MC LC

DANH MC BNG

DANH MC HNH V

DANH MC CH CI VIT TT

Anammox-Anaerobic Ammonium Oxidation:Oxy ha Amni k kh

AOB-Ammonium Oxidation Bacteria:Vi khun oxy ha Amni

NOB-Nitrite Oxidizing Bacteria:Vi khun oxy ha Nitrit

FA-Free Ammonia:Amniac t do

FNA-Free Nitrite Acid:Axit Nitrit t do

SBR-Sequencing Batch Reactor:B phn ng sinh hc lin tc

RBC-Rotating Biological Contactor:

MBBR-Moving Bed Biofilm Reactor:

SS-Suspended solids:Cht rn l lng

VSS-Volatile Suspended Solids:

UASB -Upflow Anaerobic Sludge Blanket:

AOB = Ammonium Oxidizing Bacteria ANAMMOX = ANaerobic AMMonium OXidation BOD = Biochemical Oxygen Demand (mg O2/l)CANON = Completely Autotrophic Nitrogen Removal Over Nitrite COD = Chemical Oxygen Demand (mg O2/l)DO = Dissolved OxygenFA = Free AmmoniaFNA = Free Nitrous AcidHRT = Hydraulic RetentionTime HT = HeterotrophsMAP = Magnesium Ammonium Phosphate MBBR = Moving Bed Biofilm Reactor MBR = Membrane Biological Reactor MLSS = Mixed Liquor Suspended SolidsNOB = Nitrite Oxidizing BacteriaRBC = Rotating Biological Contactor SAA = Specific Anammox Activity SBR = Sequencing Batch ReactorSHARON = Single Reactor for High Activity Ammonium Removal Over NitriteSRT = Sludge Retention Time SS = Suspended SolidsT = TemperatureTN = Total NitrogenTP = Total PhosphorusTSS = Total Suspended SolidsUASB = Upflow Anaerobic Sludge Bed VSS = Volatile Suspended Solids

PHN I: TNG QUANSNAP Single stage Nitrogen removal using Anammox and Partial Nitritation l qu trnh x l thnh phn Nit trong nc thi s dng kt hp qu trnh Nitrit ha mt phn (SHARON) vi phn ng Anammox. hiu r hn v c ch cng nh bn cht ca cng ngh ny, ta s ln lt nghin cu cc qu trnh ring r v kh nng kt hp ca chng trong ng dng x l nc thi giu Nit.1.1. Qu trnh Nitrit ha/kh Nitrit ha (Nitritation/Denitritation - SHARON)Nitrit ha kh Nitrit ha l qu trnh chuyn ha qua Nitrit (thng c gi chung l qu trnh SHARON) c xem l cng ngh mi bn vng hn so vi qu trnh Nitrat ha kh Nitrat ha truyn thng [3].SHARON l vit tt ca cm t Single reactor High Activity Ammonia Removal Over Nitrite c pht trin vo cui nhng nm 1990 ti trng i hc Cng ngh Delft bi Helliga v cng s [4]. Qu trnh SHARON thng c thc hin trong cc b c lp vi dng chy lin tc. Trong qu trnh ny, amni c oxy ha thnh nitrit trong iu kin hiu kh (qu trnh Nitrit ha) v Nitrit to thnh c kh Nitrit d dng sinh kh N2 bng cch b sung ngun carbon t bn ngoi (qu trnh kh Nitrit ha).Nhm vi khun thc hin chuyn ha sinh hc gm c Nitrosomonas v vi khun kh Nitrit ha hiu kh, h thng vn hnh di iu kin khng lu sinh khi. Qu trnh khng lu bn do khng chu nh hng ca thnh phn cht rn l lng -SS trong nc thi.

Hnh 1. S h thng Nitrit ha/kh Nitrit ha (SHARON) (ngun: [3])Cc phn ng xy ra trong qu trnh SHARON c m t nh sau:Phng trnh phn ng Nitrit ha:NH4+ + 1,5 O2 NO2- + 2 H2O + 2 H+ (1)Phng trnh phn ng kh nitrit ha:NO2- + 0,5 CH3OH 0,5 N2 + 0,5 CO2 + 0,5 H2O + OH- (2)Qu trnh ny yu cu t hn oxy v carbon hu c so vi qu trnh Nitrat ha kh Nitrat ha truyn thng. Lng Oxy tiu th gim 25% v lng carbon tiu th gim xp x 40% (Hnh 2,3). Lng bn sinh ra cng t hn so vi cng ngh Nitrit ha- kh Nitrit ha.

Hnh 2. Qu trnh Nitrat ha/kh Nitrat (ngun:[3])

Hnh 3. Qu trnh Nitrit ha/kh Nitrit ha (ngun: [3]).Mc ch chnh ca qu trnh ny ngn chn s Nitrat ha t dng ca Nitrit bng cch to ra nhng iu kin bt khng ph hp cho s oxy ha thnh Nitrat sau nhm tit kim chi ph cho sc kh v ngun carbon b sung. Cc iu kin thc hin qu trnh Nitrat ha mt phn n nh: Nhit . Thi gian lu thy lc HRT. Oxy ha tan (DO). pH. Nng cc cht nn v cc tc nhn c ch qu trnh.Qu trnh din ra nhit tng i cao (trn 250C), theo tc tng trng ring ti a ca vi khun oxy ha amoni mong mun l cao hn so vi vi khun oxy ha Nitrit khng mong mun. nhit vn hnh 350C, tc tng trng ring ti a ca vi khun oxy ha Nitrit xp x mt na so vi vi khun oxy ha amoni (tng ng 0,5 v 1 ngy-1) [3]. nhit 25-350C vi khun oxy ha amoni c tui bn yu cu ti thiu ngn hn v thi gian lu thy lc c chn c th loi b vi khun oxy ha Nitrit v gi li vi khun oxy ha amoni trong b phn ng (hnh di)

