BI GING Cng ngh mi trng Ni dung mn hc Cng ngh Mi trng(Ti liu dng cho sinh vin ngnh Khoa hc Mi trng v a chnh Mi trng)

Phn 1 l thuyt: Chng 1: M u 1.1. Khi nim Cng ngh Mi trng 1.2. Hin trng p dng Cng ngh Mi trng Vit Nam 1.3. Xu hng pht trin Cng ngh Mi trng Vit Nam Chng 2: Cng ngh phng nga, gim thiu nhim 2.1. Cng ngh sch 2.2. Cng ngh phng nga, gim thiu cht thi trong qu trnh sn xut 2.3. Cng ngh tun hon, ti ch, ti s dng cht thi Chng 3: Cng ngh x l nhim kh 3.1. Cc cht gy nhim khng kh 3.2. Cc bin php k thut gim thiu nhim khng kh 3.3. Phng php x l hi v kh c 3.4. Phng php x l bi Chng 4. Cng ngh x l nc v nc thi 4.1. Nhng vn c bn lin quan n x l nc 4.2. Cc phng php x l nc cp 4.2. Phng php x l nc thi 4.3. Gii thiu mt s cng ngh x l nc thi Chng 5. Cng ngh x l cht thi rn v cht thi nguy hi 5.1. C s la chn phng php x l cht thi rn 5.2. Phn loi cht thi v cc phng php phn loi cht thi 5.3. Cc phng php x l cht thi rn 5.4. Bi cha cht thi rn (bi thi) Phn 2 tho lun: Bi 1: Lm chuyn v tho lun v Cng ngh phng nga, gim thiu cht thi trong qu trnh sn xut Vit Nam Bi 2: Lm chuyn v tho lun v cc cng ngh x l kh thi c p dng ph bin Vit Nam Bi 3: Tho lun v bi cha cht thi (bi thi) ang c s dng Vit Nam 7. Ti liu hc tp : 1. TS. D Ngc Thnh, ThS. Trng Thanh Nam (2010), Bi ging Cng ngh mi trng, Trng i hc Nng lm Thi Nguyn.

1

CHNG 1: M U 1.1. Khi nim v Cng ngh mi trng (CNMT) 1.1.1. nh ngha - CNMT l qu trnh cng ngh nhm phng nga, hn ch, gim thiu, x l tc ng c hi gy ra do hot ng ca con ngi ln mi trng (kh quyn, a quyn, thy quyn, sinh quyn). - CNMT bao gm bin php, qu trnh lm cho cng ngh sn xut s dng t nguyn liu, nng lng, sn phm an ton hn v x l cc cht c hi pht sinh. - CNMT l tng hp cc bin php da trn vt l, sinh vt, a l hc.. nhm phng nga vic pht sinh v x l nhng cht c hi. - Ni dung ca CNMT gm: Cc nguyn l, nguyn tc, kinh nghim th hin di dng cc qu trnh v cc k thut thc hin nguyn l cng ngh , c th l: 1- CNMT l cng ngh phng nga, pht sinh cht thi nhim, tit kim ti nguyn thin nhin, gim tiu th nng lng 2- CNMT l cng ngh tun hon, ti ch, ti s dng cht thi 3- CNMT l cng ngh x l cht thi mt cch an ton v hiu qu (cng ngh cui ng ng End of pipe 4. Cch tip cn cng ngh mi trng 1.1.2. Qu trnh pht trin Cng ngh Mi trng Th h I: CN pha long Th h II: CN X l cht thi (khng kinh t) Th h III: Tit kim nguyn liu tit kim nhin liu; Phng nga v gim thiu pht sinh cht thi 1.1.3. c im ca CNMT hin nay - CNMT l loi hnh CN a dng, phc v phng nga gim thiu pht sinh, x l cht thi ca cc ngnh khc. - CNMT l cng ngh lin ngnh, kt hp tri thc ca nhiu ngnh khoa hc khc nhau : Vt l , - ha hc, - sinh hc- Xy dng, kin trc- nng lng - CNMT l loi hnh CN gn lin vi kinh t, CN ti ch, ti s dng gim gi thnh sn phm, CN phng nga, pht sinh nhim gim tiu th ti nguyn, nng lng. - CNMT lin quan cht ch ti cng ng - CNMT l CN hng ti s pht trin bn vng 1. 2. Hin trng CNMT ti Vit Nam - CNMT Vit Nam cha pht trin2

- Cc CN phng nga gim pht sinh cht thi t pht trin v km, cn nhiu CN c, pht thi nhiu ra mi trng m khng c x l VD: SX giy tiu th nhiu nc.nc thi cha nhiu cht gy nhim m cha c x l thi trc tip vo ngun tip nhn - CNMT Vit Nam ch yu l cng ngh x l cht thi bng nhng bin php n gin - CNMT x l cht thi i hi cng c cng ch * Hin trng CNMT mt s ngnh, khu vc Vit nam: - th: nhim do giao thng, nc thi th cha c x l p dng cng ngh: Thay th xng bng gas nhng chi ph ga qu t khng hiu qu; Ch to cht xc tc chuyn ha CO; NO, ..Xy dng mt s trm x l nc thi; hnh thnh mt s bi chn lp t v sinh: H Ni, thnh ph H Ch Minh, Vit Tr - Ti khu cng nghip: trin khai cng ngh nhng khng ch n CN x l (2030% c khu x l nc thi CN; Ch c mi khu cng cng nghip Bin Ha l c khu x l cht thi rn v cht thi nguy hi; Mt s khu cng nghip c l t cht thi CN: H Ni, Bnh Dng, Ph Th) - Ti c s sn xut ngoi khu cng nghip + H Ni c khong 200 nh my p dng CN sn xut sch hn: dt, giy, c kh + CN x l kh thi: lc bi tay o, tch bi, hp th kh thi bng dung dch kim, hp ph kh thi bng than hot tnh. + CN x l nc thi kt hp ha l, sinh hc: ch bin thc phm, dt, giy + CN x l cht thi rn v cht thi nguy hi: phng php chn, thiu t cht thi + CNMT ti c s y t (c 25 l t cht thi y t tp trung). 1.3. Xu hng CNMT trn th gii 1. u tin CN phng nga, gim thiu pht sinh cht thi, CN phng nga l CN t hoc khng sinh ra cht thi - Tuyn b Bergen 1990: mun pht trin bn vng cc CN p dng phi l cng ngh gim thiu, ngn nga nhng cht thi nguy hi n mi trng. - Tuyn b RiO (1992) v mi trng l pht trin bn vng khng nh bo v mi trng, cc quc gia phi tip cn phng nga theo kh nng ca mnh. - p dng cng ngh sch, CN thn thin mi trng di cc hnh thc: sn xut sch hn, CN t v khng cht thi, nng sut xanh, kim sot vng i sn phm, nh gi vng i 2. y mnh xy dng v pht trin ngnh cng nghip Mi trng - nhng nc pht trin: CN Mi trng c pht trin thnh cng nghip mi trng v tr thnh mt ngnh ng gp ng k vo nn kinh t quc dn.3

- nhng nc ang pht trin: mi bc u p dng CNMT, vn u tin x l cht thi. - Bc u hnh thnh th trng v CNMT 3. Xy dng, hon thin s phi hp lin vng, lin quc gia trong vic kim sot v phng nga nhim Bin php: chp nhn cng c chung ca quc t lin vng, lin quc gia V d: + Cng c Bazen (Thy S) qui nh vn , iu khon vn chuyn cht thi nguy hi qua bin gii + Tuyn b Stockhom v vn kim sot cht thi hu c tn lu POP (Persistent Organic Pollutants) + Cc vn bn cc ngh nh trong vic hp tc, qun l v kim sot nhim gia cc quc gia. 1.4. Xu hng pht trin cng ngh mi trng Vit Nam 1. c im: - CNMT Vit Nam cn rt tr, mi v yu - Ch yu tp trung vo CN x l cht thi, cn trnh thp hiu qu cha cao. 2. Xu hng: - Xy dng c s php l + Lut bo v mi trng 2005 + Chin lc bo v mi trng quc gia n 2010 nh hng 2010 + Cc lut v vn bn php quy khc lin quan n mi trng - o to ngun nhn lc cho vic xy dng v pht trin CNMT - a dng ha ngun u t cho pht trin CNMT - Tng cng nghin cu khoa hc - Tng cng hp tc quc t - Gio dc nng cao nhn thc v mi trng, hp tc chuyn giao CNMT mi, hin i

4

CHNG 2. CNG NGH PHNG NGA, GIM THIU, PHT SINH CHT THI 2.1. Cng ngh sch (cng ngh thn thin vi mi trng) 2.1.1 Khi nim, c im, ngha ca Cng ngh sch 1. nh ngha: Cng ngh sch l cc loi hnh cng ngh: + S dng cc loi ti nguyn mt cch bn vng + Ti s dng cht thi, cc sn phm nhiu ln + Qun l cht thi theo cch t nhim so vi cc cng ngh khc m chng thay th nh ngha: Cng ngh sch l cng ngh khng sinh ra hoc t sinh ra cht thi 2. c im CN sch: - V mt khoa hc, CN sch khng l mt ngnh CN ring bit, m l h thng bao gm cc qu trnh, cc tri thc, b quyt CN c lin quan n ti nguyn sn phm, dch v, thit b. - Pht trin CN sch mt quc gia phi ph hp vi hon cnh kinh t, quan tm n cht lng pht trin kinh t x hi, vn ha, mi trng ca quc gia. - CN sch l bin php thay i, gim thiu nhim tn gc ca qu trnh 3. ngha CN Sch - CN sch l mt cch tip cn mi khng phi khu x l cht thi m l gim chi ph tng th do tit kim nguyn ti nguyn, pht trin bn sn phm - Hin nay nu u t cho cng ngh sch l rt ln. -Cng ngh sch l cng ngh mi c li v mt mi trng cng nh c li v mt kinh t 4. Ni dung cng ngh sch hin nay gm cc loi cng ngh: -Tiu th t nng lng v ti nguyn - Thi t cht thi vo mi trng - Lm ra sn phm bn vng, tui th ln - S dng nguyn liu u vo d kim, dn khai thc - t c i vi ngi tiu dng v ngi sn xut cng nh khi thi b, tiu hy, vn chuyn5

2.1.2. Phn loi cng ngh Cng ngh sch bao gm nhng qu trnh ngn nga pht sinh nhim - CN t hoc khng sinh ra trong tng giai on - CN gim tiu th nng lng, gim pht sinh cht thi. CN tun hon ti ch, ti s dng cht thi pht sinh trong tng qu trnh cng ngh. - CN bo v ti nguyn thin nhin v bo ton nng lng. * Ch : Vic phn loi ch c tnh tng i, quan trng l li ch kinh t ca cng ngh sch i vi hot ng sn xut ca mt ngnh. - Bo v tnh bn vng ca cng ngh trong qu trnh sn xut + Bn vng v mt mi trng: bo v c h sinh thi, ngun ti nguyn. + Bn vng v mt kinh t (Gim chi ph sn xut, gim kim sot nhim, d c th trng chp nhn do sn phm thn thin MT) + Bn vng v mt x hi (Gi mi trng sng ca cng ng trong lnh, mi trng lm vic tt hn; Gn gi, tng cng nhng gi tr vn ha - x hi 2.1.3. Li ch kinh t ca cng ngh sch - Hiu qu s dng ti nguyn cao -> chi ph sn xut thp ->li nhun cao -> to th trng mi v sn phm thn thin mi trng m vn duy tr khch hng c. - Gim nhng chi ph do nhim mi trng c qui nh bi lut php, trnh nhng ri ro, s c sinh ra trong hot ng sn xut. - Tng nng sut lao ng, ng lc lm vic ca ngi lao ng do iu kin lm vic mt mi trng c cht lng tt. - L cu ni gia hot ng ca con ngi vi vic s dng hp l ngun ti nguyn 2.1.4. Xu hng nghin cu p dng cng ngh sch hn 1- Nghin cu nhm pht minh cng ngh: Tm cng ngh v lnh vc p dng cng ngh thng tin v pht minh, con ngi cn cng ngh 2- Th trng ha cng ngh mi: Cung cp ti chnh cho qu trnh chuyn giao cng ngh 3- ng dng vo cng nghip, xc nh nhng iu kin bin i cn thit bin i cng ngh, nh gi nhng tc ng tt, cha tt ca cng ngh thay th trong iu kin c th ca ni p dng, ra nhng gii php cn thit, thch ng ti a vi hon cnh p dng. y l giai on gp nhiu tr ngi nht cn s h tr ca hai bn quyt nh s thnh bi ca vic th nghim. 4- Chuyn giao cng ngh sch 5- Cung cp ti chnh cho qu trnh chuyn giao CN sch: Cn c s h tr mt phn ca chnh ph nc mun nhn CN ny, c th c h tr ca cc ngn hng quc t, v trong nc6

6- Th trng ho: Nhn rng vic p dng CN thn thin moi trng sau khi c th nghim, nh gi v chuyn giao thnh cng.Giai on ny cn c s tham gia ca c quan t vn , c bit c s tham gia ca mng li thng tin 2.1.5. Mt vi cng ngh sch 1- CN nng lng: Thay th nguyn liu, nhin liu nh s dng nng lng mt tri, gi, thy triu hay a nhit , ht nhn, nng lng sinh khi 2. Cng ngh vt liu: Thay th nhng vt liu t nhin (G bng nha cng, Gang thp bng nha cng) 3. Cng ngh sn xut : phn bn Ur: CO(NH2)2 - CN c: (1) dng than kh ha sn xut H2 sinh ra bi, kh c thm cng on x l kh, bi to, nh sng (2) N2 + H2 NH3 (3) NH3 + CO2 CO(NH2)2 - CN mi: dng kh thin nhin lm nguyn liu thay than 4. Cng ngh c kh, giao thng: Ci tin ng c, thay xng bng gas, methanol, CH3OH 2.1.6. Cc yu cu c bn v cng c ca cng ngh thn thin vi mi trng 1- Cc yu cu c bn: -Qun l c ri ro trc mt v lu di - C tnh cnh tranh - Bo tn c ti nguyn thin nhin - Ngn nga nhim trong sn xut v s dng sn phm hay dch v - Gim chi ph x hi v hng ho 2- Cc cng c trin khai nghin cu hay p dng cng ngh sch - Thit k v mc tiu mi trng : thay thit k 1 s phm d l sch bng thit k 1 vng i thn thin mi trng ca sn phm,thu hi sn phm c ti ch hay tiu hu n lc chn cht - Thit k tnh ti 3 yu t trong vng i cu sn phm l vt cht,nng lng,v tnh c - Tnh chi ph nng lng, ng b qua bt c cng on no - Tng tui th ca sn phm bng cch lm cho sn phm bn hn,c th nng cp trc khi vt b - Gim ti a tiu hao nguyn vt liu thng qua thay i k thut hoc qun l - X dng ti a vt liu ti ch - Thit k v ch to sn phm sao cho c th ti s dng hoc ti ch mc ti a 2.2. Cng ngh phng nga, gim thiu cht thi trong qu trnh sn xut (nguyn l sn xut sch hn)7

