Tgp chi Khoa hgc Tnrdng Dgi hgc Cdn Tho Phdn A • Khoa hgc Tu nhien. Cong ngh? va Mdi nvong: 18(20131 17-22
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Tap chl Khoa hoc Trirclng Dai hoc Can ThcJ website: sj. ctu. edu. vn
Sir DUNG PHirONG PHAP THU DUNG D£ SO SANH HIEU QUA KINH TE CAC GIAI PHAP XIJ^LY NlTOfC THAI AO NUOI CA TRA
TREN DIA BAN TINH AN GIANG Hoang Thi Thanh Thuy va Le Anh Tuan'
' Khoa Mdi trucmg vd Tdi nguyen Thien nhiin, Trudng Dgi hgc Cdn Tho Thdng tin chung:
Ngdy nhdn: 23/5/2013 Ngdy chdp nhdn: 29/10/2013 TUle:
Applying Collective Utihiiy Method for the economical effectiveness comparison of catfish pond wastewater treatment solutions in An Giang province Tir khda:
Ao cd tra, xu ly nude thdi, Phuangphdp Thu dung, tinh hieu qua
Keywords:
Catfish pond. M-astewater treatment. Collective Unhiiy Method, effectiveness
ABSTRACT
An Giang province has recently been facing the problems of declining water quality due to the blooming of intensive aquaculture. Four fishpond wastewater treatment systems currently being applied in the province include. (1) aeration lagoon with aquatic plants; (2) Sequencing Batch Reactor (SBR) method; (3) microbiological method; arui, (4) high-speed Purolite. In this study, the Collective Utility Method was applied to compare the effectiveness of these wastewater treatment systems according to five criteria: (a) treatment efficiency: (b) cost per cubic meter of wastewater to be treated; (c) cost of system operation; (d) total area required; and, (e) treatment rate per day.
The results showed that the SBR system gained advantages in medium-size fish farm (about 10% of the total fish farming area used for treatment)
over the others. In the case of having a greater treatment area (greater than 20% of the total raising area), using aeration lagoon ii ith water hyacinth plants could be an alternative.
TOM TAT
Tinh An Giang dang ddi phd vdi vdn de suy gidm chdt lugng nude do su bimg phdt thdm canh nudi trong thuy sdn. Hien cd bon hi thdng xir ly nude thai ao cd dang duac dp dyng d tinh An Giang, dd Id (1) ldm ho thodng khi ket hgp vdi nudi thuy sinh thuc vdt; (2) phucmg phdp xir ly dgng me (SBR); (3) phuong phdp vi sinh; vd (4) diing Purolite toe do cao.
Trong nghien ciru ndy, phucmg phdp thu dung da dugc su dung di so sdnh vd ddnh gid cdc hi thdng xu ly ndy theo ndm chi tieu: (a) hiiu qua xu ly;
(b) phi ddu lu cho mdi mil khdi nude thdi cdn xu ly; (c) chi phi vdn hdnh hi thdng, (d) td ng dien lich ddt xu ly, vd (e) ldc do xir ly mdi ngdy.
Ket qua cho thdy hi thdng SBR cd uu the han vdi diin tich trgi nudi cd co quy md vira phdi (dimg khodng 10% dien tich ddt cho xu ly) so vdi cdc hi thdng khdc. Trudng hgp cd diin lich xu ly rdng han (trin 20% tdng dien tich nudi) thi diing ao thodng khi vdi cdy trdng la beo luc binh cd thi dugc chonlua
Tap chi Klioa hgc Trudng Dai hoc Cdn Tha Phdn.4- Khoa hgc Tu nhien. Cong nglie vd Mai Inrong: 28 12013)- /"- 1 © A T VAN ©E
An Giang Id mdt Uong cdc tinh cd diln tich nudi cd con c i tra, ba sa Idn nhit d ddng bdng sdng Ciiu Long (DBSCL), gdp phin phdt Uiin kinh ti khu vuc va ddng gdp ldn Uong kim nggch xuat khau thuy sin ciia Viet Nam. Tuy nhiin, phit triin nudi trdng thiiy sin day die thucmg phdi ddi mdt vdi 6 nhiem mdi tmdng nude vi gia tdng mam benh thiiy san, lira gidm nang suit thu hogch, giy thdt thu hang loat. Hien nay, cic vimg nudi chua dugc quy hoach mgt cdch bdi ban, nghi nudi thuy sin phit Uiin mdt each ty phit, ciing li h | qui gay gidm chat lupng ngudn nude mdt do miic d nhiem cd liic vugt qud khi nang ty lam sgch ciia dong sdng.
