Giai phap cong nghe tien tien chong an mon be tdng cot thep cong trinh bien - de xuat ap dung tai
cang Hai Phong
Advanced technology solutions corrosion resistance of reinforced concrete coastal structures -proposal applies in the port of Hai Phong
Ngay nhan bai: 23/9/2014 Ngay sii^ bai: 5/11/2014 Ngay chap nhan dSng: 10/12/2014
P h a m Toan OuTc
T O M TAT:
Nudc ta cd bd bi^n dai tren 3000 km ciing vdi n h i l u hai dao, vi vay nha nddc c d i ^ da de ra nhieu chu t m o n g phat trien kinh te bien. Trong tUcrng lai, cac cong trinh bien se dupc xay di;ing ngay cang nhien, be tong cong trinh bien doi hoi phai Id loai be tong dac biet, chiu 6uac tac d^ng cua moi trUcrng bien nhU an mon, xol m o n . . .de on dinh lau dai trong dieu kien khde t^hieL Bai bao phan tich co chi an m6n cua be tong do tac ddng x4m thUc cua nU6c bien, tii do gidi thieu mpt so giai phap phuc hoi, bao V? cong trinh mpt each hieu qua.
Tii kh6a: Chong an mon be tong
ABSTRACT
Our country has a coastline of 3,000 km and many islands, so the state has also put a lot of economic development poUcy ofthe sea.
hi the future, the marine project wiD be built more, concrete coastal structures requires a special type of concrete, to withstand the impact ofthe marine environment, such as corrosion, erosion ... to stabilize l o i ^ long in extreme conditions. The paper analyzes the mechanism of corrosion of concrete due to the impact of sea wrater intrusion, which introduced a number of measures to restore, protect works effectively.
Keyword: Corrosion resistance of reinforced concrete
TS. Pham Toan DAc Dai hpc Hai Phong
1 . ThUc t r a n g v a n tfe a n m d n b e t o n g cong t r i n h b i e n
Doi vdi cac quoc gia co b d bien trai dai nhU Viet Nam thi c^c cdng t n n h xdy dung ven bien n h u cau, cdng,... dong m o t vai t r o rat quan trong trong su phat trien kinh te. Do vay, viec nghien cihj phuong phap b i o ve chong an in6n n h i m nang cao t u o i t h o cho cSc cdng trinh la mot van de het sCi'c quan trong.
Theo ket quS khao sat cua cac vien nghien cijiu linh vUc xay dung va glao t h i t i n h trang suy g i i m tuoi t h o cong trinh be t o n g va bi tong cot thep (BTCT) l i m viec trong moi trUdng bien dSng de quan tam.Thiic t ^ c 6 han 50% b o phan ket cau be t d n g va BTCT bj an mon, h u h6ng n i n g hoac bj pha huy chi sau tis 1(H-30 n i m sir dung Hau het cac ket cau nay trong qua trinh l i m viec deu t i ^ p xiic vdi mdi tri/dng khong khi va nudc bi^n. Giij'a vat lieu v i m o i trudng ludn x i y ra cac t i c ddng qua lai va b i n ^ a n be tdng ludn thay doi trang thai cau t r u e
2. Ca ch£ (in m d n hi t o n g va b e t o n g cot t h ^ p cdng t r i n h b i e n
2.1 An mdn bi tong
Be t o n g bj an mdn khi tiep xuc vdi chat idng hoac khi cd chu'a cac c h i t i n mdn. Nudc bien, nudc p h ^ n chua, nudc k h o i n g , nudc t h i i cdng nghiep l i nhijng chat Idng g i y an m d n be tdng manh n h i t C i c loai khi t h i i cua n h i m i y hda chat hoac khf hau ven bien l i c i c t i c nhan k h i g i y an mdn be t d n g . Toe tfd cua q u i trinh an m d n bi tdng phu thudc v i o d i e t i n h cCia xi m i n g sCr dung, h i m lupng v i loai p h u gia be tdng va d i e biet la nong d d cua c i c chat hda hpc gay an mdn co trong nUdc hay khdng k h i m i be tdng tiep xuc tnJc t i l p . D i e biet, khi be t d n g chiu i n h hUdng cCia nhi^t d p cao hoac cd c i c t i c ddng co hoc gay p h i hCiy c^u trdc rdng cua be tdng thi qua trinh i n m d n be tdng x i y ra c i n g nhanh. Cd hai loai i n m d n be tdng chu yeu l i an mdn hda hoc v i an m d n vat ly, n g o i i
ra be t d n g cdn cd the bj p h i hoai d o c i c vi smh vat bien.
2.1.1 An mon hda hgc
Loai i n m d n n i y cd the x i y ra diidi cac hlnh thuTc c i c phan Ung hda tan s i n pham thuy hoa cua xi mang t r o n g bi t d n g , cac p h i n dng trao d6i giii'a nudc b i l n va cac t h i n h phan cua xi m i n g t h u y hda, v i c i c p h i n dng hda hoc xiy ra trong 16 rdng ciJa kit du be tdng rdi tao ra cac s i n pham n d the tich gay ndt v d tie mat kit c^u be t d n g .
Su hda tan da xi mang trong b^ tdng t i ^ xuc vdi mdi trudng nUdc bien chu yeu xay ra khi thanh phan Ca(OH]j bj nUdc bien cd chda CO, t a n cdng, phan Ong cd the x i y ra n h u sau:
COj + Ca(OH)j = CaCO, + H^O (ZI) Tuy nhien, d i vdi lai tUong t i c tiep vdi khi cacbonic v i nudc de tao thanh Ca(HC03)2, l i chat cd d o hda tan manh. C i c p h i n dng hoa hoc x i y ra t r o n g q u i trinh i n m d n be tdng do
axit cicbonic n h i i sau: .^
CaCO^ + CO^ + HjO = Ca(HCOj), ( i 2 ) Su pha hoai cua be t d n g trong mdi t i f d n g nudc bien cdn dien ra d o cac p h i n dng trao (KK, gida chd y e u cac mudi tan MgCI, va MgSO^cd^
trong nudc bien v i c i c thanh phan Ca(0H)2d)E)j d i xi mang Ihdy hda. C i c p h i n dng trao doi cd t h e x i y r a n h u s a u :
M g S O , + Ca(0H)3 + 2Hp = CaSO^^HjO +
Mg(OH), ( i 3 ) MgClj + Ca{OH)^ = CaCI, + Mg(0H),{2^^
Trong do, mudi CaCI, cd d d hda tan mant)., con CaSO, t i c dung vdi t h i n h p h i n cda da )d m i n g 3CaOAIjO,.6HjO de sinh ettringit giy truong n d the b'ch d i xi m i n g v i l i m p h i vd c i u trdc cda da xi m i n g . Chat kiem Mg(OH), l i chat rdi tac. khdng cd t i n h dinh ket, l i m suy g i i m ciu true b£ t d n g .
Z1.2Anm6nvdtly
B i n t h i n be t d n g binh t h u d n g la m o t lo^i vat lieu khdng dac c h i c , cd n h i l u IA r6ng thdng
64ilM11ilHll 03.2015
ra be m | t v i c i d trong c i u true b§n trong. Do viy, khi ap luc thdy t m h cCia nUdc b i l n t i n g len, thi dp am t r o n g c i c 16 rong g i n be mat be tdng bj n l n lai, g i i n tiep tao ra c i c dng s u i t keo tai b l mat be t d n g dan den su bong trdc b l mat be tdng va d l y nhanh sp p h i hoai bao mdn be mat do sdng bien t i c ddng [5,6].