Hnh 4. Thi gian tn ti ti thiu ca vi khun oxy ha amoni v vi khun oxy ha Nitrit nhit khc nhau (ngun: [3])Nng oxy ha tan thp s hn ch s tng tng ca vi khun oxy ha Nitrit (Nitrit Oxidizing Bacteria - NOB) do i lc vi oxy nh hn ca chng so vi vi khun oxy ha Nitrat (Nitrat Oxidizing Bacteria). Do , DO l thng s rt quan trng trong kim sot h thng [5].Theo thng k ca Van Hulle v cng s (2007), thc t nng Ammonia (NH3) v Nitrit (HNO2) t do l cht nn ng thi l tc nhn gy c ch cho qu trnh oxy ha amni v oxy ha Nitrit ch khng phi amni (NH4+) v Nitrit (NO2-) [6].Vi khun oxy ha Nitrit c th cnh tranh o thi gi tr pH kh cao (7,5-8), do lng axit nitrit (HNO2) gim v amni t do tng. iu kin thc y vi khun oxy ha amni v c ch vi khun oxy ha Nitrit.Tuy nhin, khi nng amni v axit nitrit t do cao c th tr thnh nhng tc nhn c ch qu trnh. Vi khun oxy ha amni (AOB) b c ch nng NH3 t 8-120 mg N/l v nng HNO2 t 0,2-2,8 mg N/l trong khi vi khun oxy ha Nitrit b c ch nng NH3 0.08-0,82 mg N/l v nng HNO2 0,06-0,83 mg N/l. Trong thc t, ngng nng ny cn ty thuc v kh nng thch nghi ca vi khun. gi tr pH cao, nng Amni t do cao hn s hn ch s tng trng ca vi khun oxy ha Nitrit (NOB) do tnh nhy cm cao ca chng i vi amni t do so vi vi khun oxy ha amni (AOB) [3].Trong cc nghin cu ca Hulle v cng s nm (2010) cc tc gi ch ra rng hot ng ca vi khun AOB gim do gii hn nng bicarbonate [4]. Hiu qu oxy ha Nitrit gim nng phosphate di 0,2 mg P/l v i vi qu trnh oxy ha amni l 0,03 mg P/l. Mt vi cht nhim nh chlorate, formic, acetic, propionic v axit n-butyric, cyanide, azide v hydranine, bromide, v chloride gy tc ng c ch cho qu trnh oxy ha Nitrit nhiu hn so vi oxy ha amni [3].H thng full-scale u tin ng dng cng ngh ny c xy dng ti Rotterdam-Dokhaven nm 1999. Gia nm 2000-2005 bn h thng full-scale khc c xy dng H Lan, cc h thng t hiu qu x l Nit tng trung bnh 88%. Nm 2007, h thng full-scale u tin ca thnh ph New York c xy dng [3].Qu trnh cng c th c vn hnh trong h thng mt b (single reator system) sc kh lin tc. Fux v cng s (2006) thy rng 85-90% Nit c loi b trong qu trnh Nitrit ha/kh Nitrit ha nc p bn giu amni trong b SBR vi ti trng dng vo lin tc (ti trng khong 1,2 g NH4+-N/m3.ngy). H thng t c tnh n nh cao thi gian lu bn tng HRT l 1 ngy [7].1.2. Qu trnh Anammox (Anaerobic Ammonium Oxidation)1.2.1. Gii thiu qu trnh Anammox Oxy ha Amni k kh - ANAMMOX l mt qu trnh mi y ha hn trong Amni c oxy ha trc tip thnh kh Nit s dng Nitrit trong vai tr cht nhn in t di iu kin thiu kh [8].

Hnh 5. Chu trnh chuyn ha Nit trong t nhin [1]Qu trnh ny c d on t cch y 30 nm trong cc tnh ton nhit ng hc c bn, chnh thc cng nhn khong 15 nm trc, trong qu trnh thc nghim cng on kh Nitrat ha qui m pilot ca h thng x l nc thi nhiu giai on ti Gist-Brocades (Delft, The Netherlands). Khi tin hnh th nghim ny, Amni mt i trong nc thi u ra b phn ng ng thi lng kh N2 sinh ra nhiu hn. Sau , ngi ta chng t c rng Nitrit ch khng phi Nitrat ng vai tr l cht nhn in t trong phn ng [3]. Strous v cng s (1999) a ra phn ng tng qu ca qu trnh Anammox nh sau [9]:NH4+ + 1,32NO2- + 0,066CO2 + 0,066H+ 0,066CH2O0,5N0,15 (Anammox) + 1,02N2 + 0,26NO3- + 1,96H2O (3)Amni c chuyn ha thnh kh nit vi nitrit ng vai tr cht nhn in t t l 1:1,32, khng cn b sung ngun carbon hay oxy. Mt lng nh nitrat c to thnh (khong 10%). Cc tnh ton v cn bng khi lng trong qu trnh lm giu vi khun Anammox ch ra rng vi khun Anammox s dng CO2 lm ngun carbon sn xut sinh khi v NO2- khng ch ng vai tr cht nhn in t ca qu trnh oxy ha Amni m cn ng vai tr cht cho in t trong qu trnh kh CO2 [3]. Trong cc th nghim s dng Nit c gn nhn, ngi ta thy rng Hydroxylamine v Hydrazine c to thnh nh l sn phm trung gian. C ch ny lin quan s kh mt phn Nitrit vi s hnh thnh ca hydroxylamine (NH2OH), cht ny phn ng vi Amni to thnh Hydrazine (N2H4). Sau Hydrazine chuyn ha thnh kh Nit. S oxy ha ny s dn n s gim nng Nitrit ban u. Cht nn thc t cho cho vi khun anammox l NH3 t do ch khng phi NH4+ [8].Vi khun anammox c tm thy trong mt vi h thng x l nc thi, trong trm tch bin trn khp th gii (v d nh: Gullmarsfjorden Sweden, Skagerrak Bin Bc, Colne Estuary National Nature Reserve Vng Quc Anh, Greenland Arctic Sea, Mertz Sea Antarctica, Benguela OMZ Namibia, Chesapeake Bay M), hoc trong cc mi trng thiu kh (v d Bin en v Golfo Dulce, Costa Rica). S c mt ca vi khun Anammox c xc nh trong hn 30 loi nc ngt t nhin v h sinh thi bin trn th gii. Trong trm tch vi hm lng carbon thp, Anammox ng gp hnh thnh 20-79% tng sn phm N2 [3].Qu trnh oxy ha Amni k kh c thc hin bi vi khun t dng thuc loi Planctomycetales. C nm chng vi khun Anammox c xc nh cho n nay (Bng 1).Bng 1. Mt s loi vi sinh vt Anammox c pht hin cho n nay Chng VSVLoi VSVNgun

