Nghiên cứu áp dụng kiểm toán chất thải tại xí nghiệp chế biến thủy đặc sản xuất khẩu Hà Nội

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

ca ve moi trUdng va hieu qua kinh te.
Trong cong trinb nay chung toi tien hanh nghien
ciiu
ap dung kiem
toan chat thai tai xi nghiep Che bien Tbuy dac san xuat khau Ha Noi
(F37) vdi muc dich ap dung cong cu kiem toan vao viec giam tbieu chat
thai tai xi nghiep
nbim
tim ra
nhiing
khau ton that
nUdc,
nguyen lieu
de tix do
diia
ra nhiing phUdng an cho'ng that thoat, giam tbieu chat
thai,
tang hieu qua cua qua trinb san xuat, dong tbdi cai thien chat
lUdng
moi trUdng cho xi nghiep va nang cao hieu qua kinh te trong san
xuat kinh doanh. Cac noi dung cu the dudi day se dUdc nghien
ciiu:
1) Tim hieu day chuyen cong nghe che bien,
miJtc
do tieu thu
nUdc,
nguyen lieu va cac chat thai phat sinh.
2) Tinb toan can
b^ng
nUdc,

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

hinh cua KTMT la cong cu c6 gia
tri de cac doanh nghiep kiem tra lai kha nang tuan thu cac tieu chuan
moi trUdng, giam cac vi pham ve moi trUdng, giam thieu chat
thai
va
tang cUdng kha nang quan ly moi trUdng.
Kiem toan chat thai la
budc
d^u
tien de giam chat thai va ciing
lam giam
6
nhiem moi trUdng. N6 la qua trinb kiem tra khach quan
cac qua trinh san xuat va chat thai
nh4m
muc dich giam nguon thai
tang
s\i
dung lai boac loai bo boan toan chat thai. Qua kiem toan cac
phUdng an giam thieu chat thai dUdc nhan dang, dUdc danh gia, dUdc
lUa
ebon,
dUdc thUc hien va dUdc giam sat.
Viec
thUc
hien kiem toan giam thieu chat thai cho xi nghiep F37
dUdc thUc hien theo hudng
d^n
gom 9 bUdc theo 3 giai doan [Trinb Thi
Thanh, Nguyen Thi Ha, 2003]. Nghien

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

mui hoi thoi, mui
tanh, khi
HgS,
boa chat nhu
clo,
mercaptan, ure do qua trinh phan
buy cac chat c6 trong nUdc thai va phe thai
r4n
thai trong qua trinh
san xuat. Ngoai ra trong qua trinh san xuat che bien con
su(
dung pho
bien cac thiet bi
lanb
de duy tri boat dong cua cac may nen
lanh
va
day
CO
the la nguon gay
6
nbiim moi trUdng khong khi (khi
NHg,
freon, )
64
Khdi lUdng
chat thai ran thai bd trong qua trinh san xuat la rat
Idn
bao gom cac thanh phan nhU: dau;
v6

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

nude
thai
c6 mau va do
due
Idn.
Qua trinh phan buy cac chat nay trong nUdc
tao ra cac miii khd chiu va doc hai. Ngoai ra nUdc thai con c6 mat cac
boa chat
khii
trung nhU clo,
javen;
cac chat tay
riia,
chat boat dong be
mat dung trong hoat dong ve sinh nha xUdng.
Hien nay van de moi trUdng mdi dUdc quan tam trong eac cd sd
che bien c6 quy mo
Idn.
Con lai trong hau bet cac cd sd che bien c6 quy
mo
viia
va nhd van de moi trUdng con it dUdc quan tam.
III.
KET QUA KIEM TOAN CHAT THAI
Nhin chung moi trUdng trong xi nghiep
luon
dUdc
giiJ
thong
thoang va sach se. Trong khu vUc san xuat