Sdng b i l n chda b o t khi t i c dpng len be mat c i c k i t cau b l t d n g cdng thiTdng thuc day qua tnnh b i o m d n b l mat be tdng. Hien tUpng nay l i do c i c bot khi lan trong nudc b i l n khi va dap v i o be mat be t d n g va bi v d ra tren be mat be tdng ho^c chui vao cac Id rong hd tren be mat be tdng, tao sdng xung kich lam cho b l mat be tdng bj bong trdc.
Nhin chung, i n m d n hda hoc cung nhu i n mdn v i t ly phy thuoc trpc tiep vac dd xdp v i dd tham cda nd. Khi be tdng c i n g dac chic, do th^m t h i u cua nd cang nhd, thi sp an m d n p h i t trien c i n g c h i m . V i q u i trinh an m d n bi tdng l i mpt q u i trinh tdng hop do t i c ddng cda nhieu y l u t d gay nen. Song q u i trinh an m o n be tdng dien ra cham trong mdt thdi gian d i i {20 -r 30 nam).Trong khi dd cac d^ng an mdn khic, d i e bi^t la an mdn cdt thep, dien ra nhanh chdng d i n Sin pha huy ket cau trudc khi be tdng bi i n mdn.
2.2 An mdn cot thip
Khi cdt t h i p cdn duoc bao boc bdi c i c Idp be tdng b i o ve d i e c h i c thi mdi trudng kiem trong be tdng dd cao de tao ra mdt Idp b i o ve c i c cdt thep N l u mang b i o v^ nay bi pha huy { b l tdng bi i n mdn, bi p h i huy hay ndt), q u i trinh i n mdn c i c cdt thep se x i y ra. Dang an mdn dien hinh nhat ddi vdi cac cdt thep l i an mdn i^en hda x i y ra do t i c dung xam thuc cua cac ion clorua ngam qua b l tdng. Trong q u i trinh bi i n mdn, cdt thep se bi han rl va trUong nd the tich, Idp be tdng b i o v l v) t h i lai cang bj p h i hdy manh g i y p h i hdng k i t cau be t d n g cdt thep, V l m i t hda hoc q u i trinh i n mdn cdt th^p dien ra theo p h i n Png hda hoc:
4Fe + 6 H , 0 + 3 0 j = 4Fe(OH)^ " (2.5) V l b i n c h i t d i y la q u i trinh S e n hda xay ra ttieo p h i n dng dxy hda khd di the. Khi ldp mang thu ddng bi p h i vd, tr^n b l mat cdt thep xuat hien vd s6 c i c pin t l vi vdi 2 cue andt va catdt.Tai cac cue nay xay ra cac phan ung (Hinh 11
Hinh t So 66 qua trmh an mon dien hoa cae cot ihep irong b^t6ng
- Tai andt l i q u i trinh s i t bi hda tan, ion
Fe'* se d i vao dung dich
2Fe=2Fe=* + 4e" (2.6) - T a i c a t d t d i e n t P d U t h d a s e k l t h p p v P i O j
v i nUPc de hinh thanh ion OH"
2 H ; 0 + 0 , + 4e" = 4 0 H " (2.7) Cic p h i n Png (2.6) d andt v i (2.7) d catdt chl la budc dau cua q u i trinh tao ra ri sat tren eac cdt thep. Ri sat dupc tao ra theo cac p h i n dng tiep theo n h u sau:
2Fe^' -*• 4 0 H " - 2Fe(0H)^ (2.8) 4Fe(0H)j + O j + 2Hp = 4Fe(0H)j (2.9) 2Fe{OH)3 = Fe,0,.H,0 + 2Hp (2.10) San pham Fep^.H^O chinh l i ri sat ma chung ta quan sat dUOC tren be mat c i c cdt thep bi an mon. S i n pham nay cd t i n h xdp, tich t u tren be m i t edt thep vd^ t h i tich Idn gap 4 den 10 lan so vd! cac thanh phan ban dau, chinh vl vay da gay ndi Png s u i t lam nPt vd be tdng doc theo VI tri dat cdt thep. Cung chinh t d c i c vi t r i n i y . c i c t i e nhan xam thuc d l dang x i m nhap vao ben trong, lam gia tang q u i trinh an m d n c d t t h ^ p .
Can cd them nhdng nghien cPu danh gia t i e hai cda viec an mdn eung nhU co che an mdn b l tong va cdt th6p d l tP dd d l ra nhPng g i i i phap phuc hoi, b i o ve cdng trinh mdt each h i l u q u i .
3. G i i i p h a p t h i cong phuc h o i , b i o ve cong t r i n h cu
De phuc hdi nhpng edng trinh bi an m d n be tdng cdt thep, d Viet Nam h i l n nay dang Png dung tUOng ddi phd b i l n cdng nghe dung bom keo epoxy. Tuy nhien phUOng p h i p thi edng nay cd nhieu nhupc diem la bien p h i p thi edng thudng t h d cdng, lam cham tien dd, vdi 3 Ipp vat lieu, Idp keo epoxy khdng cd k h i nang chiu am tP be t d n g nen nen hay bi bong rdp tPng m i n g sau thi cdng. N g o i i ra, keo epoxy cd tinh ddc hai, khdng phu hop vpj xu the p h i t trien b i n vdng cua cac nganh khoa hoc hien nay tren the gidi.
Hien dai va t h i n thien vdi mdi truong hon.
edng ty Qudc T h i n g da i p dung edng nghe thi cong b i n vung khi sd dung vat lieu goc xi mang/polymer. Cdng nghe nay dupe phat t r i l n tP nhPng v i t lieu tUOng thfch vdi be tdng gdc, ehdng cd Uu diem tuyet ddi la cung t d n tai vdi be tdng nen chung ed d d ben vmh cdu, day eung la khai mem co ban eda edng ngh& c i n b i n g tU nhien, than thien vdi mdi trUdng, nd duoc xem la phUcmg e h i m cdt Idi trong cdng ngh& xP ly ben vdng edng trinh.
Thdng thudng cdng trinh dUOe xP 1^ b i n g c i c h dung may phun nudc ap lUc cao k i t hop vdi cat lam sach be mat k i t cau. Ket ndi b i n g vat lieu chuyen dpng SBR 701 hda vdi xi mang theo ty le nhat dinh, hoac dung cac lo?i polymer trung tinh ket ndi, khi Idp ket ndi nay vPa se mat, tien hanh t r i m lai b i n g hdn hop vda 3 thanh phan xi mang + cat + phu gia gdc XI mang. tao ra mot ioai vPa trat d i e biet ed mac tuong dng vdi be l o n g gde, hdn hop nay 3uac
trdn tai cdng trinh. Sau cung va cung l i quan trong nhat, b l mat k i t cau dupe b i o ve bang 1 Idp Greenseal 200 va 2 Idp Polydek (hinh 2).
• Trinh t p phun vat lieu Greenseal 200 {GS 200) bSng thiet bj ehuyen dung.
