Đánh giá thời gian lưu nước khác nhau trong hệ thống sử dụng các ao sinh học chứa bèo tấm (WOLFIA ARRHIGA) và bèo tây (EICHHORNIAA CRASSIPES) kết hợp với hệ thống hào đất để xử lý nước thải có chất hữu cơ cao

OANH GIA THOI GIAN LJU NUOC
KHAC NHAU
TRONG HE
THONG
SL/
DUNG CAC AG
SINH
HOC
CHQA
BEG
TAM
(WOLFIA
ARRHIGA)
VA
BEO
TAY
(EICHHORNIAA CRASSIPES) KET
HOP
VOI HE
THONG
HAG
OAT
DE
X(J
LY
NaOC
THAI
CO CHAT HUU CO
CAO
TS.
NGUYEN

THI
LOAN
Khoa Moi
trudng,
DHKHTN,
DHQGHN
Bai bao nay trinh bay ket qua cac
thi
nghiem de xu
ly
nude thai cd
chat
hiJu co
cao tir hd Thanh Cdng, nai tiep nhan nude thai sinh boat
tir
cac khu dan cu quanh hd va
tir
nha may san xua't bia Du Lich.
Nude
thai duge xu ly trong he thd'ng cac ao tha beo tay va beo tam ket hgp
vdi he thd'ng
Ige
qua hao da't. Trong khi thf nghiem, thai gian
luu nude
thuy
luc
duge thay ddi de tim ra hieu qua xu ly td't nha't. Dd'i vdi
nude
hd thdi gian luu
nude

thuy
lire
la 4.5 ngay thi cho ket qua
xir
ly td't
nha't. Hieu qua
loai
bd chat thai la:
NH/
= 59%;
N02"=
33.5%;
NO;
=
39,8%;
PO4'
=
63.5%;
SS = 91.7%; COD =
63.7%;
BOD5 =79.6%.
Dd'i vdi nude thai nha may san xua't bia, thdi gian luu nude thuy luc la
5 ngay thi cho ket qua xu ly td't nha't. Hieu qua loai bd chat thai la:
NH/
= 96.2%;
NOj'
=
87.6%;
NO,"
=

63.2%;
P04-'
= 53.7%; SS =
89%;
COD = 93.4%; BOD5 =96.9%.
Cac ket
qua
tren da
chiing
minh
rang
su ket hgp cua hai he thd'ng
ao sinh hge va hao da't la
thieh
hgp de
xir
ly
nude
thai cd ndng do
hihi
CO
cao.
912
ASSESSMENT OF DIFFERENT HYDRAULIC RETENTION
TIMES
IN A SYSTEM USING BIOLOGICAL PONDS WITH DUCKWEED
{Wolfia
arrhiga) AND WATER HYACINTH
{Eichhorniaa
crassipe)

COMBINED
Wrra
SOIL TRENCH SYSTEM TREATING HIGH ORGANIC
MATTER WASTE WATER
Nguyen
Thi Loan, Ph.D
Faculty of Environmental Science,
Hanoi University of Sciences, VNU
This paper presents results of experiments to treat waste water with
high organic content from two sources. One from Thanh Cong lake
receiving domestic waste water discharged from a residential area and
another from Du Lich beer production factory. Waste water was treated
by ponds with duckweed and water hyacinth combined with a soil trench
system. During the experiments, the hydaulic retention time (HRT) in
different treatment sections were changed to find the highest treatment
efficiency. Treatment efficiency was highest for wastewater from the
lake when the hydaulic retention time was 4.5 days. The waste removal
efficiency was:
NH/
= 59%;
N02-=
33.5%;
NO/
=
39,8%;
PO4-'
=
63.5%;
SS = 91.7%; COD = 63.7%; BOD5 =79.6%. The treatment
efficeney

was highest for wastewater from beer production factory when
the overall hydaulic retention time was 5 days. The removal efficiency
was:
NH4"
= 96.2%;
NO^"
= 87.6%;
NO,"
= 63.2%;
PO4-'
= 53.7%; SS =
89%;
COD = 93.4%; BOD5 =96.9%.
The results indicated that the combination of the two systems
biological pond and soil trench system is suitable for treatment of
waste water with high organic content.
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Da ed rat
nhidu
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khae nhau
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dung cac loai beo
nhir
beo Tay (hay eon ggi la beo Luc Binh; beo Nhat Ban), beo Tam, tao
de xu ly nude thai cd ndng do hiru co cao, vi chiing ed kha nang loai
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sach cac hat nhd vd ea, chat
la lung, cac cha't dang keo va nhu tuang. Bd
re
cua chiing hinh thanh
trong mdi trudng tu nhien vdi cac
di6u
kien
thich
hgp cho cac vi sinh
vat phat trien de sau dd thuc hien qua trinh oxy hoa sinh hoa cac chat
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thuc vat
nude