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

65
mua khoang 450 tan nguyen lieu,
lUdng
nguyen lieu mdi loai thay doi
theo
tiing
nam va phu thuoc vao tbdi tiet. Nguyen lieu thu mua trong
nam 2002 dUdc chi ra trong bang sau.
Bang 1 -
Li^dng
nguyen lieu thu mua trong nam 2002
STT
1
2
3
4
5
6
Nguyen, nhien lieu
sijf
dung
Tom cac loai (Tan/nam)
Muc (Tan/nam)
Ca cac loai (Tan/nam)
Tong nguyen lieu (Tan/nam)
Dien (kWh)
Dau DO (Lit)
So
litdng
302,7

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

dang ke.
Ni/dc
Nguon
nude sii
dung cua xi nghiep la nUdc gieng khoan da qua he
thong
xd li
bao gom:
Nude'diing
cho sinh hoat, nUdc dung cho san
xuat da, nUdc diing ve sinh nha xudng va nUdc dung cho cac cong
doan san xuat.
Hien nay trong tat ca cac cong doan san xuat cua xi nghiep deu
chua
lap dong ho do nudc do d6 viec tinb toan
lUdng
nUdc sd dung
chi
mang tinb chat tUdng do'i. Xi nghiep c6 hai may bdm:
66
* May bdm cong suat 30 m /b lam viec trung binh 4h/ngay.
* May bdm cong suat 12m /h lam viec trung binh 8h/ ngay.
Tong
ludng nUdc
bdm trong mot ngay la: 30 x 4 + 12 x 8 = 216
(m'^),
tinb trung binh trong mot nam tong
so'ngay
lam viec cua xi nghiep
la 200 ngay do do

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

31200
3.2.
Qui trinh cong nghe che bien
Cac loai san pham torn,
mUc,
ca dong lanh deu dUdc
che
bien theo
quy trinh chung nbu d hinh 1. Tuy nhien, tuy theo loai san pham ma
cd the bdt di mot boac mot
so*
cong doan.
Tren cd sd tbdi gian nghien
cdu
tai xi nghiep, quy trinh che bien
torn thit dong lanh dUdc
lUa
chon la doi tUdng cho kiem toan vdi trong
tam kiem toan la moi trUdng nUdc bao gom cac noi dung sau: (1) Tinb
toan
lUdng
nUdc thUc te sxi dung; (2) Tinb toan can
b§ng nUdc
cho qui
trinh
che
bien tom de xac dinh cac khau gay that thoat nUdc; (3) Tinb
can
b^ng
chat thai

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

lieu: Tom. mUc, ca
i
Tiep nhan,
rda
nguyen lieu,
bao quan.
1
Xiily
+
Riia Ian
2
1
Nhat tap chat
+
Rua Ian
3
1
Phan cd hang
i
Riia Ian
4
i
De rao nUdc, can, xep
khuon
i
Chd cap dong
i
Tach khuon, ma bang,
dong tui PE
i

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

cac yeu cau ve ve sinh thUc pham, hien nay xi
nghiep dang tien hanh san xuat theo mot
so'tieu
chuan kiem soat chat
lUdng
thuy san nhu GMP (He thong san xuat to't), HACCP (He thong
phan tich rui ro va kiem soat gia tri tdi ban). De thUc hien tot cac tieu
chuan tren dong tbdi nham giam cbi phi cho san xuat xi nghiep da dUa
ra dinh
mute
nUdc sii dung cho nguyen lieu torn nhU sau;
Tom cac loai: 20
m^/TNL;
Dinh miic da
sii
dung la 2 tan da/TNL
Tuy nhien, dinh miic xi nghiep dUa ra mdi
chi
dUdc thUc hien
trong mot so' cong doan con trong thUc te
lUdng
nUde
sii
dung cua xi
nghiep cao hdn dinh
miic
r^'t
nhieu.
Can bang
nitdc