Trong qua Uinh nuoi. cic chit thai hiiu co, khdng sinh, chit khu trung, thiic dn du thira khdng dugc xii Iy tir cac co sd nudi tham nhap vio radi trudng nude giy d nhilm, bao gdm hiln tugng nd hoa ciia tao ddc vi sy tang sinfa ciia cic sinfa vdt gay binh (Trung tdm Kfauyin nong tinh An Giang, 2003). Khi cac chit thai vdi sd lugng ldn va chit lugng chua dgt theo tieu chuan dugc thai vao mdi truong nude thi cac qud trinh ly, hoa, sinh, khi dgng hpc... ty nhien se tao cdc anh hudng khac nhau den chit lugng d vimg xung quanh (Ddng Nhu Toan, 1997). 6 nhiim hiiu co dugc danh gid bing chi tiiu nhu cau oxy sinh hgc trong 5 ngay (BODs). Chat hiiu ca trong thiiy vuc chii ylu la nguon thiic dn thiia va chat thii thiiy sinh vat. Chdt thai ldng dpng xudng nin diy tgo thinh chit biin diy thiiy vyc. Khi lugng cfadt hiiu ca qud nhilu, qui trinh phin hiiy tieu hao nhilu oxy hod tan trong thiiy vuc, gay nin hiln tugng nhiem ban thiiy vyc (Dang Ngpc Thanh, 1974). Do sy thilu hut oxy Uong ngudn nude nliilu logi thuy sinh vdt nfau cd, tdm, dpng vit nguyen sinh khd sdng dugc.
Trong nude va uong ldp can day se dien ra qud trinh phdn hiiy yira khi chdt hiiu ca, gidi phdng nhieu khi ddc cho ngudn nude nhu H2S, CH4—
(Trdn Huu Uyin va Trin Vilt Nga. 2000).
Dl dat muc tieu phat trien nghe nuoi ci tra bin vimg. thdi gian qua An Giang dS t l chiic nhilu cupc Hpi thio khoa hpc vdi sy tham gia ciia nhilu nhi khoa hpc vd cac doanh nghiep chuyen vl nghiin ciiu Uong linh vuc xii Iy nude thai di mong tim ra giai phdp xd ly nude thai tir cac ao nuoi ci tra dgt hieu qua, phii hgp dilu kiln ciia dja phuang.
Sd Tai nguyin vd Mdi trudng tinh An Giang da cd quy dinh tam thdi. uong khi ngudi din chua tim dugc gidi phdp xii ly nude thai thich hgp thi buoc phdi chita mdt diln tich toi thilu li 25% trin tong
diln tich mat nude nudi dl xii ly sa bg nude thii tnrde khi thii ra ngudn nude mat xung quanh. Giii phap niy hiln da sd ngudi dan khdng chip nhin.