Sau khi be mat b l t d n g da dupc sda chda, tien hanh phun Idp v i t lieu GS 200 theo c i c budc sau:
- Dung may phun nudc cd i p Ipc trung binh tUdi ^m {rda qua b l mat be tdng).
- Hda v i t lieu GS 200 vdi nifdc sach tl I I tieu chuan.
- DPng thiet bi phun vda ehuyen dung i p Juc cao, phun ngUoc len be mat dUdi cda gam cau e i n g .
- Phun mdt Idp duy nhat, vdi dinh mPc tP 1,3 d i n 1,5 k g / m ' (phUOng i n nay loai bd sU phan t i n g gida hai Idp vat lieu do thPi gian thi cdng tru'dc va dot thi edng sau).
'm^-
L, . . ; .-.J • •' Hlnh 2: Minh hoa bifn phap thi cong ' T r i n h t u phun vat lieu Polydek bang t h i l t bi chuyen dung.
Sau khi be m i t ldp vat lieu GS 200 khd h i n , k h o i n g t P l den 3 n g i y (tuy theo thdi t i l t thpc te), tien hanh thi cdng Idp h o i n thien Polydek theo c i c budc n h u sau:
- Phun rPa, tuPi am be m i t bang may phun nudc.
- Hda vat lieu Polydek vdi nUPe (tuy theo tinh hlnh thdi tiet luc phun).
- Khi be m i t cdn am do phun rPa nUPe, ta tien h i n h phun ngUOC l^n gam cau c i n g ldp thPnhat. Khi Idp thPnhat vua se mat, h o i c khd h i n , ta phun Idp t h d 2. Djnh mPe eda e i 2 IPp vat lieu nay la 1 lit/1,6-2m'.
- V i t lieu Polydek se khd trong k h o i n g t d 4 d i n 24 t i l n g (tuy theo tinh hinh thdi t i l t ) .
Giii p h i p tren da t d ra kha hieu q u i trong v i l e sPa chda nhdng cdng t n n h cau c i n g , ham dudng bp, tang ham edng trinh dan dung tai Hal Phdng va Oa N i n g .
4 . G i i i p h a p d i m g p h u gia Uc che an m o n cho cong t r i n h m o i
SP dung ehat Pc c h l dUpc xem la mdt b i l n p h i p hieu q u i , de i p dung v i phu hpp vdi d i l u kien ky thuat va kmh te cua Viet Nam. Mdt trong nhdng hpp ehat Pc che span mdn cdt thep hieu q u i ddoc sP dung la Canxi nitrit (CN). Co c h l ngan ngPa an mdn edt thep cua CN dUOc ly g i i i nhusau
- CN oxi hoa s i t (11) oxit kem b i n thanh s i t (III) oxittheo p h i n Png
2Fe'* + 2N0,- + 20H" = Fe,0, + H 0 + 2N0" (4.1)
- lon nitrite se cdng cd IPp mang t h u ddng sat (III) oxit b i n g each hap phu len b l mat thep va lam vpng c h i c them Idp m i n g thu ddng n i y . - lon nitrite cdn phd t o i n bd xung quanh cac vj t r i bi k h u y l t t i t s i t (II) oxit, l i m g i i m tdi da k h i nang t h i m n h i p cda ion clorua qua Idp m i n g b i o v l .
- Neu ion Cl" t i m dUOC mot v\ t r i khuyet t i t t r l n be m i t cdt thep, i n m d n b i t dau x i y ra. Khi dd hpp c h i t clorua sSt (gl) se t i c h khdi be mat thep, cac ion s i t (11) mdi se t i l p tuc bi Id ra trong mdi triTdng be tdng. lon NO," cd t h i nhanh chdng bao boc quanh c i e ion sat (li) mdi, b i o ve chdng khdi bj spxam nh^p cda ion Cl'.
Tai Mil Phdng, cdng trinh nang cap c i n g CPa C i m da dupe Png dung g i i i phap n i y . Cdng trinh sd dung 845m' b l tdng ehdng i n mdn M30 (lilu lUpng CN sd dung la 5,71/m' be tdng) cho t o i n bd k i t c i u dam dpc, dam ngang v i b i n s i n eau tau nam trong vdng khi q u y l n t r l n mat nUdc
Quy trinh thi cdng Png dung b l tdng chdng i n mdn tai d i y n h u sau:
- K i l m tra vat lieu, chl tieu ky t h u i t v l t(nh edng t i e v i eUdng d o be tdng chdng an mdn tdi thieu p h i i dat yeu cau ky thuat cua b l t d n g thudng theo chi dinh cda t h i l t k l .
- C h l tao be tdng chdng an m d n tren day t r u y i n s i n xuat be tdng thudng tai hien trudng v i sil dung CN n h u phu gia dua v i o nudc trpn be tdng theo lieu lu'ong quy dinh.
- Thi cdng be tdng ehdng an m d n ; tUOng t p n h u ky thuat thi cdng be tdng thu'dng, trong do chp trpng viec dam b i o c h i l u day v i do d i e c h i c cda Idp b l t d n g b i o v l va xP ly khuyet t i t rong, rd ngay sau t h i edng xong.
- L i p d i t d i u do an mdn trong phan b$
tdng Png dung 34 theo ddi d i i ngay h i f u q u i ehdng i n m d n va b i o vi cdng trinh: Moi cau kien l i p 2 d i u do g i n c h i t v i o cdt thep ehiu lUe, tien h i n h kiem tra eUdng dd be tdng, khoan lay mau bdt de p h i n tich h i m lUdng nitrit trong be tdng va do dien t h e i n mdn cdt thep tai thdi d i l m dau khi be tdng duac 28 ngay tudi va theo djnh kjr 2 n i m / l a n , tdi 40-50 nam.
K i t q u i k i l m tra tai h i | n trUdng sau hon 8 nam Png dung: cUdng dd bi tdng k i t c i u cdng trinh R|^| = 36MPa dat yeu c i u v l cUdng dd ehiu n l n theo TCXDVN 239:2006, h i m lUpng nitrit p h i n tfch duac trong be t d n g d d d sau 3-5cm (vung c i n cdt thep) chua x i c djnh duoc cd sp suy g i i m so vdi h i m lUOng dua v i o be tdng ban dSu, d i | n t h i edt thep dao ddng tP -70mV d i n -130mV, theo t i l u c h u i n TCVN 9348'2012 t h i edt thep chua bj i n mdn. N h u v i y ket q u i kiem tra cho thay viec dng dung CN lam phu gia dc che i n m d n cho be tdng d i dat hieu q u i t d t sau mdt sd n i m dau sP dung.
S . K l t l u | n
Xung quanh cd c h l p h i hdy be tdng va be t d n g cdt t h i p dUdi tac ddng cda mdi trudng cdn n h l l u dieu b i n l u i n , d i e b i l t la ban chat
sp an m d n be t d n g va be t d n g cdt t h e p dudi t i c d d n g cOa mdi truPng. Ly do la cd nhieu y l u t d xam thpc t i c ddng theo c i e cd c h l k h i c nhau.
Q u i trinh an mdn lai dien ra c h l m d o v i y c i c k i t q u i t h i n g h i i m nhanh neu cd m d phdng thudng khdng lot t i dung b i n chat p h i huy trong thpc t l .