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

sii
dung la:
(302,5 tan tom x 2) + (171,9 tan
mUc X
3) + (23,7 tan ca x 3)
=
1192,2 (phan).
LUdng nUdc dung cho qui trinh che bien tom:
Wt5^
= 25732 : 1191,8 x 2
^
43,18
(m^)
*
LUdng
nUdc
diing
de ve sinh nha
xudng
(nam 2002):
LUdng
nUdc dung de ve sinh nha xUdng:
1348m3
: 498,3 TNL
=
2.7
(mWNL)
Vi vay, tong
lUdng
nUdc sii dung (gom ve

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:

45,88
- 20 =
25,88
m^/TNL.
Nhu
vay
tong
lUdng
nUdc
sd
dung
vUdt
dinh
mdc
nam
2002
(W^^^j^)
la:
WvDM(tdm) =
25,88m3/TNL
x
302,5TNL/nam = 7828,7m3/nam
Can
b^ng
nUde
dUdc tinh toan
cho
tufng
cong doan,
cac ket qua

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

Rijta Ian
2, nhat tap
chat
Phan cd bang
Ru[a Ian
3, de rao, can
Xep khuon
Tach khuon, ma bang,
dong PE
Tong
Dau
Nxidc
(m^/TNL)
3,04
33,6
1,5
2,1
0,123
1,717
42,08
vao
Da
(Tan/TNL)
0,5
1
0,25
0,25
2,0
Nvidc
thai

(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

eiia
qui trinh
che
bien tom
chi
c6 cong
doan xep khuon la
nUdc
dUdc di vao san pham con
lai
tat ca cac
cong doan khac nUdc va nUde da tan deu theo eac mang thoat nUdc
thai ra ngoai. Ngoai ra trong qua trinh san xuat con mot
lUdng
nUde bi that thoat do bay
hdi,
do tham vao san nha va eac dung eu
thiet bi. Do d6 qua so lieu tong ket d bang 3.
tren thUe
te
lUdng
nudc
thai
ra la:
Wj^^
=
43,795± AWT(*)
(m'VTNL).
Dinb
mde

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

mUc
la do:
- Nudc dUdc
sii
dung ehUa hdp ly cho cong doan sd che nguyen lieu.
Trong cong doan nay torn dUde boe v6, bd dau, rut ruot dUdi vdi nUdc
ehay nhe. Tuy nhien qua thuc
te
nhan thay khong
phai luc
nao cong
nhan ciing de tay dUdi
voi
nUde. NhU vay se c6
nln2ng
khoang tbdi gian
nUdc
ehay ma khong dUdc
sii
dung do do se gay lang phi rat nhieu
nUdc.
- Xi nghiep mdi ap dung dinh miic nUdc
sii
dung trong mot so eong
doan nhu
riia
nguyen
lieu,
ban thanh pham, xep khuon. Tuy nhien, do
d

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

chUa
xac dinh dUdc chinh xac
lUdng
nUdc sii dung cho tiing eong
doan la bao nhieu, cong doan nao
vUdt
hdn so vdi dinb
mdc.
71
- Mot so van nUdc.
moi
noi bi hu hong lam nude bi ro. that thoat
ra ngoai.
- Y
thUc tiet kiem nUdc eiia
cong nhan
cbUa
cao.
- Ngoai ra
viee
dung 6'ng nhUa mem de ve
sinh
thiet bi nha
xudng,
ve sinh cac dung cu san xuat nhU thiing
difng
nguyen lieu, ro ra, thau
chau cung la nguyen nhan lam tang
lUdng
nUdc sU dung.