BrocadiaCandidatus Brocadia anammoxidans Candidatus Brocadia fulgidaNc thiNc thi

KueneniaCandidatus Kuenenia stuttgartiensisNc thi

Scalindua

Candidatus Scalindua brodaeCandidatus Scalindua brodae Candidatus Scalindua wagneri Candidatus Scalindua Sorokinii Candidatus Scalindua arabicaNc thiNc thiNc binNc bin

JetteniaCandidatus Jettenia asiaticaKhng r

AnammoxoglobusCandidatus Anammoxoglobus propionicusNc thi

(Ngun: [3])Sinh khi Anammox c mu nu. Vi khun anammox c trng bi t l tng trng ring cc i rt thp (=0,00648 ngy-1) vi thi gian nhn i l 10,6 ngy v sinh khi to thnh t (0,11-0,13 g VSS/g NH4+-N). Do lng bn sinh ra trong qu trnh Anammox rt thp v giai on khi ng ko di (ln n 1 nm). T l tiu th Nit ring ti a tng i cao (0,82 g N/g VSS .ngy) v i lc i vi cc cht nn Amnia v Nitrit (Ks 18530.9Khng hot ng

Bn Anammox377.23ABFDng lin tc>28029.5c ch

Fixed bed reactor sludge (Candidatus Kueneniastuttgartiensis, Planctomycetes KSU-1 vsimilar - Candidatus Brocadia anammoxidans)36Monod test tubesTheo m>274c ch

Bn dng ht k kh3556.89.1UBFDng lin tc38019.85.0-31%

Bn keo t kh Nitrate ha3556.815.3UBFDng lin tc390-85%

Mng sinh hc Anammox 307.8-Closed vialsTheo m-11Biofilm -70%Floc -100%

Mng sinh hc Anammox 30-24SBRDng lin tc237 mg COD/l (ti lng COD l 112 mg/l.ngy)>290 mg COD/l.ngy (ti lng COD l 136 mg/l.ngy)-100%

-100%

VialsGin onAcetate 10 mmol/l10 mmol/l10 mmol/lKhng ng k-22%-70%

VialsGin onAcetatePropionateGlucose 1 mmol/l1 mmol/l1 mmol/l-2%-1%-5%

(Ngun: [12])

nh hng ca cc cht hu c c tnh c [12]Cc cht hu c c nh hng ti Anammox bng cch gy ng c vi khun hoc kh hot tnh enzyme, v tc ng ny thng khng th phc hi. Alcohl, aldehydes, phenol v antibiotics l 4 loi cht hu c c kh nng c ch qu trnh Anammox.Alcohol v aldehydes: Trong h thng x l nc thi t nhin, vi khun Anammox tn ti vi s lng ln, tuy nhin, nng 3-4 mmol/l methanl c th c ch gn nh hon ton hot ng ca chng, nhng gi tr c ch ngng khc nhau trong cc nghin cu. Guven v cc cng s cho rng 0,5 mmol/l methanol s c ch khng th phc hi vi khun anammox. Oshiki v cng s kt lun hot ng ca vi khun Anammox gim 86% nng 1 mmol/l methanol, nhng Isaka v cng s quan st thy rng 5 mmol/l methanol ch lm gim 71% hot ng ca Anammox trong cc th nghim hng lot. S khc bit ny l do s dng cc loi Anammox khc nhau. Isaka v cc cng s cc nhm vi khun Candidatus Kuenenia stuttgartiensis, Planctomyces KSU-1, and similar Candidatus Brocadia anammoxidans, trong khi Oshiki v cng s nghin cu chng vi khun Anammox Candidatus Brocadia sinica.Vi khun anammox c th chu ng nh hng ca methanol mt mc nht nh. Tang v cng s lm giu thnh cng Anammox t bn methanogenesis c cha nng cao cc cht hu c v methanol. S khc nhau trong tc ng ca methanol ch yu l do s khc bin v loi v cc iu kin thc nghim. C ch ca s nh hng ca methanol i vi Anammox cui cng cng c tm ra l do s c ch ca formaldehyde. Nghin cu ch ra rng, nu hot ng ca Anammox l tnh (ng ng) khi cht nn khng c cung cp th nh hng ca methanol khng c tm thy. Methanol c th c chuyn ha thnh formaldehyde trong t bo do hot ng ca enzyme Anammox - hydroxylamine oxidoreductase. Formaldehyde ph hy hot ng ca enzyme v protein bng cch phn ct khng phc hi cc chui peptide, gy ra tc ng khng th phc hi i vi vi khun Anammox. C th kt lun rng, tc ng ca alcohols i vi anammox ch yu l do Anammox enzyme chuyn ha alcohols thnh dng aldehyde tng ng ca chng v nh hng trc tip ln phn ng Anammox.Phenol: Cc hp cht phenolic l him khi c mt trong nc thi th, chng thng c tm thy trong mt s nc thi cng nghip, chng hn nh nc thi t nh my bt giy, cc ngnh cng nghip dt may v ha du, nh my lc du, nh my kh ha than, dc phm, phn bn, sn xut du m v sn, nh my sn xut vn si p. Toh v cng s lm giu thnh cng Anammox Candidatus Brocadia anammoxidans t bn thi nh my x l nc thi sinh hot v kim tra tnh thch nghi s dng nc thi tng hp c cha phenol [10]. Khi nng phenol tng dn t 50 ( 10) mg/L n 550 ( 10) mg/L, kh nng loi b Nit u vo gim nhng sau dn phc hi. cc kt qu ny ch ra rng phenol c tc ng xu ti s trao i cht ca anammox, nhng hot ng ca anammox vn c tng cng nh kh nng thch nghi ca chng.1.2.2.5. nh hng ca cht khng sinh (Antibiotics) [12]Khng sinh c s dng rng ri trong cc sn phm dc dnh cho con ngi v ng vt, trong nui trng thy sn vi phc ch d phng v iu tr nhim trng. Nng khng sinh cao c pht hin trong mi trng nc, chng hn nh nc thi sinh hot, nc mt, nc ngm Bng 5. nh hng ca mt s cht khng sinh i vi AnammoxCht khng sinhLoi VSVNng nh hng

