NGHIEN
CAU
AP DUNG
KIEM
TOAN CHAT THAI
TAI
XI NGHIEP CHE
BIEN
THUY DAC SAN XUAT
KHAU
HANOI
Nguyen Thi Ha, Bui Thi Luan
Khoa
Moi
trudng,
TrUdng
DHKHTN,
BHQGHN
TOM TAT
Kiem toan moi trUdng noi chung va Kiem toan chat thai cong
nghiep ndi rieng la mot cong cu quan
ly
mdi dUdc ap dung d nUdc ta
trong mot vai nam gan day. Mac du day la cong cu mdi
nhung
qua cac
ket qua ap dung kiem toan tai nhieu cd sd san xuat cho thay cong cu
nay mang
lai Idi
ich kbong
nbd

can
b^ng
chat thai
r^n.
3) Xac dinh cac khau gay
lang
phi
nUdc
va cac nguon gay 6 nhiem
moi trUdng.
4) Xem xet, danh gia cac
phUdng
an
xii
ly, giam tbieu lang phi nUdc
cua
xi
nghiep,
63
5) De xuat cac giai phap c6 tinb kha thi
nh^m
tiet kiem nUdc,
giam CTR, xii ly nUdc thai
nh^m
cai thien moi trUdng va tang
cUdng
hieu qua kinh te cho xi nghiep.
I. KIEM TOAN CHAT THAI CONG NGHIEP
Kiem toan chat thai la mot
loai

ciiu
dUdc thUc hien tai xi nghiep
sau hdn 4 thang khao sat hien trang va tinb toan
thUc
hien cac budc
kiem toan vdi trong tam kiem toan la day chuyen che bien torn va 2
chat thai chinh la nUdc thai va chat thai
r^n.
II.
CAC VAN
Dfi
MOI
TRU6NG
CUA NGANH
CH^
BIEN
THUY SAN
Qua trinb san xuat che bien thuy san c6 anh hudng
Idn
tdi moi
trUdng dac biet la moi trUdng nUdc va moi trUdng khong khi.
Kbong
kbi
trong cac khu vUc san
xu^'t
va khong khi xung quanh
thUdng cbiu tac dong cua cac yeu to gay
6
nbiim
nhu

tom; noi tang cac loai ca,
mUc;
mai mUc; ong mUc; xUdng. vay, vay ca Day la cac chat giau chat
hiiu cd de
phto
buy sinh hoc c6 tiem nang gay
6
nhiem moi trUdng neu
khong cd bien phap thu gom,
xcL
\i kip tbdi se anh hUdng dang ke den
moi
trUdng
va
sxic
khoe con ngUdi.
Van de dang quan tam hdn ca trong san xuat che bien thuy san
la van de
suf
dung nUdc va nUdc thai. Qua trinh che bien can mot
lUdng
nUdc tUdng do'i
Idn.
Nudc thai che bien thuy san cd ham
lUdng
cac chat
ran, cac chat
huEu
cd de phan buy sinh hoc cao. Cac chat nay ton tai
trong nUdc d dang keo, dang boa tan, dang phan tan min lam cho

che
bien van de moi trUdng
cung da dUdc quan tam. Xi nghiep c6 ba cong nhan chuyen quet don
va thu gom do chat thai ran (khu
vUc
xung quanh xi nghiep) va chat
thai ran san xuat. Cong tac ve sinh moi trUdng da dUdc xi nghiep
tbUc
hien mot
each
nghiem tuc.
3.1.
Nguyen nhien lieu,
nvtdc
va hoa chat
sxi
dung
Nguyen,
nhien lieu
Nguyen lieu chinh
ciia
xi nghiep la tom,
mUc,
ca cac loai dUdc thu
mua
tiif
cac vung khac
nhau
nhU: Quang Ninb, Hai Phong, Thai Binh,
Thanh Hoa, Nghe An, Ha Tinb. Trung binh moi nam xi nghiep thu

