KHOA HOC CONG NGHE
T H U C iXIGHIEIVI IJIXIG DLJIXiG COIXIG IXIGHE B I O F L O C IXIUOI T H A M C A I X I H C A R d P H I TROIXIG M O I TRUOIXIG IXIUOC L O
Nguydn Xuan Thanh^- ^, Dao Thi Anh Tuy^t^' ^ L6 Minh Hiep^
Ld Diic Cdng^, D$ng Minh Dihig*
T6MTAT
Thir nghi&m nuoi ba ao ca ro phi trong moi tnrong nirdc lo, dien tich 200 m^/ao. Trong do ao nuoi I va ao nu6i II ap dung cong ngh? biofloc (BFT) voi mat 36 tha b m6i ao tU(3Tig ung la 6 con/m^ va 8 con/ml Ao nuoi III khong ap dung BFT (ddi chung) nuoi theo cong nghe thay nude pho bi^n hien nay, mat do nuoi 3 con/m^. Ket qua cho thay cac yeu td m6i trucmg nhuTAN.TSS, NO^- N, NO3- N. NH^-N, BOD, COD trong ao nuoi ca ro phi ap dung BFT tdt hon so vai ao khong ap dung BFT (P < 0.05). Sau 5 thang nuoi, tir kich co gidng tha ban dau 3,3 ± 0,41 g/con, d^n khi thu hoach kich co ca trung binh d cac ao tuong img la ao I:
646,3 g/con; ao II: 568,7 g/con, ao III: 659,7 g/con. Nang suat ao nuoi I dat 37 tan/ha; ao II dat 43 tain/ha;
ao ddi chiing dat 18 tan/ha. Hieu qua kinh te cua nhimg ao nuoi ap dung BFT cao hon so vdi ao khong ap dung BFT vdi loi nhuan rdng cao hon tir 5,8 - 6 lan, ty suat loi nhuan cao hon tir 2,93 - 3,78 lan. Ket qua nghien ciiu gop phan khang dinh hieu qua cua viec ling dung BFT vao nuoi ca ro phi tham canh trong mdi trudng nude lo, la co sd ti^p tuc nghien ciiu xay dung nhan rdng rod hinh nuoi ca ro phi bang BFT trong moi trudng nude lo.
Tirkhda: Card phi, cong ngh€ bioEoc (BFI), nude la.
I.MffDAU
Biofloc la tu viet tat cua ttr tieng Anh Bioflocculation (ket bdng sinh hoc). Biofloc trong cong ngh6 biofloc (Bioflocculation Technology BFT) dung de chi tap hpp vat chat hiru co lo limg trong nude bao gdm tao, ddng vat nguyen smh va vi sinh vat, hong do chiem uu the la vi sinh vat di dudng, duoc gan kdt vdi nhau bang chat keo smh hoc polyhydroxy alkanoat (PHA) [6]. BFT dua hen nguyen ly bo sung nguon cacbon theo mpt ty 16 phu hpp vdi lupng nito san co hong nude ao de lam thiic an cho vi sinh vat di dudng cd ti-ong ao, tao dieu kien cho nhom nay phat trien chiem im the. Vi sinh vat d|
dudng se chuyen hda cac hpp chat chua nito trong nude ao thanh protem cd trong biofloc, nhd do tai su dung duoc ngudn mta tir chat thai hda tan ti-ong nude ao, chuyen hda thanh sinh khoi thuc an tir nhien cho ca nudi, lam tang hieu qua sir dung thiic an nuoi ea.
giam thi^u 6 nhiem moi hudng. Tap hgp cac biofloc la ngudn thiie an tu nhi6n giau dmh dudng, chua eac axit b6o thiet y^u, carotenoids, axit amin hi do eac
' Vi?n Tai nguyen va Moi trudng bien, Vien H^n lam KH&CN Viet Nam
^ Hoc vien Khoa hpc va Cdng ngh?
^Trudng Cao ddng Kinh ik Ky thuat va Thiiy san
"Vien Nghien cmi Hai san Email: [email protected]
khoang chat vi lupng va vitamin C [7]. Do dd, BFT la mdt giai phap cong nghe sinh hpc mdi gop phan phat trien nganh nuoi trong thuy san theo hudng ben vimg, an toan sinh hoe va than thien vdi mdi trudng [2,3].
