I. Vi khun k kh

Khi nim - L nhng loi sinh vt sinh sng v pht trin trong mi trng khng c khng kh . Trong iu kin c khng kh chng s cht hoc pht trin khng ttHnh thi v cu to t bo vi khun

* Nhn ca vi khunVi khun khng c nhn in hnh v khng c mng nhn, nhng c c quan cha thng tin di truyn l nhim sc th (chromosome) tn ti trong nguyn sinh cht. Bn cht nhim sc th l ADN c chiu di khong 1 mm, khp kn, trng lng 2 t dalton (2 x 109) cha khong 3000 gen, c bao bc bi protein kim. Nhim sc th c hnh cu, hnh que hay hnh ch V, sao chp theo kiu bn bo tn dn n s phn bo. Tuy nhin, s phn bo cn ph thuc vo s phn chia mng sinh cht v vch t bo.Ngoi nhim sc th, mt s vi khun cn c yu t di truyn ngoi nhim sc th l cc loi plasmid v transposon.* Cht nguyn sinhCht nguyn sinh ca vi khun cha nhng thnh phn ho tan nh protein, peptid, acid amin, vitamin, ARN, ribosom, cc mui khong, mt s nguyn t him v sc t, ngoi ra n cn cha cc ht vi. Bn cht ht vi l nhng khng bo cha lipid, glycogen v mt s cht c tnh c trng cao vi mt s loi vi khun. V vy, n c ngha trong chn on nh vi khun bch hu c ht vi cha polymetaphosphat.Tuy nhin nu so vi t bo ca vi sinh vt c nhn in hnh (eucaryote), nguyn sinh cht ca vi khun khng c ty lp th, li ni bo v c quan phn bo. * Mng nguyn sinh (cytoplasma membrane)Mng nguyn sinh l mt lp mng mng c tnh n hi, bao gm 60% protein, 40%.lipid ch yu l cc phospholipid . Mng nguyn sinh thc hin mt s chc nng quan trng quyt nh s tn ti ca t bo vi khun nh: -L ni hpth v o thi chn lc cc cht qua 2 ch ch khuych tn b dng nh p lc thm thu vi nhng cht c phn t lng thp v vn chuyn ch ng thc hin vi nhng cht c phn t lng cao.-L ni tng hp cc enzym ngoi bo phn hy cc cht c c phn t lng qu ln khng th vn chuyn qua mng thnh nhng cht c phn t lng thp hn d hp thu.-L ni tng hp cc thnh phn ca vch t bo.-L ni tn ti ca h thng enzym t bo, thc hin cc qu trnh nng lng ch yu ca t bo v khng c ty lp th.-Tham gia vo qu trnh phn bo nh cc mc th (mesosome) v l ni gn cc nhim sc th, mc th thng gp vi khun gram (+).* Vch (cellwall) Vch t bo c mi vi khun trMycoplasma.* V (capsule)V ca vi khun l mt lp nhy lng lo, khng r rt bao quanh vi khun, c quan st bng phng php nhum mc nho. Ch c mt s loi vikhun v trong nhng iu kin nht nh mi hnh thnh v. Khun lc ca nhng vi khun c v thng nhy, t v sng.V ca vi khun ng vai tr bo v cho vi khun trong nhng iu kin nht nh. Ngoi ra, v ca vi khun cn c gi c kh nng gy bnh ca vi khun, v nh cc chng ph cu khng tng hp c v u khng c kh nng gy bnh v chng nhanh chng b thc bo bi c ch bo v cac th.* Lng (flagella)Lng l nhng si protein di v xon to thnh t cc acid amin dng D. Lng l c quan di dng trong mi trng thch hp, n ch c mt s loi vi khun nht nh. V tr lng ca cc vi khun cng c c im khc nhau, l c im phn loi vi khun v d nh phy khun t c lng mt u, nhiu loi vi khun khc c lng quanh thn nh (Salmonella, E.coli), mt vi vi khun khc li c mt chm lng u.*. PilliPili l c quan ph ca vi khun nh lng, n c th mt i nhng khng nh hng ti s tn ti ca vi khun.Chc nng chnh ca pili l bm vo cc t bo c mng nhn (eucaryote), kh nng gy bnh ca mt s loi vi khun cng lin quan n s tn ti ca pili, nu vi khun lu mt pili s khng th gy bnh c.* Nha boNhiu loi vi khun c kh nng to nha bo khi iu kin sng ca thun li chng khng. Mi vi khun ch to c mt nha bo, khi iu kin sng thun li, nha bo vi khun li ny mn a vi khun tr li dng sinh sn. Nha bo c th tn ti lu ti 150.000 nm, do dng nha bo khng c s chuyn ho v mt nc.