do hp CO gang tin dung diln tich cho hoat ddng nudi, Uong khi dilu kien gia dit kha cao, nen phin ldn khong muon bd ra mdt phin diln tich tuang doi ldn dl xii ly nude thai tmdc khi cho chdy ra mdi tmdng theo khuyin cdo. Hi^n tinh ciing da dua vao dp dung thii nghiem mpt sd phuang phap xis ly nude thai ao nuoi ca tra de tren co sd do img dung nhan rdng Uong tinh. Van de hiln nay la cde phuang phap nay chua dugc danh gia mdt each cy thi tinfa uu viet ve cdng nghi va ca kinh tl dl lim ca sd khuyin cao ngudi dan ap dung. Do viy, dya vio cac bien phdp xu ly ao cd hiln dang dugc dp dung d tinh An Giang, viec xic dinh bi|n phip hihi hieu nhat vdi tieu chi xii ly nude tuang ddi hiiu qua, gidm chi phi dau tu ban ddu. It tdn chi phi van hinh (nhan cdng va nang lugng), giam thieu diln tich dit cho xii ly la muc tieu kinh tl - kJ thu^t cho de tai nay.
2 PHirONG PHAP VA PHU'ONG TIEN Dl phin tich cho giii phip can can nhdc va lya cfagn, de tai da ap dyng phucmg phap thu dyng (Collective Utility Method), dugc nha toan hpc Lesoume phat triln tir nam 1964, vl sau dugc sii dung Uong nganh tdi nguyin nude (Dupnick, 1970). Diy la bai toan kinh tl theo thu^t phan tich ma tran giiip cho vile lua chpn phuang in ldi uu 0 cac du an da muc tieu. Dau tu he thdng xii ly nude thii ao nuoi ca dugc xem nhu mdt dy in vi dy in nay thudng phyc vu cho nhieu muc tieu khac nhau, ket qua deu nham vao lgi ich cao nhit cd thi dgt dugc cho ddi tugng cdn dau tu. Cdc muc dich ddi khi bi rang budc, ban che lin nhau, ddi hdi ngudi dilu hinh chung phii cd rapt quylt dinh tdi uu. Do cic muc tieu khdc nhau, ky hieu Z,j, (hi?u qud xii Iy, cfai phi ban diu, chi phi van hinh, di|n tich dat) nin don vi tinfa kfadc nfaau, phuang pfadp tfau dung sii dung cdng thiic sau de chuyin cic gid Ui cd sd thii nguyin khdc nhau thanh gia tri khdng thii nguyen.
Chuyin Zy d timg hang thanh chi sd kfadng thiir nguyin b,j
Z„ -minZ,
maj2, -minZ'„ (min bij = 0; max bfj = 1) Dinh U 11 gia trpng Uj (0 < a, < 1) theo mitc quan trgng ciia muc tiiu qua lay y kiln chuyin gia va ngudi dan. LTng vdi mdi bi?n phap xii 1>. ip
Tap cfii Klwa hoc Trudng Dai hgc Cdn Tlia Phdn A • Kfioa hgc Tu nhien. Cdng ngAf va Mm truong:.
dung cdng tfaiic tinh gia tri thu dung CU,. Sap thii tu giim din ciia CU, roi chpn gii tri min ciia (CUi) tiiy theo muc tieu tii thiiu hod chi phi xii ly dl dat tuy
yeu cdu chat lugng nude.
CU, = Iaj*b.j.
Yie tai chpn dja diim nghien ciiu la tai 04 ao nuoi cd tra cd dp dung bien phdp xii ly nude thai vdi cac bien phip xii Iy nude thii kfadc nfaau tai cic dia ban thugc tinh An Giang, cu thi nfau d Hinh I vd tdm tit nfau d Bang 1.