Ngoai c i c g i i i phap dUOc trinh bay d t r l n , cung d i cd r l t n h i l u nhPng n g h i l n cdu v l giai phap ehdng i n m o n b l t d n g edt t h i p cdng trinh lailn khac nhiT: Thay ddi thanh phan k h o i n g cda xi m i n g , n i n g cao d o d i e chac cda be t d n g , b i l n ddi c i c s i n p h i m t h d y hda, sOn n g i n c i c h b l t d n g vdi mdi trudng...Tuy vay, nhin mdt c i c h tong t h i , h i | n nay ehdng ta chua the e h l tao dUpc loai BTCT cd d o b i n v i d i e c h i c mdt c i c h 1;^ tudng, de h o i n t o i n ngan c i n Sli t i l p xdc cua cdt t h i p trudc mdi trudng xam thuc ma eh( han e h l m d t c i c h t d i da vdi vdi vat lieu va cdng n g h l h i l n cd. Chung ta cd the c h l tao dUpc loai b l t d n g ed chat luong cao, vdi d i e tinh l i k i t cau cd do b i n co hoe Idn, vd be tdng ed k h i n i n g b i o vi cdt t h i p , do d i e c h i c cao, chdng tham tdt, it bj t h i m ion Cl" va c i c t i e nhan x i m thUc k h i c , khi d d be t d n g se cd du kha nang b i o v l cdt t h i p , d i m bao d d b i n k i t c i u trong mdi trUdng xam thpc. Hoac n g i n c h i n c i e p h i n Png an mdn x i y ra khi c i c t i e n h i n x i m thUc t i l p xuc vdi b l mat cdt thep.
T A I L I E U THAM KHAO
|1] Pham Hiiti Hanh, LeTrung Thanh, Nguyen V^n Titan.'Be tong d i o <ong trinh bien" NXB Xay dimg. Ha n5i, 2013.
[2] TCXDVN 239:2006 "Be long nSng - Chi dan danh gi^
cKcmg do be tong tren ket d u cong tilnh".
[3] TCVN 9346'2012 "Ke't cau be tong va be tong cot thep - yeu cau bao ve chong an mon trong mdi truang bien'
[4] TCVN 9}48 2012 'Be tong cot thep - kiem tra kha nang o i l thep bl an mon - phUOng phap di^n hoa"
[51 Mehta, P.K, "Concrete in the Marine Envimnment, 1991:
Taylor & Francis Books, Inc 224p.
[6] Soutsos, U.N Concrete Durability - A Practical Guide to The Design of Durable Concrete Structure 2009 Thomas Telford 5S5p
Danh gia hieu qua XLF ly va kha nang thu hoi khi sinh hoc nu'O'c thai giet mo gia sue bang cong nghe mang loc ky khi
Efficient processing and recovery capability Bio-Reactor Wastewaters from slaughter by Anaerobic Membrane
Ngay nhan bai: 12/9/2014 NgaysCra bai: 17/11/2014 Ngay chap nhan dang: 28/12/2014
TOM TAT:
NUct thai gilt mo gia sue (ldn) veil ham Ippng hflu co v6i chi tieu COD dao dong tP 600-1350 mg/L, ham hiang can lo IPng xap xi 280 mg/L, ty- le COD:TN xap xi bang 8 lan, dupc nghien a i u xii ly b a i ^ mo hinh mang ky khi van hanh troi^ dilu kien khi hau mien Bac-Viet Nam. Kit qua thi i ^ ^ m da cho thay: khi OLR thSp hon hoac bang 2 kg COD/
m^i^y, HRT giam den 12h, chat lilcttig nt(6c sau be AnMBR ve hai chi tieuo nhilm dien hmh nay on dinh, chi tieu SS dat 7±6 mg/L, COD dat 94±43 mg/L, WOng dng hieu qua xt( ly SS va COD dat tren miic 95% va 90%; nong dO bun dat 18 g TS/L, ty le VS/TS on dinh 6 miic 78%, san lifOng bun d^t 0.07 g VS/g COD; san lilOng khi metan thUc te d?t 0.3 m ' CH4/1^ COD. Ket qua nghien cifu cho thay rang niidc thai giet mo gia sue la mot ca chat c6 tiem nang sinh khi sinh hpc cao trong viec iing dung va phat trien cua cong nghe miu^ ky khi tai Viet Nam TH khoa: Nildc thii 16 m6, c6ng nghe mang ky khi, khi sinh hpc thanh ph6 Ha npi
ABSTRACT
Wastewaters from slaughter (pig) house contains COD: 600- 1350mg/
L, TSS: 280 mg/L, COD/TN: 8 have been treated by a pOot system using Anaerobic Membrane Bio-Reactor (AnMBR) technology m ambient temperature in Hanoi City. Results from 10 month study showed that if the Organic Loading Rate (OLR) is lower than 2 kgCOD/m3.day and HRT ofthe AnMBR system reduced to 12 hours, the effluent have good water quahty with SS: 7+6 mg/L, COD: 94+43 mg/ which representing the removal efficiency for SS and COD achieved above 95% and 90%, respectvely; TS inside the bio-reactor reached 18 g TS/L, and VS/TS ratio was stable at 78%; sludge yield was 0.07 g \ ^ / g COD; methane gas yield was 0.3 m3 CH4/kg COD throuhgout the operation period. It suggests that the the application of this innovative anaerobic treatmet technology is efficient for treating this high strength slaughter house wastewater with respect to removal efficieny and biogas generation in Wetnam climate conditions.
Tii khoa: Slaughterhouse wastewater. Anaerobic Membrane. Bio- Reactor Hanoi City.
Th.S Dtftfng Thu Hang. KS Vu Diic Canh, TS TrSn Thi Hiin Hoa, TS TrSn Thi Vi#t Nga Khoa Ky thuit Moi tnidng, Tnlcfng Dai hpc Xay dUng
Du'dng Thu Hang, Vu Dufc Canh, Tran Thi Hien Hoa, Tran Thj Viet Nga
Gioi thieu
Qua trinh me tan hoa da chiJIng t d la cong nghe thich hop cho viec Lfng dung de xis ly loai nUdc thai dam dac chat hOu co, vdi cac cau hinh c6ng trinh khac nhau theo l[ch sii phat tri^n de dap iJng vdi yeu cau ngay cang cao ve qua trinh van hanh he thdng xCr ly. Cung vdi sif phat tnen cua cong nghe ky khi, nhljng nam gan day, mot vai nghi&n cisu da hUdng tdi cong nghe mang ky khi (Anaerobic membrane bioreactor-AnalWIBR), la sy tich hop cCia cong nghe len men ky khi va cdng n g h ^ mang vi loc (Beaubien et al., 1996, He et al., 2005; Zhang et al., 2007; Zhao et al., 2009;
Linetal., 2010; Hai etal., 2011). IVIang loc cd chu'c nang chinh la duy tri lai he vi sinh ky khi on d\nh, ndng dd bun cao trong be len men ky khi ket hop mang loc cho phip h | thdng tang ti\ lUOng huU co ciia ddng vao, trong khi dam bao chat lu'ong nudc sau xiS \y ve mat ham luong can, ham luong cac chat hCfu co, do mau va chl tieu vi sinh. Qua trinh chuyen hda cac chat hOu co thanh me tan triet de hon, nang luong t h u hdi cao hon, cd the bii dap mot phan nang lUong can cung cap cho bom hut nUdc qua mang. Ivldt sd ket quS nghien ci!iti cho thay cdng nghe niy cd nhieu Uu diem so vdi cdng nghg xiS 1^ smh hoc t r u y i n thong khac nhu- Gi5m t\iu t h u nSng lUong d o khdng dn cap khi cung cap oxy cho qui trinh phSn huy chat hCfu cO; Giam khdi tich b i i n tao thSnh; Thu hdi dUOC khi biogas lam nang lUong sinh hoc; Hoat dong on djnh, ngay ca d cac tram cdng suat nhd; XiS ly tai lu'ong d nhiem Idn, kich thUdc va dien tich cdng trinh XLf ly smh hpc nhd, phCi hop vdi khu vUc dd thi va ven dd; vi T i l t kiem chi phi xSy diJng cdng trinh I3ng t h i i cap, loc va giam chi phi xiy diTng cac cdng trinh x i i ly b i j n can len men do li/ong biin can smh ra nhd.