171,9
23,7
498,3
700 000
400
[Nguon: Phong Ke toan Tai
chinh
cua xi nghiep F. 37]
Hod chat
Hoa chat
svL
dung chu yeu la chlorin vdi khoi
lUdng
khoang 30 kg/
nam. Chlorin
diing kbit
trung nguyen vat lieu, dung cu thiet bi, tiep
xuc vdi san pham, ngan chan
su
phat trien cua vi sinh vat va khong
lam anh hudng tdi chat
lUdng
san pham. Ngoai chlorin xi nghiep con
dung
H2O2
de ngam va tay
tr^ng mUc
tuy nhien
lUdng
dung khong

lUdng
nude khai thac trong mot nam c6 the Udc tinb
nhu d bang 2.
Bang 2-
Li^tfng nUdc suf
dung cho cac muc dich khac nhau trong
Xi nghiep
STT
1'
2
3
4
5
Loai nvtdc
svt
dung
Nude
sinh boat
Nude
san xuat da
Nude
ve sinh cong nghiep
Nude
cho cac cong doan san xuat
Tong
hxidng (m^/nam)
3120
1000
1348
25732

vkn
de xac dinh
lUdng
chat thai di vao dong thai;
(4) Tinb toan chi phi cho viec
sii
dung nUdc vUdt dinh mvic va dUa ra
cac bien phap
nhim
tiet kiem nUdc cho xi nghiep; (5) De xuat giai
phap tiet kiem nUdc sii dung, giam thieu
lUdng
nUdc thai va xii ly nUdc
thai d cong doan cd dac tinb 6 nhiem cao.
67
Nudc
da—>
Nudc
da—•
Nude—•
Da_>
Nude—•
Da->
Nudc—^
Nudc—•
Thiing->
carton
Nang
lUdng—^
Ngu3'en

May do kim loai
i
Bao goi, dong tbung carton
i
Bao quan kho lanh
—•Nudc thai
.
Nudc thai,
CTR
—•Nudc thai
Nudc thai,
nhat tap chat
—•Nude thai
—•Nudc thai
Nude thai,
bao bi thai bd
^
Thiing
phe thai
Hinh 1: Quy trinh cong nghe che bien
68
3.3 Tinh toan can
b^ng
nxidc
va chat thai ran
Binh
mite ni/dc sti
dung
Nham dap
ling

trong qud trinh san xuat tom
* Ludng nude
sii
dung trong cac cong doan san xuat:
Ta
so' lieu bang 2, ta thay rang
lUdng
nUdc dung trong cac cong
doan san xuat la
25.732m2/nam.
Theo bo phan
ki
thuat cua xi nghiep
ti le
sii dung nUdc so
sanh
vdi dinh
mdc
de san
xu^'t
1 TNL torn,
mUc,
ca trong thUc te tUdng iing la 2: 3: 3.
Tii
ti le nay va can
cii
vao
lUdng
nguyen lieu thu mua moi loai nam 2002 c6 tong so' phan
nUdc

smh
nha xUdng) cho 1 TNL
(tom) la:
43,18 + 2,7
= 45,88
m^
69
Nhu
vay
lUdng
nUdc
sii
dung vUdt dinh
miic
tinh tren
1 TNL
doi
vdi
nguyen
heu
dau
vao
la tom rat
Idn
(gap
hdn
2-3
Ian),
tUdng iing
la:

dUdc
cbi
ra d
bang
3.
Bang
3:
Lifdng nUdc suf
dung
va
nifdc
thai trong
cac cong doan
san
xuat
TT
1
2
3
4
5
6
7
8
Cong doan che bien
Tiep nhan nguyen
lieu,
riia,
bao quan
Sd che nguyen lieu

(m^/TNL)
3,54+
Aw
34,6+ Aw
1,75+Aw
0,25±
Aw
2,l±Aw
1,717+Aw
43,975±Aw
(*)Ghi
ehu:
A^
-
LUdng nLf6c chenh
lech do that thoat (bay hoi,
ng^'m, )
hoac do con
lai tii
cong doan
trxidc
^WT{*)"
^^^^ Lutdng nUdc
chenh lech do that thoat (bay hdi, ngam, ) hoac do con
lai
tCt
cong doan
trU6c
70
Trong cac cong doan