B A N D 6 V! TRI TTHU M A U - Ky hieu VI trf thu mSu
- O l m l xa Long Giang, huyen Cho lJa\. tinh A G Di^m2: x a Phu ThuSn, huyen Thoai Stin, tinh AG O l n n 3 xa VTnh Bmh, Ch&u Thanh. An Giang DSTTA >3 Hoa Bmh Thanh, Ch&u Thanh, tinh AG
6 H C T H A P
Hinh 1: Ban do vj tri nghien cuu Bang I: SI lugng va dien tich mat nude cac ao lua chpn nghien cuu
Thong so Ky hieu Sd ao nudi (cdi) Diln tich mat nude nuoi (m-)
Kfau nuoi ca tra Khu nuoi ca tra Kfau nuoi cd tra Kfau nuoi cd tra giong tgi xd Phu Thuan tai xa VTnh Binh tai xa Long Giang Hoa Binh Thanh_
(Ao PT) 19 112.400
(Ao VB) 7
(Ao LG) 1
(Ao HBT) 1 2.000 - Ao PT nuoi cd tgi xa Phu Thuan, huyin
Thogi Son ciia Cdng t> Thiiy san Nam Bd. ap dung xii ly nude thii bang phuang phdp vi sinh. Hd nudi khoanh radt viing diln tich khoang 4 m- Uong ao nuoi, phia dudi cd Idt bgt nylon, ca tap tmng den diem nay in. he thdng xu Iy bd tri may bam nit nude tir diem niy va bam vdo bdn chiia. 6 day nude thdi dugc khuiy iron nhd ldp dgt bam canh
khuay. Qua trinh niy nfaam lam dn dinh nude thii.
dilu hoa cic thdnh phdn cd Uong nude thai cung nhu ndng do chat d nhiem trudc khi dua qua be xti ly chinh cd dl cic sgi nhua tdi chl lam gid the dpe theo chieu dii ciia bl. Cudi ciing nude dua sang bl ling de Idng Uong nude thdi tmdc khi thai ra kinh npi ddng-
Top chi Khoa hgc Tnrdng Dai hgc Can Tho Phdn .4: Kfioa hoc Tu nhien. Cdng ngfie vd Mdi tnt&ng. 28 '20/3/ 1 "•
A o VB nudi cd Ua tai xd Vinh Binfa, huyen Chdu Thanh ciia Cdng ^ Vilt An. Qud Uuih xir ly n u d e bdng hd sinh hgc thyc vdt noi gdra luc binh, beo v a lau say c h i l m 1/3 dien ticfa hd ddng thai cd thd nudi ca tap. Cudi cimg nude ty chdy qua lam t h o i n g nhan tao ddng tfadi cd bd tri may k h u i y trdn be radt.
A o LG nudi cd tra tgi xa Long Giang, huyen C h g M d i cua ong V u o n g Binh Thanh, gdm mpt day 7 ao nudi vdi trpng lugng cd t h i nudi k h i c nhau. N u d e tiiii tap t m n g vdo mdt m u o n g thodt n u d e c h u n g va dan ra hd cd l i p dgt he thdng xii ly n u d e thdi theo p h u a n g phdp dang m l .
A o H B T nuoi cd tra giong Hda Binh Thanh, tiiugc Trung tam g i i n g thiiy san tinh An Giang.
N u d e thai dugc xii ly b i n g p h u a n g p h i p Purolite tdc d o cao. Ddy la p h u a n g p h i p xir ly cao phdn tii, cdc chdt d nhiem lo liing hay hoa tan trong nude sau khi xit ly bdng cac hoa c h i t se ldng xudng ddy va se d u g c logi ra ngodi, p h i n n u d e trong se dugc t i i tuan hodn vdo ao nudi cd.
Cac chi tiiu d n h i l m n u d e d u g c chgn d l d i n h gia Uong n g h i i n ciiu nay la: Nhu c i u oxy sinh h o i (BOD5). nhu c i u oxy hoa hgc (COD), tdng c h i t rdn lo lirng (TSS), Ammonia-nitrogen (N-NH3), tdng dgm (TP), tdng lan (TP) va t i n g sd CoIiform/iOO mL. M i u n u d e thai tir c i c ao nudi ca trudc khi xii ly d u g c thu ngay'tgi diem t i l p nhdn nude thai ciia 4 he thdng xir ly; mau nude thai sau khi dd d u g c xir ly qua he thdng xii ly nude t h i i d u g c thu ngay d i u ra ciia he thong xii ly nude thdi. Thu m i u nude t h i i t m d c vd sau xii ly tCr thdi diem thang 9 n i m 2009 d i n thdng 12 n i m 2009 vdi thdi gian 7 ngdy thu mau mdt ldn, tan sudt 11 ldn (mau n u o c p h i n tich 03 lan ldp lai rdi ldy t m n g binfa).
