny t nhiu c mn. Di y l thnh phn ncthi ca nh my ch bin c kh mui.

Bng 2: Thnh phn nc thi nh my ch bin c kh mui

Thng s n vNi tp trung

B nc mui Nc thi khc

COD mg/l 5.250 873BOD5 mg/l 5.250 670

SS mg/l 371 119

pH 6,17 6,77

Cl- mg/l 45,76 16,7

SO42- mg/l 26,8 10,01

N tng s mg/l 1,240 164

P tng s mg/l 4,72 5,25

S liu bng 2 cho thy vic ch bin c kh mui sn sinh ra mt

lng nc thi c cha nng mui rt cao, t 17 cho n 46 g/l. Nc

thi vi hm lng mui cao nh vy khin cho cc t bo vi khun thamgia trong qu trnh x l nc thi b c ch, b mt nc, do p lc thm

thu dn n hiu sut x l gim. V vy ngoi vn nhim cht hu c,

mt vn c bit khc cn phi quan tm trc khi thit lp mt h thng

kim sot nhim l vic nc thi ca l vic nc thi ca qu trnh ch


11/21

bin hi sn cha hm lng mui (Na+, Cl-, SO42-) rt cao, khin cho vic

x l tro nn kh khn.

R rng nhim mi trng nc ni chung v nhim cht hu c

do cc ngnh cng nghip ch bin thc phm, nht l cng nghip ch bin

thu sn trong iu kin nhim mn t n mc c bit nghim trng,

i hi phi c nghin cu x l nhm m bo mi trng.

4. Cc phng php x l nc thi

4.1. Phng php c hc

Phng php ny c dng loi b cc vt rn kch thc ln

bao gm nhng cht l lng v cc cht lng ng c bn cht v c hoc

hu c. tch cc ht l lng ra khi nc thi, thng ngi ta s dng

cc qu trnh thy c (gin on hay lin tc); lc qua song chn hoc li,

lng di tc dng ca lc trng trng hoc lc ly tm hay lc.

+ Lc qua song chn hoc li chn: y l bc x l s b nhm

kh tt c cc tp cht c th gy ra s c trong qu trnh vn hnh h thng

x l nc thi nh lm tc bm, ng ng hay knh dn.

+Lng: Qu trnh ny c dng loi b cc tp cht dng

huyn ph th ra khi nc. S lng ca cc ht xy ra di tc dng ca

trng lc. tin hnh qu trnh ny ngi ta thng dng cc loi b lng

khc nhau nh: b lng ct (cp I)-c nhim v tch cc cht rn hu c v

cc cht rn khc v b lng trong (cp II)- c nhim v tch bn sinh hc ra

khi nc thi.

4.2. Phng php ha l

+ ng t v keo t: Qu trnh lng ch c th tch c cc ht rn

huyn ph hp nhng khng th tch c cc cht gy nhim bn dng


12/21

keo v ha tan v chng l nhng ht rn c kch thc qu nh. tch cc

ht rn mt cch c hiu qu bng phng php lng cn tng kch thc

ca chng nh s tc ng tng h ca cc ht phn tn lin kt thnh tp

hp cc ht nhm tng tc lng ca chng. Vic kh cc ht keo rn bnglng trng lng i hi trc ht cn trung ha in tch ca chng, sau

lin kt chng vi nhau. Qu trnh trung ha in tch c gi l qu trnh

ng t, khc vi qu trnh keo t l qu trnh to thnh cc bng ln hn t

cc ht nh. Cc cht keo t thng dng l Al 2 (SO 4 ) 3 , FeCl 3 ,

+Tuyn ni: Phng php tuyn ni c s dng tch cc tp

cht phn tn khng tan, t lng km ra khi pha lng . Trong mt s trnghp, qu trnh ny dng tch cc cht ha tan nh cc cht hot ng b

mt. V nguyn tc, tuyn ni c s dng kh cc cht l lng v lm

c bn sinh hc. Qu trnh tuyn ni c thc hin bng cch sc cc bt

kh vo pha lng. Cc bt kh dnh bn vi cc ht v khi lc ni ca tp

hp bng kh v ht ln s ko ht ni ln b mt sau chng tp hp

li vi nhau thnh lp bt cha hm lng cc ht cao.

4.3. Phng php ho hc

Cc phng php ha hc dng trong x l nc thi gm c: trung

ha, xy ha kh. Phng php ny dng kh cc cht ha tan trong h

thng cp nc khp kn. i khi ,chng cn dng x l s b trc khi

x l sinh hc hay sau cng on ny, nh mt phng php x l nc thi

ln cui trc khi thi vo mi trng.+Phng php trung ho: Nc thi cha axit v c hoc kim cn

c trung ho a pH v khong 6,5-8,5 trc khi thi vo ngun nc

hoc cho cng ngh x l tip theo. Phng php trung ho c th thc hin

bng nhiu cch ph thuc vo th tch, nng nc thi, ch nc thi,


13/21

kh nng sn c v gi thnh ca tc nhn ho hc. Trong qu trnh trung

ho mt lng bn cn c to thnh. Lng bn ny ph thuc vo nng

v thnh phn ca nc thi cng nh loi v lng cc tc nhn s dng

cho qu trnh.