Phn loi vi khun : Gm c 4 loi* Vi khun c hnh trn : chng c gi l khun cu

* Vi khun c hnh que : c gi l khun que

* Vi khun c hnh xon : c gi l xon khun

* Vi khun c hnh du phy : c gi l khun phy

II. ng dng v x l nc thi ca vi khun k kh - Gm qu trnh t nhin v nhn to : Qu trnh x l nc thi sinh hc nhn to * Qu trnh x l nc thi trong b UASB

Hnh 1 : B lc kh H thng x l k kh tc cao Khc vi h thng x l hiu kh, trong h thng x l k kh ti trng ti a cho php khng tu thuc vo kh nng cung cp kh ca h thng m ph thuc vo cc yu t sau y:Kh nng lu gi lng bn hot tnh trong h thng khi h thng vn hnh. Nu h thng c kh nng gi c lng bn cng nhiu th h thng c th chu c ti trng cng ln. V th cn thit phi hnh thnh cc ht bn c kh nng lng cao, kh b tri ra ngoi h thng. thi gian tip xc gia bn v nc thi;Tc cc phn ng cao v cc c cht c kh nng i vo su trong bn ni c mt vi sinh cao;Bn hot tnh c thi gian thch nghi vi cc c tnh ca loi nc thi m n x l;Mi trng thch hp vi sinh vt trong h thng c kh nng pht trin tt.T khi hnh hnh, h thng x l k kh c nhiu dng khc nhau nh lc k kh vi dng nc thi i t di ln (Upflow Anaerobic Filter-UAF), h thng mng lc c nh vi dng t trn xung (Dowflow Stationary Fixed Film- DSFF), h thng x l k kh vi dng hng ln qua mt lp bn (Upflow Anaerobic Sludge Bed- UASB), h thng s dng lp bn ng (Anaerobic Fluidized Bed- AFB) v.v. Tuy c nhiu u im, nhng nhng h thng x l k kh ny vn lin tc ci tin gim thi gian lu nc trong h thng v gia tng tc x l. Vo nm 1983, h thng x l tc cao vi lp bn ht m rng (Expanded Granular Sludge Bed- EGSB) c hnh thnh bi gio s Lettinga v cc cng s ca ng. L do h thng x l k kh tc cao c nghin cu v p dng trong thc t l:Gim c vn u t khi xy dng h thng: vi tc x l cao s lm gim kch thc ca cng trnh khi phi x l mt lu lng thi nht nh;Gim din tch xy dng ca h thng, ph hp vi nhng nh my c mt bng nh;H thng c n nh cao ngay c vi nhng iu kin hot ng khng thun li.M hnh phng th nghim ca h thng x l k kh tc cao c minh ha trong Hnh 2 :

.