Sii dung p h u a n g p h i p phong van tryc t i l p c i
B a n g 2 : ThdDg tin v e cac faf t h o n g x u ly nirde t h a i d a n g a p d u n g tai cac a o nudi
nhdn bdng phieu d i l u tra k i t hgp khao sdt thue t i . Phdng v i n lanh dao, can bg mdi trudng vd hp nuoi cd, npi dung v l ddnh gia miic dp quan Upng cua c i c y i u td l i l n quan d i n q u y i t dinh d i u t u he t h i n g xii ly nude thai (do ddy la c i c ddi t u g n g cd tinh chat q u y i t dinh n i n chi t i i n h i n h d i i u tra 03 phieu/nfadm ddi tugng, tdng cpng 9 phieu).
3 K E T Q U A V A T H A O LU4.N Cdng nghe x u ly vd cdc y i u td cd l i l n quan den van hanh he thdng xit ly nude t h i i tgi c i c ao nudi ca ehpn nghien ciiu dugc Uinh bdy Uong B i n g 2.
K i t qud pfaan tich mdu n u d e thai ao nudi ed t m d c khi qua he thong xir ly nude thai d u g c trinh bay Uong B i n g 3. H i i u s u i t xii ly cac chi t i i u d n h i i m ciia 04 he thong xii 1^ ao nuoi cd chpn n g h i i n ciiu dugc t h i h i l n Uong Bdng 4. Cac muc tieu liln quan d i n quyet dinh d i u t u he thdng xOr ly n u d e t h i i ao nuoi c i tra dugc Uinh bay trong Bdng 5. Nliu trinh bdy d p h i n Uen, mdt h | thdng x u ly n u d e thai ao nuoi ca Ua hieu qua la h? thdng phii dap iing mgt so myc tiiu c a ban (1) Chi phi d i u t u thdp; (2) Chi phi van hanh thap; (3) Dien tich c i n cho bd Ui he thdng xii ly ft; vd (4) H i | u suit xii ly cao (ty 11 con lai chua xir ly dugc phai thdp).
T r i n thuc t i , he t h i n g xii ly nao cd chi phi d i u tu. chi phf vdn hanh, d i l n tich xii ly, thdi gian xii Iy cGng nhu ty le khdng h i i u q u i ^ h i n cdn lai chua xii ly dugc) cang thap thi he thdng xii Iy dd c i n g cd hieu qud. Tuy nhiin, do ca 04 he tfadng xii ly d i u cd thdi gian xii ly n h u nhau (01 ngay) n i n chi tiiu nay khdng dua vao trong qua trinfa tinh toan hieu qua kinh te. De lap cac budc tinh theo p h u a n g p h i p thu dung, c i n xac dinh cac myc tiiu theo Bang 5. Ket qua tfnh gid tri thu dung theo timg p h u a n g phap x u ly nude thai ao nudi ca tra dugc Uinh bdy tai Bdng 6.