ChloramphenicolChloramphenicol200 (98 2)%a

(68 10)%b

20 (36 5)%

Penicillinsb-lactams100 (36 10)%

Ampicillinb-lactams800 (94 4)%

Tetracycline hydrochlorideTetracyclines1001000c 20% - 80%

Tetracycline hydrochlorideTetracyclines10d 60%

ChloramphenicolChloramphenicol2501000c 20% -80%

ChloramphenicolChloramphenicol20d 25%

(Ngun: [12])Cc bng chng thuyt phc ch ra rng hot ng ca vi sinh vt b c ch bi cc cht khng sinh. Tang v cng s nghin cu nh hng i vi anammox nc thi dc phm giu cht khng sinh polypeptide antibiotics colistin sulfate v the macrolide kitasamycin. S c ch i vi anammox quan st thy trong mt thi gian di vn hnh. Tuy nhin mi lin h liu lng/phn ng cha c nghin cu. C rt t nghin cu v nh hng ca khng sinh i vi anammox, cc nghin cu gn y ch tp trung vo 3 loi khng sinh chloramphenicol, b-lactams v tetracycline, cng cha c nghin cu no ch r tc ng ca khng sinh i vi tng loi Anammox ring bit.1.2.2.6. nh hng ca mn [12] mn cao s dn n p sut thm thu cao v vi sinh vt trong mi trng c mn cao c th b cht hoc khng hot ng. Nh vy, p sut thm thu trong nc thi tp trung c th c ch vi khun. Mt lng ln nc thi c mn pht sinh t cc ngnh cng nghip nh ch bin thy sn, dt nhum, khai thc du kh, kh t v thuc da. Mc d x l sinh hc c cho l b c ch bi mui, phn ng anammox vn l mt qu trnh y ha hn x l nc thi c nng mui cao. Qu trnh anammox c tm thy ph bin trong mi trng nc bin thiu oxy, mt s nh nghin c lm giu vi khun anammox t trm tch bin v nh gi kh nng thch nghi ca chng trong mi trng c nng mui cao.

Bng 6. nh hng ca mn i vi Anammox M hnh thc nghim(loi chim u th)MuiNng (g/l)c tnh bnnh hng

SBRNaCl5Khng thch nghi(1) Tng kh nng gi sinh khi Anammox

(2) Hot lc ring Anammox (SAA) gim nh, nh hn

0.4 g N/g VSS .ngy (khi NaCl l 0 g/l)

10Khng thch nghi(1) Tng kh nng gi sinh khi Anammox

(2) SAA tng k

SBR (CandidatusNaCl613.530Dng lin tc vi s thch nghi dn dnNRR c duy tr xp x 1.65 kg N/m3.ngyVn hnh n nh vi NRR mc 1.7 kg N/m3.ngyNRR gim mnh

(Ngun: [12])

Khi x l nc thi c cha thnh phn mui c bit l nc thi c nng mui cao cn xem xt tc ng ca mn l mt yu t gy c ch chnh i vi qu trnh anammox. Khi mn mt gi tr nht nh (3-15 g NaCl/l) thc y s hnh thnh bn Anammox dng ht v lm tng kh nng lu gi ca vi khun trong b phn ng, nhng mn cao c ch Anammox. Tuy nhin, hiu sut qu trnh anammox di iu kin mn cao tng dn nh kh nng thch nghi ca vi khun.Tc ng ca mn ph thuc vo loi mui, loi bn cc iu kin th nghim. Dapena-Mora v cng s chng minh c rng NaCl khng nh hng ti Anammox khi nng mc di 8,78 mg/l. Khi nng KCl cao hn 7,45 g/l hoc nng Na2SO4 cao hn 7,1 g/l Anammox b c ch. Cc nng u vo ca Na2SO4, NaCl v KCl tng ng l 11,36 g/l, 13,46 g/l, 14,9 g/l. Kartal v cng s kt lun rng vi khun anammox t h thng nc sch c th thch nghi vi mi trng c nng mui cao c 30 g/l. Nng mui (90% NaCl v 10% KCl) tng dn vi gradient nng 5, 10, 30, 40, 60, 75 v 90 mg/l; hot lc ti a ca Anammox v hiu qu x l Nit ca bn cha mui l tng t trong mi trng bn nc ngt. Mc d, hot ng ca vi khun anammox gim nhanh chng v khng khi nng mui l 45 mg/l trong b SBR thch nghi mui, h thng vn c th phc hi sau . Khi vn hnh trong thi gian di di iu kin ng mui cao, chc nng ca h thng Anammox gim st, tuy nhin kh nng thch ng ca vi khun Anammox c chng minh trong cc th nghim thc t. Jin v cng s cho rng nh hng ca mn i vi Anammox gim t 67,5% xung 43,1% nh kh nng thch nghi. Vi khun anammox chu ng c mui, ngn nga cc tc ng c hi lu di gy ra bi nng mui cao. Liu v cng s vn hnh thnh cng v n nh qu trnh anammox nng NaCl 30 g/l t hiu qu x l 1,7 kg N/m3,ngy. Yang v cng s t c hiu qu x l cao 4,5 kg N m-3 d-1 khi nhit xung quanh (23-26 0C) vi nng mui cao tng ng. Candidatus Kuenenia stuttgartiensis c cho l loi vi khun anammox c kh nng chu ng mui cao.1.2.2.7. nh hng ca cc ngun khc nh hng kim loi nngKim loi nng kh phn hy sinh hc v c th tch ly trong sinh vt, gy ng c tch ly sinh hc. Mt s loi nc thi giu Nit nh nc r rc, thng cha nhiu ion kim loi nng. Hiu r hn nh hng ca kim loi nng ti Anammox c ch cho vic x l nc thi loi ny. Nhn chung, 1 mmol/l HgCl2 c ch hon ton hot ng ca Anammox. nh hng ca phosphate v sulfidePhosphate v Sulfide l hai cht v c ph bin gy c ch qu trnh Anammox. SO42- thng chuyn ha thnh H2S trong phn hy k kh v gy hi cho qu trnh. S khc bit v loi chim u th (hoc cp bn) v iu kin vn hnh, nh hng ca phosphate v sulfide trong cc nghin cu l khc nhau. Tuy nhin, cc nghin cu gn y ch yu c thc hin i vi chng vi sinh Candidatus Kuenenia stuttgartiensis, do cha c kt lun i vi mt s chng vi khun anammox khc.Bng 7. nh hng ca Photphat v Sulfua i vi Anammox Tc nhn iu kin vn hnhBn cy (loi chim u th)Nng (mmol/l)nh hng