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vira
ed
tac
dung
lam sach nude sdng hd, gia thanh
xii
ly re, khdng de lai doc hai cho
mdi trudng ddng thdi sinh khdi
ciia
thuc vat cd the
sir
dung cho muc
dich chan
nudi hoac lam nguyen lieu cho mot so nganh san xua't. Kha
nang xu ly nude thai
ciia
cac thuc vat nude da duge chiing to bang kha
nang quan sat d cac
viing
nude gay d
nhidm,
bang cac thi nghiem
trong phdng
thi
nghiem, d Pilot va trong thuc te d cac hd sinh hoc
tuang ling hoac tren kenh
rach
(Lam Minh Triet, 1998).
Beo tay cung duge

sir
dung de xir ly
nude
thai chua dau thuc vat.
Ket qua
thi
nghiem cho thay: hieu qua xu ly dau dat tir 92,7-97,9% va
COD dat
tir
84,4-98,8% (Nguyen Trung Viet, 1992). Ket qua nghien
euu qua trinh xu ly nude thai
Id
giet mo va che bien thit heo bang
h6
sinh hge vdi su tham gia
ciia
beo tay va tao cho thay qua trinh nay
lam
giam dang ke ham lugng
BOD5,
COD va cha't la
lirng.
Dae biet la h6
sinh hge vdi su tham gia
ciia
tao ra't
thich
hgp de lam giam dang ke
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Coliform (Lam Minh Triet, va Van Buuren, 1990). Mot nghien
ciiu
khae sic dung mot so loai thuc vat nude nhu beo luc binh, tao
chlorella, rau mudng, rau ngo de xu ly nude thai. Cac loai thuc vat
nay
sir
dung
CO2
ddng thdi cung cap oxy cho vi sinh vat (Lam Minh
Triet, 1990).
Tuy nhien
viee
xir ly nude thai bang he thd'ng
Ige
qua hao dat van
con la
mdfi
me d Viet Nam. He thd'ng hao da't duge
sir
dung rat pho
bien de xir ly nude thai tai nhieu nai tren the gidi,
thi
du nhu My va
Nhat Ban. He thdng nay trong thuc te gdm cac hao dao vdi do sau
khoang
tir
0,3 m den 1,5 m va ehieu rdng khoang tu 0,3 den 0,9 m.
Dudi
day duge trai mot
Idp

da hoac sdi khoang
5-15
em, tren
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dd
dat cac cac d'ng phan phd'i nude cd due
Id
va sau dd lai phu mot
Idp
da
va sdi
len
tren d'ng. Tren
cimg
la
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da't phu ed trong cay. He thd'ng
loc
qua hao da't la phuang phap ra't td't de xu ly nude thai sinh boat bdi
vi no dan gian, dn dinh va
chi phi
tha'p. Trong dieu kien tdi uu, dat la
mdi trudng xu ly nude thai ra't td't vi nd
sir
dung cac mdi tuang tac giira
re
cay, sinh vat va vi sinh vat da't trong cac
Idp
da't
sau

dudi be mat
khoang ma'y ehue em, nai khu he sinh vat
phiic
tap, da dang va day
dac nha't (Camp et
al,
1977).
Tir nhiJng
thao
luan
tren, muc dich
ciia
nghien
ciiu
nay la:
-
Sii
dung hd sinh hge ket hgp vdi
Igc
qua hao da't de xu ly nude
thai cd ndng do cha't hiru ca cao trong ciia
nude
hd Thanh Cdng va nha
may bia Du Lich.
- Tim thdi gian luu
nude
tdi uu de dat duge hieu qua xu ly
cao nha't.
Ooi tucfng
va