2.2.1. nh ngha v sn xut sch hn * nh ngha: Sn xut sch hn l vic p dng lin tc chin lc phng nga tng hp v mi trng vo cc qu trnh sn xut sn phm v dch v nhm nng cao hiu sut v gim thiu ri ro cho con ngi v mi trng. - Vi qu trnh sn xut, sn xut sch hn gm bo ton nng lng v nguyn liu, loi b nguyn liu c hi, gim lng v tnh cc ngun thi, pht sinh ngay ti ni sn xut - Vi sn phm: sn xut sch hn gm gim nh hng tiu cc trong sut vng i sn phm t khu khai thc nguyn liu n khu thi b cui cng. Ch : Vi nh ngha trn, sn xut sch hn thc cht l s phng nga, gim thiu nhim mi trng trong qu trnh sn xut v tiu dng. - Sn xut sch nh ngha vi mt s thut ng khc thng c s dng trong nhng nm 90 nh nng sut xanh, nh gi vng i sn phm (LCA) * Sn xut sch hn l g ? - Sn xut sch hn l mt cng c qun l gip ci thin v c mi trng v kinh t - Mt s p dng lin tc chin lc phng nga tng hp i vi cc qu trnh sn xut, cc sn phm v dch v nhm nng cao hiu sut v gim ri ro n con ngi v mi trng - Mt cch tip cn (cch ngh) mi v c tnh sng to i vi cc sn phm v qu trnh sn xut:

* Ti sao thc hin SXSH ? V:- Gim tc ng mi trng - Gim lng ti nguyn tiu th - Ci thin hin trng kinh t - Tun th lut php - Qun l tt hn

* i vi cc qu trnh sn xut: Lin tcPhng nga Chin lc

Sn phm & dch v

Con ngi

- Gim tiu th nguyn liu v nng lng cho mt n v sn phm8Gim thiu ri ro = SXS H

Tng hp (khng kh, n c, t)

trnh

Mi trng

- Loi b ti a cc vt liu c hi - Gim lng v c tnh ca tt c cc dng thi v cht thi trc khi chng ra khi qu trnh sn xut * i vi sn phm: - Gim cc nh hng tiu cc n mi trng trong sut chu k sng ca sn phm t khu khai thc n thi b * i vi dch v: - SXSH a cc yu t v mi trng vo trong thit k v pht trin cc dch v

2.2.2. Cc c hi Sn xut sch hn

Qun l 2.2.3. Ni dung ca snni xut sch hn Qu vi tt trnh SX Ci tin v thay i, i mi cng ngh, tun hon ngay ti ch

Thay i nguyn liu th, ph tr

Thay i, thit k li sn phm

- Qun l tt ni vi - Thay i nguyn liu u vo - Kim sot tt qu trnh sn xutSn 2.2.4. Cc k thut - Chim lnh u th - CiTng li ch kinh tc cnh tranh

xut sch hn- Gim thiu pht sinh cht thi

- Ti s dng v tun hon cht thi - Ti ch cht thi - Ci tin cht lng sn phm

Sn xut sch hn - Gim thiu pht sinh cht thi

9

Cc k thut SXSH 2.2.5. Li ch ca sn xut sch hn * SXSH em li nhng li ch g ? Tun hon Gim ti ngun Ci tin sn phm

Thu hi v ti s dng ti ch

To ra sn

phm c ch

Thay i quy trnh sn xut

Qun l tt ni vi

Thay nguyn liu u vo

Kim sot tt hn quy trnh SX

Ci tin thit b

Thay i cng ngh

- Tit kim chi ph thng qua gim tiu th nng lng v nguyn liuthin hnh nh - Ci thin hiu qu hot Ci ng ca cng ty ca Tng li v ch kinh t u ca sn phm tt hn - Cht lng ng cng ty

- Thu hi c mt lng nguyn liu b hao ph trong qu trnh sn xut - C kh nng ci thin mi trng lm vic (sc kho v an ton) - Ci thin hnh nh ca cng ty - Tun th cc quy nh mi trng tt hn - Tit kim chi ph x l cui ng ng - C c ccnng c hi th trng mi v tt hn Tng sut - Thun li trong vic t ISO 14000Chim lnh u th cnh tranh

Ci thin mi trng lin tc

2.2.6. Cc v d cc c hi SXSH1. Qun l ni vi tt - Thng xuyn kim tra, bo dng thit b - Kho cht cc van v kim tra cc ng ng trnh r r - Gim lng dung dch bm theo vt th khi di chuyn gia cc b m in - Lu tr ho cht ni thch hp - Trnh cc s c do r r, ri vi - Bo n ng ng v thit k cc h thng phn phi hi hp l 2 - Thay i nguyn vt liu u vo - Thay dung mi hu c bng nc - Thay th axit trong ty r bng peroxit10

- Thay th axit formic bng HCl trong nhum vi - Thay th ty Clo bng ty xy 3 - Kim sot quy trnh sn xut tt hn - Ti u ho v kim sot cc thng s vn hnh (pH, nghit , thi gian) - Ti u ho qu trnh chy trong l hi (CO2 > 12%; O2 < 2%) - Ti u ho dung t nhum - S dng h thng camera pht hin nhanh cc sai st trong vn hnh 4 - Ci tin thit b - Thay th qu trnh lm sch bng dung mi bng lm sch c hc - Ra ngc chiu nhiu bc - S dng sng phun sn hiu qu cao - Thay th h thng thit b lm lnh s dng gaz Freon bng thit b dng gaz Amonic 5 - Thay i cng ngh - Thay th my nhum Winch bng my Jet - Thay th in bt bng in kh - Thay my xeo giy c bng my mi 6 - Thu hi v ti s dng ti ch (trong phm vi nh my) - Thu gom nc trng pha long dung dch bt giy v nghin thu lc - Ti s dng nc lm lnhTun hon dung dch nhum - Thu hi nc ngng v dng li cho ni hi - Ti s dng li dung dch trung ho (sau nu v git) ca cc m nhum 7 - Sn xut cc ph phm c ch - S dng mt r sn xut cn - S dng cc mnh vi vn trong sn xut thm m - S dng ni tng trong ch bin hi sn sn xut thc n gia sc 8. Ci tin sn phm

Nc

sn xut 11 sch hn Nguyn liu

X l cui ng ng Kh thi Qu

Nng lng

sn xut cng Cht thi nghip rn Nc thi

- S dng giy xm (khng ty) thay cho giy trng nhng ni cho php - Loi b thuc nhum c cha cadimi c hi khi sn phmphm - Sn xut v s dng ti nilon d phn hu SnSn phm

Ho cht

- Thit k li bao b sn phm (t lp hn, c th thu hi ti s dng) 2.2.7. So snh gia sn xut sch v cng ngh truyn thng x l cui ng ng Mt s li th ca sn xut sch hn X l cui ng ng (CN truyn thng) 1. Cch tip cn ch ng 2. Mang tnh phng nga, ch ng ngn nga 3. Gim nhim ti ngun 4. Cc k thut lin quan: qun l ni vi, thay i nguyn liu, cng ngh, ci tin thit b trong dy chuyn sn xut 5. Gim tiu th nguyn liu ho cht, nng lng 6. Gim chi ph sn xut do: 7. Gim nh mc tiu th nguyn liu, nng lng 8. u t c hon vn 1. B ng v th ng 2. Gii quyt hu qu, sinh ra cht thi v x l chng 3. Cht nhim c kim sot bi cc h thng x l 4. Cc cng ngh, thit b x l ngoi qu trnh sn xut chnh 5. Khng thay i nh mc nguyn liu, ho cht, nng lng 6. Tng chi ph sn xut do: 7. u t xy dng h thng x l cht thI 8. Vn hnh h thng (nhn cng, ho cht, bo dng...) 2.2.8. Hin trng sn xut sch hn Vit Nam * Chnh sch v m: - T nm 1996 n nay chnh ph tip nhn 20 d n quc t v ti cp nh nc v SXSH, gim thiu cht thi v cc lnh vc lin quan. SXSH. B KHCN v Mi trng ban hnh k hoch hnh ng quc gia v SXSH: 2001-2005 * Cc hot ng v SXSH nc ta 1. Ph bin thng tin v nng cao nhn thc 2. Trnh din k thut nh gi SXSH ti doanh nghip nhm thuyt phc gii cng nghip tip nhn tip cn SXSH vo hot ng SX kinh doanh 3. o to ngun nhn lc v xy dng nng lc quc gia v SXSH 4. H tr chnh sch12

22/9/1999, B trng B KHCN v Mi trng k tuyn ngn quc t v

Gn 200 doanh nghip tham gia cc d n trnh din cc mc khc nhau, trong c 21 doanh nghip ch bin thu sn v 20 doanh nghip nhum

Xu th ngy cng c thm cc doanh nghip tham gia cc d n SXSH 60 doanh nghip thc hin nh gi SXSH vi s hng dn ca Trung tm Sn xut sch Vit Nam u t: 1,15 triu USD Tit kim: trn 6 triu USD

SXSH gip ci thin mi trng lao ngV d cng ty Lin doanh Plastic Vnh Ph gim 46% dung mi MEK (Methyl ethyl Keton) gim 29% Toluen, gim 25% bt PVC 2.3. Cng ngh tun hon, ti ch s dng cht thi 2.3.1. Cc khi nim - Khi nim cng ngh tun hon cht thi: l CN s dng li cht thi cho qu trnh sn xut. V d: nc ngng t hi nc c tun hon li ni hi sn xut hi nc, bt giy thu hi t qu trnh lng ,tuyn ni nc thi c tun hon li sn xut bt giy - Khi nim cng ngh ti ch cht thi: l CN ti sn xut cc cht thi thnh nhng sn phm mi. CN ti ch cn c th l qu trnh thu hi li cc phn gi tr hoc hon nguyn li thnh cc nguyn liu cho 1 qu trnh sn xut khc. V d: St vn lm nguyn liu sn xut cc sn phm c kh,nha thi c ti ch thnh cc sn phm nha ti sinh,Giy lai c ti ch thnh ba Cton,giy bao bti ch du thi,ti ch rc thi hu c. - Khi nim cng ngh ti s dng cht thi: l qu trnh s dng li mt cht thi m khng c s chuyn i v hnh dng, vt l, tnh cht ha hc V d: Cht thi c th ti s dng Thy tinh, nha,chai bnh bia, nc gii kht, Vi, da ,Bao b (hm h, thng nha) vn chuyn nhiu ln cc sn phm hng ho c im: - Thng l sn phm hon chnh a vo s dng - S dng li c th cho mc ch ban u, c th cho mc ch khc 2.3.2. ngha ca cng ngh C ngha c bit trong phng nga, gim thiu, pht sinh cht nhim, th hin qua nhng c im sau: + Gim thiu nhu cu tiu th th ban u + Gim thiu tiu th nng lng do tit kim, n gin cc qu trnh sn xut + Gim thiu lng cht thi pht sinh gim chi ph s dng cht thi h gi thnh sn phm13

+ Ko di vng i s dng (tng tui th sn phm) * u im: -Tn dng c ngun nguyn liu thay v sn xut t nguyn liu th,tit kim chi ph khai thc,tit kim c nng lng cn ch khai thc,hn ch khai thc ti nguyn thin nhin

- Gim thiu c ngun thi cn x l, gim c chi ph nng lngcn cho x lcht thi theo cc phng pp truyn thng

- To cng n vic lm trong lnh vc ti ch thng qua hot ng thu gom vnchuyn,lm sch v ti ch Nhng vn pht sinh: - Trong qu trnh ti ch, ti tun hon cht lng sn phm thng thp hn sn phm t nguyn liu th - i hi qu trnh loi b tp cht -> tng chi ph sn xut - Tiu hao nng lng, tng chi ph lm mi, tng chi ph vn chuyn - a s cng ngh ti ch d gy nhim mi trng trong qu trnh sn xut, ti ch li chi ph x l mi trng * Nhc im:

- Li pht sinh 1 lng cht thi t cc qu trnh phc v ti s dng,ti tun hon,tich nh thu gom, vn chuyn,lm sch.V d; Ti ch nha thi sinh ra cht thi rn, nc thi,kh thi cn phi x l

- Ti ch,ti s dng cht thi lm nguyn liu i hi qu trnh loi b tp cht phctp dn n tng chi ph

- Sn phm ti s dng thng c cht lng thp,tiu hao nng lng nhiu hn,tnchi ph lm mi v chi ph vn chuyn

- Xut hin tim nng gy nhim mi trng,nu khng quan tm ti cht thi mipht sinh

- Li pht sinh 1 lng cht thi t cc qu trnh phc v ti s dng,ti tun hon,tich nh thu gom, vn chuyn,lm sch.V d; Ti ch nha thi sinh ra cht thi rn, nc thi,kh thi cn phi x l

- Ti ch,ti s dng cht thi lm nguyn liu i hi qu trnh loi b tp cht phctp dn n tng chi ph

- Sn phm ti s dng thng c cht lng thp,tiu hao nng lng nhiu hn,tnchi ph lm mi v chi ph vn chuyn

- Xut hin tim nng gy nhim mi trng,nu khng quan tm ti cht thi mipht sinh 2.3.3. Tnh hnh p dng cng ngh tun hon, ti ch, ti s dng 1. Mt s cht thi c th c ti ch, ti s dng14

a. Giy cc loi b. Nha cc loi c. Kim loi d. X ca cc qu trnh nung chy e. Cc loi g f. Thy tinh: chai l, cc loi knh, dng gia nh g. Cao su h. Du m, vi, nc, bn thi, cn lng i. Rc ch, rc sinh hot 2. Tnh hnh cng ngh ti tun hon,ti ch,ti s dng mt s quc gia * Canada: ch yu s dng ti ch cht thi rn: x l gang, x xp c nghin s dng thay ct trong xy dng. X than y l c dng lm gch nh Tro bay c dng sn xut va b tng xy dng Bn (cht thi Boxit) sn xut gch chn * Vit Nam: CN 3R cn yu, c tnh t pht Ti ch cht thi cc lng ngh pht trin mnh, c s sn xut nh * Nht: CN 3R pht trin Ti ch c 25% x than, 50% bn than, 25% cht thi khc ti s dng; 26% cht thi rn, 100% x l gang, vt liu xy dng, 93% thp c quay li sn xut thp - Quan im ca Nht: s dng li cht thi khng ch trong qu trnh sn xut m trong sut vng i sn phm, s dng li c nhng ph tng ca sn phm * Thy in: Bt cc c s sinh ra cht thi phi tun hon v s dng li 75% cht thi, 45% x l gang c tun hon s dng li 80% lp t c ti ch 2.4. Mt s cng ngh ti ch cht thi

15

1.Cng ngh ti ch nha thi (CN km dng thi)

2. Cng ngh ti ch kim V loi (Nhm, st) lon bia, nc ngt Cng ngh ti ch StPhn loi Nu chy Phi c c sn phm Ct Bavia Sn phmXong, ni, nhm, chuNc lm mt Khi thi Kim loi Ting n, Bi CTR khng phi kim loi (giy qung co) Kh thi X than, x kim loi