Trong m hnh ta thy, dng nc thi i vo h thng theo chiu t di ln, qua mt lp bn ht m rng, cha nhng vi sinh vt k kh phn hu cht hu c cha trong bn thi. Vi vic bm tr li mt phn dng ra (11), lm tc dng ln ca h thng c th t trn 6 m/h, cao hn nhiu so vi tc dng ln t 0.5 n 1.5 m/h thng c p dng cho h thng UASB. S thay i ny em li s tip xc tt hn gia nc thi v qun th vi sinh vt cha trong lp bn ht v lm cc cht hu c c th thm su vo lp bn ht m khng cn s xo trn c hc. Do tc dng ln cao c th lm gia tng s ra tri bn t h thng. S ra tri bn c th ngn nga bng chp thu kh t u ca h thng. Chp thu kh hot ng nh mt thit b phn tch 3 pha: rn, lng, v kh. y l mt phn quan trng ca h thng EGSB. N gip cho h thng thu hi c kh sinh hc to ra trong qu trnh phn hu cht hu c, ngn nga bn ht tro ra ngoi h thng v gim cht rn l lng trong dng ra sau x l.H thng x l k kh EGSB c th c s dng x l nc thi c nng nhim hu c thp (COD < 1000mg/L), v nhit nc thi thp ( t 8- 12oC) vi hiu sut x l kh cao (>90%). Kt qu x l ca h thng EGSB vi nc thi cha acid bo bay hi (Volatile Fatty Acid- VFA), ng, nc thi bia, mch nha cc iu kin hot ng khc nhau bng 2 :C chtTh tch m hnh x l (L)Nng COD u vo (g/L)Ti trng hu c (kgCOD/m3/ngy)Nhit (oC)Thi gian lu (gi)Hiu sut x l COD (%)

VFA1 * 40.5-0.810-1210-121.6-2.590

VFA2 * 40.5-0.95-124-82-490

VFA2 * 40.5-0.953480

Sucrose+VFA2 * 40.5- 1.15-78490

Bia1 * 2250.5- 0.812201.580-85

Mch nha1 * 2250.3-1.44-8162.456

Mch nha1 * 2250.3-1.49-15201.5-2.466-72

Mch nha2 * 700.2-1.83-664.947

Mch nha2 * 700.2-1.83-1210-153.567-78

Bng 2: cho thy h thng EGSB c kh nng x l nhiu c cht khc nhau nh acid bo bay hi, ng, bia, mch nha vi thi gian lu nc t 1.5-4.9gi, hiu sut x l kh cao khi x l c cht VFA Bng 3. Kh nng x l ca m hnh EGSB vi nc thi dt nhum nhit 30oC, m hnh 4,3L.

Thi gianThuc nhumThi gian luTi trng hu cHiu sut (%)