Ca rd phi la loai rong mudi, rpng nhiet cd kha nang chiu dung vdi su bien dpng di6u kien mdi trudng tuong doi Idn. Ca rd phi an tap, pho thuc an rdng, thiic an d cac tang nude do vay, ca ro phi la loai nudi phii hpp vdi cdng ngh6 biofloc de chiing sii dung cae hat biofloc tao ra tir viec tai sir dung chat thai chiia mta trong ao [5]. Tuy nhi6n, trong h6 thdng nudi biofloc phai van hanh lien tuc thiet bi quat nude sue khi, dam bao dii 6 xy hoa tan cho ca nudi, vi sinh vat hoat ddng binh thudng va cac hat biofloc lo lung d trong nude, lam tang chi phi dau tu ea sd vat chat, hang thiet bi, eong trinh nudi liic ban dau. Viec ling dung cdng nghe biofloc doi hoi ngudi nuoi can phai CO nhiing hieu biet nhat dinh vk cdng nghe, ddi tupng nudi, dieu kien mdi trudng sinh thai va can dupe tap huan day du cac ky thuat de van hanh he thdng CO hieu qua
Bai vi^t nay se cung cap eac ket qua nghien eihi ap dung cdng nghe biofloc nudi ca rd phi tham canh trong mdi trudng nude lo, gop phan khang dinh hieu qua ciia viee img dung BFT vao nuoi ca rd phi, tao CO sd tiep tiic nghien ciiu, hieu chinh hoan
83
KHOA HOC CONG NGHE thien, ky thuat, xay dung, nhan rdng md hinh nudi ca
rd phi trong mdi trudng nude Ig bang BFT.
Z.PHUDNBPHAPNGHByCUU 2.1. Thdi gian va dia di^m thuc hifen Thdi gian nghien ciiu: 01/5/2019 - 20/10/2019.
Dia diem nghien ciiu: Co sd thuc nghiem cua Vien Tai nguyen va Mdi trudng bien (phirdng Bang La, quan Dd Son, thanh pho Hai Phdng).
2.2. Bd h i thi nghiem
Thuc nghiem nudi ea rd phi ap dung theo dtr thao Quy trinh ky thuat ling dung cdng ngh§ biofloc (BFT) nudi tham canh ca rd trong mdi trudng nude Ig. Thi nghiem dugc thirc hien tren 02 ao ap dung BFT va 01 ao nudi ddi chiing khdng ap dung BFT, dien tich 200 mVao.
Ao duoc lot bat HDPE toan bg day va bd ao duoc bd tri he thdng sue khi day va quat nude (Hinh 1).
Hinh 1. Ao nudi thyc nghiem Do man nude ao nudi cap ban dau 8%o da dugc tao biofloc.
Tao biofloc bang each su dung hon hgp ri dudng, thiic an nudi ca, bdt dau nanh (ty le 3:1:3) dupe nau chin, d^ d chd mat (nhiet do 25''C), (30 g ri dudng chiia 50% carbonhydrate (C) : 10 g thiic an dp dam 3596 : 30 g bdt dau nanh/m' nude) sau do sii dung hdn hpp nay u vdi che pham smh hpc cd chua chiing vi khuan Bacillus spp. chua mat dd vi khuan>10' CFU/g (su dung san pham CP-Bioflus 30 g / m ^ . Qua trinh u duoc tien hanh ti-ong didu kien sue khi. khuay dao trong 48 gid de len men, sau dd dua vao ao nudi lien tuc trong 3 ngay, mdi ngay mdt lan vao liic 9 - 1 0 gid sang. Khi nude ao dat dp trong
30 - 40 em tien hanh bd sung chd pham voi thanh phan ehu yen la vi khuan Bacillus spp ehua mat dd vi khuan>10^ CFU/g lien tiic ti-ong 3 ngay vao Itic 10 gid, Iirgng che pham sii dung la 0,15 g/mVngay cho den khi ao nudi xuat hien biofloc, kiem tra ehi sd FVI (Floe Volume Index) bang phdu Idng dat 0.1 - 0,2 ml/L thi dimg tao biofloc.
Mat dp nudi: Ao 1: 6 con/m^, Ao il: 8 con/m^, Ao III: 3 eon/m^ (ao ddi ehirng, nudi theo quy trinh thdng thudng, khdng ap dung BFT. Quy trinh ky thuat nudi ca rd phi nude Ig thdng thudng hi6n nay dang dugc ap dung nudi vdi mat dd 3 eon/m^, nude duac thay thudng xuyen ke hi thang nudi thii 3, trung binh 1 tuan thay nude 1 lan, lugng nude thay bang 1/3 luong hong ao de bao dam chat lugng nude)
Ca gidng dua vao lam thi nghidm la gidng ca rd phi don tinh due la ket qua lai xa khac loai giira ca bd Oreochromis aureus va ca me Oreochromis niloticus. c a gidng da dupe thuan hda dp man, khdi lugng ca gidng tha ban dau 3,3 + 0,41 g.