phudng
phap nghien
curu
Hai ddi tugng
xir
ly la hai ngudn nude thai
tir
hd Thanh Cdng va
CO
sd san xuat bia Du Lich. Cac mau nude hd duge lay
tir
nhieu diem
khae
nhau va trdn vdi nhau de
la'y mlu
tong hgp. Cac
mtu
t\x
nha may
bia duge la'y tii diem cud'i cua cdng thai.
Cac thdng sd ly, hoa hgc de danh gia chat lugng
nude
nhu pH,
P04"\
NOj-,
NO,-,
NH4^
BOD5, COD
duge
do theo nhu phuang phap

915
md ta trong "Standard methods"
(1990).
Thiet
ke thi
nghiem
Md hinh xu ly nude thai duge trinh bay trong hinh 1
irdc
ai
-
Be ye'm
khi
1
—•
Be
hieu
khi
1 (beo
tam)
—•
H
Be
hieu
khi
2 (beo
tay)
—>
Be
yem
khi

2
—1
He thd'ng loc
qua hao da't
Nu6c<
r
.an
xitly
Hinh 1: Mo
hinh
xu ly
nicdc
thdi
Tirng bude
trong qua trinh
xir
ly deu ddng mot vai trd nhat dinh.
Nude
thai
duge
dua vao be ye'm
khi
1 (trong be ye'm
khi
ed
cay
xoan
nhua de cho vi khuan bam vao) de
lang
va phan buy can

Idng
dua tren
boat ddng ciia vi sinh vat ky khi. Nude thai sau khi qua cdng doan
yem khi duge dua vao
chau
beo tam 1 de trong khoang thdi gian ma ta
da dinh trude. Trong qua trinh quang hgp, beo tam se hap thu
COj
va
tao ra mot lugng oxy dang ke cho qua trinh oxy hoa hie'u
khi
dd'i vdi
cha't
hiJu
ea. Bd
re ciia
beo
edn
giu lai va
Igc
sach cac hat nhd vd co,
cac chat la
lirng,
cac chat dang keo va nhu tuang,
cac
chat ban
htru
co
va cac cha't doe cung duge xu ly nhd beo tam. Be hieu khi 2 chira beo
tay gdp phan loai bd

nito
va phdt pho va cac chat khae ra khdi
nude
thai thdng qua qua trinh hap thu cac chat dinh dudng ciia cay beo tay.
Be yem
khi
2 ed the
giiip
loai bd nita thdng qua qua trinh phan nitrat.
Qua trinh phan nitrat do cac vi khuan tuy nghi thuc hien trong dieu
kien thieu oxy va ty le cac bon: nita it nha't la 2:1 (Metealf & Eddy,
Inc.
1991). Tiep sau dd nude thai di vao he thd'ng
Igc
qua hao dat, he
thd'ng nay tiep tuc loai bd can la lung, nita va phot pho thdng qua cac
CO
che'
Igc,
lang, hap phu, hap thu v.v.
Thdi gian luu nude trong he thd'ng ciia bdn dgt thi nghiem de
xir ly
nude thai hd Thanh Cdng va nha may bia Du Lich duge trinh
b^y
b
916
bang
1
va 2.
Bang

1:
Thdi gian luu
nude
trong he thdng ciia bdn dgt thi nghiem
de
xijf
ly nude thai ho Thanh Cong
Birdc
xir ly
Be
ye'm khi 1
Be hieu
khi
1
Be hieu khi 2
Be ye'm khi 2
long
thdi gian
Dot
xiSr
ly 1
2
1
5
0
3.5
Dgt
xir
ly 2
2

1
1
0.5
4.5
Dot
xijr
ly 3
3
1
1
0
5
Dot xiir ly 4
3
2
1
0
6
Bang
2:
Thdi gian luu nude trong he thdng
ciia
bdn dgt
thi
nghiem
de xu ly nude thai ciia nha may bia Du
Ljch
Bude xiir ly
Be ye'm
khi

1
Be hieu khi 1
Be hieu khi 2
Be
ye'm khi 2
Tong thdi gian
Dot xir ly 1
2
1
1
1
5
Dot
xiJr
ly 2
3
2
1
1
7
Dot xu ly 3
3
1
0.5
0.5
5
Dot xir ly 4
2.5
2
1