(ngy)(mg/L)(gi)(kg CODm-3.ngy-1)CODCH4-CODThuc nhum

0-6101.215.0-20.0>957590-95

7-2820-251.215.0-20.0>9570-7585-90

29-5220-251.613,0-15.0>9575-8088-90

53-6340-601.614.0-15.0>9570-8086-88

64-72 *60-1001.615,0-20,0>9560-7090-95

* u im- Khng tn nhiu nng lng - Qu trnh cng ngh khng i hi k thut phc tp - To ra lng bn c hot tnh cao , nhng lng bn khng sn sinh khng nhiu gim chi ph x l- Loi b cht hu c vi lng ln,hiu qu - X l BOD trong khong 600 150000 mg/l t t 80-95% - C th x l mt s cht kh phn hy. - To ra kh c ch* Nhc im- Din tch cn dng x l cht thi ln . - Qu trnh to bn ht tn nhiu thi gian kh kim sot.-Cn nhit kh cao.* Lc k kh Lc k kh vi sinh trng gn kt trn gi mang hu c Vt liu hc- Chiu dy lp vt liu l 2m. - Vt liu lc c th l Dng tm (cht do). Vt liu ri ht, nh ht polyspiren c ng knh 3-5 mm* Nguyn tc hot ng- Nc thi c tip xc vi vt liu. - Khi nc thi chy qua lp vt liu lc, vi khun to thnh mng vi sinh vt . - Cht hu c khi tip xc vi mng vsv s b hp th v phn hy.Bn cn c gi li trong khe rng ca lp lc. - Sau 2-3 thng lm vic x bn mt ln,thau ra lcX l nc thi bng lc k kh vi vt liu gi lng trng n ( ANAFLUX ) Vt liu hc* Ht Biolite:Kch thc nh hn 0.5mm vi nhng c tnh: - Cu to l nn din tch ring l kh ln- Khi lng ring nh. - Chu c va p .u im : t b tt nghn trong qu trnh lm vic Khng ty tri cc qun th sinh hc bm trn vt liu. Nhc im: gi lu lng 5 10 m3/h gi cho lp vt liu trng thi xp trng n. phi thu hi cc ht vt liu theo dng nu mun loi b huyn ph cn phi t thm thit b lng trong tip theo. Trong nhiu trng hp, phi thc hin axit ho s b* Nguyn tc hot ng- Nc thi c bm hng ln qua lp vt liu lc -Vi sinh vt trong nc thi c c nh trn lp vt liu ht. - Lp vt liu ny khng c t c nh v c khuynh hng gin n khi c dng nc i qua. X l nc thi bng phng php k kh tip xc.- Cng trnh gm mt b phn ng v mt b lng ring bit vi mt thit b iu chnh bn tun hon.*Nguyn l lm vic:- Nc thi cha x l c khuy trn vi vng tun hon v sau c phn hy trong b phn ng kn khng cho khng kh vo. Sau khi phn hy, hn hp bn nc i vo b lng: nc trong i ra v bn c lng xung y.* u im - C th chuyn bn t b ny sang b khc mt cch d dng - Lc b c BOD5 ti 80 95% v COD t 65 90% ( ty thuc vo bn cht ca nc thi)ng dng: Phng php trong cng nghip ny t chu nh hng bi lu lng, thch hp i vi vic x l phn chung, x l cc nc thi c nh hp, ct cn, cng nghip ha cht, cng nghip bt giy, cng nghip ng.Qu trnh x l nc thi k kh bng phng php t nhin* Ao h k kh - Ao h k kh l loi ao su. Cc VSV k kh hot ng sng khng cn oxy ca khng kh. Chng s dng oxy cc hp cht nh nitrat, sulfat oxy ha cc cht hu c thnh cc axit hu c, cc loi ru v kh CH4, H2S, CO2, , v H2O.-Nguyn l lm vic: Nc thi dn vo h c t chm m bo cho vic phn phi cn ng u trong h. Ca x nc ra khi h theo kiu thu nc b mt v c tm ngn bn khng cho ra cng vi nc. - ng dng: Loi ao h ny c th tip nhn loi nc thi ( k c nc thi cng nghip) c nhim bn ln, ti BOD cao v khng cn vai tr quang hp ca to.iu kin trong x l nc thi sinh hc- Nhit : nhit ti u l 30-35 - Thi gian lu : ty thuc vo nc thi v iu kin mi trng , thi gian lu xy ra hot ng rao i cht k kh- pH : t s VFA v kim c ngh duy tr thp hn 0.1 m bo h thng vn hnh n nh- Canh tranh gia vi khun metan v vi khun kh sulfate- Cc yu t gy c : Oxy , hp cht vng benzen , mn , tannin ..

KT LUNVic gim gi thnh ca x l nc thi m vn m bo cht lng x l l mt mc tiu thc y cc nh cng ngh mi trng tm kim nhng cng ngh mi. Ngy nay, vic p dng cc cng ngh sinh hc trong x nc thi c nhiu trin vng, c bit x l k kh c nhiu u im vt tri so vi x l hiu kh. X l k kh tc cao l mt cng ngh mi, p dng thnh cng vi qui m trong phng th nghim ti nc ta, vi cc loi nc thi v nhit khc nhau. N lm tng ti lng x l ca h thng, gim din tch mt bng xy dng v gim chi ph xy dng, vn hnh h thng. p dng vo thc t, cn tin hnh nhng m hnh vi qui m pilot, tin n xy dng nhng h thng x l qui m nh, trn c s , rt ra nhng kinh nghim thit k, xy dng, v vn hnh h thng, bin h thng x l ny thnh hin thc ti nc ta.

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