PhotphatGin onGin onBn FBR kh nitrate haMng sinh hc RBC nitrate ha5 hoc 5020 100%Khng c ch

(Candidatus Kuenenia stuttgartiensis)

Gin on

Vi khun Anammox(Candidatus Kuenenia stuttgartiensis)20 50%

Gin on

Mng sinh hc RBC1.8 37%

3.6 80%

Gin on

(Candidatus Kuenenia stuttgartiensis)Vi khun Anammox 9.22c ch

Gin on

Mng sinh hc Anammox(Candidatus Brocadia sinica)20 (phosphorus) 20%

SulfuaGin onDng lin tcDng lin tcGin onGin on

Bn FBR kh nitrate haBn FBR kh nitrate haBn FBR kh nitrate haVi khun Anammox(Candidatus Kuenenia stuttgartiensis)Vi khun Anammox (Candidatus Kuenenia stuttgartiensis)1 hoc 52 (cp tng t)2(cp lin tc)2>5Tng dn20%60%60%100%

(Ngun: [12])1.2.3. u im qu trnh Anammox [12] Khng yu cu b sung ngun carbon hu c t bn ngoi Lng bn to thnh tng i nh. Hiu sut x l Nit cao Yu cu th tch b phn ng nh hn n 50% Gim kh nhiu yu cu v nng lng, nng lng tiu th gim 60-90 % so vi cng ngh Nitrit ha/kh Nitrat ha truyn thng Gim lng CO2 pht thi (n 90%) do trong sut qu trnh bicarbonate c s dng thay v to thnh CO2 (nh trong qu trnh kh Nitrat ha truyn thng). Nh vy qu trnh ny ng gp t hn i vi hiu ng nh knh. N2O (mt loi kh nh knh kh mnh, tc ng gp hn 300 ln CO2) khng c coi l sn phm trung gian ca qu trnh Anammox.

1.3. Nitrit ha mt phn/Anammox trong hai b phn ng c lp (h thng 2 b)S kt hp ny thng c gi l Qu trnh SHARON-ANAMMOX kt hp hoc Qu trnh x l Nit t dng. Qu trnh c thc hin trong hai b phn ng ring bit. Trong b th nht din ra phn ng oxy ha khong 50% Amni thnh Nitrit (Nitrit ha mt phn). Nitrit to thnh s s dng sinh kh Nit thng qua qu trnh Anammox trong b th hai [3].Mc ch ca b th nht l to ra mt dng vo c thnh phn n nh thch hp cho b phn ng Anammox th hai (vi t l s mol Amni/Nitrit l 1,32:1 theo phng trnh phn ng Anammox do Strous a ra nm 1999). Tuy nhin trong thc t, t l ny rt kh c to thnh, nhng c duy tr gn vi t l 1:1 ngn nga s c ch ca thnh phn Nitrit trong b th hai bng cch cp Amni t bn ngoi [3].

Hnh 6. S kt hp SHARON-ANAMMOX trong hai b phn ng ring bit (ngun: [3]).Phn ng xy ra trong b th nht to hn hp Nitrit v Amni c thnh phn 50:50 nh sau:NH4+ + 0,5 O2 + HCO3- 0,5 NH4+ + 0,5 NO2- + CO2 + 1,5 H2O (6)Cc thng s vn hnh quan trng trong b SHARON to dng vo n nh cho b ANAMMOX l nhit , DO, pH, thi gian lu thy lc (hydraulic retention time-HRT), cht nn sn c). S nhy cm ca vi khun oxy ha Amni v Nitrit i vi cc thng s trn l khc nhau v cn c kim sot cn trng.Nhn chung, cc iu kin vn hnh trong b th nht c l: pH 6,6-7,0, nhit 30-400C, HRT = 1 ngy, khng lu bn [3]. Trong trng hp x l nc p bn, phn ln khng yu cu b sung cc cht nn do thnh phn ca chng thng kim cn thit.Vic kim sot cc yu t c ch qu trnh trong b phn ng Anammox l rt quan trng m bo hiu qu x l ca h thng kt hp ny.Qu trnh Nitrit ha mt phn n nh trong b phn ng u tin c kt hp vi qu trnh oxy ha Amni k kh trong b th 2 nhm m bo rng vic loi b Nit din ra thng qua qu trnh t dng. Hai yu cu rt cn thit trong bc Nitrit ha mt phn. Th nht, cc cht oxy ha Nitrit phi lin tc b c ch, th 2 t l Nitrit/Amni to ra phi l 1.3 (phng trnh phn ng (3)). Nu qu nhiu Nitrit c to thnh, cc cht l lng u vo cn c b sung trc tip vo b Anammox to cn bng ha hc. do Nitrit c th b ch hon ton trong qu trnh anammox nng ln hn 100 g NO2-N/m3, Amni nn c b sung hi d mt cht p ng phng trnh phn ng (3). Khng phi tt c cc iu kin qu trnh c ch s oxy ha Nitrit c hiu r rng thi im hin ti. nhit trn 300C cc tc nhn oxy ha Amni pht trin nhanh hn so vi cc tc nhn oxy ha Nitrit do s oxy ha Nitrit c th c chn ng hon ton bng cch kim sot cn thn thi gian lu bn HRT. S c ch hon ton cc tc nhn oxy ha Nitrit nng 1 g NH2OH/ m3 (hydroxylamine, mt sn phm trung gian ca phn ng monooxygenase nitrosomonas) c a ra bi Stuven v cc cng s (1992). Amni bt u c ch nitrosomonas nng gia 10 v 150 g NH3/m3, trong khi hot ng ca vi khun nitrobacter gim ng k nng gia 0,1 v 10 g NH3/m3.S hnh thnh hn hp Nitrit/Amni ph hp ph thuc vo t l kim/Amni trong dng vo. i vi qu trnh oxy ha Amni thnh Nitrit, 2 proton tng ng c to ra trn mi mol Amni chuyn ha. Nc p bn cha thnh phn bicarbonate nhiu hn khong 1,2 ln so vi Amni, do khong 60% Amni s c oxy ha thnh Nitrit kt qu t l Nitrit/Amni vo khong 1,5. Nh th khng cn b sung cht nn trong bc Nitrit ha. Trong b phn ng th 2, Nitrit cng vi thnh phn Amni cn li ng vai tr l cht cho in t c chuyn ha thnh kh Nit theo phng trnh (3). Vi b phn ng c thit k nh vy, hai qu trnh khng din ra trong cng mt b phn ng (tri ngc vi b phn ng fixed-bed hay b tip xc sinh hc xoay vng) v c th kim sot ring r. S kt hp Partial nitritation/anammox c nghin cu v trin khai bi mt s tc gi qui m phng th nghim v pilot trong thi gian gn y t hiu qu x l Nit trn 80%. Cng ngh ny cho php h thp gi thnh x l nh vo vic gim cc chi ph nng lng cho qu trnh sc kh (40%), ngun carbon (100%) so vi qu trnh Nitrat ha/kh Nitrat thng thng. X l Nit trong qu trnh kt hp ny yu cu t oxy (1,9 kg O2/kg N so vi 4,6 kg O2/kg N), khng b sung Carbon (so vi 2,6 kg BOD/kg N) v lng bn to thnh nh (0,08 so vi xp x 1 kg VSS/kg N) [3]. Do qu trnh kt hp ny khng yu cu ngun Carbon t bn ngoi, x l COD v Nit c th c ti u v tin hnh c lp, khc vi qu trnh cnh tranh phc tp x l COD v Nit trong qu trnh x l Nit truyn thng. Mt gii php kh thi l t mt h thng kh Nit (anoxic) trc h thng Nitrat ha mt phn.So snh vi qu trnh Nitrat ha/kh Nitrat ha truyn thng, h thng kt hp Partial nitritation/Anammox trong hai b phn ng c lp gim pht thi CO2 hn 100%, do qu trnh tiu th CO2. Gi thnh qu trnh ny gim 90% so vi cng ngh truyn thng [3].i vi cc h thng full-scale, qu trnh Nitrit ha mt phn nn c thc hin trong b CSTR hoc SBR nh c im d thao tc iu chnh thi gian lu bn SRT. Trong khi , mng sinh hc hoc b phn ng sinh hc to bn dng ht c cho l thch hp vi qu trnh anammox do vi khun anammox d dng hnh thnh bn dng ht hoc mng sinh hc c kh nng cha nng sinh khi cao trong b phn ng.