+ Phng php xy-ho kh: Phng php ny s dng cc cht xy

ho nh Cl dng kh v dng ho lng xy ho cc cht c hi trong

nc thi thnh cc cht t c hn v tch ra khi mi trng nc. Qu

trnh ny tiu tn mt lng ln tc nhn ho hc nn ch dng trong nhng

trng hp khng th dng cc phng php khc.

4.4. Phng php x l sinh hc

Phng php x l sinh hc c s dng lm sch nc thi

sinh hot cng nh nc thi sn xut khi nhiu cht hu c v mt s cht

v c nh H2S, cc sunft, amoniac, nit... Phng php ny da trn c s

s dng hot ng ca vi sinh vt phn hu cc cht hu c gy nhim

bn trong nc thi. u tin cc vi sinh vt c kh nng phn hu s b gy

cc i phn t hu c nh protin, xenluloza, tinh bt, cht bo, to thnhcc cht n gin hn. Cc cht ny tip tc c cc vi sinh vt khc phn

gii to thnh cc hp cht v c tan trong nc.Sau nhm vi sinh vt

chuyn ho c trng s loi b cc hp cht nh lu hunh,nit v c lin

kt. Ngi ta c th phn loi cc phng php sinh hc da trn cc c s

khc nhau. Song nhn chung c th chia chng thnh 2 loi chnh sau:

Phng php x l hiu kh v k kh.4.4.1. Phng php x l hiu kh

Qu trnh x l nc thi bng phng php hiu kh c th xy ra

iu kin t nhin hoc nhn to.Trong iu kin t nhin,qu trnh din ra


14/21

vi hiu sut thp v chm hn so vi qu trnh x l trong iu kin nhn

to.

Phng php ny li dng kh nng phn hu cc hp cht hu c

ca vi sinh vt hiu kh.Do trong iu kin nhn to, nng cao hiu

sut x l ngi ta b sung lin tc xy v duy tr nhit trong khong 20-

40o C.x l bng phng php hiu kh trong iu kin nhn to bao gm:

b thng kh sinh hc (b aeroten), lc sinh hc hoc a sinh hc.

+ X l trong cc aeroten: y nc thi c cho chy vo

b cha bn hot tnh, b ny lun c sc kh m bo lun bo ho

oxy v duy tr bn trng thi l lng . Khng kh c cp vo nc thi

bng cch nn kh qua b phn khuych tn ngp nc hay bng sc kh,

hoc dng khuy c hc thi khng kh vo cht lng.

+X l trong cc b sinh hc: y l thit b phn ng sinh hc

trong cc vi sinh vt sinh trng c nh trn mt lp mng bm trn vt

liu lc. Nc thi c phun t trn xung qua lp vt liu lc. b mt

mng lc, vi sinh vt hp th cht hu c v chng s dng oxy ho tantrong nc thi oxy ho cc cht hu c ca nc thi.

4.4.2. Phng php k kh:

Phng php k kh c dng x l nc thi nhim cht

hu c cao cng nh ln men bn cn sinh ra trong qu trnh x l bng

phng php sinh hc. y l phng php c in nht dng d n nh

cn trong cc vi khun ym kh phn hu cc cht hu c.

Tu vo loi sn phm cui cng m ngi ta phn loi qu

trnh ny thnh: ln men ru, ln men axt lactic, ln men metan...Nhng

sn phm cui cng ca qu trnh ln men l: cn, axt hu c, axeton, kh


15/21

(CO2, H2, CH4 ). S phn hu k kh cc cht nhim trong nc thi c th

gm ba pha: pha thu phn (axt ho), pha sinh axetat v pha sinh metan.

trc tin cc cht nhim c thu phn v to thnh cc axt bo hay hi

bi cc vi khun ym kh tu tin (vi khun sinh axt). Sau cc axt nyc vi khun sinh axetat bin i thnh axetat, CO2, H2 (bi vi khun sinh

axetat). Cui cng c axetat, CO2, H2, c vi khun sinh metan bin i

thnh metan.

Phn ng ca s to thnh metan xy ra nh sau:

CO2 + H2A CH4 + 4A + 2H2O (H2A l cht hydro)

Hoc:

CO + 3H2 CH4 + CO2 ; CO + 2H2O CH4

Hay c th c to thnh do phn gii axt axetic :

CH3COOH CH4 +CO2 ; CO2 +H2 CH4 + H2O ;

Qu trnh phn hu cht hu c trong iu kin ym kh c

minh ho trn hnh 1.