da sU dung cua xi
ngbiep vdi
torn la: 2 tan/TNL. NhU
vay
CO
the thay
lUdng
da
sii
dung trong cae eong doan la
phii
hdp vdi
dinh
mile
dat ra.
TU
cac ket qua tinh toan tren ta c6 the dUa ra sd do can bang nUdc
nhu trong hinh 2.
Nguyen nhan dan den
sii
dung
ni/dc vUOt
dinh
mdc
Cac ket qua tinh toan can bang nUdc ket hdp vdi qua trinh khao
sat eac dieu kien san xuat trong xi nghiep. nguyen nhan dan den
lUdng
nUde
sii
dung vUdt hdn nhieu so vdi dinh

moi
cong doan doi khi tuy thuoc vao loai nguyen lieu,
miJc
do saeh.
ban
eiia
nguyen
lieu,
ma
lUdng
nUdc dinb
mdc
c6 the thay doi, va
khi
do rat kho xac dinh
lUdng
nUdc
sii
dung do viec thay nUdc phu thuoe
vao mau
nUdc
va
mUe
do cam quan cua ngUdi eong nhan.
- Xi ngbiep ebUa c6 dong ho do
nUde
eho
ttfng
eong doan san xuat
do do

Nude:
3.04m-
Da: 0.5 tan
2,lm;i+0,123m;!
Nudc
0,9mH0.817m'^
Tom nguyen lieu: 1000kg
Tie]D
nhan nguyen lieu
Rua
Ian
1
Bao quan
Nirdc:
33,6m'^
Da: 1 tan
NUdc:
l,5m^
Da: 0,25 tan
Da: 0,25 tan
Nudc:
—•
Nudc thai
3,04
±
Aw(m-J)
Da: 0,5 tan
^ V Nudc
thai:
3,36±

1,777
±
Aw(m'^)
Bao goi carton
Bao quan
Hinh 2:
Sd
do can
b^ng
nUdc
trong qua trinh san xuat torn
72
Can bang chat thai ran trong qud trinh che bien tom
* Qua ket qua theo doi cua bo phan ky thuat
ciia
xi
nghiej)
cho thay:
- 1000 kg
nguyen lieu
(XL) dau vao sau khi
ciua
sd che khoi ludng
BTP
thu dUdc trung
binh
la 500 kg. Khdi ludng phe thai thu dude la
470 kg.
Nhu vay
lUdng phe

trong eac eong doan nay la: Phe thai ran di vao dong
thai
long
=
BTP
-TP
=
500 - 490
-
10kg.
Tii
ket
(jua
tren ta
eo
sd do can bang chat thai ran nhU sau (hinh 3):
Tom
nguyen lieu 1000kg
Xiily
Phe
thai ran
Ihu
gom: 470kg
Phe
thai
r^n
di
vao dong
thai:
30kg

nguyen nhan lam cho nude
thai
che
bien
thuy san
noi
chung
bi
o
nhi6m
cac chat
hUu
cd nang. Oo do
e^n
phai c6 bien phap nham han
ehe
tdi
da
lUdng
phe
thai
nay. Co nhU vay mdi lam giam
dvrdc
nong do
cac chat 6
nhiom
trong nude thai.
3.4.
Tinh chi phi do viec
suf

nUde
v6i tong nang
lUdng tieu
thu la:
(1) May hut nudc
tiT gicng
Ion:
7.5kW/h x 12h/ngay x 71 ngay/nam =
6390 kW/nam
(2) May bdm
Idn;
3.7 kW/h x
4h/ngay
x 71ngay/nam
=
1051 kW/nam
(3) May bdm nhd: 1.5 kW/h x 8h/ngay x 71 ngay/nam
=
852 kW/nam.
Tong = 8293
(kW/nam)
Chi phi cho
sii
dung nUdc vUdt dinh
mde
tinh theo
gia
dien trung
binh la 1000 dong/kW. NhU vay chi
phi

chi
phi
xii
ly
nUdc
thai,
chi
phi cho eae van do
moi
trUdng phat sinh do
nUde
thai kbong dap
ling
dUoe cac yeu cau ve
nUdc thai
ebo phep theo TCVN 5945 - 1995.
3.5.
De xuat cac
phiicfng
an giam thieu va
xi
ly
nUdc
thai
Qua ket qua phan tich nUdc
thai
trUdc va sau
xii
ly
ciia

chuan hien hanh (xem bang 4).
TT
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Bang 4. Ket qua phan
Thong so
Nhiet do
pH
COD
BOD
SS
Ve
Pb
As
Cd

ni/dc
thai tai x
TCVN
5945-1945
(Loai B)
40
5,5-9
100
50
100
5
0,5
0,1
0,02
1
10
1
60
6
0,005
0,5
10.000
TCVN
6984-2001
(Q<50m3/
s,Fi)
—
6-8,5
60
30