(Viae d i l da chiing mmh nhCmg uu diem vuot trdi trong Cciu hinh be mang ky khi, tuy nhien, rat it nghien ciJu ijfng dyng mang ky khi de xCr ly nudc thai giet md gia sue, hau het cac dng dung deu thUc hien tren nudc thai cdng nghiep thUc pham va nudc thai sinh hoat (Fuchs et al., 2003). Trong k h i d d , nudc t h i i giet m d gia siic dac t r U n g c d mau do den hoac nau sam, ham luong can idn va miii hdi tanh. Ham li/ong cac chat d n h i l m trong nUdc thSi phat smh tai cac CO sd giet mo vi che bien gia siic rat cao, dac biet la cac chat hCru co va d m h dudng.Tim kiem cong n g h f xCf ly nudc thSi giet mo gia sue phiJ hop va day chuyen cong nghe b i n vCfng v l mat mdi trUdng, hoat ddng on dinh va k h i thi, tiet kiem nang lUOng va dam bio chat luong nUdc sau xCr ly theo quy dinh ciia BTNMT ludn la yeu cau cap bach vdi tat c i c i c co sd va cac nh^ qu^n ly. Muc t i l u cOa nghign cdu nhSm danh gia hieu q u i xis 1^ va k h i nang thu hdi k h i smh hpc cua nudc thai giet m d gia sue (Ion) bang cong nghe mang loc ky khi tren m d hinh phdng t h i nghiem v i d i l u kien thuc t l tai Viet Nam
Mo hinh t h i nghidm mang ky khi v^ ca chat dau v^o Ca chdt ddu vdo
N g u y i n l i l u nap l i r u d c t h i i g i l t mo gia sue duoc t h u gom tir hd t h u nudc t h i i giet m d va rda long, ngay tai khu san giet m o cua co sd giet mo gia sue Cong t y cd phan Thjnh An (tai Van Phuc, Thanh Tri, Ha Noi) vao ca
03.2015BWnVitQl 6 7
g i l t m o (til 12h00den 14h00 hang ngay). Nu6c t h i i duoe dua ve va b i o quan trong cac t h i i n g chda ri#ng b i | t d nhiet d d 4 ° C trudc khi nap lieu cho m d hlnh se dua ve nhiet do khdng k h i tai thcri diem van hanh md hlnh. Bim cay dupc lay t d bim be metan trong tram xd ly nddc ttiii Yen Sd, t h i n h phd Ha Ndi, nap vao md hinh vdi ham lui?ng 6Sg TS (5.0 g VS)/L, the tich cay nap 5L v^o b^ p h i n dng ky khf tai thdi diem khdi dong md hlnh.
M6 hinh AnMBR trong phong thi nghiem
J
^ J
""
^
- ' ^ t 1
Bang 1. Cac thdng so van hanh m d hinh AnMBR de xii ly nude thai giet md va Giai
doan van hanh 1 2 3 4 5
Ngay
1-51 52-109 110-176 177-240 241-270
Tai t r p n g thiiy l u c - VLR(L/ngay)
25 3 3 5.0 10.0 15.0
Thoi gian luu
nUdc- HRTih]
48h 36h 24h 12h 8h
Thong luong lpc qua mang - Flux
(m'/m^- ngay) 0.025 0.033 0.050 0 100 0 1 5 0
Thdi gian luti b i i n - SRT (ngay) 350 350 700 700 700
he bien gia sue Tai lupng hiru CO trung binh
OLR- (kgCOD/m'-
ngay) 0.29 0.50 1.10 1.91 2.85 Bang I.Thanh phan va dae t i n h nddc thai g i l t mo gia sue nap lieu eho md hinh
Thong sd D d n v j Gia t n dien hinh
Hinh 1. Soilo ini hinh AnMBR trong phong till nghiem r S^ diHa nudc thai dau vdo (ihe tkti ang tdt 51); 2.Bm mlk thdi vA) bi; 3 ffln/i Uo lnang khi smh m; 4.Binh cfttfu ifti'de tndn hodn lai; S.Mdy nen khi; 6.8epWn iing ki khi, 7 Bam hut nil6cqaanidng;8.Bid«ia msdc sau xUly: 9.lhi?lbiiloiipiaSiiuo mdng: W Mang IK
Hi thdng AnMBR quy md phdng t h i n g h i f m dUOe md t i trong Hlnh 1 dUdi day, bao gdm: thdng ddng nddc thai chda x d ly, be p h i n dng ky khf {dung tieh hdu dung 5L), b d m i n g vi loc mini, may nen khi va he thdng sue khi trong b l p h i n dng, he thdng t h u khi sinh h p c v i hi thdng bom nap nddc thai, bOm hdt qua m i n g (Hinh 1). M i n g vi loc sd dung trong md hinh l i dang m i n g tim ph^ng, cd dien tieh lpc be mat l i 0.1 m2 v i kieh cd khe h d la 0.4pm do Nhat B i n s i n xuat. Vat l i f u c h l tao mang la Polyvinylidene Fluoride (PVDF).