1.4. Kt hp Nitrit ha mt phn v Anammox trong mt b phn ng ng nht (One single reactor).Qu trnh ny thng c gi di tn Deammonification - Kh Amni ha, CANON - Completely Autotrophic Nitrogen removal Over Nitrit Qu trnh t dng hon ton x l nit qua nitrit , SNAP- Single stage Nitrogen removal using the Anammox and Partial nitritation X l nit kt hp qu trnh nitrit ha mt phn v anammox trong mt b , DEMON hoc Aerobic/anoxic deammonification kh amoni ha hiu kh/thiu kh [3]. trnh nhm ln vi cc h thng c th, trong cc nghin cu gn y qu trnh ny thng c gi l qu trnh kh Amoni ha hoc i khi l Nitrit ha mt phn/Anammox trong cng mt b. So vi cc h thng s dng qu trnh nitrat ha mt phn (partial nitrification), qu trnh kh amoni ha ch cn mt b phn ng. Do din tch xy dng kh nh v chi ph u t thp. Nhc im ca qu trnh ny l phi kim sot nhiu yu t phc tp trong sut qu trnh. Qu trnh kh amoni ha 2 giai on (two stage deammonification process) pht thi N2O t hn, trnh c ri ro do tnh c cao ca nng Nitrit i vi vi khun Anammox, nhng cn kim sot t l Nitrit/Amni u vo ca qu trnh anammox v tiu th lng kim ln hn so vi h thng 1 giai on (one-stage process) [3]. Qu trnh kh amoni ha da trn s tn ti song song v kt hp ca vi khun AOB hiu kh v vi khun oxy ha amoni k kh (Anammox) trong mt b phn ng c lp. Qu trnh din ra trong iu kin gii hn oxy nhm trnh s c ch ca oxy i vi vi khun Anammox ng thi to cc iu kin ph hp cho qu trnh Nitrit ha mt phn. Trong thc t, mt vi h thng c th cung cp cc iu kin a thch hai loi vi khun ny c th tn ti song song l h thng mng sinh hc (moving beb biofilm reactors -MBBR), cc b phn ng sc kh lin tc (SBR hoc RBC) hoc bn dng ht. Vi khun AOB oxy ha amoni thnh Nitrit. Di iu kin DO thp, tc tng trng ca vi khun NOB thng nh do i lc thp ca chng vi oxy so vi vi khun AOB v vi Nitrit so vi vi khun Anammox [3].Nng Oxy ti u trong dng vo h thng kh amoni s dng mng lc sinh hc c th khc nhau v cu to ca b phn ng v thnh phn dng vo. Trong cc th nghim ca Van Hulle v cng s (2010), mng sinh hc mng v c, lp lu gi mng, thnh phn COD ca dng vo v nhit cn c xem xt quyt nh nng DO bn trong b phn ng [4].Trong qu trnh ny, mt phn Amni c oxy ha thnh nitrit (nitrit ha mt phn) nitrit sau ng vai tr l cht nhn in t cho s oxy ha amoni, v phn Amni cn li chuyn ha thnh N2 nh vi khun Anammox. Nitrat (NO3-) c to thnh ch yu l do vi khun Anammox. S c mt v hot ng ca vi khun oxy ha Nitrit NOB c th nh hng ti hiu qu c qu trnh v s oxy ha Nitrit thnh Nitrat cn c ngn chn hoc gim thiu. Mt s chin lc vn hnh c tc dng kim sot qu trnh da trn iu kin pht trin khc nhau ca vi khun AOB v vi khun NOB l DO, pH, FA (Free Ammonia) v thi gian lu bn SRT.Qu trnh kh amoni ha l qu trnh x l Nit t dng c cho l bn vng v ph hp i vi loi nc thi c thnh phn giu Amoni v t l C/N hoc COD/N khng thch hp nh nc thi t qu trnh p bn. Third v cng s (2001) a ra phn ng xp x cho qu trnh nh sau [13]:1 NH4+ + 0,85 O2 0,13 NO3- + 0,435 N2 + 1,4 H+ + 1,43 H2O (7)Ging nh cc qu trnh c sn sinh H+ (hoc tng t tiu th HCO3-), kim c tiu th. Nu qu trnh c p dng x l nc p bn t bn thy phn k kh, thng thng loi nc thi ny c kim cn thit c kh nng gim pH m bo h thng hot ng mt cch n nh. M t qu trnh kh Amni:Qu trnh kh Amni c tin hnh theo 2 phn ng c m t nh sau:Qu trnh Nitrit ha c th hin phng trnh (8) (bao gm s tng hp cc t bo) [14].NH4+ + 1,38O2 + 1,98HCO3- 0,018C5H7NO2 (Nitrosomonas) + 0,98NO2 + 0,98NO2- + 1,89CO2 + 2,93H2O (8)Qu trnh Anammox (bao gm s tng hp t bo) [15]:NH4+ + 1,32NO2- + 0,066CO2 + 0,066H+ 0,066CH2O0,5N0,15 (Anammox) + 1,02N2 + 0,26NO3- + 1,96H2O (9)Da vo phn ng s (8), qu trnh Nitrit ha mt phn vi mc ch to dng vo c thnh phn ph hp cho bc Anammox tip theo vi t l NO2-N/NH4-N l 1,32 c th vit nh sau:2,34NH4+ + 1,85O2 + 2,66HCO3- 0,024C5H7NO2 (Nitrosomonas) + NH4+ + 1,32NO2 + 2,54CO2 + 3,94H2O (10)Do qu trnh kh Amni c th c vit li da vo phn ng (9) v phn ng (10) nh sau:2,34NH4+ + 1,85O2 + 2,59HCO3- 1,02N2 + 0,26NO3- + 5,83H2O + 2,41CO2 + 0,024C5H7NO2 (Nitrosomonas) + 0,066CH2N0,15O0,5 (Anammox) (11)T cc phng trnh phn ng nh trn c th rt ra nh sau: Lng Oxy cn thit cho qu trnh Nitrit ha mt phn (phn ng (10)) l 1,81 g O2/g NH4-N ch bng 43% nhu cu oxy cho qu trnh oxy ha amni thnh Nitrat (4,2 gO2/g NH4-N). thc hin qu trnh Nitrit ha mt phn (phn ng (8)) cn kim l 1,1 mmol HCO3-/mmol NH4-N v t l ny l ph bin trong nc p bn. Qu trnh Nitrit ha mt phn tiu th kim do xy ra hin tng gim pH. Nu kim cung cp khng trong b Anammox s xy ra hin tng tng pH do ion H+ c s dng trong qu trnh tng hp t bo (phn ng (9)) dn in gim trong sut qu trnh Nitrit ha do s chuyn ha ca hydrogen carbonate thnh CO2 (phn ng (8)) v trong phn ng Anammox (phn ng (9)) do s chuyn ha Amni v Nitrit thnh kh Nit, v trong qu trnh kh Amni ha (phn ng (11)). Hiu sut x l Nit cao nht trong qu trnh kh Amni l khong 89% do s hnh thnh mt lng nh Nitrat (phn ng (11)). Lng bn to thnh tng i t trong c hai qu trnh nitrit ha (0,15 g/g NH4-N; phng trnh phn ng (1)) v Anammox (0,12 g/g NH4-N; phng trnh phn ng (9)) v nit s dng tng hp t bo l t so vi nng nit u vo (khong 1,4% trong qu trnh kh amoni ha, phng trnh phn ng (11)).Mt vi im hn ch ca qu trnh Nitrit ha mt phn/Anammox c ch ra trong nghin cu pht thi N2O trong h thng SNAP s dng cng ngh MBBR nh sau [16]: Nitrous oxide (N2O) c th l sn phm trung gian hoc sn phm cui cu qu trnh Nitrit ha v kh Nitrit ha. N2O l mt kh nh knh, tc ng gy hi gp 320 ln so vi CO2. Kh nh knh gy ra hin tng m ln ton cu v nh hng ti tng ozone trong tng bnh lu. Lng N2O ln pht thi trong qu trnh x l sinh hc cn c xem xt gim thiu nhm hng ti vic bo v mi trng. H thng kt hp Nitrit ha mt phn/Anammox lm pht sinh mt lng ng k N2O vi ti thiu l 2% Nit v c c x l. Khi nng DO khong 3 mg/l trong h thng MBBR (Moving Bed Biofilm Reactor) pht thi N2O ln nht vi t l sinh kh ban u v ti a tng ng l 6-11% v 10-30%. Mt lng nh hn N2O to thnh trong h thng Partial Nitritaton/Anammox trong qu trnh vn hnh lin tc DO khong 1-1,5 g/l. N2O ban u l 2-3% v cc i l 2-6%. Khi b MBBR c t di iu kin thiu kh trong thi gian di c qu trnh oxy ha Amni v s pht sinh N2O u chm dt. Kh N2O sinh ra trn ln kh N2 trong sut giai on thiu kh khng th khng nh chc chn rng s pht sinh N2O l ging nhau trong pha v hiu kh v thiu kh. Nhng s liu chc chn v s pht sinh N2O cc iu kin vn hnh khc nhau (tnh ton da trn ng gp pht thi N2O trong pha thiu kh) c nh gi cao v nn c xem nh mt cng c so snh.