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±

A^
(m-)
S'^i
ehe nguyen lieu
|Nudc
da tan: 1.5+
A\v
Nude
thai:
1,5±
A^y
(m*')
Riia lim
2, nhat tap chat [Nudc
"dd
ta"nro"25±2?u,
Phan cd hang
Rua
Ian
3,
de rao, can,
xep khuon
Nude thai
2,1
±
Awta'O
Chd dong, cap dong.
tach khuon, ma bang,
dong PE
Nude thai

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

thai ran di vao dong thai trong eong doan
na>-
la:
Phe thai ran
di
vao dung
thai -
NL - BTP - Phe
thai
ran thu gom.
= 1000 kg- 500kg -
470
kg
=
30 kg
500 kg BTP sau
khi (lua
cae cong doan
riia Ian
2, nhat tap
chat,
phan cd
bang,
riia
kin 3 de tao den thanh pham (TP) cudi cung trung
binh cd kbo'i
lUdng
la 490 kg LUdng phe
thai
ran di vao dong thai long

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

BTF:
500kg
1
RUa. nhat tap chat
phan cd hang
I
Phe thai
r^n
di vao dong
thai:
10kg
Thanh pham 490kg
Hinh 3: Sd do can bang chat thai ran
Tu!
sd do can bang chat thai ran ta thay tong
lUdng phe
thai di vao
dong thai trong qua
trinh
san xuat torn la: 30 + 10
=
40 (kg/TNL)
73
LUdng phe
thai
nay
di
vao trong nUdc
thai
va day cung chinh la

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

dung
ni^dc
viftft
dinh
mufc
gay ra
Chi phi dude
tinh chii
yeu tren cd sd
dien sii
dung
eiia
may bdm
nUdc tUdng
Ung v6i
tong
lUdng
nUdc
sii
dung vUdt dinh
miie ciia
xi
nghiep hang nam:
7828.7nr',
tUdng
dUdng vdi
71 (ngay)
sii
dung
Xi ngbiep eo 3 may bdm

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

nang
lUdng
cho
viec
bdm nUde
diing VUdt dinh
mdc
la: 8293 x 1000
^
8.293.000 (dong).
Viec diing
nUdc vttdt
qua so vdi dinh
miic
se lam tang ehi phi san
xuat
eiia
xi nghiep
len
8.293.000 dong. O day ehung toi
mdi
chi tinb
den chi phi cho viee bdm nUdc. Trong thUe te, viee
sii
dung vUdt dinh
mUc
se lam tang them eac ehi phi khac eho xi nghiep nbU
ebi
phi eho
hao mon may bdm. bao dUdng may bdm,

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

xi nghiep
thay rang, he tbo'ng
xii
ly nUde thai hien tai ehUa hieu qua va khong
74
dap
ijfng
dudc cac tieu
chuin
chat
lUdng
nUdc thai hien hanh ciia Viet
Nam (TCVN 5945- 1995
Loai
B, va TCVN 6984 - 2001 (Q< 50m3/s,
Fi).
Nudc thai sau xii ly cua xi nghiep van con vUdt tieu chuan cho
phep do'i
vdi
cac cbi tieu BOD, COD,
pho't
pho tong so', dau md
dong
thUc
vat va coliform. Do do can c6 bien phap cai tao lai be
thong xii ly
nUdc
thai de nUdc thai dau ra dap
itng dUde
eac tieu

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

Dau md khoang
Dau md dong
thUc vat
Mn
Tong nitd
Tong phot pho
Hg
S2-
Coliform
Dtfn
vi
oc
_
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
MPN/
100ml
tich

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

80
3
0,5
0,05
0,01
5
10
-
_
5
-
-
5000
nghiep F.37
Ni^dc
thai
trifdc xuf
ly
25,2
7,92
1970
1025
112
0,85
0,01
0,01
0,001
0,82
32,4
0.15

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

sii
dung
75
nUdc vUdt dinh
miic
khong chi gay thiet hai ve kinh te cho xi nghiep
ma con lam tang khoi
lUdng
nUdc thai ra moi trUdng. De ban che cac
thiet hai ve kinh te va giam tac dong mdi trUdng, dudi day la cae bien
phap dUdc de xuat.
Cac
phi/cfng
an tiet kiem
nUdc
-
Ldp
dat dong ho do
lUu lUdng
nUdc d
tifng
khu
vUc
che bien ban
che
lUdng
nUdc sii dung vUdt dinh
mdc,
dong tbdi de phat hien nhiing
khau gay ton that nUdc cho xi nghiep.