Quy t r i n h v a n hanh m d h i n h AnMBR trong phdng thf nghiem
Md hlnh duoc van hanh trong 270 n g i y vdi c i c c h l dd thdi gian luu thdy Idc va v i t i i trpng chat hdu co k h i c nhau d l danh g i i ve hieu q u i x d l y nude t h i i va nang suat sinh khi, d p dn dinh cda he thdng vdi nudc thai giet m o va che bien gia sue v i sd thay d6i cda dieu kien nhiet do mdi trddng d i e t n m g 6 m i l n BSc Viet Nam (dao ddng t d 10-30oC). C i c thdng so van hanh md hlnh ddOC trinh bay d B i n g 1. Nddc t h i i dUOc nap 1 1 ^ v i o be chda va k h u l y deu, sau d d bom v i o b^ p h i n dng k| khi theo tai trpng thdy lUc x^ djnh. Khi sinh ra t d b l p h i n ifng se dupe thu lai v i o binh chda khi, mot phan dung de sue khi tuan h o i n lai be phan dng tif d i y be tao ddng t u i n hoan bun trong be va giam thieu k h i nang t i c nghen mang Ipc
MidntkhcdccMtiiuchdth/angnU&cvabim Od< vdi c i c m i u n u d c nddc thai dau v i o va nddc sau x d l y cua be p h i n dng sinh h o c eae ehi tieu DO, pH, nhiet dp dupc do dac hang ngay bdi c i c t h i l t bi do nhanh. Viec l l y mau nddc d l phan tieh c ^ ch! t i ^ u COD, BOD, SS, NitO t d n g sd (TN), Amdni (NH^-N), Phdt pho tdng so (T-P)
COD TN NH4-N P04-P S042- pH D o kiem
mg/L mg/L mg/L mg/L mg/L mg/L
mg/L theo CaC03 754 70
Sunfat, va d p k i l m ddpc thdc hien 1 lan trong 1 tuan. Ddi vdi mau biin cay va bun trong b^ phan dng ky khi, tich cac chl tieu MLSS, TS, VS, COD, VFA, va do kiem duoc thUe hien 1 lan trong 1 tuan. Viee phan tich tuan t h d cae phdong phap ti&u chuan {APHA 2003) va phdong phap HACH vdi thiet bi do quang phd DR2100 (HACH, USA) Khi sinh hoc ddpc thu gom va phan tich thanh phan khi (1 lan 1 tuSn) b i n g thiet bj do nhanh test kit GAC25 (Nhat Ban).
Ket q u a va t t i i o luan Bdc tinh cua nddc thdi giit mo gia sue Oac t i n h eda nUde t h i i giet m o gia sue (lonl sd dung trong md hinh thf nghiem, dddc mo ta trong Bang 1 dudi day.
Ham luong hiiu cO vdi chi tieu COD trong nddc thai giet md gia sue ed gia trj trung bmh 900 mg/L, t f le COD:TN xap xi bang 8 lan. Neu so sanh vdi cac ket q u i phan tfeh nddc thai giet m o gia sue tai cac nghien cdu va bao cao tren the gidi, chl tieu COD trong dai t i l 1800-30000 mg/UTKN dao ddng 120-450 m g f l . (Masse and Masse, 2000; Bazrahhan et al., 2009; Hsiao et a l , 2012; Kundu et al., 2012). cac chi t i ^ u dien hmh n h u COD va TN trong nUdc thai giet m o dUOc phan tich trong t h d i gian 9 t h i n g lien tuc tai CO sd giet m d gia sue Thjnh An va cac Id m o tai Ha Npl. d i u nhd hon n h i l u lan. Nguyen nhan la do, mdt phan do lUOng nddc sd dung tai cac co sd trong nddc nhieu hem, dan den ham luong chat d nhiem loang hon. Mdt phan mau, mot trong nhdng chat d n h i l m hoa tan dien hinh trong nudc t h i i giet md gia sue t h u d n g cd chi tieu COD khoang 375 g/L va TKN xap xi 2 g/L. thi tai Thinh An cung n h d hau het c i e eo s6 trong nddc deu thu gom phan ldn lupng tiet khi giet md de b i n , khien ham Idpng c i c ehat d nhiem nay giam dang ke.Ty le NH4-N chiem 90% cua
TN, chdng t d ehu y l u N trong nddc thai giet mo gia sue cd ngudn gdc t d nudc tieu gia sue chay true tiep uao cac mang thu. Ham lupng can lo Idng kha thap (xap xi 280 mg/L) va dao ddng nhieu, phan Idn Idng va da thda thai bd duoc g i d lai tnJoc \\J6\ thu cua ho thu nude thai.
Nhiit dp, dp pH, dp kiem va nito.
Mo hmh dLioc dat trong phong khdng co he thong on nhiet de thich iing voi nhiet do khong l<hi, Nhiet dd cua niJdc thai va be phan ling duoc ghi nhan tang t u 10°C den 30°C trong 110 ngay dau (giai doan 1 va 2) va giam nhe dan t u 30"C den 25''C trong 160 ngay sau (giai doan 3 va 4) Cac ehi tieu khac nhu pH (7 4) va do kiem trung binh 1730 mg/L) tuong ddng v6i cae ket qua phan tich dac tinh nudc thai trong cac nghien cuu tren Niidc thai sau be mang ki khi cd do pH t i n g rat nhe, t d 7 4 den 7,9, nhung dd kiem tang dan dang k^, 180% t d cuoi pha 2 va pha 3. den 1300 mg/L theo CaCO,. Oieu nay la do qua trinh ehuyen hda cua protein trong nude thai giet mo thanh ammonia, sau dd, ammonia ket hop voi axit cacbonic trong nudc tao ammonia bicacbonat (Fannin, 1987), Do da tdng nito trong nUdc thai giet md trUdc va sau xd ly cd gia tri tdong ddong nhau, TN va NH4 sau x d l y tang 5%
Hiiu qud xCrly nifdc thai theo SS vd COD bdng mang loc ky khi
Nudc thai sau mang loe ky khi trong, ham luong can lo Idng (SSI Irong nude thai thap, dat 5±6 mg/L (<:1B mg/L) trong ca thdi gian thi nghiem, do CO che loc chan qua mang. Hinh 2a md ta ham lu'ong SS trong nuoc thai g i l t mo trudc va sau be AnMBR, va hieu qua xd ly nucfC thai theo chi tieu nay theo % va Hmh 2b bieu thi sU anh hudng cua tai luong hC/u co (OLR) doi voi hieu qua loai bo SS trong nudc thai trong
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W (b) Hlnh2 Hi^u qui xiily nirdcthii ttieo can l0l^g{SS)thfDthcri gian va anh hucmg cOa tai luong hOu tif (OLR)
^ • ^ ^ ^ ^ ^ ^ ^
c h u y i n hda trong giai doan 3 va 4, g i i m xudng 0.01 9 VS/g COD e h u y i n hda d pha cudi cung.
Theo Metzer v i Temper (1990), Borja (1995) va Mass^ va Masse (2000), s i n Idpng bun tich luy t d t trong be ky khf khi x d ly nddc t h i i giet m o vdi b l ky khi len men am (30-35°C) cOa tuong dng vdi mde 0.05 v i 0.07 g VS/g COD. So s i n h cae ket q u i , ddi vci cdng co chat l i nddc t h i i giet mo gia sdc, be m i n g ky khi van hanh vdi n h i l t d d thKp (td 1 0 ^ den dudi 3 0 ^ ) cd s i n Idong bdn thap hon so vdi be ky khi truyen thdng, nhdng lat dn dmh d mde cao khi nhiet d p 6 30°C. Khi OLR tang 3 kg COD/m^ngay, s i n IdOng bun suy g i i m ; quan s i t tai b l p h i n dng n h i n thay bdn tao bpt v i vang m d n6i lin n h i l u mau den t r l n mat b l ddng t l i d i trong pha n i y . Hien tdpng n i y chdng t d t i i Idpng hdu cd da vupt qua ngddng c h u y i n hda eua he vi sinh ky khi trong b l , c i e methanogens bj dc ehe, q u i trinh phan g i i i va ehuyen hda cac chat khdng ddOc hoan thi#n, dan den tinh trang tfch luy c i e chat b l o trong be t r i m trong, ndng d d bun suy giam v i ndi v i n g .