60,2
9,21
0,002
12.000
Nifdc
thai sau
xijf
ly
24,8
7,8
1449
811
36
0,25
0,01
<0,01
0,001
0,65
24,5
0,11
51,59
9,56
< 0,002
0,33
14000
Nguon; [Bao cao danh gia tac dong moi trUdng Xi nghiep F. 37, 20031
Qua cac ket qua tren thay
r^ng
van de moi trUdng dang quan tam
hang dau trong xi nghiep la van de moi trUdng nUdc. Vdi viec

- Nang cao y
thdc
tiet kiem nUde va tay nghe cua cong nhan.
- Dua ra cac bang dinh
mijfc
nUdc
s^
dung cho
tCfng
cong doan che
bien va cac so' gia thich hdp vdi moi loai nguyen lieu de tiet kien nUdc
va dam bao chat
lUdng
san pham.
- Han ehe
lUdng
nUdc
sii
dung trong cong doan sd che nguyen lieu:
(1) Thay dung
nUde
bang vdi sang diing nUdc bang chau hoac c6 the
lap he tbo'ng vdi c6 te bao quang tU
ngat
khi khong sii dung; (2) Trong
qua trinh sd ehe nguyen lieu
c^n
tach ngay phe thai ra khdi chau nUdc
riia. Khong bo phe thai vao chau nUdc ma
chi

dung may bdm
ap luc de tang hieu qua lam sach.
Lap
dat cac van khoa nudc tai dau
cac 6'ng
nhua
mem
diing
de ve sinh thiet bi, nha xudng.
- Nudc
t\i
cong doan tach khuon va ma bang gan nhu la nUdc sach
boan toan do do
c^n
xay dUng be thu hoi nudc trong cong doan nay de
sii
dung cho eac muc dich khac yeu
cdu
chat
lUdng
nudc kem hdn nhU
dung de
riia l4n
1, lam nUdc nhung ung hay thu hoi nudc nay de lam
ve sinh c6ng nghiep. Ludng nudc dung de tai su dung nay khoang
1,717
m^/TNL.
NhU vay
lUdng
nUdc tiet kiem dudc trong mot nam se

toi da kinh phi cho
xii
ly nUdc thai
cbiing
tdi de xuat ra bien phap cai tao lai he tbo'ng xii ly
nUde
thai nhU sau;
Nudc thai sau khi qua be xii li ye'm khi eiia xi nghiep c6 cae tb6ng
so dau ra nbu nhiet do la 24,
8^C,
pH=
7,8, ty le BOD: N: P khoang
100:
5: 1. Day la dieu kien rat thich hdp cho qua trinh xii li hieu khi
thdng
qua be Aeroten [TranVan Nhan, 1999] hieu suat xii li eiia be Udc
tinb khoang 85- 95%. Nhu vay, nUdc thai
d^u
ra se e6 ham
lUdng
cac
chat
hflu
cd phii hdp
vdi
tieu chuan TCVN 5945- 1995 loai B. Nudc thai
tiep tuc dUdc dUa qua be lang 2 de loai bd cac chat ran
Id liing
tao
thanh sau qua trinb xii ly hieu khi. Tai day mot

Be Aeroten
Biin tuan hoan Cap khi
Hinh 4.
Stf
do he thong
xu"
ly
nUdc
thai de xuat cho Xi nghiep F.37
77
Cac thong so' ciia he thong
xii
ly nvtdc thai nang cap
* Tinh toan the tich cac be can xay dUng:
a. Be Aeroten
The tich be Aeroten tinh
b^ng
cong
thufc
[Trinh Xuan Lai, 2000]:
V
=
Qxt
trong do, V la the tich be
(m^)
Q la
luu lUdng
nUdc thai (
m^I
h)