Nu chy, to

St ph liu

16 Phn loiGia cng s b

Bi, CTR khng phi st, nha n, Bi, Khi

2

2

Bn thnh phm

nhim nhit

Thp cun Rt dy thp

Thp trn Ct (ct thp) Thp xy dng

Thp dt t dp Ty r Lm sch M. Niken, Km

3. Cng ngh ti ch giyCt Dp Ty r

mSn phm (inh) Lm sch M km Sn phm (dy thp)

Sn phm (Ke, cht, bn l)

Giy vn cc loi Phn loi NaH Ngm kim Javen Ngm ty NghinNc Hi nc

CTR khng phi giy nh ghim, nilon, keo dn Hi kim Nc thi Nc thi Hi Clo

nh ti Xeo Nc thi

Than

Ni hi Sy Bi, X Cun Ct Bao gi Sn phmTing n Bi Giy loi

17

CHNG 3 CNG NGH X L NHIM KHNG KH 3.1. Cc cht gy nhim khng kh 1. Cht nhim dng ht: - Bi l nhng thnh phn nh, rn hoc lng phn tn trong pha kh - Kch thc: t 1/10 n 1000 m D = 0,002m 500 m ra do t nhin hay nhn to - S lng bi trong khng kh: vi trm phn t/ cm3 100.000 phn t/cm3 cng thnh phn ln: 60 m 2000 m - Cc loi bi: + Bi Silicat; + Bi than; + Bi kim loi nng v hp cht ca n + Bi canxicacbonat; + Bi cng nghip c bit 1 m = 10-6m - Thi gian tn ti: vi giy ti vi thng ph thuc vo tc lng cn ca bi sinh

% p thc hn b d (m ) theo kch Bng. Phn loi bi, hi, kh cLoi Bi

1 ,6 Di kch thc (< m)

0,1-2000

1 , 6 2 , 5 2 , 5 4 4 6 3, 6 , -3 1 0 1 0 1 6 1 6 2 5 2 5 4 0 >40

2 ,0 8 c tnh , 6 1trong QT p, ph n, mi, Pht 3 sinh 8 ,3 2 khoan..., cc cht rn nh , qung, than, 1 7 ,5 6 kim loi. Mt s bi c dng si c ngun 2 0 ,6 gc ha hc, thc vt hoc khong. Cc bi 1 8 ,7 ln c lng do trng lc, cn bi nh c 1 4 ,5 7 khuynh hng bay l lng trong khng kh. 1 2 ,5 2 ,0 218

Sng Khi

0,01 10,0 0,001-0,1

L sn phm ca ca QT ngng t cc ht cht lng Pht sinh do ngng t cc ht rn trong QT lm nng chy kim loi hoc cc phn wnge ha hc. Hay t t chy nguyn liu

Hi Kh

0,005 0,0005

L th kh m trong iu kin bnh thng chng l th lng hoc rn L dng vt cht m nhit thng chng khng dng th lng hoc rn

2. Cht nhim dng sol, kh v hi: - Cc cht nhim hu c: hi dung mi, Hi cc HCBVTV hu c, CFC.. - Cc cht kh nhim v c: SO2, NOx, NH3, CO2,, CO, N2O. - Hi kim loi nng : Hi Hg, Pb, Cd, Zn - Cc dng sol: l tp hp cc phn t cht lng hoc rn to thnh cc ht nh li ti phn tn trong khng kh 3- nhim do nhit: - nh sng mt tri - Nhit t ni la, thin thch - T cc v n nhit hch - Nhit pht ra t cc nh my, l cao ... 4- nhm do ting n: - V n trong t nhin - Giao thng, xy dng ... - Khu cng nghip nh: ca, phay, ba my, ng c .... 3.2. Cc bin php k thut gim thiu nhim khng kh 3.2.1. Kim sot ngun thi cng nghip

1. Thit b t nhin liu trong cng nghipL hoc thit b nung, t, sy

Cp nhin liu

nung, t, sy

Ngun thi

Ki ms ot nhin li u:

Kim sot cng ngh t:

Kim sot cui ng ng:

- Lm sch nhin li u; - Thay thnhin li u; - Nhin li u sch.

-

Hiu qu nng lng; Cng ngh t; Cp

-

Lc, ht bi; - X l kh thi; Khuych tn kh thi.

Ch chy; khng kh

19

2. Qu trnh sn xut dy chuyn cng nghKim sot nhim:

Cp nhin liuThay th nhin liu:

Thay th vt liu, nguyn liu, t c hi hn; Lm kn dy chuyn sn xut; Thu gom ngun thi x l; p dng cng ngh sn xut sch hn.

3.2.2. Kim sot ngun thi giao thngng c t trongCi tin ng c:

ng xX L kh thi:

Metanol; Etanol Kh t nhin; Hydro; Nhin liu sinh hc; Nng lng in; Nng lng mt tri.

-

Hiu qu nng lng ca ng c; Ci tin Cacbuarat; T l khng kh/nhin liu ti u; Lm kn cc van v trc khuu; ng c 2 th 4 th

-

Ci tin ng x; Lp thm thit b x l kh thi.

Lm kn bnh cha, van, khuu v giong nhin liu bc * Mt s bin php kim sot ngun gy nhim khng kh t giao thng: - Thay th nhin liu t nhim - Thay xng v Diezel bng CNG (compressed natural gas) - Kh thi t phng tin chy bng NG cha 75 80% CO2, 90% CO, 10 25% HC so vi dng xng. - Khng cn b phn lc, ch bin, chuyn i v vn chuyn - Khng c kh bay hi trong chu trnh ca nhin liu (khng c cht sinh ung th) - Khng cn ph gia kim loi tng cng sut n - Thay th nhin liu t gy nhim (tip) Thay th xng v Diezel bng LPG (Liquefied petroleum gas) - Gim pht thi CO, VOC, SO2 v bi - Tng pht thi NOx (do nhit nh la cao) - Gim hiu ng nh knh20

hn ch

3.2.3. Gii php phng nga nhim nhit * Mt s gii php thng p dng nhm phng nga v gim nhim nhit: H lm mt i phun nc Thp lm mt + Thp lm mi t nhin + Thp lm mt cng bc Ci thin thng kh trong khu vc sn xut Pht trin trng cy xanh 3.2.4. Kim sot nhim ting n * Mt s gii php c p dng: p dng bin php gim thiu ti ngun: thit k v ch to cc b phn gim m v ng dng chng trong ng c my bay, xe vn ti, xe khch, moto, my mc c kh Ci tin thit k my v quy trnh vn hnh my, kim sot chn ng, tng cng bc ngun m bng vt liu ht m Hn ch ting n do xe c bng cch quy hoch t chc cc ng giao thng hp l Thit lp khu cng nghip tp trung, tng cng vnh ai ngn ting n xung quanh khu vc, trng hc v bnh vin. Thit k cch m lm cho ting n khng xuyn qua kt cu bao che trong phng. - Gim cng giao thng trong vng c yn tnh Khuyn khch cng nhn s dng dng c chng n nh nt tai, bao tai Gio dc nhn nhn bng phng php truyn thng, phim nh v chng nhim ting n.. * Kim sot ting n trong nh: B tr cng trnh xa ngun n trong iu kin c th B tr cy xanh xung quanh nh ht m B tr cc phng ph nh hnh lang, bp pha gn ting n, cc phng ng, phng lm vic pha yn tnh Tng, sn v trn phng tm dng kt cu cch m tt 3.2.5. Gim thiu nhim kh trong sinh hot - Thay th s dng than t ong bng gas hoc du ho,tt nht bng in - S dng my ht mi v ht bi - Tng cng cy xanh( vn treo,cy leo) - Ci tin cc thit b un nu,l nng tiu thu t nhin liu - Tit kim nng lng dng trong gia nh21

- Thu gom v vn chuyn cht thi sinh hot vo khu x l - Tng cng v sinh ng ph - Gim thiu nhim ni tht 3.2.6. Cc bin php phng nga nhim khng kh 1. Thay th nguyn liu: - Dng nguyn liu c t cht nhim hoc gim bt hm lng cht nhim trc khi t: Gim S trong than, dng du nh thay cho du nng, thay nguyn liu c bng nguyn liu mi. - Tng cng s dng ti nguyn nng lng sch: Nng lng mt tri, gi, thy in, a nhit, nng lng nguyn t. 2. Gim tin cht sinh kh nhim: p dng cc bin php ci thin cht lng nguyn liu nh gim lng S trong nguyn liu nhm gim lng SOx pht thi khi t nguyn liu 3. Ci tin cng ngh sn xut v p dng cng ngh sch: Nng cao hiu sut s dng nguyn liu, gim tiu hao nng lng, tun hon tng phn ti s dng cc hi kh thi ra, thay th cng ngh sn xut. Tin ti s dng cng ngh sn xut khng c cht thi. 4. Kim sot quy trnh sn xut: Kim sot cc cng on trong cc dy chuyn sn xut, c bit l cng on cui ng ng. 3.3. Phng php x l hi v kh c * Khi nim hi v kh c: Khc vi bi v sol, kh v hi tn ti di dng cc phn t ring bit ln vo khng kh theo cc chuyn ng chaose. iu kin bnh thng hi c th ngng t c, cn kh th ch ngng t c khi to c p sut hoc nhit ph hp (p sut cao, nhit thp). * Yu cu:

- Tnh cht ca cht nhim cn x l (tnh cht vt l, ha hc, kh nng phn ngvi cc cu t khc, nhit bay hi, ngng t, nhit chy)

- Tnh cht ca hn hp kh (thnh phn kh trong hn hp, kh nng chy n, ngngt, hm lng bi, nng d kh nhim)

- Tnh cht ca qu trnh cng ngh (lin tc, gin on, nng sut, lu lng kh, sch kh)

- Chi ph u t, xy dng, v tr t thit b- X l hi v kh c c th bng phng php thiu hy, ngng t, hp ph, hp th. * Cc phng php x l kh thi:22

Phng php hp th (vt l, ha hc, sinh hc) Phng php hp ph (ng, tnh) - Phng php nhit v xc tc Phng php thiu hy - Phng php ngng t - Phng php sinh hc* X l kh thi: Cng ngh v nguyn tc 3.3.1. Phng php hp th 3.3.1.1. Nguyn l, phn loi, c im * Nguyn l ca PP: C s ca pp ny l da trn s tng tc gia cc cht cn hp th (kh, hi) vi cht hp th (thng l lng - nc hoc dung dch v c, hu c long) hoc da vo kh nng ha tan khc nhau ca cc cht khc trong cht lng tch. Kt qu kh hay hi nhim c tch khi hn hp kh cn x l. *Phn loi: Ty thuc vo bn cht ca s tng tc ni trn m ngi ta chia ra lm thnh s hp th l hc v ha hc. V d: Hp th vt l (CO2 trong nc) v hp th ho hc (NOx, SO2 trong dung dch kim). - Hp th vt l: l qu trnh da trn s tng tc vt l n thun, ngha l ch bao gm s khuych tn cc cht cn hp th vo trong lng cht lng v s phn b ca chng gia cc phn t cht lng. Th d: NH3/aceton, Co/benzen, trimetylamin/du ha, SO3/H2SO4 ,.. ha tan ca mt cht cn hp th trong lng cht lng lun l hm ca nhiu bin D= f(x1, x2, x3,..xn, T, S, P, kD..) Hp th ha hc: L qu trnh lun i km vi m hay nhiu phn ng ha hc

n c 2 giai on: khuch tn v cc phn ng ha hc. Qu trnh hp th ha hc ph thuc vo tc phn ng ca cc cht. Qu trnh ny c s dng rng ri trong k thut. + Cht c hp th hp th ngay vi cht hp th Th d: NH3 + H2O NH4OH NH4+ + OH SO2 + H2O H2SO3 H+ + HSO3+ Cht c hp th phn ng vi cc thnh phn hot ng trong cht hp th (dung dch ca cc cht hot ng) nh CO2, hay SO2 hp th trong NaOH Th d: CO2 + 2 NaOH Na2CO3 + H2O Na2CO3 + H2O + CO2 2 NaHCO3 * c im:

23

- S ho tan kh trong dch th: Khi lm sch cc tp cht ho hc th kh, qu trnh ho tan kh trong dch th ng vai tr quan trng. Khi tip xc vi cc dch th trong phi k ti nc, n c th ho tan cht lng, cht rn v cht kh. Nh bit, thng quan st thy hi ho tan trong nc, c hp th O2 c trong nc. Lng kh ho tan trong dch th ph thuc vo tnh cht ca kh, dch th v iu kin ho tan: nhit dch th v p sut kh trn b mt dch th, p sut ring phn ca kh cng ln, lng kh c ho tan vo dch th cng nhiu. Quan h ny c gi l nh lut Henry v biu th theo cng thc: C = H.p Trong : C - nng cc cu t trong dch th p - p sut ring phn ca cu t trong hn hp H - hng s ph thuc vo tnh cht ca kh, dch th v nhit - Cc hin tng xy ra khi lm sch cc tp cht kh ho hc trong kh: + Hp th kh khi ra kh bng dch th. i khi, kh sau khi ho tan vo dch th li c phn ng ho hc vi chnh dch th (nc) hoc vi cu t ho tan trong . V d, kh SO 2 c th phn ng vi NaOH ho tan trong nc. Qu trnh ny gi l hp th ho hc c s dng rng ri trong k thut. + Cho thm mt cht kh no chuyn cc tp cht ho hc th kh thnh trng thi lng, rn v c tch ra thnh sn phm thu hi. Phng php ny kh kh khn v phc tp, nn t c ng dng trong sn xut. Trong cng nghip luyn kim, ho hc thng dng phng php hp th. lm sch cc tp cht kh ho hc c trong kh khi ra bng dch th th phi to s tip xc tt gia chng. Mt khc chn dch th c kh nng hp th cc cu t cn lc m dch th khng gy tc dng ho hc vi cc cu t khc c trong kh. Cc kh ho tan trong nc iu kin tiu chun (00C v 760mmHg, tng ng vi 101325N/m2) vi lng vi trm gam kh trong mt kilogam nc gi l cht ho tan tt, v d, amoniac, hydro florua, axt clohydric (HCl). Cng trong iu kin trn, kh no ho tan trong nc ch vi phn chc v vi phn trm gam trong 1 kilogam nc gi l cc cht ho tan yu (O2, N2, CO). (9.1)

24

Do vy khi lm sch cc kh: amoniac, HCl c th ra bng nc vi lng khng nhiu, cn khi lm sch SO2 yu cu lng nc nhiu hn. c bit trong thc t khng dng nc kh CO. Trong mt s trng hp hp th cc cu t khng dng nc m s dng cc dch th khc: Du khong (i vi CS2) axt sunfuric. Chn dch th hp th hoc dung dch hp th ch yu ph thuc vo tnh cht ho hc cc cht hp th v cc cu t b hp th. Nu ch cn loi tr tp cht kh ho hc trong kh, th khuynh hng chn cht hp th c tc dng ho hc vi cc cu t b hp th. Nu yu cu khng ch lm sch kh m cn s dng cc tp cht thu c th cn chn cht hp th thch hp. Nng kh hp th v cng nh nn nhit hp th to ra khng ln v dung dch hp th c th dng li nhiu ln. - Tiu chun la chn dung dch hp th: + C tnh ho tan chn lc, ch hp th tt cht nhim cn x l + nht nh, nhit dung b, nhit si khc xa vi hn hp kh vo + Khng to kt ta, t bay hi, C th hon nguyn, r, d kim + Khng c, khng n mn, khng gy nhim nc thi * Nhc im ca phng php:

-

Nu dung dch sau hp th khng c kh nng hon nguyn v phi thi b th s

xut hin nc thi cn x l

- Thit b hp th ni chung n gin d vn hnh nhng chim nhiu din tch3.3.1.2. Cc loi thit b hp th Cn c thit k sao cho kh nng tip xc gia kh thi v dung dch hp th l tt nht. 1. Thit b kiu mng cht lng. 2. Thit b kiu mng a quay. 3. Thp hp th loi m 4. Thp hp th si bt 5. Thp hp th kiu a chp 6. Thp phun (kiu thng rng, kiu phun thun dng tc cao (Ventury), kiu phun sng c kh) 3.3.1.3. ng dng: (mt s v d hp th trong cng nghip)

- Dng x l cc cht nhim c kh nng ho tan hoc phn ng tt vi dungdch (v d: SO2, NOx, CO2, HF,...) c bit l cc oxyt axit v c, thch hp vi dung dch hp th mang tnh kim. + S hp th CO225

+ S hp th SO2

- Mt s dung dch hp th c kh nng hon nguyn thu hi kh nhim v sdng li dung dch hp th, nh vy s xut hin mt s cng nghip hp th nh hp th vi mt s kh nhim hoc dung dch hp th c gi tr. Hp th bng du, hp th bng axetylen. Hp th cc cht hu c c cha lu hunh

Lc bi

X l

X l

SOx

NOx

X l cc cht

ng khi

nhim khc S tng qut h thng x l kh thi

3.3.1.4. Mt s v d c th lm sch kh bng phng php hp th 1. Phng php lm sch anhydrit sunfur SO2 Trong nhiu nh my sn xut ng, niken, km, ch, ngoi sn phm chnh l cc kim loi trn, cn thu hi c sn phm ph l kh SO2. Khi nng kh SO2 khng thp hn 3,5% trong kh, c th thu hi n ch to axit sunfuric H 2SO4 bng phng php tip xc hoc phng php ra. Khi nng SO2 gim, gi thnh ch to H2SO4 tng ln. Khi nng SO2 qu nh khng nn s dng n sn xut H2SO4. lm sch kh ny c th dng mt s phng php. Tuy nhin, trong iu kin sn xut th cc phng php ny cha c p dng ph bin. 1.1. Phng php lm sch SO2 bng sa vi: Kh SO2 c thu hi trong thp ra bng sa vi, sa vi tc dng vi SO 2 theo phn ng: SO2 + Ca(OH)2 = CaSO3 + H2O - u im ca phng php l cho mc lm sch cao, nhng tn tht lng sa vi ln. - thc hin qu trnh lm sch kh trong thp ra c m th cn phun dch th vo thp vi lng ln loi tr s tc bn trong lp m do phn ng CaSO 3 v

26

thch cao (CaSO4.2H2O) dng phng php tun hon bn nho nhiu ln. Lng dch th cp vo thp l s m3 ng vi 1000m3 kh cn lm sch khi nng SO2 = 0,5%. - Khi nng SO2 tng, lng dch th cp vo thp t l thun vi s thay i nng SO2 trong kh. C th thay sa vi bng bt vi. Khi lm gim ng k mc lm sch kh. tng mc lm sch kh v gim lng vi th kch thc ca n phi nh: Ca CO3 + SO2 = CaSO3 + CO2 1.2. Phng php lm sch SO2 bng amniac (c chu k): Sau khi lm sch bi, asen, selen trong kh, nu cn cha SO2 vi hm lng nht nh th kh c lm ngui n nhit 35 - 400C sau ra kh bng dung dch cha (NH4)2SO3. Khi :

( NH4 ) 2 SO3 + SO2 + H2O 2NH 4HSO3

Khi dung dch nhn c l amonbisunfit n nhit si, phn ng tin hnh theo chiu ngc li cho thot ra SO2 v cho thu c amon sunfat. p dng phng php ny cho thu hi SO2 c nng cao ch to lu hunh nguyn t axt sunfuric v cc sn phm qu khc. vn chuyn SO2 d dng cn nn SO2 di tc dng p sut 20 - 30 N/cm2 (2 3 at) to SO2 lng v lm ngui n 15 - 250C hoc ch lm ngui n nhit 150C. Sau khi chng ct SO2 dung dch amon sunfit c lm ngui v mt ln na li c s dng thu hi SO2. Theo phng php ny, cht hp th c thc hin chu k vng, dung dch hp th SO2, sau khi lm bc hi SO2 dung dch c lm ngui v li c em s dng. y gi l phng php c chu k. Mc du cht hp th c hon li sau mi chu k nhng n cng b tn tht mt phn kh mang ra ngoi (dch th dng nh git) v mt phn to phn ng (NH4)2SO4. Amon sunfat nhn c cn phi a ra khi chu trnh thm vo mt lng amoniac nhn c (NH4)2SO4 mi cn thit b vo tn tht. Phng php c ng dng Lin X c cho nhiu sn phm qu: Anhydrit sufur nng cao, amon sunfat nhng yu cu phi lm sch bi asen, selen v lm ngui kh, dung dch n nhit thp ng thi c tn tht nhit nung nng, lm si dung dch thu hi SO 2. Theo phng php ny, cc cht ng vai tr hp th l cc cht gy phn ng: amon sunfit, nhm sunfat, xiliin, piriin C5H5N, etanolamin... trong cc cht hp th tt nht l amon sunfit. 1.3. Phng php lm sch SO2 bng amoniac (khng c chu k): Theo phng php nu, thu hi SO2 dng dung dch sunfit theo phn ng (9.4) v cho bisunfit. Mt na amon bisunfit cho tc dng vi cc axt (sunfuric, nitric, phosphoric) cho SO2 v mui amon.

4NH4HSO3 + H2SO4 (NH 4)2SO4 + 2SO2 + 2H2OMt na amon bisunfit cn li tc dng (trung ho) vi amoniac theo phn ng:27

NH4HSO3 + NH4OH (NH 4)2SO3 + H2OSunfit nhn c thu hi SO2 trong kh v amoniac v cc axit khng c ti sinh nn chng b tn tht. 1.4. Phng php lm sch SO2 bng oxit km: Kh cha SO2 cn lm sch khi ra bng dung dch cha ZnO, khi phn ng: ZnO + SO2 + 2.

1 1 H2O = ZnSO3 . 2 H2O 2 2

ZnSO3.2 H2O c to thnh dng pha rn c th c tch ra khi dch th

1 2

bng phng php lc hoc ly tm. ZnSO3.2 H2O c lc dng tinh th, khi nung n 3500C th b phn hu thnh H2O, SO2, ZnO. Kh SO2 thot ra c nng cao cn ZnO dng chun b bn hp th. u im ca phng php l khng yu cu lm ngui kh v dung dch hp th. - Mt phng php tng t l hp th SO2 bng MgO, khi phn hu MgSO3 cn phi nung n nhit cao (9000C) kh thc hin. - Lm sch SO2 trong kh theo phng php khc nhau khng ch dng cc cht hp th khc nhau m cn cho cc sn phm thu c khc nhau v cc iu kin cn thit tin hnh phn ng cng khng ging nhau. V d, phng php amoniac chu k th yu cu lm ngui kh v dch th nhiu hn, cn phng php amoniac khc th ch cn lm ngui kh v dch th t hn. Cc phng php dng vi, km, magie, khng yu cu lm ngui kh trong dch th hp th. Tng ng vi cc phng php lm sch khi khc nhau, hiu qu mi phng php lm sch kh cng khc nhau, ngoi ra hiu qu cn ph thuc vo cc iu kin cng ngh, thit b tin hnh nghin cu qu trnh. Sau khi lm sch SO2 trong kh theo cc phng php trn, lng SO2 theo tnh ton trong kh c thnh phn sau (%). Phng php sa vi : 0,005 - 0,01 Phng php km : 0,01 - 0,02 Phng php dng aminic : 0,01 - 0,03 Phng php aminic - km : 0,02 - 0,03 2. Phng php lm sch hydro clorua trong kh: Trong sn xut magie v cc sn phm khc, kh thot ra thng cha HCl, lm sch kh ny thng p dng cc phng php sau: HCl c th ho tan trong nc v

1 2

28

n c kh nng to thnh dung dch axit clohydric (HCl). Nu lng axit c chun ho l 27% c c dung dch axit clohydric theo phng php ny. Vi axit trn c n hi hi HCl 400C khong 1889N/m2 (14,2 mmHg) gi tr ny tm c khi dng phng php ni suy. V vy, khi cn c 27% HCl trong dung dch theo phng php hp th HCl bng nc ch trong trng hp nu trong kh cha HCl ln hn 14,2.100/760 = 1.87% v dch th khng c nung qu 400C trong qu trnh hp th. Trong cc iu kin khc nhau ca dch th, yu cu nng HCl trong kh cng c thay i tng ng. Kh ho tan HCl trong nc s to ra lng nhit ng k. Lng nhit ny ph thuc vo hm lng axit nhn c. Nu ho tan mt phn t gam HCl trong nc vi lng khng gii hn s to ra lng nhit l 1990 kJ (473 kcal) cn khi ho tan mt phn t gam HCl trong th tch nc nh trn nhn c dung dch c nng m c HCl th cn phi ly nhit i. Trong trng hp ny dng kh cha HCl qua lin tip cc thit b hp th, trong dch th v kh chuyn ng ngc chiu nhau. Cc thit b hp th trc y l thit b si bt, trong c ng rut xon c nc chuyn ng ly nhit to ra. Gn y ngi ta s dng cc thp ra c m v thp rng, pha trong cng t ng rut xon trong cc mng tun hon. nhn dung dch axit clohydric khi hp th HCl bng nc c th khng cn ly nhit ra trong my lnh c ng xon. Phng php ny da trn c s ly nhit bc hi ca nc do dch th hp th truyn n, do vy duy tr nhit khng i. Khi lm ngui nh vy c th nhn c dung dch axit clohydric nh hn 22%, cn tip tc dch th hp th bo ho axit clohydric s dn n to nhit v dch th b nung nng. Trng hp lm sch kh HCl khng to dung dch axit hn (v d, khi nng HCl trong kh thp) khi dung dch axit yu s c trung ho bng vi hoc kim v c tho ra ngoi. Khi lm sch kh HCl tt hn th khng dng phng php hp th HCl bng nc m bng dung dch vi trng thi huyn ph, tn tht nc cng nh trn nhng mc lm sch HCl cao hn. Phng php ny thc hin trong thp ra rng. Phng php n gin lm sch HCl l ng dng dung dch kim soda (natri cacbonat - Na2CO3.10H2)) nhng i vi nhng cht kim ny him v t nn ch dng khi chng c coi l nguyn liu tha ca nh my khi s dng n khng mt tin. Trong cc nh my sn xut magie, thu hi HCl s dng magie oxyt ngm nc, khi tc dng vi HCl theo phn ng. Mg(OH)2 + 2HCl = MgCl2 + 2H2O (9.8) 3. Phng php lm sch clo trong kh: Mt trong cc phng php nghin cu v c ng dng ph bin l lm sch kh clo trong thp ra bng vi hoc magie oxyt. Phng trnh phn ng gia clo vi cc cht trn c dng nh sau:29

2Cl 2 + 2Ca( OH ) 2 = Ca( OCl ) 2 + CaCl 2 + 2H2O

(9.9) (9.10)

2Cl 2 + 2Mg( OCl ) 2 = Mg( OCl ) 2 + MgCl 2 + 2H2O

Cc phng php phn ng trn c tin hnh theo chiu thun khi trong dch th hp th c d mt lng oxyt ngm nc. Nu ton b oxyt ngm nc phn ng th phn ng tin hnh theo s sau:

Cl 2 + H2O HCl + HClO

(9.11)

Cc axit to thnh tc dng vi cc axit nhn c ban u l Ca(OCl)2 hoc Mg(OCl)2 do vy tn tht cc oxyt ngm nc v mc lm sch HCl hon ton gim. hp th clo c tt th hm lng vi (CaO) trong dch th khng nh hn 10 - 20g/dm3. Dung dch nhn c cha Ca(OCl)2 hoc Mg(OCl)2 trc khi thi ra ngoi phi x l dung dch ny phn ho s lin kt . Tin hnh phn ho ny bng dung dch HCl hoc nung nng ng thi cho thm cht bin tnh: Mui ng, mui niken ng thi tc dng tng h vi mt ca. Hp th HCl bng sa vi thng tin hnh trong thp c m, nhng c nhc im d gy bn lm tc lp m. Gn y ngi ta lm sch kh clo thnh cng trong thp ra rng c vn tc dng ln. bo v cc chi tit ca thit b khi b tc dng cc axit c trong kh, b mt cc chi tit c ph lp vt liu chng g. 4. Phng php lm sch cc kh axit flohydric HF hexaflosilixic H2SiF6 Kh ra t cc nh my sn xut criolit (NaAlF6, AlF3.3NaF) v t cc b in phn sn xut nhm thng cha axit flohidric. Nh lm sch kh ra t b in phn sn xut nhm cho nhn c HF hoc dung dch kim no (thng l dung dch natri cacbonat Na2CO3) v NaF. Khi dng nc l cht hp th th khng hon ton thu hi HF m ch nhn c thnh phn cha HF. Qu trnh thu hi ny c thc hin trong 4 hoc 5 thp rng t ni tip nhau. Trong thp th nht, dch th (dch th hp th) c nng axit m c nht, sn phm thu hi t thp ny c cha HF. Thp cui cng c phun dung dch vi nng axit long (khong 3 - 5% axit) ng thi c cp thm nc mi. Lng nc d trong b cha c chuyn n b k trc. Khi hp th HF s to ra mt lng nhit ng k. S tng nhit dch th l khng ng mong mun v tng n hi h trn mt dch th. Do vy lng dch th trc khi phun qua ng phun s c lm ngui trong ng xon trong cc thit b lm ngui (hnh 9.4). Cc thp ra v cc b cha sn phm c HF c ni thng vi nhau. Cc b cha c ch to bng ch cn m ca thp gm nhng phin hoc ng tr vnh khn.