Cht hu c

CO2 H2 HOAc

CH4 CH4+CO2

1

2

Cht hu c

CO2

H2 HOAc

CH4

CH4+CO

2

2

Cht hu c

CO2

H2 HOAc

CH4 CH4+CO2

2a

R-COO-

2b

1 3


16/21

Hnh 1. Qu trnh phn hy cht hu c trong ln men mtan

1: Vi khun ln men

3: Cc vi khun axetic sinh hidro

R: Gc cacbuahidro

2: Vi khun sinh mtan

2a: Vi khun dinh dng hidro

2b: Vi khun dinh dng nitrat

Qu trnh sinh mtan nhn chung chu nh hng ca cc yu t nh:

nhit , pH, hm lng bn, mc khuy trn, iu kin ym kh v cc

nguyn t vi lng. Nhn chung nhit ti u cho qu trnh l 35 oC, pH thch

hp l pH trung tnh . Hm lng bn v mc khuy trn cng l yu t rt

quan trng quyt nh hiu qu x l. Thng thng hm lng bn t 7-9% l

ti u. ng thi qu trnh x l ny i hi iu kin k kh do vy s mtan

ha sinh hc phi c tin hnh trong b kn. Ngoi ra phi k n nh hng

ca dng vi khun, thi gian lu m bo hiu sut kh ca cht gy nhim

v iu kin khng cha ha cht c .

Da trn nguyn tc phn hy cht hu c trong iu kin ym kh, ngi

ta xy dng mt s h thng x l nc thi sau y

+ H ym kh.

+ H thng m bn k kh dng ln (UASB).

+ H thng UASB ci tin.

Trong h thng UASB, nc thi sau khi c iu chnh pH s c

bm t di ln qua lp m bn (to ra t cc bng hoc cc ht sinh khi hot

ng) bng bm nh lng. Hn hp bn ym kh trong h thng s hp thu cc

cht hu c ha tan trong nc thi, phn hy v chuyn ha chng. Kh sinh ra

cc ht bn chuyn ng lin tc v cc lp bn c trn u. Mt s ht

b ri ra khi lp bn nhng b mt by kh chng lng xung tr li lp bn.


17/21

Bn hot tnh l sinh khi, ng vai tr quyt nh i vi vic phn hy

v chuyn ha cht hu c. Trong m hnh ny bn c hnh thnh hai vng r

rt: b tnh t y ln, lp bn c hnh thnh do cc ht cn keo t nng

t 5-7%, pha trn lp ny l lp bn l lng nng t 1000 3000 mg/ltgm cc bng cn chuyn ng gia cc bn y v bn hot tnh t ngn y ri

xung. Trn b mt tip gip vi pha kh, nng bn trong nc l b nht.

Nng bn hot tnh cao cho php h thng lm vic vi ti trng cht hu c

cao. Nghin cu s phn b bn v vi sinh vt theo tng ca m hnh UASB thc

nghim cng cho bc tranh tng t. phn phn ng ca UASB vi chiu cao

l mt mt v chia lm bn phn (t di ln) th tng 1 hm lng bn l

25,79 27,38 g/l trong tng 2, 3 v 4 cc s liu tng ng l 21,98 23,54;

5,09 5,28; 0,12 0,13 g/l.

So vi x l hiu kh, x l nc thi nhim cht hu c bng phng

php phn gii k kh c nhng u vit hn th hin nhng c im sau:

+ Khng cn xi nh trong x l hiu kh nn chi ph nng lng thp.

+ Ch sinh ra mt lng nh bn d tha.

+ Thu hi c lng kh metan c gi tr s dng (70 80% tng lng

kh).

+ Kh nng kh COD cao.

Trn th gii, h thng UASB c s dng s l nc thi t vi thp

k nay v c hng trm c s s dng phng php ny s l cc loi nc

thi khc nhau.

Vit Nam c nhiu c s s dng m hnh ny kt hp vi phng

php s l hiu kh: nh my bia Vit Nam, nh my bia Cn Th, nh my


18/21

Vedan ( ng Nai), Cty cao su Long Thnh( ng Nai), song tt c h thng ny

cn nhiu vn cn gii quyt.

Trong my trm nm gn y, ti phng cng ngh To, Vin cng ngh

sinh hc Trung tm Khoa Hc T Nhin v Cng Ngh Quc Gia, cc nghin

cu s l nc thi cng nghip c tin hnh v thu c mt s kt qu

kh quan. Phng th nghim thc hin ti: nghin cu x l nc thi hu

c giu Nito v Pht pho thuc chng trnh trng im cp nh nc KC-04-

02. Nc thi ch bin thy sn l i tng nghin cu ca ti ny. y l

vn phc tp i hi nhiu nghin cu t c s phng th nghim n nhng

ng dng thc tin, t s l hiu kh n k kh v phi hp gia chng vi nhau.