0.5
6
Ket qua va thao luan
XCrlynm^c
thai ho Thanh Cong
Hd Thanh Cdng la ho nhan tao do con ngudi dao dap de tao canh
quan va dieu hoa
khi
hau cho
viing
dan cu xung quanh. Hd Thanh
Cdng cd dien tich 6,5 ha va cd do sau trung
binh
3-4m. Trong hd mgc
917
rat nhieu beo tay va eae loai thuc vat thuy sinh khae. Hd cung
ttiu
nhan duge lugng buc xa
tir
mat trdi
Idn,
tao dieu kien thuan
Igi
cho
qua trinh quang hgp cua thuc vat trong hd. Nhung khi thuc vat phat
trien qua muc va
chet
di thi lai la chat gay d nhiem
ehinh
cho nude ho.

Ve
miia
mua, hd la nai
ehiia
mot lugng nude
Idn
do mua, nude
mira
chay tran vao mang theo nhieu cha't
gay
d nhiem.
Khi
miia
khd den thi lugng nude dua vao hd ehu ye'u la nude thai
khdng ed
nude
mua pha
loang nen
ndng do eae cha't
bdn
trong hd cang
dam dac. Dac biet vao
miia
he, ea chet va ea noi dau thudng xuyen vao
buoi sang, ham lugng oxy hoa tan trong nude cd luc giam tdi
ehi
con
nhd ban 2 mg/1. Theo nghien
eii'u
ciia Le Hien Thao (1998) cac thong

sd ly hoa danh gia cha't lugng nude hd la
NH4"^
= 4.7
^
7.9
mg/1;
N02'=
2.6
^
3.1 mg/1;
NO,"
= 6.3
^
6.9
mg/1;
PO4-
= 2.2
-f-
3.5 mg/1; SS = 25
^
66
mg/1;
COD = 48
-^
456
mg/1;
BOD5 =22
^
345 mg/1.
Trong nghien

ciiu
nay nude hd
Thanh
Cdng
duge xii
ly lam bdn
dgt nhu trong bang 1. Thdi gian luu
nude
trong he thd'ng
xir
ly
duge
thay ddi de tim ra thdi gian
xi!r
ly tdi uu nha't. Ket qua
xir
ly
duge
trinh
bay d bang 3.
Bang 3: Ket qua xu ly
nude
thai
nude
ho Thanh Cdng
trong bdn dgt
Cac
thong
so ly,
hoa

NH4^
NO2
N03-
PO;'
SS
COD
Dotl
Trudc
xir
ly
(mg/1)
0,774
0,468
0,220
0,002
50
400
Sau
xir
ly
(mg/1)
0,580
0,43
0,170
0,001
6
150
Dot
2
Truac

xirly
(mg/1)
0,916
0,102
0,176
0,005
120
260
Sau xir
ly
(mg/1)
0,374
0,068
0,106
0,002
10
80
Dot
3
Trudc
xirly
(mg/1)
0,800
0,332
0,308
0,005
120
260
Sau xir
ly

(mg/1)
0,194
0,128
2,640
0,003
10
80
Dgt
4
Tru6c
xirly
(mg/1)
0,799
0,140
0,440
0,060
128
440
Sau xu
ly
(mg/1)
0,232
0,064
1,760
0,004
13
120
918
BOD.,
200

80
220 45
220
45 420
80
100
80
60
40
20
Hieu suat xii ly
nude
thai ho Thanh Cdng
• Dgt 1
•
Ddt2
• Dots
•
Dgt
4
NH4'
NO2'
NO3"
P04'^
SS
COD
BOD5
Hinh
2: Hieu qua
xu'

ly
nude
thdi cua ho Thanh Cong qua bon dat
Hieu qua xu ly cho ea bdn dgt duge the hien d Hinh 2. Ta thay
rang thdi gian luu nude khae nhau da cd anh hudng
Idn
de'n kha nang
loai bd cha't chat d nhiem ciia nude thai. Nhin ehung trong ea bdn dgt
xir
ly, can la lung, COD va BOD5 duge loai bd vdi ty le khoang 60%
de'n 80%. Tuy nhien hieu qua loai bd nita va phd'tpho chi dao ddng
trong khoang tu 20% de'n 60%. Dieu nay ed the la do thdi gian luu
nude chua
dii lau
de thuc vat thuy sinh ed the ha'p thu duge nhieu cac
cha't dinh duang ehuyen hoa tu chat
hiru
ea
eiia
nude thai.
Ne'u
tinh
de'n kha nang loai bd eae chat d
nhidm
ehinh thi dgt
xii
ly 2
la hieu qua nha't
vi
dgt nay ed ty le loai bd