Tii
cac
so'
lieu dUa ra d bang 2 ta c6 tong
lUdng
nUdc diing cho san
xuat ciia Xi nghiep (gom nUdc diing trong cac cong doan san xuat, nUdc
san xuat da, nUdc ve sinh cong nghiep) la
28.080m3/nam.
Trung binh
so ngay san xuat trong nam la 200 ngay. NhU vay,
khoi lUdng
nudc
sii
dung trong mot ngay boat dong san
xu^'t
la:
28080m3:
200 ngay =
140,5
m3/ngay
(5,85m3/h).
Nong do BOD ra khdi be xii li ye'm kbi la:
SQ
=
811mg/l
Nudc thai
d^u
ra theo de xuat la:
Sc =

lang 2 va
the
tich
bekhiC
triing [Trinh Xudn Lai, 2000]:
Cong
thiic
tinh the tich be lang 2 va be khii triing la tUdng tU
nhau do do se tinh toan the tich cho be lang 2.
Dien tich mat
b^ng
cua be lang 2 dUdc tinh theo cong
thiic:
Q{l + a)-C„
s=
c,.v,
Q la
lUu lUdng
nUdc thai can xii li
(m^/b)
^
la he
so'tuan
hoan
(thUdng
c6 gia tri 0,25
-H
1)
Co
nong do

-
0,6; Co
=
3400mg/l ta tinh dUdc dien tich mat
b^ng
ciia be
l^ng
la: S
=
9,36
m2
Chieu cao cua be
l^ng
ddt 2 (h) thUdng
tii
3,7 - 6,1m, do do
neu lay b = 4 m ta c6
th^
tich be
idng
can xay dUng la: V
=
S
X
h
=9,36 X
4 = 37,5
m^
The
tich

nguyen nUdc mat. Ngoai ra muc dich
xii
li nUde thai khong chi
dCfng
d
viec
de nUdc thai dau ra dat tieu
chu4n
xa thai. LUdng nUdc nay con
CO
the tuan hoan
tai
sU dung de diing eho cac cong doan c6 yeu
c&u
ehat
lUdng nUdc
khong cao nhu qua trinh ve sinh cong nghiep.
Dieu
nay c6 the
giiip tiet
kiem khoang
1348m-Vnam
tUdng dUdng vdi
so'tien
la 729.000d6ng/nam
Ngoai ra nUdc thai
tiep
nhan nguyen lieu va nUde thai trong eac
cong doan ehe bien nen tach rieng va
xii

ling
dUde
cac tieu chuan moi trUdng TCVN 5945 - 1995 loai B va
TCVN 6984 - 2001( Q<50
m3/s,
Fl).
Cac thong so
6 nhilm
con cao
80
hdn tieu chuan cho phep: BOD vUdt tieu
chuanl6
Ian,
COD vUdt
14
Ian,
dau md dong tbUc vat vUdt 2,5
Ian,
pho'tpho tong
so'vUdt
1,6
Ian,
va coliform vUdt 1,4
Ian.
4) Xi ngbiep da ap dung dinb
mdc sii
dung tuy nhien viec tbUc
hien con chUa dUdc triet de va thieu dong bo trong tat ca cac cong
doan. Do do,
lUdng

126 tneu dong va hieu qua
kinh
te la khoang
729.000d6ng/na.m.
TAI LIEU THAM KHAO
1) Bao cao DTM. Xi nghiep Che bien Thuy dac san xuat khau
Ha Noi, 3-
2003.
2) Dang Xuan Toan, Tran
ling
Long.
Hudng
dan kiem toan giam
thieu chat thai cong nghiep, Ha Noi, 1999.
3) Hoang Thi Trung Hieu. Nghien
ct2u xii
li chat ran
Id
liing
trong
niidc
thai
che
bien Thuy san bang
phitdng
phap keo tu.
Khoa luan tot nghiep khoa moi trUdng, 2002.
4)
Tr^n Diic
Ha.