30

Trong cc trng hp khng cn thu hi thnh phn cha HF m cn lm sch hon ton HF th kh c ra bng dung dch natri cacbonat Na 2CO3, khi thu hi c dung dch NaF ch to criolit. Trng hp ny kh c dn qua mt thp v trn mt thong ca dung dch kim c n hi ca HF bng khng v vic lm sch kh ch tin hnh trong mt thit b. Trong trng hp cn thu hi HF v c bit c H2SiF6, nu s dng thp c m s khng c li, v khi gy tc bn cc l rng ca m do lng SiO 2 khi H2SiF6 tc dng vi H2O. khc phc hin tng ny th cn tng mt phun dch th (ln hn 15 - 20m3/m2.h). Nhiu nh my hin nay p dng thnh cng phng php hp th c hc. 5. Phng php lm sch nit oxyt trong kh Trong nhiu nh my ho - luyn kim - thi ra mt lng kh cha nit oxyt, ch yu do qu trnh thot kh nit oxyt t nguyn liu hoc n ho tan trong mt s hp cht trung gian. Phn ln cc trng hp cc kh ny c lng khng ln, nhng nng nit oxyt thng ln hn 1%, thng trong kh c cha c O2. Trong qu trnh ho luyn ca luyn kim c nng nit oxyt khng ln, phn ln cc trng hp, th tch cc kh ny tng ng k khi lng O2 cng nhiu. Thng trong kh khng ch cha NO v NO2. Cc kh cha ln hn 5% (so vi hm lng tng ca nit oxyt) c th lm sch theo phng php ra bng dung dch kim ngay c bng nc duy nht, khi mt phn nit thot ra theo phn ng: 3NO2 + H2O 2HNO3 + NO (9.12) Nit oxyt NO s b oxy ho bi oxy trong khng kh, vn tc oxy ho gim theo mc gim nng NO v O2 v nu tng nhit . V vy, phng php lm sch ny ch ng dng khi hm lng nit oxyt ln hn 1% ch to axit nitric (HNO3). lm sch nit oxyt, kh cha nit oxyt c ra bng dung dch cc cht oxy ho. KBrO 3, KMnO4, H2O2 cho kt qu lm sch tt nhng cc cht phn ng ny t, cn cc cht phn ng khc cho hiu qu lm sch thp hn. Mt phng php khc l phn ho nhit nit oxyt. V d, trong phazmatron khi c mt cc cht hon nguyn th kh: H2, kh thin nhin hoc dch th hon nguyn nh: Du ho, benzen,... S phn tch ho nhit thc hin nhit thp hn 10000C ng thi lm thot ra O2, N2. Thc t phn ng tin hnh khng hon ton. Kt qu tt hn t c l s dng cc cht hon nguyn th rn. V d, than cc. Khi nhit 8000C s phn ho NO xy ra 95 - 96% v khi 10000C - t khong 100%. Ngoi ra, s phn ho nhit nit oxyt khi hn hp kh vi NH 3 nhit tng i thp (nh hn 2500c) v dng cht xc tc l cc vanadioxyt mangaoxyt. Lng d NH3 c trong kh hn hp sau khi xy ra phn ng c hp th bng nc, axit sunfuric (hoc dung dch c nng NO yu). NO2, NO c th phn ho bng nung nng chng khi c mt cc kh hon nguyn khi c cht xc tc l plantin. Trong31

nhiu trng hp c th s dng cc cht xc tc r tin, ch yu l cc vanadioxyt, mangaoxyt. Phng php ny ng dng i vi kh cha 0,5% nit oxyt v lng O2 thp hn 0,5% nhng hon ton khng c mt cc kh: SO2, H2S v cc kh ny s lm hng cht xc tc. Do vy thy r cc phng php lm sch cc kh nu trn u cng knh v t. 6. Phng php lm sch ihydro sunfua trong kh Kh ra t cc nh my luyn kim c th cha ihydro sunfua H2S, kh ny cn c lm sch. Thng th lng kh ny ra khng ln v hm lng H2S trong kh thp, nn vic lm sch kh khng nhm s dng li H2S m l v sinh mi trng. lm sch kh ny s dng dung dch natri cacbonat ra H2S. Khi c phn ng: H2S + Na2CO3 = NaHS + NaHCO3 (9.13) Khi s dng natri cacbonat th hm lng dung dch 25 - 30g/l cn nu dng Kali cacbonat K2CO3 th hm lng dung dch n 15 - 20%. Dung dch nhn c c th ti sinh bng cch thi CO2 qua dung dch . Ngoi ra, cn nhiu phng php hp th H2S bng st (qung st dng lt), axit asen. Mt s trong chng c ti sinh bng cch thi khng kh ng thi nhn c lu hunh nguyn t. 7. Phng php lm sch cacbon oxyt trong kh Trong nhiu nh my cng nghip thi ra mt lng cacbon oxyt CO ra kh quyn. Do pht trin cng nghip v tng c v quy m lng kh cacbon oxyt cng tng theo v ngy cng pht sinh vn : Cn thit phi lm sch kh ny. Phng php n gin lm sch kh CO l t kh ny to thnh CO2 (nu cho php x kh CO2). S chy c th thc hin nhit gn 10000C. Nhiu trng hp c th tn dng lng nhit do phn ng chy xy ra. Qu trnh phn ng chy xy ra khi c mt cc cht xc tc cha ng v cc kim loi khc. Trng hp nng CO thp cn hm lng O2 cao th kh c t trong bung t ni hi. Khi c cht xc tc nhit khong 5000C, phn ng gia CO vi H2O nh sau:500 C CO2 + H2 + 9,5kcal CO + H2O 0

(9.14)

C th s dng cht xc tc ca hn hp cc oxyt ca st v crm (87% Fe 2O3 v 6,5% Cr2O3) vi cc cht MgO v K2O c chc nng kch thch phn ng. Lm sch kh CO c th thc hin ra kh trong dung dch ng - amoniac. Phn ng xy ra chm, thng ng dng phng php ny trong sn xut c p sut hng trm atmotphe. 8. Phng php lm sch cacbonyl clorua (COCl2) trong kh Khi tin hnh ra kh bng nc nng hoc dung dch kim qu trnh lm sch c tin hnh chm nhng khng hon ton. lm sch kh hon ho hn c th thc hin vic nung kh (t) nhit khong 8000C khi c mt hi nc.

32

Nhng nm gn y bt u p dng trong con ngi lm sch cc tp cht c trong kh bng phng php l bin cc tp cht thnh khi bi. Thc cht ca phng php ny l b sung vo kh cn lm sch mt lng kh khc cha cc cu t phn ng vi kh tp cht cho lin kt rn dng khi bi, tip theo s c lc trong cc thit b thu bi. V d, lm sch SO2 th cho thm NH3 vo kh v kh c mt hi H2O s to thnh (NH4)2SO3 (khi nhit thp) sau kh ny c a qua thit b lc in hoc thit b lc ti vi. Tng t nh vy c th lm sch cc kh HCl, HF... 3.3.2. Phng php hp ph 3.3.2.1. Khi qut v hp ph * Hin tng hp ph: Hp ph l hin tng gy ra s tng nng ca mt cht hoc mt hn hp cht trn b mt tip xc gia hai pha (rn-kh, rn lng, lng kh) Ph ht ch th phi thay cht hp ph hoc ti sinh cht hp ph c dng li. * Khi nim: Hp ph l hin tng lin kt cc phn t ca mt cht lng, hoc kh ln b mt ca mt cht rn khc bi lc tng tc gia cc vt th ( lc Van Der Waals) v lc ht tnh in. Mt s cht hp ph thng dng: Than hot tnh, sng phn t, oxyt nhm, Silicagen, acrinamit, PAC, oxyt st, zeolit, ..Than hot tnh l 600-1200m2/g. Bentonit l 800m2/g. * Phn loi hp ph: - Hp ph vt l: l loi hp ph gay ra do tng tc yu gia cc phn t; Lc tng tc l lc Vn der Waal. Trong nhiu qu trnh hp ph kh, s hp ph c th xy ra di tc ng ca cc lc phn t gy ra s vi phm cc nh lut kh l tng v hin tng ngng t. Dng hp ph ny gi l hp ph phn t hay hp ph van der Waals. - Hp ph ha hc: l loi hp ph gay ra do tng tc mnh gia cc phn t v to ra hp cht b mt gia b mt cht hp ph v cht b hp ph. Hp ph ha hc c to ra do p lc ha hc. i vi cc cht b hp ph l cht kh, qu trnh ph thuc vo nhit v p sut. Lng kh b hp ph l a. Ta c: trnh hp ph. - Hp ph tnh: Kh nng hp ph ca mt cht hay dung lng hp ph ca mt cht ph thuc vo tnh cht, trng tri ha hc ca cht b mt, cu truc l xp ca cht hp ph cng nh ph thuc vo nhit v p sut ca qu trnh hp ph. Ty thuc vo c trng tng tc ca cht b hp ph vi b mt cht hp ph ta c hp ph vt l hay hp ph ha hc. Trong trng hp chung, ta c phng ttrinhfcho lng cht hp ph : a = am {h.k/(1-h).[1+ h(k + 1)]}33

a = f(T, P)

Nhit tng lm gim qu trnh hp ph, ngc li, p sut tng lm tng qu

trong : a lng cht b hp ph (mol/gam) am - lng cht b hp ph ng vi s lp y lp n phn t (mol/gam) h P/Ps ca n. k - h s biu hin s tng tc ca cht hp ph v cht b hp ph. - Hp ph ng : Thc cht qu trnh lm sch kh thi bng phng php hp ph l qu trnh ng. M l lng cht c hp ph ta c : M = a. S . L a hot cn bng; L- chiu dy ca lp hp ph ; S din tch thit din ngang ca thiets b hp ph ; 3.3.2.2. Nguyn l ca phng php x l hi v kh bng phng php hp ph: vi P l p sut ring phn ca cht b hp ph, Ps p sut hi bo ha

- Cht nhim c tch khi dng kh do b gi li trn b mt ca cht rn. Chtrn ny gi l cht hp ph. Kh nhim c hp ph gi l cht b hp ph. - Nu ta chn c cc cht hp ph chn lc th ta c th loi b c cc cht c hi m khng nh hng n thnh phn ca cc cht kh khng c hi. 3.3.2.3. Cc cht hp ph v ng dng

Cc cht hp ph thng dng trong mc ch ny l than hot tnh dng ht hoc dng bt, than bn sy kh hoc c th l t st hot tnh hay diatomit, betonit. Hay cc cht nh: Than hot tnh; Silicagel; Zeolit, sng phn t, oxyt nhm,Silicagen, acrinamit, PAC, oxyt st, zeolit, ..Than hot tnh l 600-1200m2/g. Bentonit l 800m2/g. * ng dng (Hiu sut hp ph c th t n 98%) 1. Thu hi li hi dung mi (sn, nhum, keo dn,...) 2. Tch v thu hi xng du kho xng 3. Tch v thu hi hp cht hu c halogen cc thit b tch m ca cng nghip thc phm hoc cc qu trnh sn xut ho cht. 4. Lm sch kh thi c mi - Hp ph hi dung mi: + Cht hp ph: c l xp mn nh than hot tnh, silicangen, keo nhm, thu tinh l xp + Than hot tnh cht hp ph k nc nn ng dng hiu qu khi m kh thi n 50% Thit b: Tng si v lp ht chuyn ng u im ca si carbon hot tnh so vi than hot tnh Hiu qu thu hi cao trn 99% Gim tht thot dung mi do phn hu nhit kh c than HT lm xc tc Gim nguy c chy n, c ng dng thu hi dung mi c nhit cao.34

- Hp ph SO2: + Cht hp ph: vi, molit. + tng hot tnh ca cht HP ph ho hc, thc y qu trnh chuyn ho SO2 thnh SO3. Cc ph gia cn thm: dng mui v c r tin hay oxit mangan + Ti sinh bng phng php trch li c thc hin bng nc nng v thu c kh sufuaric long (10-15%) ng dng khc: Hp ph H2S bng than hot tnh Hp ph H2S bng zeolit Hp ph hi thy ngn bng than hot tnh, oxisilic, bt, zeolt, silicagen

Hp ph mi bng than hot tnh Khi hm lng hi thu ngn c th hp th bng cc vt rn kh: Than hot tnh cha clo, pirluzit MnO2 (qung mangan) sau khuy trn trong kh SO2). 3.3.3. X l kh v hi bng phng php thiu hy phn hy kh hay hi c c hi cho mi trng thnh mt cht hay nhiu cht khc t hoc khng c hi c th thc hin bng ngun nhit phn hy nhit hoc phn hy thng qua cc phn ng ha hc, hoc kt hp c hai phng php t. 3.3.3.1. Thiu hy bng nhit - N thiu hy cht kh thi cha cc hp cht hu c nh hi dung mi, hi l cc ha than, hi t. Trong nhit cao hi s b phn hy thnh than, kh v hi nc. tc sy ra nhanh ngi ta thng tin hnh phn hy nhit vi s c mt ca cc cht xc tc. Kh oxit nit c xc tc v nhit cao

Qu trnh kh NOx din ra khi tip xc vi kh kh trn b mt xc tc Cht xc tc c th l kim loi nhm platin (paladi, ruteni, rodi..) hoc niken, crm, ng, km.. tng din tch b mt tip xc, ph ln cc cht XT cc vt liu xp nh s, oxit nhm, silicagen Cht kh: metan, kh t nhin, kh du m, CO, H2 hoc hn hp nit-hydro * Nguyn tc: Di tc dng ca nhit v s c mt ca oxy trong khng kh. Cc cht nhim c oxy ho thnh nhng cht khng c hi (CO2, H2O) hoc d x l hn bng cc phng php khc so vi cht nhim ban u. * Qu trnh xy ha khng xc tc: C th tin hnh khng xc tc trong cc l t (nu mun thu hi nhit) hoc trn cc dn la, ming ng thi (khng thu hi nhit). ng thi cn c nhiu ph tr t kh thi.35

Nhit chy thng khong 800 11000C - ng dng: X l khi ca nh my rang c ph, kh thi khu vc ch bin rc, hi cc dung mi v cc kh hi hu c. - Hn ch: Khng thch hp khi lu lng kh thi qu ln v ch p dng vi cc kh c kh nng chy. * Qu trnh xy ha c xc tc: - Mc ch: gim nhit chy cn thit v nhit chy theo phng php ny nh, khng vt qu 250 3000C - Xc tc: cc kim loi nng hoc oxyt ca chng (Fe, Cr, Co, Cu, Mo, Ni, Va) cc cht phi kim loi hoc cht tr. - u im: Nhit xy ha thp hn phng php nhit do tit kim c nng lng - Nhc im: Cn thit b xc tc do cng knh, tn km; xc tc c th b ng c do s c mt 1 s thnh phn trong kh thi; cn c qu trnh hon nguyn xc tc - ng dng: + Qu trnh kh NOx din ra khi tip xc vi kh kh trn b mt xc tc + Cht xc tc c th l kim loi nhm platin (paladi, ruteni, rodi..) hoc niken, crm, ng, km.. + tng din tch b mt tip xc, ph ln cc cht XT cc vt liu xp nh s, oxit nhm, silicagen + Cht kh: metan, kh t nhin, kh du m, CO, H2 hoc hn hp nit-hydro + XL hi HCN trong cng nghip m in, x l NOx trong sn xut HNO3 (xc tc tm kim loi pt, t = 300 8000C), x l aldehyt hp cht hu c sinh ra trong qu trnh t cht hu c - xc tc hnh cu, x l H2S trong cng nghip luyn kim + Kh NOx c xc tc chn lc 3.3.3.2. Thiu hy bng phng php ha hc y l phng php kh ph bin i vi cc kh c hi. Th d: SO2(SO3) + NaOH => Na2SO3(NaSO4) NOx + NH4OH => NH4NOx

i vi cc cht c hu c nh thuc thuc tr dch hi, ngi ta s dng cc phn ng oxy ha kh hoc thy phn trong mi trng thch hp thay i cu trc phn t hay dng tn ti ca chng tr thnh cc cht t, hoc khng c cho ngi v thc vt. Th d: Phn ng vi ozon c tia cc tm, y l phng php rt hiu qu i vi cht thi hu c hoc dung mi. Cht tr dch hi + O3 ==== CO2 + H2O + cc cht khng c Hay s dng cc cht oxy ha mnh kh c nh thuc tm, ...36