Bng 8. So snh mt s qu trnh trong x l nc thi cha Nit [3]:c trngNitrat ha/kh nitrat ha thng thngNitrit ha/kh nitrit ha (SHARON)Nitrit ha mt phn/Anammox trong hai b c lpNitrit ha mt phn/Anammox trong mt b (SNAP)

S b phn ng2222

iu kin vn hnhHiu kh/thiu khHiu kh/thiu khHiu kh/thiu khGii hn oxy

Nhu cu oxy(g O2/g N)4,57/03.43/01,71 (1)/01,94

% O2 tit kim (2)-24,9%62,6%57,5%

Tiu th kim (gCaCO3/gN)7.07/-3,577.07/-3,57 (3)3,57/0,243,68

Kim sot pHCKhngKhngKhng

Ngun Carbon yu cu3,72,300

% carbon tit kim-37,8%100%100%

Loi vi khun ch yuAOB,NOB/vi khun kh nitratAOB/vi khun kh nitritAOB/AnammoxAOB/Anammox

Lu gi sinh khiKhng/khngKhng/khngKhng/cC

Lng bnNhiuttt

(1) Nu qu trnh nitrit ha mt phn ln n 60% th nhu cu Oxy s tng ln n 2,06 mgO2/gN(2) So snh vi cng ngh Nitrat ha/kh nitrat ha thng thng(3) kim to ra trong bc kh nitrat v kh nitrit d dng(4) Da vo methanol