Tien hanh thi nghiem:
Duy tri biofloc trong ao nudi bang viec bd sung carbonhydrate va che pham smh hpc chiia ehung vi khuan chu yeu la Bacillus sp., vdi mat do vi khuan>10^ CFU/g, dinh ky tudn/lan. Ch^ pham sii dung san pham CP-Bioflus, lugng che pham 0,15g/mVlan. Nguon eac bon la mat ri dudng chua 50% carbonhydrate (C). Xac dinh luong carbonhydrate bd sung theo Avnimelech, 2007 [4].
Cdng thuc de ling dung tinh nhanh luong C (ri dudng) bd sung hong ao nudi nhu sau:
X = [C/N (% p„,„„ X % N , , „ J - %C ^ ^ ^]/%C ri
dinmg
Trong do: X la sd lupng ri dudng edn them vao de dat ty le C/N mong muon; C/N la ty le ean dat; % N|,rote,n la ham lugng nito cd trong Ig protein; % C jhuc an la % cac bon trong thanh phan thuc an; % C „ dirmg la
% cac bon trong thanh phan ri dudng.
Theo hudng dan ciia Avnimelech, 2012 [3] va cae ket qua nghien eiiu xac dinh ty le C/N trong he thdng BFT nudi ca rd phi nude Ig ciia nhdm tac gia chira duoe cdng bd, da xac dinh ty le C/N = 15/1 la phu hpp. Ri dudng ehua 50% carbonhydrate, luong ri dudng duac bd sung tir 30 - 40% lirong thuc an cho ca an, tinh tu lan bd sung ri dudng trudc tiiy theo dd dam trong thiic an, dinh ky bd sung 1 tuan / I Idn 84 NONG NGHIEP VA PHAT TRIEN NONG THON - KY 1 - THANG 6/2020
KHOA HOC CdNG NGHE Cho ca an: Su dung thiic an cdng nghiep dang
ndi, khdng tan trong nude eua tap doan thiic an fliiiy san CF Group. Giai doan dau su dung thiic an cd dp dam cao tir 30 - 35% (ham lugng protem thd trong thirc an) khi ca Idn tren 300 g/eon cho an thiic an cd dp d^m thtip hon (thiic an cd do dam 18 - 20%). Cho ca an 2 Idn/ngay vao Itic sang sdm va chi^u mat (7 g i d v a l 6 g i d ) . Khi khdi lupng ca< 100 g/con, cho an 5 -7% tdng khdi lugng ca hong ao. Ca dat khdi luang
> 100 gr cho an 3 - 4%. Khdi lugng ca > 300 g cho an 2%. Lugng fliiic an cho an tiiy thudc vao tmh hinh thdi tiet va siic khoe eua ca, lugng thuc an ca an trong 1 gid la du.
Trong qua trinh nudi tiiy timg dieu kien thuc te tien hanh cap them lupng nude do qua trinh bdc hai hoac xa bd biofloc Idng dong, dam bao dd sau muc nude hong ao on dinh 1.3 m.
Theo doi thi nghiem:
Cac yeu td mdi trudng nhu nhiet dd, pH, DO, dp man, dp kiem duac quan trde lien tue hang ngay, de kip thdi di^u ehinh trong ao nudi.
Cac yeu td TAN, TSS , NO,, NO3, BOD, COD quan trde 1 tudn/lan.
Ki^m h a tdc dp sinh trudng eua ca nudi 15 ngay/lan.
Thu mSu biofloc de xac dinh chi sd the tich (FVI)lhian/ldn.
Theo ddi ddy du lupng thiic an cho ca an hang ngay d cac be thi nghiem.
Danh 0a cac thinghi€m:
Cae ehi tidu danh gia thi nghiem gdm:
+ Ty le sdng eua ca (S - %).
+ Tang trudng khdi luong cua ea (WG).
+ Tdc dd sinh trudng tuong ddi ciia ca (SGR -
%/ngay).
+ Tde dd sinh trudng tuyet ddi ciia ea (DGR - gr/ngay).
+ Thuc an tieu thu theo khdi lupng khd (DFI) (g/con).
+ Hieu qua su dung thiic an: he sd thiie an (FCR); hieu qua su dung protem (PER) (g/g).
2.3. Phuong phdp phan tich
Cae ydu td mdi trudng n^n duac do true tiep bao gdm cae thdng sd nhiet dp, pH, DO, dp man, dd kiem bang may do nhanh hoac Test kit ciia SERA.
cac yeu td mdi trudng dinh dudng gdm, tdng nita dang amonia CTAN), tdng chat rdn la liing CTSS), nihite (NO2), niti-ate (NO3), nhu cau d xy sinh hda (BOD), nhu edu d xy hda hpc (COD) dugc thu, phan tieh mdu va xu ly sd lieu ddi vdi timg thdng sd theo tai lieu hudng ddn ciia APHA, 1998 "Standard methods for the examination of the water and wastewater (22nd ed.) [1].