NO3',
P04"^
va can la lung cao
nhaft.
Ly do loai bd
NO3'
cd the la do dgt nay cd mia ngay luu nude d be
yem
khi
2, nai cd dieu kien tdi uu cho qua trinh phan nitrat xay ra.
Xuly nifdc
thai nha may bia
Theo Ngan hang The Gidi (1998) mot
m^
bia duge san xua't ra
thi
thai ra 3-5
m^
nude
thai.
Nude
thai chua xii ly thudng
chiia
khoang 10-
60 mg/1 can la lung,
1,000-15,000
mg/1 B0D5,
1,800-3,000
mg/1 COD
va khoang 30-100 mg/1 nita va khoang 10-30 mg/1 phd'tpho. Nude thai

nha may bia cd ham lugng cac chat
hffu
ea cao d trang thai hoa tan va
trang thai la lirng. Trong dd
chii
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khae
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sir
phan buy
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thai
nha may bia ed COD,
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va lugng cha't ran huyen phii (SS) cao
hon
nhieu so vdi tieu ehuan Viet Nam. Ngudn phat sinh
nude
thai trong
qua trinh san xuat la
tir
eae cdng doan:
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riia
nguyen vat lieu: loai nude thai nay

ehiia
nhieu cac cha't
vd ca va eae manh vun hiru co.
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hiru
ea.
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lanh,
nude ngung, nude
riia
eae thiet bi (may
Ige,
bdn
ehiia,
thie't bi nap bia vao

chai )
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rira
thie't bi nap bia vao
chai
cd ham lugng cac chat la lirng, COD, BOD5 rat cao.
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riia
va trang chai
Ion
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doan rira, chiet thanh
triing,
dan nhan.
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tir
bd phan
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hai.
Dd'i vdi nude thai d xudng bia Du Lich cung tie'n hanh xu ly lam 4
dgt vdi thdi gian
xii
ly cac dgt la khae nhau nham
tim
ra thdi gian xir
ly thieh hgp nhat dd'i vdi loai nude nay.
MSu
duge la'y ngay d ehd cd
dudng d'ng
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nude thai d trong xudng san xuat bao gdm tat ca cac
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Ig,
ve sinh
ciia
can bd cdng nhan eua
xudng deu do true tiep dd ra cdng, nude ed mau trang due va mdi thdi
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thdng so hoa, ly deu giam (Bang 4). Tuy nhien BOD5 va COD ham
lugng van vugt qua tieu ehuan cho phep do ed ham lugng ban dau
qua cao. Cd hieu qua td't nhat la dgt
xir
ly 3 vi tat cac thdng so hoa,
ly deu giam nhieu ban eae dgt xir ly
khae.
Ta thay vdi 5 ngay xii ly
nhu d dgt 3 de xu ly nude thai d xudng bia Du lich la td't va phii hgp
nha't vi chi can thdi gian it nhat ma lai hieu qua (xem hinh 3). Nhin
ehung phuang phap
xii
ly nhu tren bude dau da dem lai thanh cdng
920
Bang 4 Ket qua xii ly
nude
thai ciia nha may bia Du
trong bdn dgt
Lich
Cac
thfing

s6'
ly,
hoa
NH4'
NO2
NO,
PO4'
SS
COD
BOD,
Dotl
Trudc
xirly
(mg/I)
1,019
0,468
0,946
0,003
100
460
287
Sau
xirly
(mg/1)
0,387
0,383
0,620
0,002
13
260

70
Dgt
2
Trudc
xirly
(mg/1)
0,800
0,192
0,616
0,006
150
3.800
3.325
Sau
xirly
(mg/1)
0,039
0,043
0,352
0,004
17
440
162
Dot
3
Trudc
xirly
(mg/1)
0,6708
0,477