Cht hu c + KMnO4 ==== Mn2+ + CO2 + H2O + cc cht khng c Cht tr dch hi hu c + KMnO4 ==== MnO2 + cc cht khng c 3.3.4. Phng php ngng t Phng php ny c s dng thu hi cc dung mi hu c bay hi nh xng du, axeton, axit etylen, toluen. Phng php ngng t ph bin nht l phng php im nhit (lm lnh). Thng hi dung mi c nng cao ngi ta dng phng php ny thu li dung mi bay hi.Cn nng thp ta nn s dng phng php hp th hay hp ph. - Phng php gim nhit : Cc cht hu c bay hi c lm lnh ti im sng, b ngng t v tch khi dng kh thi. C hai phng php lm lnh: Phng php lm lnh trc tip v phng php lm lnh gin tip. + Dng tc nhn lnh trc tip tip xc vi kh thi, gy hiu ng ngng t cht nhim c hi, sau tch kh c hi ngng t ra khi tc nhn lm lnh. + Phng php lm lnh gin tip: L phng php dng phng tin trao i nhit (gin tip), cht thi c hi ngng t c thu hi d dng, khng cn c thit b phn tch Hiu sut ngng c xc inh theo cng thc: N = 100(Co CR)/Co Trong : Co - nng hi ban u CR nng hi u ra Gi tr tuyt i ca hiu sut ngng t: P = 100(mi / CoVoMi) (%) mi khi lng ca cht i c ngng t Vo lu lng kh u vo 3.3.5. Phng php th sinh hc: phng php mi trong x l kh * Nguyn tc: dng kh nhim di tc dng ca vi sinh vt b phn hu cht t hoc khng c hi Kh nhim phi ho tan trong nc (c hp th) sau c vi sinh vt x l Nhit dng kh gii hn trong 15 60oC, tt nht l 30 - 40oC Sau khi hp th kh nhim dung dch x l c pH = 5 - 8, khng cha kh gy c hi cho vi sinh vt * C 2 phng php: Phng php lc sinh hc: dng vt liu lc, bn trong nui dng vi sinh vt. Cho dng kh i qua cc vt liu lc ny vi sinh vt s phn hu kh nhim - Vt liu lc: vt liu hu c c b sung dinh dng nui sinh vt - Phng php ra sinh hc c 2 giai on l:37

(%)

Giai on 1 l kh nhim c hp th bng 1 thp rng Giai on 2 l dung dch hp th kh nhim c a qua 1 b bn cha vi sinh vt (bn hot tnh) kh ra c lm sch 3.3.6. Lm sch kh bng phng php trao i ion Phng php ny xut hin trong nhng nm gn y nhiu nc trn th gii. Ionit (cht trao i ion) l nhng cht rn khng ho tan trong nc, l cc vt cht polyme c tnh axit, kim, mui. Cng thc ho hc ca chng l: HR, ROH (R biu th trng thi polyme ca vt cht). Ionit c th tc dng ho hc theo phn ng i vi cc kh nh sau: ROH + HClkh RCl + H2O (9.15) HR + NH3 kh NH4R (9.16) Tng t nh vy trong nhiu trng hp c th thu li cc cu t axit hoc kim tnh c trong hn hp kh. Trn c s ny p dng ionit lm sch kh. ti to ion trao i dng mui thc hin bng cch phun dung dch axit yu (~5%) hoc kim tng ng vi ionit chuyn i thnh dng ban u. V d, phn ng: RCl + NaOH NaCl + ROH (9.17) lm sch cc kh, ng dng cc ionit dng lp ht vi kch thc 0,2 0,3mm hoc dng vt liu x c ng knh 5 - 36m. thu bi cc kh thc hin trong cc thit b: Lp si v lp lc tnh. Phng php lm sch kh bng vn chuyn c trao i ion cho hiu sut thu bi cao, ng thi c th thu hi c nhiu cu t khc nhau, khng nh hng c hi khi c mt hi nc. Phng php ny ng dng ch yu lm sch kh ra t my qut v khi lm sch cc kh nng, nhiu bi gp mt s kh khn. 3.3.6. Gii thiu mt s cng ngh x l hi v kh gy nhim 1. X l nhim kh trong ngnh nhit in a. Cc cht nhim kh Bi, SO2, NOx, hi kim loi, 1 s cht hu c b. S cng ngh 2. X l nhim kh thi trong ngnh ho cht sn xut xt clo a. Kh nhim: Cl2 b. S cng ngh x l 3. X l nhim kh thi trong nh my thuc bo v thc vt (tr su) a. kh nhim: bi (thuc bo v thc vt), hi dung mi b. S cng ngh x l 4. X l nhim kh thi trong nh my sn a. Kh nhim: hi dung mi38

b. S cng ngh x l 3.4. Phng php x l bi Phng php x l bi c phn loi theo nguyn l hot ng trong qu trnh x l. 1. Phng php trng lc 2. Phng php qun tnh 3. Phng php ly tm 4. Phng php tch bi bng lc 5. Phng php tch bi bng lc tnh in 6. Phng php tch bi t * Cc phng php x l bi c th chia thnh cc nhm sau: Bng 3.1. Cc phng php x l biLc Thng lc gm Lc c vt m Lc ti (mng) Dp bng nc Dn ma Sc kh a quay Dp bng Kh bi da vo tnh in lc ly tm Lc tnh in Thit b s dng lc qun tnh Thit b s dng lc ly tm(cyclon) Thit b quay Kh bi da vo trng lc Bung lng bi

Lc kiu venturi Bng 3. 2. Vng lc v hiu qu x l ca cc phng php STT Thit b x Kch thc ht ph hp (m) Hiu qu x l (%) 1 Thng lng bi 2000 - 100 40 70 2 Cyclon hnh chp 100 5 45 85 3 Cyclon t hp 100 5 65 95 4 Lc c vt m 100 10 n 99 5 Thp lc t 100 0,1 85 99 6 Lc ti (mng lc) 10 2 85 99,5 7 Lc tnh in 10 0,005 85 - 99 la cho c thit b x l bi hiu qu cao cn quan tm n cc yu t sau: 1 . Thnh phn ht bi v kch thc ht bi 2. Trng thi v thnh phn ca kh 3. tinh lc kh cn thit 3.4.1. Phng php trng lc * Nguyn l: - Lm cho bi lng ng di tc dng ca trng lc.

39

- Khi dng kh cha bi chuyn ng ngang nu c s thay i t ngt v tit din chuyn ng th tc d dng kh s thay i, di tc dng ca trng lc ht bi s lng xung v tch khi dng kh. * u, nhc v phm vi ng dng ca phng php trng lc: - u im Cu to n gin, u t thp, c th xy bng vt liu r tin nh gch. Tn tht p sut thp, gi thnh vn hnh r C th lm vic nhiu iu kin nhit v p sut khc nhau. C cu cng knh, chim nhiu khng gian Ch c kh nng tch nhng bi tng i ln

- Nhc im

- Phm vi ng dng Tch s b nhng bi c ng knh tng i ln trc khi vo cc thit b tch bi bc cao * Thit b lng bi - Bung lng bi - Cu to: Mt khng gian hnh hp c tit din ngang ln hn nhiu ln so vi tit din ng ng dn kh vo cho vn tc dng kh gim xung rt nh, do ht bi di tc dng ca trng lc thi gian ri xung chm y v bih gi li m khng b dng kh mang theo. Bung lng bi c p dng lng bi th c kch thc ht t 60-70m tr ln. Tuy vy, cc ht bi c kch thc nh hn vn c th b gi li trong bung lng.

- Cc loi bung lng: 1. Bung lng n gin 2. Bung lng nhiu tng 3. Bung lng c vch ngn + B mt ct ngang ca bung lng c tnh: S = a.h = V/w (m2) Trong : a chiu rng ca bung lng; V lu lng kh qua bung;40

h chiu cao ca bung lng w vn tc kh qua bung

+ B mt rng cn thit (F): Trong : w1 vn tc lng bi; + Thi gian lng ht bi:

F = V/w1 V lu lng dng kh v bi V1v = V.t (m3) L = F/a = V1v /h.a

T = h/w1 (s)

+ Th tch lm vic ca bung lng: + Chiu di cn thit ca bung lng:

Vn tc kh ng gia v trong hnh bao c chn ph thuc vo dng bi v mc lc bi mong mun. i vi cc thit b lc bi hnh bao t trc tip sau cc l cao ca nh my luyn kim en, chn vn tc kh vo ng gia l 10m/s, cn vn tc kh trong thn hnh bao l 1m/s. Khi i vi cc ht bi kh ln (ln hn 25 - 30m) mc lc bi t 65 - 85%. Bng 3.3. Vn tc ti a cho php ca kh i trong cc bung lng bi Bi Khi lng ring ca ht, kg/m3 2720 2200 2780 1270 3020 8260 6850 1180 Kch thc lng ca ht, m 335 261 71 64 117 14,7 90 1370 1400 Tc ti a cho php ca kh, m/g 4,3 5,0 6,4 1,75 5,6 7,6 4,7 4,0 6,6

Phi nhm Aming vi Tinh bt Bi phi kim loi ca cc l nu luyn Ch oxyt Thp ht Phoi g Mn ca 3.4. 2. Phng php qun tnh

* Nguyn l: L phng php lm thay i chiu hng chuyn ng ca dng kh mt cch lin tc, lp i lp li bng nhiu loi vt cn c hnh dng khc nhau. Khi dng kh i hng chuyn ng th bi do c sc qun tnh ln s gi hng chuyn ng ban u ca mnh v va p vo cc vt cn ri b gi li hoc mt ng nng v ri xung y thit b. Trong cng nghip p dng ph bin thit b lng bi hnh bao. Kh cha bi chuyn ng t pha trn xung qua ng gia (ng tr thng hoc loe pha di), cha bi chuyn ng qua ng gia vi vn tc ln li b i chiu 180 0, do lc qun tnh cc ht bi c tch ra khi dng v ri xung boongke. * Mt s thit b p dng PP qun tnh 1. Thit b lc bi qun tnh kiu Venturi 2. Thit b lc bi qun tnh kiu mn chn un cong 3. Thit b lc bi kiu qun tnh kt hp vi thng lng bi41

3.4.2.1. Thit b lc bi qun tnh kiu Venturi * Cu to:

* Nguyn l hot ng: Khi dng chy ca kh b thu hp tit din th bi s p st vo thnh vt cn v lt vo cc khe 2 ri vo by bi 3. Ti y dng kh s b ht ngc tr ln ri thot ra ngoi, cn bi trong by 3 th ri xung phu cha bi ca thit b. 3.4.2.2. Thit b lc bi qun tnh kiu mn chn un cong

* Cu to

* Nguyn l hot ng: Dng kh i qua khe h gia cc tm chn ca dy trc s b chn li bi cc tm chn ca dy ng sau v do n s thay i hng chuyn ng theo cc g hnh vng cung ca tm chn i tip n cc dy tm chn tip theo. Trong qu trnh thay i hng chuyn ng, bi s b gi li trong lng mng v ri xung phu cha bi ca thit b. 3.4.2.3. Thit b lc bi kiu qun tnh kt hp vi thng lng bi * Cu to:

* Nguyn l hot ng:42

Kh cha bi i vo thit b qua b phn cn bi gm sng chn bi 3 v ghi l sch 4. Sng chn bi gm nhng thanh trn xp k nhau vi khe h nht nh kh sch i vo mng 2 v thot ra ngoi, cn bi b gi li bn di. cui b phn cn bi, dng kh m cc bi i vo thng lng v hnh thnh 1 dng tun hon i qua ghi l sch 4 nhp li vo dng kh chnh. Bi trong dng tun hon nh lc qun tnh v trng lc ri xung phu cha 5. * ng dng: p dng kh ph bin lc tro trong kh thi l hi. 3.4.2.4. Cc thit b thu bi theo nguyn l c tm chp Cc bung thu bi c tm chp gm hai phn chnh: li tm chp v thit b thu bi (thng l xyclon). S cng tc ca thit b c tm chp c trnh by trn hnh

Hnh. S cng tc ca thit b c tm chp Dng kh cha bi chuyn ng trong ng gp cc tm chp t nghing nn dng b t bin i chiu chuyn ng theo cc pha khc nhau. Cc ht bi khi gp tm chp vn c khuynh hng chuyn ng theo hng c nn va p vo tm chp, ng thi b phn x theo chiu ngc li v chuyn ng theo hng ca dng kh n tip theo pht trin. Theo nguyn l tch bi trn, kt qu cc kh qua li tm chp c lm sch, lng kh ny chim 80 - 60% th tch chung ca kh, cn dng kh chuyn ng theo hng khc c hm lng bi tng ln nhiu. Lng kh ny chim 10 - 12% th tch chung ca kh v s c tip tc tch bi trong xyclon. Sau khi c tch bi trong xyclon, lng kh ny li c hp nht vi dng kh chnh c lm sch bi khi qua cc tm chp.