Phuong phap xac dinh chi sd the tieh Biofloc (FVI) bang phdu do hnhoff de lang 20 -30 phut.
Phuong phap danh gia tang trudng eiia ea nudi va hieu qua sir dung thiic an.
+ Tang trudng khdi lugng cua ea (WG) (g) = Khdi lugng ea trung binh liie thu Wf (g) - Khdi lupng trung binh ea luc tha Wi (g).
+ Tdc dp smh trudng tuong ddi ciia ca (SGR -
%/ngay) tinh theo edng thiie sau:
SGR (%.ngay-0 -
(LnWf -LnW,) xlOO + Tdc dp sinh trudng tuyet ddi cua ea (DGR - g/ngay) tinh theo edng thiie sau:
(Wf-VVil
DGR(g.ngay-l) =
Wi va Wf theo thu tu la khdi luong Idn trudc va khdi lugng Idn sau; t Id sd ngay theo doi thi nghiem.
+ Xac dmh ly Id sdng (%) va nang sudt cd nudi sau khi kdt thuc thi nghiem.
Ty le sdng (%) = (sd ca con sdng/sd ea tha nudi) xlOO.
+ He sd tieu tdn thiic an FCR
FCR = Tdng lugng thtrc an da cho ca an /tdng luong ca tang them lue thu hoaeh.
+ Thiie an tieu thu theo khdi Itrpng khd (DFI).
DFI (g/con) = Tdng lupng thiic an tieu thu hang ngay (g)/sd ca nudi.
+ Hieu qua sii dung protein (PER): PER = WG /protein tieu thu (g).
+ Lgi nhuan = Tdng doanh thu - Tdng chi phi.
KHOA HOC CONO NGHE + Ty suat lgi nhuan (%) - Loi nhuan/Tong chi
phi X 100.
+ Loi nhuan bi^n {%) = Lgi nhuan/Tong doanh thu X 100.
+ Gia thanh san pham (dong/kg) = Tong chi phi/ san luong ca.
2.4. Phuong phdp xii ly s6 li6u
Su dung phdn m^m ung dung Microsoft Office Excel 2010 de phan tich, tinh toan, xu ly so lieu, ve bi^u do, do thi. Dimg phuong phap phan tich phuong sai (ANOVA) de Idem dinh su sai khac co y nghia cac yeu to moi truang trong cac ao nuoi thii nghiem.
S.KErgUANGHBICUU
3.1. Bi& dOng cic y^u td moi truing trong ao thi nghiem
3.1.1. Ket qua quan trie cac yeu td mdi truong nin.
K^t qua quan trac cac yeu to moi trudng nen the hien tai bang 1.
Bang 1. Bi^n dOng cic y^u t6 moi trudng n^n trong qua trinh thi nghifem
Yeu to moi Uumig Nhiet CC) pH (1-14) DO (mg/1) Do man (««)
30.8 + 0,5 (29,2 ^- 32,4)
8,13+0.25 (7.56 T 8.54)
4,66+1,22 (3,23 + 6.58)
(2-i-8)
30,8+0,5 (29,2 + 32.4)
8,11+0.23 (7.48 + 8.45)
4,97+1,22 (3,11 + 6.95)
(2 + 8)
30,8+ 0,5 (29,2 + 32,4)
8,25+0,15 (7,99 + 8.56)
4,71+1,17 (3.21-7.12)
4,5+2,1 ( 2 - 8 ) Cac ket qua tai bang 1 cho thay, tai cac ao nuoi nhiet do dao dpng tir 29,2 - 32,4''C. pH tii 7.5 - 8,5, DO tir 3,11 - 7,12 mg/1. Do man nuoc ao bien dong tir 2 - 8%o, luc ban dau 8%o sau do giam dan. den liic thu hoach do man chi con dat 2%o do anh huong ciia mua va bo sung them nuoc, do man giam xuong trong qua trinh nuoi. Cac yeu to moi truong n^n quan trdc duoc phii hop cho ca ro phi sinh tnrong, nam trong khoang thich hop cho biofloc phat trien [8.10,11],
3.1.2. Kit qua quan trie cac yeu td dinh dudng ti-ong nidi trudng.
Ket qua theo doi cac yeu to dinh duong trong moi truong qua cac dot quan trSc tai cac ao thi nghiem the hit^n tai bang 2.