- 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

diing chau riia de nhiing
phan nguyen lieu da dUdc xU ly; (3) Nudc
diing
trong cong doan
ruta
l§n
3 c6 the quay vong tai
sii
dung cho cong doan
riia Ian
1. LUdng
nUdc nay khoang
2,lm'^/TNL
nhU vay tong
lUdng
nUdc tiet kiem dUdc
trong cong doan nay trong mot nam khoang 636
m^/nam
tUdng
dUdng vdi sd tien tiet kiem la 344.000 dong. Nen lam ve sinh kho
(nhu dung khan Udt hay dung cu ve sinh co xat) trUdc kbi dung nUdc
de xa
Ian
euo'i.
- Thay viec
diing
6'ng
nhUa
mem de ve sinh
b^ng

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

la: 1,717
m^
x 302,7 =520
m^/nam.
76
Tuy nhien, viec quay vdng tai
sii
dung nUdc
riia
ciing can xem xet
them qui dinh eiia Nganh
nb4m
tranh nbiim
b^n
trong thanh pham.
Nude riia
Ian
3 c6 the tai sii dung de ve sinh nha xUdng se phu hdp hdn.
Phi/cfng
an
xiC
ly
nUdc
thai
Qua khao sat dac tinh nUdc thai ciia xi ngbiep, he
thd'ng xii
ly hien
CO,
dong tbdi de han che den
miic

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

lUdng
bun nhd se dUdc
tuan hoan lai be Aeroten de tang
toe
do
xii
li ciia be. Sau khi qua be
lang 2 nUdc thai dUdc khu trung de dam bao ham
lUdng
coliform eho
phep
CO
trong nUdc thai. Co the bieu
diln
be thong xii ly cai tien nay
bang sd do sau (binh 4):
Nudc thai tiep nhan nguyen lieu
Nudc thai
che
bien
Nguon
tiep nhan
Be
xii
ly yem khi
3 ngan
Be
kh^
triing
Be lang2

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)

t la tbdi gian
luu
bay tbdi gian can de oxi hoa chat hiiu cd tii nong
do ban dau den nong do cuo'i. t dUdc tinb bang cong thiic sau.
t =
o
~c
p-X-d-z)
trong do:
SQ
la nong do BOD
d^u
vao
Sc
la nong do BOD
d^u
ra
p la toe do oxi hoa rieng
thUdng tii
12-30
g02/kg
biin boat tinh
X heu
lUdng
biin boat tinh trong be Aeroten tii 2-
5
kg/m^
z la do tro ciia
biin,
thUdng la 0,3.

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 =

20mg/l
(nUdc
thai dat
tieu chuan loai A TCVN 5945- 1995)
Cac gia tri p, X
ebon
gia tri trung binh la:
p
= 21g02/kg biin
boat tinh .
78
X = 3,5
kg/m3
Tbdi gian
luu
cua nUdc thai trong be la: t
=
15,37 h
The tich be Aeroten can xay dUng la:
V
=
Q
X
t = 5.85
X
15,37
«
90 m3
b.
The'tich be

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

biin
boat tinh trong be Aeroten (thUdng cd
gia
tri 2800
-
4000 mg/1)
Ct nong do biin trong dong tuan hoan (mg/1) (thUdng c6
gia tri 10000
mg/m^)
V]
Van toe
l^ng
cua mat phan cbia phu thuoc vao nong do can
l^ng.
Doi
vdi
nong do
biin
can trong dong tuan boan la 10000
mglm^
gia tri
V]
c6 do
Idn
la
0,34m/b
Nhu vay vdi Q = 5,85
m^/h,
cac gia tri a, Co, lay trung binh la:
a