(Ngun: [3])

PHN II: TNH HNH NGHIN CU TRN TH GII V VIT NAM2.1. Tnh hnh nghin cu trn th gii2.1.1. Qu trnh Anammox Cho ti gia nhng nm 90, s oxy ha ca Amni c bit n l ch xy ra di iu kin k kh nhng s tn tht Nit trong sut qu trnh ngy cng c thy r. Di iu kin gii hn oxy, mt phn ng k ti lng Nit c loi b trong h thng x l nc r rc ca bi chn lp rc Mechernich [17]. Lng Nit mt i ln ti 70% c quan st thy trong h thng Nitrat ha bng tip xc sinh hc xoay vng ti Koelliken x l nc r rc giu Amni t bi chn lp rc thi nguy hi [18]. Qu trnh kh Nitrat ha d dng c loi tr nh x l COD trc . iu ny c chng minh r rng trong cc th nghim hng lot, m hnh ha ton hc v phn tch vi sinh rng Nitrit to thnh trong cc lp mng lc sinh hc hiu kh gn n b mt khuch tn vo lp su thiu kh bn trong ca mng sinh hc, ti n phn ng vi amni cn li hnh thnh kh Nit [19]. Qu trnh ny c pht hin u tin trong b phn ng kh Nitrat ha fluidised-bed x l nc thi t b phn ng sinh kh metan tuy nhin s tn ti ca qu trnh oxy ha Amni k kh tng c d on t trc hn 2 thp k trong cc tnh ton nhit ng hc c bn. Trong mt b phn ng fluidised-bed qui m th nghim khc s dng nc thi thy phn bn t nh my x l nc thi sinh hot v dung dch Nitrit tng hp, t c hiu qu kh Amni l 82% v Nitrit l 99% [40]. Kh nng loi b Nit ti a trong b ny l 1,5 kg N m-3 d-1. Mt vi thng s quan trng nh t l ring cc i ca Amni tiu th (455 nmol mgprotenin-1 min-1), t l tng trng ring cc i (0,0027 h-1, gp i thi gian 11 ngy) v sinh khi to thnh (0,0660,01 mol C mol-1 NH4-N) (199) [9]. 2.1.2. Qu trnh Nitrit ha mt phn/Anammox H thng x l full-scale p dng cng ngh kh Amoni ha c a vo s dng thng 4 nm 2001 trong b moving-bed s dng Kaldnes l vt liu bm dnh nh my x l nc thi Hattingen (c). Mt b phn ng c th tch 104 m3 v hai b c th tch 67 m3 vi tng din tch b mt mng sinh hc hot ng (total effective biofilm surface area) l 4700 m2 cho php t hiu qu x l 70-80%. Ti lng N 120 kg/ngy v hiu sut x l 400 g N/m3 ngy. Trong trng hp nng Oxy c gi di 1 mg/l [3].Mt s h thng full-scale khc s dng qu trnh kh amni ha nc p bn hin ang c vn hnh ti mt s nh my [3]:- Strass (o), x l nc thi ca khu vc c dn s tng ng 200.000 ngi (ti trng ln ti 340 kg NH4+-N/ngy) bng b SBR th tch 500 m3 cho hiu qu x l NH4+-N v Nit tng tng ng l 90% v 86%.- Glarnerland Zurich (Thy s): s dng b SBR 400 m3 x l nc thi ti lng nhim 635 kg N/ngy (hiu sut oxy ha amoni khong 500 g N/m3.ngy t hiu qu x l trn 90%.- Rotterdam Dokhaven (H Lan): x l nc thi sinh hot khu dn c 620.000 dn, ti lng nhim 700 kg N/ngy s dng bn dng ht. B phn ng nh gn (th tch 72 m3) v hiu qu x l NH4+-N v Nit tng tng ng l 95% v 85% (http://www.paques.nl)- Himmerfjarden Grodigen (Thy in) x l nc thi khu dn c tng ng 278.000 dn, a vo s dng thng 4 nm 2007. Hai b phn ng 900 m3 s dng sc kh lin tc (sc kh 40 pht trong pha hiu kh vi DO t c khong 3-4 mg O2/l v 20 trong pha thiu kh) v x l nc thi ti lng nhim 600 kg N/ngy (h s loi N l 300 g N/m3.ngy (http://www.syvab.se).

2.2. Tnh hnh nghin cu Vit NamMt vi nghin cu x l nc thi p dng qu trnh Nitrit ha mt phn/ Anammox c tin hnh trong nhng nm gn y:Nghin cu c thc hin bi Phm Khc Liu v cng s (2008) x l nc r rc bng qu trnh SNAP. Qu trnh ny c pht trin trong cc b phn ng s dng vt liu bm sinh khi l t si acrylic. Th nghim np lin tc nc thi cha nng amoni 240 mg-N/l ti trng 0,6 kg-N/m3/ngy cho thy s vn hnh n nh vi hiu sut chuyn ha amni 85-90% v hiu sut loi nitw 75-80%. Kt qu tng t t c trong mt b phn ng khc vi nng amni 500 mg-N/l v ti trng ln n 1 kg-N/m3/ngy vi hiu sut loi nit 80%. Qu trnh sinh ra rt t bn, hiu sut sinh bn 0,045 mg VSS/mg-N x l. S tn ti ng thi vi khun oxy ha k kh amni (anammox)v vi khun oxy ha nitrit v oxy ha hiu kh amoni trn lp bn bm dnh c xc nhn. Cc chng vi khun AOB v NOB tng t vi Nitrosomonas europaea v Nitrospira sp; cc chng vi khun anammox tng t vi cc chng c bit trc l KU2 v KSU-1 c pht hin bng k thut phn tch gen 16S rDNA [1].Nm 2012, L Cng Nht Phng v cng s tin hnh nghin cu x l amni nc thi git m bng qu trnh nitrit ha mt phn/anammox trong mt b phn ng (qu trnh SNAP), s dng gi th poly acrylic v si bng tm. Kt qu cho thy m hnh hot ng hiu qu vi hiu sut x l t 92% ti trng 0,04 kgN-NH4/m3.ngy v 87,8% ti trng 0,14 kgN-NH4/m3.ngy [2].

KT LUN

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