TAN (mg/l) TSS (mg/1)
Bang 2. Kft qua theo dsi cic yAi t6 dinh duOng trong mdi trudng tai c i c ao thi nghigig Yeu td moi
truong
NO, - (mg/1) NO,-N (mg/1) NH,-N (mg/1) BOD (mg/1) COD (mg/1)
0,66+ 0,27' (0,23^1,18)
" 2734 + 67,6' (90,7 + 378.5) 0,13+0,06' (0,01 - 0,28) 2,22 + (0,18- 0,03 + 0,02 (0,00 + 0,09) 6,55 + 2.29' 11,9+10,2) 8,16 + 4 , 0 1 ' (3,8 17.3)
0,69 ± 0,25' (0,26 + 1,281 289,4 (132.7
b 69,0"
- 392.6) 0.17+0,09' (0.01 + 0.36)
2.47±1.27' 10.21-4.67)
0.03+0.02' 10.00 + 0.09) 6.84+2.34' ( 2 . 9 - 1 1 , 6 )
(0,12^1,98) 204.7 ± 75,6' (38,7 + 331,3) 0,24±0,13' (0,02 + 0,56)
3,36+2,02"
(0,25 + 7,79) 0,06+0,03' (0,00 + 0,15) 8,11:
(3,6 H 3,' 16,5) 12,28 + 7,11'
(3,9 + 25,8) Ghi chu: Sd heu cd cac chu cai in thudng khac nhau trdng cimg mdt hang cho thay sukhac biet cd y nghia thdng ke (P<0,05). Sdlieu cd chUcaiin thudng gidng tiong cimg mdt hang cho thay khdng khac biit coy nghia thdng ki (P>0,05).
Trong cac ao nuoi, TAN co xu huong tang d^n theo thoi gian nuoi, Ao nuoi so I bidn dong tu 0,23 - 1,18 mg/1, trung binh 0,66 mg/1. Ao nuoi so II bien dpng tit 0,26 - 1,28 mg/1, trung binh 0,68 mg/L Ao s6 III (ao ddi chiing) TAN bidn ddng tir 0,12 - 1,98 mg/1, trung binh dat 1,12 mg/1. Trong cic ao thi nghiem ap dung BFT, TAN giam sau khi bo sung ngudn cacbon la mat ri dudng va che pham sinh hoc (CP bio plus), biofloc phat trien, vi k h u i i di dudng da CO sinh khdi Idn de hap thu nito tao thanh cac hat floe. Trong BFT, yeu td TAN trong mdi trudng dugc Emerenciano etal. (2017), Azrni va Little (2008) de nghi nen duy tri ham lutmg TAN dudi 1 mg/L trinh ddc hai vol smh vat nudi [5, 9], Vi vay, TAN dugc thudng xuyen theo ddi va didu chinh cho phii hgp.
Ket qua theo ddi gii tri TSS trong qua trinh thi nghiem cho thay, TSS cOng cd xu hudng tang cao g cudi vu nudi so vdi dau vu nudi. Thdi gian dau vu nudi TSS tang len, sau dd qua trinh hut bd biofloc va thdm nude mdi TSS duy trinh dn dinh. Ao nudi I, TSS bien ddng tir 90,7 - 378 mg/1, trung binh 273,4 mg/1.
Ao nudi II bien ddng tir 132,7 - 392 mg/1. trung binh 289,4 mg/1. Ao nudi III ham luong TSS, bien ddng tir 38,7 - 331,3 mg/1, trung binh 204,7 mg/1 thap hon cd y nghia thdng ke (P<0,05) so vdi hai nghiem thiic thi nghiem. O cac ao nudi TSS nhd hon 500 mg/1 nim
86 NONG NGHIEP VA PHAT TRIEN NONG THON - KY 1 - THANG 6/2020
KHOA HOC CONG NGHi trong gidi han d^ nghi cua Emerenciano etal (2017)
[91.
Bien ddng cua ham lugng nitorite d ao nudi I tu 0,01 - 0,28 mg/1, tiung binh 0,13 mg/1. 6 ao nudi II ham lugng nitonte bien ddng tu 0,01 - 0,36 mg/1, hung binh 0,17 mg/1. Ao ddi chiing ham lugng nitorite bien ddng tu 0,02 - 0,56 mg/1, trung bmh dat 0,24 mg/1, cao hon cd y nghia thdng ke (P<0,05) so vdi hai ao thi nghiem. 6 cac ao nudi nitorite dugc kiem soat nhd hon 1 mg/1 nam trong gidi han de nghi ciia Emerenciano et al (2017) [91. Bien ddng ham lugng nitorate d ao nudi I tir 0,18 - 4,33 mg/1, hung binh 2,22 mg/1/. Ao nudi II bien ddng tu 0,21 - 4,67 mg/1, trung binh 2,47 mg/1. Ao nudi HI ham lugng nitorate bien ddng tir 0,25 - 7,79 mg/1 cao hon CO y nghia thdng ke (P<0,05) so vdi hai ao thi nghidm. O cac ao nudi nitorate dugc kiem soat nhd hon 20 mg/1 nSm trong gidi han de nghi cua Emerenciano et al., 2017 [91. Bi^n ddng NH3 tai ao nudi I hr 0 - 0,09 mg/1, trung binh 0,03 mg/1, ao nudi II ham lugng NH3 bien ddng tir 0 - 0,09 mg/1 trung binh 0,03 mg/1. Ao nudi III (ao ddi chung) ham lugng NH3 bien ddng tir 0 - 0,15 mg/1, trung binh 0,06 mg/1, cao hon cd y nghia thdng ke (P<0,05) so vdi cac nghiem thuc thi nghiem.