0,546
0,003
200
4.600
4.267
Sau
xirly
(mg/1)
0,026
0,068
0,201
0,001
20
300
134
Dgt
4
Trudc
xirly
(mg/1)
0,968
0,426
0,788
0,004
125
2.600
2.256
Sau
xirly
(mg/1)

0,098
0,060
0,440
0,002
15
160
95
Hieu suat xii ly nude thai nha may bia
•
Dot
1
r—t
Dots
0014
NH4*
NO2'
NOj'
P04^
SS COD
BOD5 •—'
Hinh 3: Hieu qua xir ly
ni(dc
thdi nhd may bia Du Lich qua bon
dm
Thdi gian luu nude dai dii de qua
trinh
phan buy eae chat huu ea
trong dieu kien yem
khi
sang cac chat vd ca. Cac chat nay se duge beo

ta'm va beo tay hap thu trong eae ao hieu khi tiep theo. Dgt xu ly 2 va
4 ed hieu qua xu ly
cQng
tuang tu nhu dgt 3 nhung thdi gian luu nude
trong he thd'ng lau ban.
921
Ket luan
1.
Hd sinh hge ket hgp vdi
Ige
qua hao da't ed kha nang xu
ly
nude
thai cd ham lugng cha't
hiJu
ea cao. Cay beo
taim,
beo tay cd kha
nang ha'p thu td't cac cha't hiiu ca trong mdi trudng song bi
nhilm
cha't hiru ea nang. Ndng do chat hiiu ea trong nude thai da
duge
giam
dang ke sau eae dgt xii ly.
O
hd Thanh Cdng COD giam
tiJr
260 mg/1
xudng edn 80 mg/1,
BOD5

giam tir 220 mg/1 xudng con 45 mg/1 trong
dgt xir ly 2. O nude thai nha may bia Du Lich COD giam
tii
4600
mg/1 xudng edn 300 mg/1, BOD5 giam tir 426 mg/1 xudng edn 134
mg/1 trong dgt xii ly 3.
2.
Thdi gian xir ly td't nha't dd'i vdi nude thai hd Thanh Cdng la 4,5
ngay va dd'i vdi nude thai d xudng bia Du Lich la 5 ngay.
Tai lieu tham khao
1.
Le Hien Thao, 1998. Danh gia so bo hien trang
nude
a ho
Thanh Cong. Tuyen tap cdng trinh khoa hge trudng Dai hgc
xay
Dung.
Sd
2-1995.
2.
Lam Minh Triet va J.C.L Van Buuren, 1990. Xu ly
nude
thdi
bang ho sinh vat vdi su tham gia cua tdo vd beo
liic
binh a
Viet
Nam.
Tuyen tap cac bao cao Khoa hge Nude - Nude thai va
mdi trudng. Trung tam nude va mdi trudng, trudng Dai hoc

Bach Khoa thanh phd Hd Chi Minh. TPHCM
1-1990.
3.
Lam Minh Triet, 1990.
Vai
trd cua thuc vat nude trong qua
trinh xu ly nudc thdi. Tuyen tap eae bao cao Khoa hge
Nude
-
Nude thai va mdi trudng. Trung tam nude va mdi trudng,
trudng Dai hgc Bach Khoa thanh phd Ho Chi Minh. 1990.
4.
Nguyen Trung Viet va cdng su 1995.
Sic
dung beo tay di
xk ly
nudc thdi nhd mdy dau thuc vat. Tuyen tap eae bao cao Khoa
Hgc Nude-Nude thai va mdi trudng. Dai hgc Tong hgp thanh
phd Hd Chi Minh.
5.
Camp, Dresser and Mekes,
Inc,
Boston, MA, 1977. Waste
922
water treatment facilities for sewered small communities.
Process design manual. Environmental Protection Agency,
Cincinnati, OH. Office of Technology Transfer.
6. Metealf & Eddy, Inc. 1991. Waste water Engineering:
Treatment, Disposal, and Reuse).
7.

Standard Methods for water and waste water examinations,
1990.
EPA,
16"'edition.
8. World Bank Group, 1998. Pollution Prevention and Abatement
Handbook. Toward Cleaner production. Washington, D.C.
923