Yeu to D o n vj Kfau nuoi ca t r a Kfau nuoi ca t r a tai xa Pfaii T h u a n tai xa Vinh Binh
K h u nudi ca t r a tai xa L o n g G i a n g
K h u nuoi ed t r a g i i n g Hoa B i n h T h a n h Cdng nghe x u ly
nude thai
Ho l i m thodng k i t hgp thyc vat
Phucmg phap dgng m l
P h u a n g phap vi sinh
Purolite toe dp cao Tong chi phi dau tu
he thong Tong lui?ng n u a c thai x u ly trong ngay Phi nhan cong Phi dien va hoa chat Phi bao d u o n g Chi phi Idiac Thoi gian x u Iv
Trieu dong mVngay dong/thang dong/m-' dong/nam ddng/nSm n.eay
200 44.960 1.000.000 0 4.050.000 0 1
395 25.000 1.500.000 8,45 1.875.000 0 1
330 400 1.500.000 340 0 0 1
52 750 l.SOO.OOO 480 78.000 0 I
r<ip chi Khoa hoc Tnrdng Dal hoc Can Thtr Phdn .A Khoa hoc Ttr nhien. Cong ngbe ra Sloi tnrdng- 2S {20 lii: 11-22 4 Bang 3 : D a o d o n g v l h a m l u o n g cac c h a t 6 n h i e m a o n u o i ca q u a 11 ISn t h u m i a
t Kliu nuoi ca t r a K h u n u o i ca t r a K h u n u o i c i t r a I d u a u d i ca t r a giong H o a T h a m so ^ . ^ p^^^ T b u a n lai xa V i n h B m h tai l a L o n g G i a n e B m h T h a n h 14,0-49,0 66,0- 92,2 4 3 , 0 - 1 5 4 , 0
0 , 2 4 - 1 , 8 9 2 , 7 0 - 3 , 1 0 0 , 2 4 - 5 , 1 0 390.000 - 580.000 B a n g 4 : Hieu su5t TSS ly (%) cac chi tieu 6 n h i l m ciia 04 h e t h o n g \\i ly nirffc t h a i a o n u 3 i
B O D C O D T S S N - N H j T N T P Coliforms T r . b i n h ~ Phu Thuan 45,80
VTnh Binh 38,30 L o n g G i a n g 91,88 Hoa Binh Thanh 62,00
B a n g 5: C a c m u c tieu kinh te lien q u a n he t h o n g s i r ly niro'c t h a i a o nuoi ca t r a BODj
C O D TSS N - N H , TN TP Colifomis
2,6 - 24.0 4 . 0 - 8 0 , 0 25,6 - 1 2 6 , 7 1,26-4,97 2.20 - 8,30 3 , 6 0 - 1 1 , 9 0 1 0 . 0 0 0 - 5 5 . 0 0 0
2,2 - 10,0 6.0 - 72,0 1 0 , 5 - 6 5 , 6 0 . 9 0 - 2 , 2 0 1 , 7 0 - 8 , 7 0 3,00 - 12,00 1 . 2 0 0 - 1 7 . 0 0 0
10,8-198,0 4 6 , 7 - 2 5 0 , 0 9 3 3 , 0 - 11490,0
0,81 - 4,24 1 , 8 0 - 1 0 , 0 0 2,90 - 14.20 1 6 . 0 0 0 - 2 9 . 0 0 0
58,64 44.30 91.72 59.14
68.30 50.00 99,30 62.20
45,00 51,60 54,70 55,80
4 8 p 0 4 7 J 0 58,10 43,20
41,96 46,57 57,65 26,67
77,37 76.67 74.64 44,83
55.08 50.66 75.43 50.55
Hieu suat Chi phi ban d a u
r i ) (VNB)
Cbi phi vSn banh (d/m')
Dien tich
Tong l u o n g T L - - -; . - . T h o i g i a i thai ^ (m"'/ngay) (n^a>
Phii Thuan VTnh Binh Long Giang Hoa Binh Thanh
58.64 44.30 91,72 59.14
200.000.000 395.000.000 330.000.000 52.000.000
1.8 2.700 10,7 1.250 465,0 16 547,0 92
24.800 25.000 400 750 Bang 6: Gia trj thu d u n g theo t i m g p h i r o n g p h a p \\s ly n u d e thai