Bien dd dao ddng BOD hong cac ao nudi thudng thap d dau vu va tang dan d cudi vu, gia tri cao nhat d hai ao thi nghiem tuong ung la 10,2 mg/l va 11,6 mg/1, d ao ddi chung la 16,6 mg/1. COD hong ao nudi ca cung tang dan tii' dau vu den cudi vu, nguyen nhan cua hien tugng nay la do theo thdi gian nudi su gia tang lugng thirc an thira, san pham phan huy, san pham bai tiet cua ca, sinh vat chdt. Lugng COD cao nhat d ao I la 17,3 mg/1, ao II la 18,1 mg/1 va d ao ddi chung ham lugng COD cao hon cd y nghia thdng ke (P <0,05) so vdi cac ao thi nghiem, dat cao nhat 25,8 mg/1. 6 cac ao nudi ham lugng BOD va COD dugc kiem soat nam trong gidi han cho phep theo QCVN 02- 26 : 2017/BNNPTNT [11].
Nhu vay, hi cac kdt qua quan \xic cac yeu td mdi hudng cho thay, hidu qua lam sach mdi tnrdng cua cac ao nudi ca rd phi ap dung BFT tdt hon so vdi ao ddi chiing khdng ap dung BFT. Viec ap dung BFT nudi ca rd phi da kiem soat tdt cac yeu td mdi tnrdng gdc nito sinh ra tii ngudn thuc an du thira, xac chet va san pham bai tiet cua cac smh vat cd trong ao, duy hi chat lugng nude tdt, giam chi phi thay nude so vdi ao ddi chiing.
3.2. Bi^n ddng chi sd th^ tich biofloc (FVI) Kdt qua theo doi bidn ddng chi sd the tich biofloc trong cac ao nudi the hien tai hinh 2.
Ket qua cho thay chi sd th^ hch biofloc (FVT) dugc tang theo thdi gian trong qua trinh nudi. Cudi vu nudi FVI dugc duy tri hi 40 - 60 ml/L, day la nguong phii hgp cho ca rd phi sir dung cac hat biofloc lam thirc an [3, 5].
17 18 19 20 21
Hinh 2. Bidn dOng chi sd th^ tich biofloc (ml/L) trong c ^ ao nudi
Tai ao nudi I va ao nudi II ap dung BFT vdi mat do nudi 6 con/m^ va 8 con/m^, gia tri FVI khdng cd su khac biet cd y nghia thdng kd (P>0,05) giira hai ao. Ao nudi I gia tri FVI bien ddng tir 12,1 -55 ml/L, ao nudi II, FVI bien ddng tir 14,6 - 57 ml/L. 6 ao nudi III (ao ddi chiing khdng ap dung BFT), FVI thap hon cd y nghia thdng ke (P < 0,05) so vdi cac ao nudi ap dung BFT, gia t n FVI bien ddng tir 1,5 - 31,7 m l / L
3.3. Sinh hudng ciia ca
Ket qua theo ddi sinh tnrdng khdi lugng cua ca rd phi tai cac ao nudi thuc nghiem tai hinh 3.
i
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Hmh 3. Tdc dp smh tnrdng khdi lugng ciia ca trong c4c ao nudi thi nghiem
NONG NGHIEP VA PHAT TRIEN NONG THON - KY 1 - THANG 6/2020 87
KHOA HQC CONG NGHt
dat 568,7 g/con, ao ddi chdng nudi 3 con/m" ca dat trung binh 659,7 g/con.