-
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

be khii triing
c^n
xay dUng la:
37,5m3
*Chi
phi cho xay dUng he thong nUdc thai de xuat [Tran
Diic
Ha, 1998].
79
Chi phi ebo xay dUng lm3 be Aeroten Udc tinh la 900.000d6ng.
Chi phi cho xay dUng be
l^ng
2 va be
khii
triing Udc tinh la
600.000d6ng/m3.
Nhu vay ehi phi diing de xay dUng eho toan he tho'ng la:
900000
X
90 +600000 x (37,5 + 37,5)
=
126000000 dong =126 tneu dong
Qua tinh toan sd bo tong chi phi eho xay dUng, cai tao lai he thong
xU li nude thai cua xi nghiep Udc tinh la 126 trieu dong. Day la khoan
dau tu
ckn
thiet vi no khong
nhOng giiip
eho xi nghiep dap Ung dUdc
cae tieu chuan moi trUdng ma con giup giam eac tac dong tdi nguon tai

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

li sd bo trUdc kbi dUa vao he
tbo'ng xU li chung nham tang hieu qua cua qua trinb xii li.
KET LUAN
Qua qua trinh nghien
crfu
thUc hien kiem toan chat thai vdi do'i
tUdng chinh la day chuyen ehe bien tom cua Xi nghiep F. 37 c6 the dUa
ra mot so ket luan sau:
1) Xi nghiep da quan tam den eong tac bao ve moi trUdng. Moi
trUdng lam viee va moi trUdng xung quanh luon dUdc
giU
gin ve
sinh sach se dam bao cae dieu kien san xuat an toan cho eong
nhan.
2) Khi thai va chat thai
rin
ciia xi ngbiep chUa phai la van de moi
trUdng can quan tam dae biet. Tuy nhien, Xi nghiep nen c6 bien
phap de tan dung nguon chat thai
r^n
nb^m giam lUdng
chat thai
r^n
di
vao nUdc thai lam tang ham
lUdng
cac chat 6 nbiim.
3) Nude thai cua xi nghiep
khi
thai ra moi trUdng chUa dap

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

nUdc sii dung tang gap hdn hai
l^n
so vdi
lUdng
nude dinb
miic.
Tinb trang that thoat nUdc la do nhieu nguyen
nhan nhU: ebUa
s^
dung hdp ly
n\Xdc
trong cong doan sd ehe nguyen
lieu ciing nhU qua trinb ve sinh cong nghiep, chua lap dat dong bo
do nUdc va chUa thUc bien cac bien phap tai sii dung nUdc.
6) Cac giai phap tiet
kiem
nUdc dUa ra la rat kha thi, de dang ap
dung dong tbdi se mang lai hieu qua to't ve kinh te va moi trUdng.
Theo tinh toan sd bo chi rieng khau tach khuon, ma bang va khau
rUa
Ian
3 da c6 the tiet kiem dUde 1156
m^/nam,
tUdng dUdng vdi
614.000d6ng/nam
7) Da de xuat mo hinh nang cap He tho'ng
xii
ly nUde thai cho Xi
ngbiep F.37 nham dam bao van de moi trUdng nUdc cho xi nghiep
va khu xung quanh vdi tinh toan sd bo kinh phi dau tU khoang

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.

Xit
li
niidc
thai sinh hoat quy mo vita va nho.
TrUdng DH Kien True. NXB Khoa hoc
Ki
thuat, 1998.
5) Trinb Thi Thanh, Nguyen Thi Ha. Qiao trinh kiem toan chat
thai cong nghiep. NXB DHQG Ha Noi,
2003.
6) Trinh Xuan Lai. Tinh toan thiet ke cac cong trinh
xii
li niidc
thai. NXB Xay dung, Ha Noi, 2000.
7) Trinh Van Nhan, Ngo Thi Nga.
Gido
trinh cong nghe
xit
li
nude thai. NXB Khoa hoc
Ki
thuat.
Ha Noi, 1999.
81