Ty le khong hieu qua Chi phi dau lu Chi phi van hanh Dien tich he thong xii ly
Phii TfauSu 0.698 O.OOO 0.000 I 000
Vinh Binh 1.000 0.014 0.016 0.353
Long G i a n g 0.000 1.000 0.850 0.000
Hoa Binh Thanh 0.687 0.079 1.000 0 003 Lanh dao
T> le idiong hieu qua Chi phi diiu tu Chi phi van hanh Dien tich he thona XTi K Sum
Xep hang
0.091 O.OOO 0.000 0.250 0 341 2
0.130 0.003 0.007 0.088 0.228 1
0.000 0.220 0.340 0.000 0.560 4
0.089 0.017 0.400 0.001 0.507 3 Doanh nghiep
Ty ie khong hieu qua Chi phi dau tu Chi phi van hanh Diln tich he thong xu h' Sum
0.160 0.000 0.000 0.250
0.230 0.003 O.0O5 0.088
0.000 0.220 0.255 O.OOO
0.158 0.017 0.300 O.OOI X e p hang
Can b o moi tniimg
1 Ty le idiong hieu qua
Chi phi dau t u Chi phi van hanh Dien tich he thong xii Iv Sum
XIpliViiB
0.453 O.OOO 0.000 0.120 0.573
0.650 0.002 O.OOI 0.042 0.696
0.000 0.140 0.076 0.000 0.216
0.447 0.011 0.090 0.000 0.S4S
Tap chi Khoa hgc Tnr&ng Dai figc Cdn Tha Phdn .4-Khoa hoc Tir nliien. Congnghe vd Moi tnrang- 28 f 2013/ l~-22 Ttr cic dilu kiln nlu Uln vi kit qud trinfa
biy tgi Bing 6 cho thdy: he tfadng xii ly nude thai ao nudi ca VTnh Binfa dgt hieu qui nhdt vd theo thii tu tilp theo la he thdng xii ly nude thai Phii Thuin, he thdng xii Iy nude thii ao nuoi ca Long Giang vi cudi cung li he thdng xii ly ao nudi ca Hda Binh Thanh.
Thyc tl nghiin ciiu trong khudn khd de tai niy cho thay gia thuyet ban diu d^t ra la hgp ly va phii hgp thuc tien. Kit qud dk tdi di chiing minh dugc rdng Uong truong hgp hp nudi ci cd dugc mgt dien tich vira phii thi he thdng hd lam thodng nhin tgo kit hgp thuc vgt thiiy sinh (nhu he thdng xii ly ao nudi VTnh Binh) li phucmg an uu tiln do co thi xu ly mdt lugng nude thii tuong ddi ldn, nhu ciu di|n tfch dat vira phai (khoang 10% tdng diln tich nudi), chi phi van hdnh cho xu ly thip, cdng nghe xir ly don giin, chi phi hda chat vd ndng lupng thdp - ddy cung chinh li nhtrng tiiu chi ma ngudi nudi ca trin dia bdn tinh An Giang ddt ra ddi vdi mgt hi thdng xix ly nude thai cd thi chdp nhgn ddu tu.
Trudng hgp quy dat ciia hd null con tuang ddi ldn thi viec dp dung ho lim thodng tu nhiin kit hgp thyc vat thuy sinh (nhu he thdng xii ly nude thii ao ci Phii Thuan) ciing li phuong an dugc xem xet chpn do cd the xii ly lugng nude thii ldn, khdng tin chi phi hda chit va nang lugng vd die biet cdng nghe nay rdt don giin, khdng cin cdng nhin van hanh, chl dinfa ky vl sinh logi bdt lugng thuc vit thiiy sinh trong ao, dam bdo mat dp phii hgp phuc vy cho qui Uinh xii ly tdt han.