Sau 5 thang nudi ca dat kich ca trung binh d timg ao cd su khac nhau, ao I nudi mat dp 6 con/m^
ca dat trung binh 646,3 g/con, ao H nudi 8 con/m^ ca
Bang 3. Sinh trudng tuong ddi - SGR ftngiy') vA sinh trudng tuyCt ddi - DGR (g .ngay') Sd ngay theo
doi 16 15 16 16 15 15 15 15 15 16 TB
Ao SGR («.ngay')
14,39 2,93 2,41 4,48 1,58 1,66 1,45 2,46 1,82 0,58 3,38
nudi I DGR (g .ngay')
1,86 1,21 1,51 4,93 2,74 3,69 4,06 9,28 9,44 3,60 4,23
Ao nudi II SGR (%.ngay')
13,81 3,27 2,32 3,79 1,51 1,78 1,27 3,05 1,37 0,63 3,28
DGR (g .ngay')
1,73 1,31 1,43 3,82 2,28 3,44 3,09 10,31
6,41 3,42 3,72
Ao nudi III SGR (%.ngay')
14,58 2,87 2,51 4,83 1,48 1,90 1,09 2,53 1,68 0,41 3,39
DGR (g .ngay')
1,92 1,22 1,61 5,69 2,81 4,63 3,31 10,15 9,19 2,61 4,31 Ao nudi I nudi theo BFT mac du cd mat do nudi
6 con/m^ gap hai lan mat dd nudi theo quy trinh ky thuat thdng thudng d ao nudi III, nhung tdc dd sinh trudng d hai ao tuong duong nhau. Nhu vay, nudi ca bang BFT se nudi duoc vdi mat do cao hon, cho nang suat Idn hon he thdng nudi thdng thudng. Trong cung hd thdng BFT vdi mat dd thap d ao I cd tdc dp sinh trudng nhanh hon so vdi nudi d mat dd cao d ao II.
3.4. Khai toan hidu qua kinh td khi ap dung BFT nudi ca rd phi trong mdi trudng nude Ip quy md thu nghidm
Ket qua d bang 4 cho thdy hd sd thiic an (FCR) d ao nudi I la 1,22; ao nudi II la 1,31 va ao ddi chung nudi theo quy trinh thay nude, khdng tao hat floe lam thiic an cho ca ro phi he sd thiic an tang len den 2,01.
Thiic an tieu thu theo khdi luong khd (DFI) o ao nudi I la 0,8 kg thiic an/con/154 ngay; ao nudi II la 0,7 kg thuc an/con/154 ngay; ao nudi ddi chiing la 1,2 kg thiic an/con/154 ngay. Hieu qua sii dung protein (PER) d ao nudi I la 3,18 kg ca/kg protein, ao nudi II la 3,03 kg ca/kg protein, ao ddi chung la 2,03 kg ca/kg protein. Nang suat ca d ao nudi I dat 37 tan/ha; ao nuoi II dat 43 tan/ha, ao ddi chiing dat 18 tan/ha. Cd the thay rang hieu qua sir dung thuc an, protein, loi nhuan, ty suat loi nhuan, loi nhuan bien d nhung ao nudi ling dung BFT cao hon so vdi ao nudi
khong ung dung BFT, trong dd ao nudi I cho gia hi cao nhat va hieu qua kinh te nhat (Bang 4).
Bang 4. Kdt qua theo doi cdc chi tidu d cAc ao thii nghidm nudi ca rd phi
Chi tieu theo dOi Tdng lugng ca tang them (kfi) Luong thiic an tieu thu (kg) Luang protein tieu thu (kg) FCR
DFI (kg/con/154 ngay)
PER (kg/kg) Ty le sdng (%) Nang suat (kg/m^
Tong chi phi (dong)
Tdng doanh thu (dong)
Loi nhuan (ddng) Ty suat loi nhuan
00
Loi nhuan bien (%) Gia thanh san xuat (dong/kg ca)
Ao nuoi I 743,2
910 234 1,22 0,8 3.18 96,3 3,7 17395.000 24.750.000 7355 000 42.3 29.7 23.283
Ao nuoi II 856,1
1125 282,75
1,31 0,7 3,03 94,6 4,3 21.360.500 28.380.000 7.019.50O 32.9 24,7 24.792
AoIII (BC) 363,5 730 178,7 2,01 1,2 2,03 92,3 1,8 10832.000 12.045.000 1.213.000 11.2 10,1 29.638
NONG NGHIEP VA PHAT TRIEN NONG THON - KY 1 - THANG 6/2020
KHOA HOC CONG N G H l
Nhu vay, vdi cung dien tich va mdi trudng nudi, ung dung cdng nghe BFT nudi ca rd phi cho hieu qua kmh te cao hon so vdi ao khdng ap dung BFT, loi nhuan rdng cao hon tir 5,8 - 6 lan, ty suat loi nhuln cao hon tu 2,93 - 3,78 lan, trong dd ao nudi I cd hidu qua cao nhat.
4 . KET LUAN VJi Krai NGHI
Ung dung BFT nudi ca rd phi trong mdi trudng nude Ig giup cho hieu qua lam sach mdi trudng tdt hon, cac ydu td mdi trudng ludn diroc didu chinh, ki^m soat, dam bao nkn trong gidi han cho phep, giam thieu thay mrdc, ddng gdp quan trong trong viec sir dung tai nguyen nude, giam d nhiim mdi trudng.