Hinh 3' Hieu qua xd ly niMc th^i theo ham linmg chit hihi ca (COD) theo thdi gian va inh hir^g ciia tii lirong liii^ ca (OLR) q u i trinh v i n h i n h md hinh t h i nghiem. Ket
q u i cho t h i y hieu q u i loai b d SS kha on dinh, dat tren 95% trong hau het t h d i gian van h i n h v i Sl/ thay ddi cda OLR t d 0.3 d i n 3 0 kg COD/
m3.ngiy l i m suy g i i m khdng dang k l h i l u qua loai bd SS. So vdi mdc quy dinh edt B, QCVN 40:2011/BTNMT \i 100 mg/L thi chat Idpng nudc sau AnMBR ludn thip han trong sudt thdi gian v i n h i n h m d hinh thi nghiem.
Hlnh 3a va 3b tdong t d m d t i sd dao ddng eda chi tieu COD trong nddc t h i i trudc va sau x d ly, v i s u i n h hddng eua OLR ddi vdi hidu q u i loai bd COD trong nddc t h i i g i l t md. K^t q u i eho thiy, ham Idpng COD t r o n g nddc t h i i dao ddng tif 600 den 1350 mg/L, nhUng trung binh xap xi 700 mg/L trong 2 giai doan dau v i 900 mg/L trong 2 giai doan sau. D i l u nay ddoc ly g i i i do sd gia tang edng suat giet mo tai co sd trong 4 t h i n g sau T^t, nhdng Idpng nddc sd dung t r l n dSu gia sdc g i i m n&n nddc t h i i d i m dac hOn ve t h i n h p h i n hdu cO. H i m IdOng COD trong nddc t h i l SBuxiJiy dao ddng n h i l u hon so vol chi t i l u SS tOWig dng, dat 94±43 mg/L, thSp hon 150 mg/L trong 4 pha 3&u {theo quy djnh eda cdt B, QCVN 40:2011 /BTNMT) v i cd t h d i diem vdOt mde quy djnh trong pha cudi cung Hieu q u i x d ly COD (%) suy g i i m va dao ddng k h i rd ret khi t i n g OLR t d 0.3 den 3.0 kg COD/m^ngay (Hlnh 3b), Khi OLR nhd hon 2.2 kg COD/m^ngiy, hieu q u i loai bd COD trong nUdc t h i i dn dinh d mdc 90%, nhung khf tang OLR t d 2 . 2 d i n 3.0 kg COD/
m'.ngiy, g i i t n n i y chl dat t r u n g binh 85%. Viec t i n g t i i trong t h d y Ide, g i i m thcri gian Idu nddc (HRT) t d 4 8 h xudng 12h d6ng t h d i vdi tang OLR khdng i n h h d d n g d i n g k l vdi hi^u q u i loai bd SS v i COD trong nUdc thSi, nhdng i n h hddng d i n g ke khi HRT g i i m t d 12h den 8h, OLR tang
tren 2 2 d i n 3 0 kg COD/m^ngiy.
Md hlnh AnMBR trong t h i nghiem, vdi dieu kien van h i n h 6 nhiet d p khf hau mien Bic {dao ddng t d 10-30°C), hoat ddng dn dinh d mde OLR len d i n 2 kg COD/m^ngiy, tdong dng HRT 12h.
Mdc t i i Idpng hdu ca nay tdong ddong so vdi k i t q u i nghien cdu cda He (2005) dng dung edng nghe AnMBR de x i i ly nddc thai c h l bien thdc pham dam dac, vdi t i i trong hdu ed < 2 kg/m'.ngay, hi^u q u i x d ly SS v i COD dat tren 99,9% va 90%. Trong nghien cdu B l AnaMBR dng dung mang UF x d ly nudc t h i i d d thi d nhiet dp 370C trong thf nghiem cua Lin (2010) cho h i l u qua loai bdTS, COD va BOD tUOng dng l i 100%, 90% va 88% vdi OLR dao ddng t d 0.23- 2 gCOD/L. ngay, chat IdOng nddc sau xd ly dn djnh hon so vdi eac cau hinh dng dung edng nghe ky khf n h d CSTR, UASB v i AF trong cae nghien cdu trudc day.
Sinh khoi bim vd dp sudt hdt qua mdng Hinh 4 bieu thj ndng dp bun trong be mang ky khf trong t h d i gian van h i n h md hlnh. Ket qua eho thay sU tang s i n luong bun dSn theo thdi gian va duy tri tdOng ddi dn djnh trong t d n g pha d 4 pha dau t d 6 g TS/L den 10.5 g TS/L, sau do suy g i i m rd ret d pha t h d 5. Ty le VS/TS dn d m h 6 mde 78%, t u y tai dau cie pha ed xu hudng g i i m khi chuyen pha. Ndng d d bun tang trong 240 n g i y dau chdng t d viec t i n g t i i trong thuy Idc va g i i m thdi gian idu nudc khdng lam suy g i i m chat lUtmg v i ndng dd bdn trong b l do co che g i d lai bun vi sinh n h d m i n g , vi v i y duy tri ndng d d bdn cao trong be, ddng thdi khdng i n h hudng tdi c h i t Idpng nddc sau mang ky khi theo COD v i SS. S i n Idong bun trong 2 pha dau d mde 0.04 g VS/g COD chuyen hda, tang den 0.07 g VS/g COD
Hinh 4: Nong do bun trong be mang ky Mil va thcii gian iKu nifte Sdn luang khi sinh hoc thu hdi tdnUdc thdi giet mS gia sdc
Hlnh 5 bieu thi s i n Idong khf sinh hpc (biogas), % khf metan [CH^) trong khf sinh hoc thu hdi t d be mang ky khf. Vdi ca che hoat ddng cda md hlnh, mot phan ddng biogas sinh ra t d be, ddpc bom tuan hoan lai be p h i n dng, tao ddng tuan h o i n cho bdn trong be, ddng thdi tao ddng trUOt qua m i n g , han che Idp bdn ddng trdn mang, g i i m k h i n i n g tSc mang trong be.
K i t q u i eho thay, Idpng biogas thu ddpc tang khi OLR tang, nhdng sut g i i m nhanh ehdng 6 pha 5. Ldong khi thu ddpc tdi da tap trung d mdc 3.7-4.4 L/ngiy d pha 4. Xet ve ham lUOTg metan trong biogas, dd thi cho thay %CHj tang t d pha 1 den cudi pha 3 va pha 4. Cu the, %CH^ duy tri d mdc 33% trong toan pha 1, fen 46% d dau pha 2, tang nhanh d i n 76% d cudi pha 2 v i t o i n pha 3, c h i t luong khi van duy tri d mde tdt niy. Sang pha t h d 4, dau pha ghi nhan si/ suy g l i m d thdi diem chuyin pha, k h o i n g 50% CH^ trong biogas, sau d d tang v i dn dinh t r d lai t d g i d a den cudi pha 4, %CH^ c h i l m 73%. Sang pha 5, %CH^ sut g i i m 6 3iu pha nhd 3iu pha 4, nhdng tJep tue g i i m dan xudng 47% d cudi pha 5.