43

Hiu sut thu bi trong thit b c tm chp ph thuc vo mc tch bi khi qua tm chp v xyclon. Nu k hiu l phn kh i ra vi nng bi cao th mc bi kh trong bung c tm chp c xc nh theo biu thc gn ng nh sau: = x [1 - (1 - )(1 - 1)] Trong : x - mc thu bi kh trong xyclon 1 - mc thu bi kh trong li tm chp Biu thc trn ch ng khi 0,1 - 0,2, bi v khi = 0 th mc thu bi trong thit b c tm chp bng 0. Do c cu trc n gin, r tin v tr lc nh nn cc bung thu bi tm chp c s dng kh rng ri thu hi bi cc kh thi cc nh my ca cc ngnh cng nghip khc nhau. Mt trong cc kiu c s dng ph bin nht Nga l kiu bung thu bi tm chp ca Vin nhit lin hp BTH c ch to t thp gc. S lng tm chp lm t thp gc 40 40mm trong li t 11 n 75 ci, chiu rng B t 209 n 1425mm, khi chiu cao li H t 595 dn 4038mm. Tch bi ra khi dng kh trong cc thit b ny ch yu da vo lc qun tnh. Khi tng tc kh gn tm chp, hiu sut thu bi tng t bin. Thng thng thit b lm vic vi vn tc kh 12 - 15m/s. xyclon c th thu bi mc cao th vn tc ca kh khi vo xyclon phi nh hn vn tc kh gn tm chp. Khi tng kch thc ht bi, hiu sut thu bi s tng ln. Ngoi ra do mi mn tm chp cng tng th mc thu bi cng gim nn thng ch dng thit b tm chp thu hi cc bi c kch thc ln hn 20m. Nhit khi vo thit b (gn tm chp) khng c vt qu 4500C. Nu nhit kh qu cao (khong 6000C) th tm chp cn c ch to bng gang c. Thnh ca xyclon c ch to bng thp l dy 12 - 15mm chng bo mn do cc ht bi va p, cn phu xyclon c ch to bng thp l dy 6 - 8mm. 3.4.3. Phng php ly tm (Xyclon) * Nguyn l: L phng php lm tch bi ra khi dng kh cha bi nh tc dng ca lc li tm. Khi dng kh v bi chuyn ng theo mt qu o trn (dng xoy) th cc ht bi c khi lng ln s chu tc dng ca lc li tm vng ra pha xa trc hn, phn gn trc xoy lng bi s rt nh. Nu gii hn dng xoy trong mt v hnh tr th bi s va vo thnh v v ri xung y. Ngha l dng kh c a vo theo phng tip tuyn vi thn hnh tr ca thit44

(6.1)

b nn s chuyn ng xoy c bn trong thit b t trn xung. Do chuyn ng xoy, cc ht bi chu tc dng ca lc ly tm lm cho chng b vng v pha thnh hnh tr ca xyclon ri chm vo c tch ra khi dng kh. Di tc dng ca trng lc, cc ht bi ny s ri xung y phu thu bi pha di ca xyclon. Khi ta t tm dng xoy mt ng dn kh ra, ta s thu c kh khng c bi hoc lng bi gim i ng k. *Cc loi thit b lc bi ly tm - Thit b lc bi ly tm kiu nm ngang - Thit b lc ly tm kiu nm ng * u nhc im v phm vi ng dng (xyclon) - u im: + Gi thnh u t thp + Cu to n gin, d vn hnh + Chim t din tch xy dng + Khng c b phn chuyn ng + C th ch to bng nhiu loi vt liu khc nhau ph thuc vo nhit , p sut lm vic cng nh kh nng n mn ca dng kh. + C th lm vic lin tc + Chi ph sa cha, bo dng thp + Thch hp vi bi c d5 - C th phn loi phng php x l sinh hc theo 2 cch chnh: + Phng php hiu kh: L phng php s dng nhm vi sinh vt hiu kh phn hu cc cht hu c. Cn b sung O2 lin tc v nhit x l t20 - 40 0C; pH = 6,5 8,5, c cht dinh dng nui vi sinh vt. + Phng php ym kh: Phng php s dng vi sinh vt ym kh l vi sinh vt khng ly oxy trong khng kh m ly oxy trong hp cht ho hc khc. Trong nc thi, phng php hiu kh tc dng hn.

4.3.2.1

. X l nc thi bng phng php hiu kh trong iu kin nhn to

* C s l thuyt: X l sinh hc hiu kh thc cht l thc hin cc qu trnh xy ha cc cht hu c v v c c th oxy ha sinh hc c nh vi sinh vt. a/. C ch phn gii hiu kh. Di tc dng ca cc vi sinh vt h hp hiu kh, cc cht nhim c xy ha hon ton. Cc qu trnh xy ha bao gm: - xy ha cc hp cht hu c khng cha Nit (gluxit, pectin...) y y z CxHyOz + (x + ). O2 xCO2 + H2O 4 2 2 - xy ha cc hp cht hu c c cha Nit (protein, axit amin...) CxHyOz + (x +y z 3 + ). O2 xCO2 + (y - 3)/ 2H2O + NH3 4 2 4 y z - 5). O2 C5H7NO2 + n (x-5) CO2 + n (y - 4)/ 2 H2O. 4 2

- Qu trnh oxy ha km theo s to thnh sinh khi vi sinh vt (bn hot tnh) CxHyOz + nNH3+ n (x +

- Qu trnh t hy ca Bn Trong qu trnh lm sch nc, bn hot tnh cng thng xuyn i mi do thi gian th h ca vi khun bin ng t 20 60 pht. C ch t hy cng l mt qu trnh kh amin bng xy ha. C5H7NO2 + 5O2 5CO2 + NH3 + 2H2O + E NH+4 NO3Ngoi ra cn xy ra cc qu trnh nitrat v phn nitrat ha ( nhng vng thiu oxy), qu trnh sunfat ha, photphoril ha.71

C ch tm tt ca phng php x l hiu kh: Vi sinh vt hiu kh dng oxy tan trong nc xy ho cc hp cht hu c d phn hu ra khi ngun nc. Vi sinh vt Cht hu c + O2 ------------> H2O + CO2 + NH3 Vi sinh vt NH4 + O2 --------------> NO3 + H+ + H2O + Q Gm b thng kh sinh hc, lc kh sinh hc, b lc sinh hc, h sinh hc. b/. Tc nhn sinh hc. Vi sinh vt c kh nng phn hy hu ht cc hp cht hu c c trong t nhin v c mt s cht tng hp hu c. Chng s dng cc cht hu c v mt s nguyn t khong lm ngun dinh dng pht trin, sinh trng. Cc vi sinh vt tham gia vo qu trnh lm sch nc thi trong h thng x l hiu kh rt a dng v phong ph, ch yu l vi khun v nguyn sinh vt. Bn hot tnh vi s hin din ca trn 20 chng vi khun khc nhau, trong c mt s chng chim a s: v d nh: Aerobacter, Bacillus, Pseudomonas, (h hp hiu kh) Cellulomonas biazotea, Rhodopseudomonas, Nitrobadet (h hp ty tin) v mt s vi khun dng si (Thiothrix, Microthrix).

Mt th in hnh v s tng trng ca vi khun trong b x l

* Cc yu t nh hng: a/. pH v nhit : Gi tr pH c nh hng rt ln n hoch lc enzim trong t bo v qu trnh hp th cc cht dinh dng vo t bo, h thng x l sinh hc him kh c th hot ng c trong di pH kh rng t 5 9. Tuy nhin pH ti u cho qu trnh trong khong 6,5 8,5. Nhit c vai tr quan trng trong x l sinh hc v nhit quyt nh vn tc ca phn ng oxy ha, cc qu trnh sinh trng v pht trin ca vi sinh vt. Vi a s vi sinh vt, nhit trong cc h thng x l c th bin ng t 16 37oC, nhit ti72

u: 25 30oC. Di y l biu thc th hin nh hng ca nhit ti tc phn ng oxy ha kh sinh hc. RT = R20. QT-20 Vi : RT, R20: Tc phn ng nhit x l v 20oC Q: H s nhit (Q = 1,0 1,04). T : Nhit x l oC b/. Thnh phn v ngun dinh dng. duy tr s pht trin ca vi sinh vt, m bo qu trnh lm sch nc thi cn p ng nhu cu dinh dng ca vi sinh vt. Cc nguyn t nh hng quyt nh ti qu trnh xy ha l C, N v P. Mc nh hng ph thuc nhiu vo bn cht cc cht nhim c trong nc thi. Thc nghim cho thy t l C: N : P ti u l 100: 5 : 1. Thng thng trong nc c cc nguyn t khong v vi lng. Do c trng cng ngh, mt s loi nc thi cng nghip ngho N v P. S thiu ht ny s km hm s pht trin ca mt s vi sinh vt trong qu trnh xy ha. Thiu N v P trong thi gian di l mt trong cc nguyn nhn lm thay i tng tc gia cc nhm vi khun trong bn hot tnh. Cc vi khun dng si pht trin mnh lm cho bn xp. Hin tng ny gi l s phng ln ca bn, khi bn s kh lng, lm tng ch s th tch lng gy kh khn cho qu trnh tch bn b lng th cp. c/. Cc cht c: Cc cht c v c, hu c, nht l cc ion kim loi nng, cc ion halogen c kh nng c ch thm ch v hot h enzim oxy ha kh vi sinh vt. V vy cn phi kim tra v m bo hm lng ca chng khng c vt qu nng gii hn cho php. Di y l nng cho php ca mt s tc nhn trong x l hiu kh. Cc kim loi nng 2mg/l. Phenol v hp cht cha phenol < 140 mg/l Cc mui xyanua < 60mg/l. d/. oxy ho tan. thc hin qu trnh xy ha, vi sinh vt cn O2 di dng oxy ho tan. Trong cc h thng x l him kh, oxy c cung cp lin tc nhm p ng nhu cu oxy cho qu trnh oxy ha. Thiu xy ha tan cng l mt trong nhng nguyn nhn lm phng bn do vi khun dng si pht trin. Vic cung cp O2 cn c tc dng to ra ng nht trong thit b, lm r cc khi bn c kch thc ln, gim cc im cht - trong thit b, nng cao hiu qu lm sch v rt ngn thi gian lu ca nc trong h thng x l. Hiu sut s dng O2 trong thit b x l ph thuc khng ch vo phng thc cp kh, cng sut thit b, p lc nn... m cn ph thuc vo nhit , tnh cht nc thi, t s F/M [vi F: ngun dinh dng (Food) v M: lng sinh khi (Microorganismes)], tc 73

sinh trng, c trng hnh thi v sinh l vi sinh vt. m bo tc oxy ha th oxy ha tan cn t t nht 4mg/l.

e/. T l F/M (Food/Microorganism): - Nu F/M >1, tc l d tha dinh dng nn vi khun sinh trng nhanh, kh t hy v thi gian to nha bo gim dn n kh nng to bng km, nc c v bn kh lng.- Nu F/M 2tC5H7NO2 + (x-10t)CO2 + (y-11t)/2 H2O + E

Trong bn hot tnh:CxHyO2 + NH3 + O2 C5H7NO2 + CO2

bn hot tnh Trong iu kin thiu oxy, s sy ra qu trnh kh nitrit. Oxy c gii phng t nitrit s oxy ho cht hu c v nit s c to thnh.. Theo phng php ny nit s c loi ra khi nc thi. Vi sinh vt NO3 -----------> NO2 + O2 Vi sinh vt Cht hu c + O2 ------------> N2 Qu trnh t oxy ha VSV:

+ CO2

+ H2O

C5H7NO2 + O2 5CO2 + NH3 + 2H2O + E VSV t dng ha nng v c: NH3 + CO2 + O2 TB vsv + NO2NO2- + CO2 + O2 TB vsv + NO3Nc thi cn x l c do chy qua song chn rc (1) nhm loi b cc tp cht ln v rc trc khi cho chy vo b iu ha v lng s cp (2). B iu ha v lng s cp c chc nng tch cn lng trong nc thi sao cho hm lng cn l lng ca nc thi vo b Aeroten (3) phi 80mg/l ng thi iu ha lu lng, pH, cht dinh dng ca nc thi trc khi vo b Aroten. Sau nc thi c chuynvo b Aroten (3), y cc cht nhim c oxy ha bi bn hot tnh. Khng kh c cp lin tc vo b Aroten thng qua h thng phi di y b Aeroten. Nc thi c x l trong b Aroten c ln bn hot tnh chy vo b lng th cp (4). Ti y nc thi sau khi x l c tch bn thot ra phn trn ca b lng (ca thot nc 7) v chy ra ao, h. Bn lng y b lng th cp (4) c bm bn (5) dn vo b x l bn (6) hoc thit b tch bn, cn mt phn c tun hon tr li b Aeroten. *Cc thng s quan trng trong b Aeroten:

Thi gian lu ca nc thi ( n , h)Thi gian lu ca nc thi l i lng biu th thi gian c cp kh trong h thng Aeroten.75

Thi gian lu ca nc thi c tnh theo cng thc di y: n = X (1 Z ).k , h n Vi: Sv, Sr : l hm lng BOD5 ca nc thi v sau x l, mg/l X: Hm lng sinh khi trong b Aeroten, mg/l, g/m3. k: H s oxy ha ca bn hot ha [g/kg sinh khi, h Zo: T l bn khng hot ng, Zo= 0,1 0,3. Ch s th tch lng ca bn: SVI, ml/g Ch s th tch lng ca bn l i lng biu th th tch lng ca 1g bn hot tnh kh. SVI =Vl . 1000, ml/g. X Sv Sr

Vi: X: l lng bn trong b Aeroten, mg/l. VL: dung tch lng ca bn ti sau 30 pht. SVI ti u t 80 150ml/g.

Dung tch hot ng ca b Aeroten: VA, m3 VA c tnh theo cng thc sau: VA = ViQ . n 24

Q: Tng lng nc thi trong 1 ngy m m3/ ngy. n: Thi gian lu ca nc trong b Aeroten, h. Tui ca bn: ( B), ngy

Tui ca bn l i lng biu th thi gian lu ca bn trong h thng Aeroten. Tng lng bn hot tnh trong h thng Aeroten B =_________________________________________________________________

lng bn hot tnh thi ra hng ngy B =V A . X A + VL . X L VT . X T

Vi: VT: Th tch bn thi hng ngy, m3 /ngy. VA: Th tch hot ng ca b Aeroten, m3 VL: Th tch bn lng, m3. XA: Hm lng bn trong b aeroten, mg/l hay kg/m3. XL: Hm lng sinh khi trong bn lng. mg/l hay kg/m3. XT: Hm lng sinh khi trong bn thi, mg/l hay kg/m3. i vi Aeroten thng thng thp th B t 4 16 ngy; Aeroten cao ti B t 0,8 4 ngy.

Ti trng ring: TR

Ti trng ring l i lng biu th kh nng oxy ha (BOD hoc COD) ca mt n v sinh khi trong thi gian 1 ngy. TR: c xc nh theo biu thc sau:76

TR =

SV SR .Df.24 X .V A

Vi: SV, SR: ln lt l hm lng BOD5 trc v sau khi x l, mg/l. X: hm lng sinh khi, mg/l. VA: dung tch hot ng ca b Aeroten, m3 Df: Vn tc dng vo, m3/h. * Phn loi b Aeroten: 1. Phn loi theo nguyn l lm vic: - B Aeroten thng thng. Loi ny c th phn bit thnh: + B Aeroten x l sinh ho khng hon ton. BOD20 ca nc thi x l t 60 80mg/l, tng ng vi thi gian lm thong vo khong 2 gi. Trong b ny ch oxy ho nhng cht hu c d oxy ho, mt phn cht khng ho tan v keo cng c hp th. Loi ny cn c ngn phc hi bn hot tnh. + B Aeroten x l sinh ho hon ton. BOD20 ca nc thi c x l t 15 20 mg/l, thi gian lm thong t 4-8h v khng qu 12h. B Aeroten sc cha cao. x l nc thi c nng nhim bn cao BOD 20 > 500 mg/l. Ti trng trn bn (sc cha) vo khong 400 - 1000mg/gr bn kh khng tro tnh trong ngy m. B Aeroten loi ny thng p dng x l nc thi cng nghip thc phm (sa, tht...). 2. Phn loi theo s cng ngh: Theo cch phn bit ny c Aeroten mt bc v Aeroten hai bc. Loi Aeroten hai bc thng p dng x l nc thi c nng cao. 3. Phn loi theo cu trc dng chy: Ngi ta phn bit ba loi, cn c vo phng php a nc v bn hot tnh vo v ra khi b: B Aeroten - y, b Aeroten - trn v b Aeroten kiu hn hp 4. Phn bit theo phng php lm thong Phn bit theo phng php lm thong c loi: Aeroten lm thong bng bm kh nn, Aeroten lm thong bng my khuy c hc, Aeroten lm thong kt hp. Ngoi ra, cng cn k n loi Aeroten lm thong p lc thp, tc l khng dng bm kh nn m dng qut gi. 4.3.2.3. Phng php hiu kh s dng b lc sinh hc - B Biophin l mt thit b x l sinh hc nc thi trong iu kin nhn

to nh cc vi sinh vt hiu kh.B lc sinh hc (Biophin) l thit b trong cc vi sinh vt sinh trng c nh trn lp mng bm vo mt vt liu lc. Nc thi c ti t trn xung qua vt liu lc, tip xc vi vi sinh vt xy ra qu trnh phn hu hiu kh. Lp vt liu lc rt mng77

song cng c th xy ra song song 2 qu trnh st b mt l qu trnh phn hu ym kh v lp ngoi c phn hu hiu kh c O2. B Biophin l mt thit b x l sinh hc nc thi trong iu kin nhn to nh cc vi sinh vt hiu kh.