Kt lun: Trong nhiu gii php x l nc thi c a ra cho n

nay, phng php cng ngh sinh hc c nh gi cao nht vi chi ph r v

hiu qu. Phn cp, phn quyn trong qun l l vn then cht, song cn c s

phi hp cht ch hn na gia Nh nc, cc nh khoa hc v cc doanh nghip

gii quyt nhng tn ti v nh hng cho tng lai trong cng tc qun l v

bo v mi trng sn xut thu sn, hng ti s pht trin bn vng.5. Phn tch im mnh im yu ca phng php la chn

Kt qu phn hng c s cng nghip theo cc tiu ch bo v mi trng

ca ngnh Ch bin thy sn

Bc u nh gi mc nhim v tnh tun th ca 20 nh my

thuc ngnh ny da trn 8 tiu ch bo v mi trng, kt qu cho thy (hnh 1):

Mc mu sc c trng cho mi trng tp trung mt s mc c th nh

sau: km (en), t (nu) v kh (xanh da tri). Hin cha c c s t tt (xanh

l cy), xut sc (vng) v cha t ().


19/21

Trong 03 mc t c ca ngnh ch bin thu sn, mu nu chim t l

kh cao (60%), con s ny cho thy tnh hnh mi trng v cc bin php bo v

mi trng ca ngnh ang mc trung bnh. S lng c s thuc mc kh

rt t, chim 15%, y l nhng c s sn xut kh n nh, cng ngh tin tinv c ch trng n cng tc bo v mi trng.

Trong s 25% cc nh my c xp hng km, phn ln l cc c s cn

xen ln trong khu dn c cha c quy hoch. Mc d sn xut n nh, thay

i cng ngh, song nhim mi trng nh hng n dn c l iu khng th

trnh khi.

* nh gi theo tng tiu ch, ngnh Ch bin thu sn c nh gi

nh sau:

Kt qu quan trc ca mi nh my trong vng 02 nm tr li y c

s dng nh gi tiu ch 1. Kt qu phn tch cho thy, 90% nh my khng

t TCVN (5945-1995, B) i vi nc thi sau h thng x l.

iu nay cho thy, cht nhim ca ngnh Ch bin thu sn rt c th,

mc tc ng v mt mi trng n cc khu vc xung quanh l kh cao mc d

mt s nh my c h thng x l nc thi hon chnh. Kt qu quan trc nc

thi sau h thng x l ca cc nh my thuc ngnh trong mt vi nm tr li

y cho thy, hm lng BOD5, COD cn mc kh cao, mc vt TCVN

i vi 02 thng s ny t 1 - 35 ln. Cc ch tiu khc nh SS, N tng c vt

tiu chun quy nh nhng khng ng k.

y l ngnh c nhiu nhy cm v mi trng bi mc nhim ca

nc thi v c th ca mi hi, do lun c cng ng quan tm. T nm

1999 n nay, c 12 c s c khiu ni t pha cng ng, trong c 7 c s b

x pht hnh chnh t nht l 01 ln, c 02 c s b x pht 2 ln, l X nghip


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Ch bin thu sn Ho Cng v X nghip Ch bin thu c sn s 10. S can

thip ca cng ng ch yu l vn nc thi v mi hi. Nc thi ca mt

s nh my b khiu kin nm trong khu vc dn c, gy nh hng trc tip

n hot ng dn sinh ca con ngi.

Hnh 1

S c mi trng khng xy ra i vi ngnh Ch bin thu sn trong vi

nm tr li y. y cng chnh l kt qu ca vic bc u p dng cc cng

ngh x l nu trn, v c bit l vic p dng cng ngh sinh hc trong vic x

l nc thi. Nh vy cng vi vic khc phc nhng yu im ca ngnh cho

thy s ti u cng nh u im vt tri ca cng ngh x l nc thi vi

ngnh, c trc mt cng nh lu di.

6.Gii php pht trin cng ngh trong khu vc:

a. Lng ghp cc yu t mi trng vo quy hoch pht trin thu sn;


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b. Nghin cu nh gi nhim trong NTTS t la chn cc

phng php x l nc thi ph hp

c. Ti cc c s ch bin thu sn t nhn, do kinh ph hn hp nn khu

x l nc thi thng b b qua. V vy cc c quan qun l phi thng xuyn

kim tra, hng dn ngi sn xut nhng phng php x l nc thi, nhm

bo v mi trng.

An ninh sinh thi l vn quan trng hng u trong bo v mi trng.

Vit Nam cn pht huy li th ca ngi i sau trong pht trin nui nh gi

tc ng mi trng.

Cong Nghe Xu Ly Nc Thai Trong Che Bien Thuy San

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