Nudi ca rd phi bang BFT se nudi duoc vdi mat do cao va cho nang suat Idn hon he thdng nudi thdng thudng.
Ung dung cdng nghd BFT nudi ca rd phi cho hieu qua kinh te cao hon so vdi ao khdng ap dung BFT, lgi nhuan rdng cao hon ttr 5,8 - 6 Idn, ty suat loi nhuan cao hon tir 2,93 - 3,78 lan.
Trong he thdng BFT ca su dung biofloc nhu la mot ngudn thuc an giup giam he sd thiic an (FCR), hieu qua su dung thiic an tang len, tang nang suat san lugng ca nudi, giam chi phi san xuat, giam gia thanh san pham, tang lgi nhuan so vdi cdng nghe nudi cac rd phi dang ap dung.
Kdt qua nghien ciiu nay mdi thuc hien d quy md thii nghiem, nen cac chi phi san xuat cdn cao, sd lan lap lai chua cd, chua cung mat do nudi d cac ao thuc nghidm nen viec danh gia hieu qua chua thuc su khach quan. Be danh gia chi tiet hieu qua, md rdng ap dung BFT d quy md san xuat, can tiep tuc nghien ciiu vdi sd lan lap lai nhi^u hon, xay dung md hmh nudi phii hgp, tang cudng ky nang giam sat he thdng nudi va phan ung nhanh vdi nhung didn bien heu cue trong he thdng nudi hen ca sd nhimg hieu bidt thuc te hon nua vd BFT.
L^flCAMON
Xin chan thanh cam on di tai "Nghien cuu xay dung md hinh nuoi ca ro phi tham canh trong moi tiiidng nude lo bSng cdng nghe Biofloc tai Hal Phdng", Vien Tai nguyen va Moi trudng biin
(IMER), Vien Han lim Khoa hoc va Cong nghe Viet
Nam (VAST), Sd KH&CN Hai Phong da bd ti-a de thuc hien nghien cuu nay.
TAI UEU THAM KHAO
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2017Sep; 10(5): 1012-1016.
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Aquacultiire 356: 351-356.
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11. Thdng tir sd 12/2017/TT-BNN PTNT ngay 7/6/2017 cua Bd Ndng nghiep va Phat tiien ndng
KHOA HOC CONG NGHt
thon ban hanh Quy chuan ky thuat Quoc gia ve yen hieu: QCVN 02 - 25 : 2017/BNNPTNT: Ca sa nuoi ca cau ky thuat ddi voi ca so san xuat giong va nuoi ca ro phi - Y4u cau ky thuat bao dam ve sinh thii y, bao ro phi. Co so san xuat ca ro phi giong - Yen cau ky ve moi tnrdng va an toan thuc pham, ky hieu: QCVN thuat bao dam ve sinh thii y va bao ve moi trudng ky 02 - 26: 2017/BNNITNT.
EXPERIMENTAL OF APPUCATION BIOFLOC TECHNOLOY FOR TILAPIA INTENSIVE CULTURE IN BRACKISH WATER
Nguyen Xuan Thanh, Dao Thi Anh Tuyet, Le Mmh Hiep, Le Due Cong, Dang Minh Dung Summary
Expenmental with three tilapia culture ponds in brackish water, area of 200 m Vpond. In pond I and pond 11 with biofloc technology (BFV), stocking densities 6 fish/ni^ and 8 lish/m^ respectively. Pond III without BFT (conUol) cultured by the current popular water exchange technology, the stocking densiues 3 iish/ml The results showed that, environment factors m fish culture pond, such as TAN, TSS, NOj - N, NO3 - N, NH3-N, BOD, and COD with BFT was better than without BFT {P <0.05). hi five months experiment, from the initial stocking size of 3.3 ± 0.41 g/fish to harvest the average fish size in ponds I, II and III were 646.3 g/fish; 568.7 g/fish, 659.7 g/fish. respecUvely. Productivity of pond I was 37 tons/ha; pond II was 43 tons/
ha; control pond was 18 tons/ha.The economic efficiency of with BFT ponds was higher than the without BFT pond, with a net profit 5.8-6 Umes, and the profit margin 2.93 - 3.78 times. The research results contnbute to affirming the effectiveness of application BFT in intensive tilapia culture m brackish water, which is the basis for further research and development tilapia culture model by BFT m brackish water.
Keywords: Tilapia, BioSoc technology (BFT), brackish water
Ngudi phin bi^n: TS. Pham Anh Tuin Ngiy nhjn bM: 21/01/2020 Ngdy thdng qua phSn bidn: 21/02/2020 Ngiy duydt dang: 28/02/2020
90 NONG NGHIEP VA PHAT TRIEN NONG THON - KY 1 - THANG 6/2020