H i m luong CH, thSp trong biogas trong giai doan dau do 2 nguyen nhan: (1) nhiet d d mdi trudng trong 2 pha dSu ghi nhan thap hon 30°C, tham tri d pha 1 la dddi 2 0 ^ , cd i n h hudng rd ret den k h i n i n g sinh trddng va phat t r i l n cua hi VI sinh vat ky khf, ddpc eho la sinh trddng
va p h a t r i l n t h u i n led d d i i nhiet d p am (30- 35'>C) hoac ndng { 5 2 - 5 5 0 , {il) quan the vi sinh ky khi, d i l n hinh la nhdm methanogens cd vai t r d quyet dinh trong q u i trinh chuyen hda sinh metan, s i n pham cudi eda q u i trinh Idn m e n chat hdu ca, van can 1 k h o i n g t h d i gian thfch nghi vdi d i l u kien mdi trudng v i eo chat mdi.
Trong dieu kidn thi nghiem n i y t h d i gtan thich nghi l i 60 ngay, eao hon k h o i n g t h d i gian thfch nghi d nhiet d p Idn men I m (30-35°C) la 43 ngay trong bao c i o cua Borja (1994) nhung tucrng ddng vdi IMasse va Masse {2000) thdc hien qua trinh ky khf nddc t h i i giet md gia sdc mac dd b l mang ky khi dupc khcri ddng vdi nhidt dd thap hem 20°C, khdng t h u i n loi nay. Khi nhiet d d mdi trddng tang v i on djnh d 25-30°C, ket q u i
%CH4 tang rd ret v l t u o n g dong vdi mdc tdi du {73%-76%) dUOe ghi n h i n trong biogas cua q u i trinh len men, ehdng t d sUcan b i n g cda quan the vi smh ky khf trong be p h i n dng. Mang da gidp he bun dupc luu g i d dn dinh trong be ky khf, smh khdi bdn trong giai doan nay p h i t trien d mdc cao (0.07 g VS/g COD ehuyen hda) t r w i g giai doan n i y . Sang pha 5, sinh khdi bun sut g i i m , bdc Id chat luong khi ddng thdi edng suy g i i m lien tuc, ehdng t d he vi sinh da bi m i t can b i n g . T i l Idpng hdu c o t r d t h a n h y l u t d gidi han trong pha nay. K i t q u i ham lupng CH, trong biogas v l nhdng \-y giii n l y phd hop vdi ket q u i so s i n h t h i tich CH, thue te t h u hdi t d be m i n g ky khi vdi the tich CH^ tfnh t o i n theo ly thuyet q u i trinh c h u y i n hda COD trong be, ddoc bieu thi trong Hinh 6
Hlnh S: Sin liiong khi anh hoc (bioQas) va %0I, anh ra td benungkyktii
Hinh 6: The tich khf CH, smh ra tfiiic t l tir be ming kK ktiiso vdi thJ tfdi Mli tinh theo ly thuylt
Tdn tai k h o i n g each Idn gida the tich CH, thuc t l t h u hoi t d be mang ky khf vdi the tich CH, tfnh t o l n theo Ij? thuyet qua trinh chuyen hda COD trong nddc t h l i g i l t m d gia sue (40- 60%), trong giai doan khdi ddng b i n dau den
n g l y t h d 90, d i n cud! pha t h d 2 va giai doan cudi q u i trinh van hanh, pha t h d 5. Sang pha 3, s i n Idpng khi metan thdc te dat 1.6 L/ngay, tucmg d d p n g 0.29 m*CH4,/kg COD; xap xi b i n g d pha 4, vdi s i n Idpng khf thdc t e dat 2.8 L/ngay, tdcftig ddcfng 0 3 0 m^C, A g COD. Trong 2 pha n i y , the tieh khf thdc t l t h u ddpc ttiap hOn ly thuyet xap xf 15%. Lupng khf hao h u t nay phan ldn do bj k h u i c h tan v l hda tan v i o nddc t h l i dau ra khi bom hut qua mang. Theo b l o c i o eua Kim (2002), 30% luong khf metan bi hda tan v i o nddc dau ra tai nhiet d p 35oC v l ed the len d i n 50% tai 1 S t trong md hinh x d ly nudc thai sinh hoat b i n g mang ky khj. Ket q u i dat ddpc cao hem ket q u i nghien edu cua He (2005) dng dung cdng n g h l AnMBR de x d ly nddc t h i i c h l bien thuc pham dam dae, nang s u i t khi bicigas on dinh d mdc 0.123 m'/kg COD. cho thay r i n g nddc t h i i giet md gia sue l i mdt coehat ed tiem n i n g sinh khi smh hpe cao trong viee dng dung v i phat trien cua cong nghe mang ky khi. Dieu n i y eung dUOe chdng minh trong nghien cdu cua Borja (1998) khi x d ly ky khf nddc t h i l giet md gia sue d dieu kien len mem I m , nang suat smh khi metan tdi du dat 0.2-035 m'/kg COD.
Ket l u i n
Md hlnh m i n g ky khi ddpc thiet lap vdf m i n g MF (0.4pm) dang tam p h i n g trong b l phan dng ky khi, van h l n h trong dieu kien khf h i u mien file-Viet Nam, nhidt d d thay doi t d 10°C den 30°C trong 270 ngay. d e x d ly nddc t h l i g i l t md gia sue (lOn) tai cd s6 Id md quy md cdng nghidp tai Ha Ndi. Ket qua thf nghiem da chdng t d :
{i) H i m lucmg hdu eo vdi chi tieu COD trong nddc t h i i giet md gia sdc dao ddng t d 600- 1350 mg/L, cd gia tri trung binh 900 mg/L, t ^ le COD:TN x l p xi b i n g 8 l l n , t y Id N H , N chiem 90% cua TN. H i m luong can lo ldng k h i thap ( x l p xi 280 mg/L) va dao ddng nhieu. Phan ldn m l u (tilt) dupc t h u hdi, Idng va da thda t h i i bd dupc g i d lai tai CO sd.
{ii) Hieu q u i x d ly SS va COD dat tren mdc 95% v i 90%, tuong dng, khi OLR tang den 2 kg C 0 D / m 3 j i g l y , HRT b i n g 12h. Chat lupng nude sau be AnMBR ve hai chi tieu d nhiem dien hlnh nay dn 3inh, chf tieu SS dat 7+6 mg/L, COD dat 94±43 mg/L, thap hon mde quy djnh theo cua cdt B, QCVN 40:2011/BTNMT
(iii) Viec t i n g t i i trong thiJy Ide va g i l m t h o i gian luu nUde khdng lam suy giam chat lupng v l ndng d p bun trong be do c o c h l g i d l a j bun vi sinh nhd m i n g khi OLR b i n g 2 kg COD/m'.ngiy, HRT 12h; ndng d p bdn dat 18 g T S ^ t y le VS/TS on a n h d mdc 78%; s i n lupng bun dat 0.07 g VS/g COD. S i n Idpng khf metan t h d c t e o n dinh v l dat mde eao, 0.3 m* C H / k g COD.
{iv) Khi OLR t i n g den 3 kg COD/m'.ngay, HRT g i i m xudng 8h, s i n Idpng b u n va nang suat khisinh hoc suy g i l m nghidm trpng, md hlnh be p h i n drig m i n g ky khf cd d i u hidu ho ^ t ddng kem dn djnh.
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