Cic h | thong xir ly sinh hgc kit hop hoa ly, mic dil hi|u qui xur Iy c6 cao hon he thdng xii ly bang dat ngap nude hodc hi ldm thoang nhu neu Uen, tuy nhien do khdu van hanh khd phiic tap, ddi hdi cdng nhan phii cd kiln thiic co bin vi mgt nhugc diim niia la chi phf van hdnh he thdng khd cao - ddy la diim md cac hi nudi ca khd chdp nhan diu tu. Nhin chung. cd 04 he thong xii ly nude thai trong pham vi nghiin ciiu deu con nhung tdn tai can cd diiu chinh, bd sung phii fagp mdi cd kha ndng dat hieu qud xu ly tdt hon.
4 KET LU^N VA DE XUAT
Phuang phap thu dyng dugc ap dyng kha phd biin Uong bai toan kinh tl tai nguyin nude. Nghiin ciiu nay cho thay phuang phdp thu dung cung cd the dugc phdt triln cho trudng hgp lya chgn giai phdp phii hgp uong nudi uong thiiy sin khi can bo qudn ly ngdnh tdi nguyin va mdi trucmg cung nhu ngudi ndng dan phii can nhdc lya chpn hgp ly giiia cic thdng sd ciia yeu td kinh tl. moi Uudng vi quin K he thdng.
Tuy nhiin lua cfapn Uong nghien ciiu nay cd the se khdng phii hgp Uong tuang lai neu cd su bien ddng dang kl ciia phuang thiic canh tac ci tra. biln ddng dit dai, gia ci thi trudng, dieu kien quin ly he thong nuoi trong thuy sdn,... Khi dd, cdc gia tri Uong bdi todn, tien uinh tinh toin va chpn h? sd gia Upng phai dugc dgt lai.
Mdt sd de xuat qua nghiin ciiu nay:
- Can nghien ciiu b6 sung thim ho$c dilu chinh mgt so cong dogn trong quy trinh xii ly ciia cua 04 fae thdng xu ly nghien eiiu nhu bd sung them cdng dogn xii ly vi sinh trudc khi thdi nude ra ngudn tilp nhgn (song, kinh rgch) vi hiu hit cic he thdng xii ly deu cd nong dp Coliforms ddu ra cdn vugt kha cao so tieu chuan quy dinh hodc doi vdi he thong xii ly ao nudi ca Long Giang thi can nghien ciiu Uang hi thim mdt bon chiia hoic ho chiia cd thi tich phii hgp nhdm lang cdn vd dn dinh nude trudc khi bom qua diy chuyin xii ly chinh.
Can nghien ciru img dung thir nghiem thim mpt s6 cdng ngh| xii ly nude thai khdc da va dang ling dung tai mgt sd tinh hoic nghiin ciiu cong nghe mdi iing dung thu nghiem Uong dilu kiln ciia tinfa An Giang dl so sdnh hieu qua Vy thugt cung nhu hieu qua kinh tl cua chiing nhim chgn loc dugc mOt phuong phip xii' ly toi uu nhdt.
TAI LIfU THAM KHAO
1. Cue Thdng kl tinh An Giang (2010). Nien gidm thdng ke 2009. An Giang.
2. DangNgpcThanh(1974). Tliiiysinhhge dgi cuong. Nha xuit bin Dgi hpc vi Trung hpc chuyen nghiip Ha Ndi.
3. Dang Nhu Toan (1997). A/d? 50 vdndeca ban ve kinh te vd qudn ly mdi trudng. Nha xudt bdn Xay dung.
4. Dupnick, Edwin (1970). Water Reallocation in the Sahnarita-Continental Area. File report 324-H, System Engineering Department, the University of Arizona, Tucson.
5. Lesoume, Jacques (1964). Le calcul Economique. Dunod, Paris, France.
6. Nguyen Xudn Thanli (2003). Cugc chiin Catfish: Xudt khdu cd tra vd cd basa cua Viit Nam sang thi trudng My. Case study in Fulbright Economics Teaching Program.
7. Trin Hiru Uyin, Trin Vilt Nga (2000). Bdo vi vd sit dicng ngudn nude. Nha xuat ban Nong nghiep Ha Npi.