Vng Ym kh

Nc thi Vng hiu khCht hu c

Vt liu mMng sinh hc

O2Sn phm cui

CO2

Mng cht lngKhng kh

Qu trnh x l din ra khi cho nc thi ti ln b mt ca b v thm qua lp vt liu lc. b mt ca ht vt liu lc v cc khe h gia chng cc cn bn c gi li v to thnh mng - gi l mng vi sinh. Lng oxy cn thit xy ho cc cht bn hu c thm nhp vo b cng vi nc thi khi ta ti, hoc qua khe h thnh b, hoc qua h thng tiu nc t y i ln. Vi sinh hp th cht hu c v nh c oxy m qu trnh oxy ho c thc hin. Nhng mng vi sinh cht s cng vi nc thi i ra khi b v c gi li b lng t II.

78

4 1 2 3

1. B lc 2. Lp vt liu lc 3. Gi 7 vt liu lc

4. B phn phn phi nc thi 5. B lng Nc sau x l 6. Bm nc thi 7. Bm kh Kk C th phn bit b Biophin theo mt s tiu ch nh sau:

1- Theo mc x 6 l: Biophin x l hon ton v khng hon ton. Biophin5 ton, cn Biophin nh git dng x cao ti c th x l thi hon ton hoc khng hon Nc

l hon ton.

2- Theo bin php lm thong, Biophin lm thong t nhin v Biophin lm thong nhn to. Trong trng hp lm thong nhn to th b Biophin thng gi l Aerophin. 3- Theo ch lm vic: Biophin lm vic lin tc v Biophin lm vic gin on c tun hon v khng tun hon. Nu nng nhim bn ca nc thi ln b Biophin khng cao lm v vi khi lng c th t lm sch th vic tun hon l khng cn thit. Trong trng hp ngc li th tu theo nng ca nc thi m nn hoc bt buc phi tun hon. 4- Theo s cng ngh: B Biophin mt hay hai bc. B Biophin hai bc thng c p dng khi iu kin kh hu khng thun li, khi khng c iu kin tng chiu cao cng tc ca b v khi cn nng cao hiu sut x l. 5- Theo kh nng chuyn ti: Biophin cao ti v Biophin nh git (Biophin thng thng) 6- Theo c im cu to ca vt liu lc: Biophin cht liu khi v Biophin cht liu bn. Biophin cht liu khi c th phn bit nh sau: - Biophin nh git c kch thc vt liu lc 40 - 60mm, v chiu cao cng tc 2 4m. - Biophin cao ti c kch thc vt liu lc 60 - 80mm v chiu cao cng tc 2 - 4m. - Biophin c chiu cao ln (thp lc) c kch thc vt liu lc 60 - 80mm, chiu cao cng tc 8 - 16m. Biophin cht liu bn c th phn bit: - Biophin vi cht liu lc dng rn: vng ng hay nhng cu to khc. Vt liu c th l snh, cht do hay kim loi. Tu thuc vo loi vt liu m khi lng ly trong khong 100 - 600 kg/m3, rng 70 - 90%, chiu cao lm vic 1 - 6m.

B lc sinh hc

B x l bn

79

- Biophin vi vt liu rn dng an li hay khi c c ghp t cc tm hay cc bn phng. Cc khi c c th lm bng cht do v cng c th l fibroximang. Khi lng cht do t 40 - 100kg/m3, rng 90 - 97%, chiu cao 2 - 16m. Khi lng fibroximang 200 - 250kg/m3, rng 80 - 90%, chiu cao lm vic 2 - 6m. - Biophin vt liu mm v rul (cun) lm t li thp, mng cht do hay vi tng hp c c nh trn khung hay di dng cun. Khi lng 5 -60kg/m3, rng 94-99%, chiu cao cp phi 3-8m. i vi Biophin cht liu bn cng cn k n loi a quay sinh hc - l b cha y nc c y hnh lm. Dc theo b ch cao hn mc nc mt t c t trc gn cc a bng cht do, xi mng aming hay kim loi vi ng knh 0,6-0,3m. Khong cch gia cc a 10-20mm, tc quay ca trc a 1-40 v/ph. Biophin cht liu mm v rul thng ch s dng khi lu lng nc thi n 10.000 m3/ng.m, cn Biophin cht liu rn dng khi q < 50.000m3/ng.m, a quay sinh hc q < 500 m3/ng.m. 4.3.2.3. B xyten xyten l cng trnh hiu qu cao, dng x l nc thi bng phng php sinh hc tng cng vi vic s dng xy k thut v bn hot tnh m c. xyten l dng b cha c mt bng hnh trn. Bn trong lm tng (hnh tr) phn chia vng lm thong v vng lng. Ti khong gia tng phn chia c ca s nc bn t vng lm thong trn vo vng lng. Trong khong di tng phn chia lm ca s bn hot tnh tun hon t vng lng sang vng lm thong. Vng lm thong c np y kn, pha trn t ng c in ca thit b lm thong tuc bin v ng dn cp xy k thut. Vng lng c thit b khuy trn bng cc song chn t ng t = 30...50mm, khong cch gia chng l 300mm. Phn di ca song chn treo ci no bnh cu. Phn lng lm vic vi lp bn l lng c ng tho iu chnh mc bn. Nguyn l lm vic ca xyten nh sau: Nc thi dn theo ng trung tm vo vng lm thong. Di tc ng ca p lc ng do tuc bin gy nn m hn hp nc thi v bn hot tnh bo ho xy tro qua ca s lng chng vo vng lng. Do cc song chn hng dng m hn hp nc bn chuyn dch dn theo cho vi ca vng lng, v y bn c tch ra khi 4.3.2.4. Mng xy ho tun hon (MOT) Trong nhng nm gn y MOT c s dng rng ri x l nc thi vi quy m nh. MOT l loi cng trnh x l nc thi bng phng php sinh hc hon ton. Thi gian lm thong ko di t 1-3 ngy. C th dng x l nc thi vi nng80

BOD20 = 1000 - 5000 mg/l v i vi nc thi sinh hot th khng cn qua lng m ch cn cho qua song chn rc vi khe h mt li 8mm. Sc cha tnh theo bn hot tnh vo khong 200gr BOD5/(kg.ng.m). Mt phn bn hot tnh c khong ho ngay trong mng. Khi ti trng bn khong 50gr BOD5/(kg.ng.m) th thc t bn hot tnh c khong ho hon ton. Do s lng bn hot tnh gim khong 2,8 ln, tc l cn khong 30gr cht kh tnh cho mt ngi trong ngy. MOT c hnh dng ch nht hoc hnh trn, y v b thng c gia c, chiu su cng tc t 0,7m n 1m, tc chuyn ng ca nc trong mng khng nh hn 0,3m/s, th tch cng tc khong 0,3m3/ngi, lm thong bng c hc (my khuy trc nm ngang).

B Oxyten

4.3.2.5.

Phng php hiu kh s dng h sinh hc

H sinh hc l h cha khng ln lm, c s dng kt hp x l nc thi bng phng php sinh hc. Thc cht ca qu trnh x l nc thi bng h sinh hc l s81

dng khu h vi sinh vt ( Vi khun,to ) t nhin c trong nc mt lm sch nc. So vi nhng cng trnh sinh hc trong x l nc thi trong iu kin t nhin th h sinh hc c p dng kh rng ri hn c v ngoi chc nng x l nc thi, chng cn mang li nhng li ch khc nh: + Nui trng thu sn. + D tr ngun nc ti tiu cho cy trng. + iu ho vi kh hu trong vng. X l nc thi bng h sinh khng i hi nhiu vn u t do bo tr vn hnh n gin. C th kt hp x l nc thi vi nui trng thu sn v iu ho lu lng nc ma. Theo nguyn tc hat ng ca h c th phn bit ba loi h sau: 1. H hiu kh. 2. H ym kh. 3. H tu tin ( H ym Hiu kh ). 1. H hiu kh: H hiu kh l h m trong cc cht nhim c chuyn ha bng qu trnh oxy ho nh cc vi sinh vt h hp hiu kh. Tu theo phng thc cp kh m ngi ta chia chng thnh hai loi: a/. H lm thong t nhin: xy cung cp cho qu trnh oxy ho ch yu do s khuych tn khng kh qua mt nc v qu trnh quang hp ca cc thu thc vt nh: Rong, To. m bo cho qu trnh oxy ho, th chiu su ca h t 0,6 -1 m, Ti trng BOD khong 250 300 kg/ha.ngy, Thi gian lu ca nc trong h khong 3 12 ngy. Nhm h ny ch thch hp khi kt hp x l nc thi vi nui trng thu sn. b/. H hiu kh lm thong nhn to Ngun xy cung cp cho qu trnh sinh ho ch yu bng cc thit b bm kh hoc khuy c hc. V c cp kh nhn to nn chiu su ca h c th t 2 2,5m. Ti trng BOD5 khong 400 kg/ha.ngy. Thi gian nc lu trong h t 1 3 ngy. Din tch h cn thit m bo thi gian v hiu qu xy ho hu hiu c tnh theo cng thc sau:Q t F = H

,m

2

Trong

Q : Lu lng nc thi cn x l, m3/ng t : Thi gian lu ca nc.82

ngy

H : su ca lp nc trong h, m Thi gian lu ph thuc vo BOD dng vo v nng lc xy ho ca h. Thi gian lu ca nc thi bin ng t 3 12 ngy. 2. H k kh: - c im: Dng lng v phn hy cn lng bng phng php sinh hc t nhin da trn c s sng v hot ng ca vi sinh k kh. Loi h ny thng dng x l nc thi cng nghip c nhim bn ln, cn t dng x l nc thi sinh hot, v n gy mi thi kh chu. H k kh phi t cch xa nh v x nghip thc phm 1,5 2 km. duy tr iu kin k kh v gi m cho h trong ma ng th chiu su h phi ln 2 - 6 m, thng th t 2,5 - 4,5m

- Tnh ton: Cch tnh n gin nht l theo kinh nghim, din tch h kkh bng 10 - 20% din tch h Facultativ. Thi gian lu nc trong ma h 1,5 ngy, trong ma ng 5 ngy. Hiu qu gim BOD vo khong 65 -80% trong ma h v 45 - 65% trong ma ng. Dung tch ph thuc vo hm lng cc cht nhim, thi gian lu ca nc v nhit x l. - c im cu to ca h: + H nn c 2 ngn lm vic d phng khi x bn trong h. H mt bc c din tch t 0,5 7,0 ha. H nhiu bc th din tch mi bc l 2,25 ha. + Ca x nc vo h phi t chm, phi m bo vic phn b cn lng ng u trong h, nu din tch h di 0,5 ha th ch cn mt ming x: nu ln hn th phi b tr thm. + Ca tho nc ra khi h thit k theo kiu thu nc b mt v c tm ngn bn khng thot ra cng vi nc. 3. H hiu k kh (ty nghi): H tu tin cn c gi l h hiu k kh . Phn ln cc ao, h nc ta l nhng h hiu k kh. H tu nghi thng c su trung bnh t 1,5 n 2 m, di tc dng ca khu h sinh vt rt a dng trong nc bao gm: Cc vi khun ym, hiu kh, thu nm, to v nguyn sinh vt. Trong h thng xy ra 4 qu trnh sau: - Qu trnh phn gii ym kh xy ra lp bn y v lp nc su. Cn lng, cc cht hu c kh hoc chm phn hu c chuyn ho ym kh, to ra cc sn phm trung gian ( ru, axit, CO2, , H2 S ). vng ym kh cn xy ra qu trnh kh Nitrat nh mt s vi khun t dng ho nng. - Qu trnh oxy ho hiu kh xy ra lp nc mt. Di tc dng ca vi khun hiu83

kh v h hp tu tin cc sn phm phn gii ym kh nh cc axit hu c, ru s c oxy ho hon ton. Qu trnh quang hp xy ra trn lp nc mt nh to v mt s thc vt h ng: CO2 sinh ra do phn gii ym kh v oxy ho hiu kh c to v mt s thc vt h ng kh bng qu trnh t dng quang nng. Qu trnh ny cn to ra mt lng ng k O2 cung cp cho qu trnh oxy ho hiu kh trn lp nc mt, nht l vo nhng ngy lng bc x mt tri cao. Tuy nhin m bo cn bng sinh thi trong h tu tin th hm lng to khng c vt qu 100 mg/l. Qu trnh tiu th sinh khi: Khi hm lng N v P trong nc thi cn x l cao, to s pht trin mnh gy bng n to. Nu khng c tiu th, sinh khi to s tch lu, t hu gy nhim th cp. Ti lp li cn bng sinh thi nhng h c hin tng bng n to s rt kh khn.

Cc khu vc trong mt ao x l nc thi

* Mt s yu cu khi la chn h hiu ty nghi: T l chiu di, chiu rng h thng ly bng 1:1 hoc 2:1 nhng vng c t gi nn lm h c nhiu ngn,vng c nhiu gi nn lm h c din tch rng.

thc

Hiu qu x l v thi gian nc lu trong h c xc ng theo cng sau:E= St 1 = S a 1 + k t .t

Trong :

E : Hiu sut x l ca cng trnh; % Sa: BOD5 ca nc thi x vo h, mg/l St : BOD5 ca nc sau c x l, mg/l t : Thi gian nc lu trong h, ngy84

t=

S a St kt .St0

kt: H s ph thuc kiu h, nhit , tnh cht ca nc thikt = k 20 .C (T 20 )

i vi nc thi sinh hot 0,5 < K20 < 1 i vi nc thi cng nghip 0,3 < K20 < 2,5 C : Hng s nhit i vi h t nhin C = 1,035 1,074 i vi h tip kh nhn to C = 1,045 0 T : Nhit ca nc trong h, 0 C 4.3.3. X l nc thi bng phng php ym kh 4.3.3.1. c im chung: - Dng vi sinh vt ym kh ln men cc kh, cht nhim. Sn phm cui cng l CH4, H2, mt s cc kh c tnh kh: H2S, RSH, NH3. - Gm 3 giai on: + Giai on thy phn nguyn liu u vo vi khun s dng cc cht dinh dng + Giai on to thnh axit: nguyn liu, cht nhim, vi khun, vi sinh vt ym kh phn hu to axit hu c: CH3COOH, C2H5COOH. + Giai on phn hu axit hu c to metan, CO2 - Cc yu t nh n 3 giai on trn: + Nhit ti u: 350C + Liu lng cht dinh dng c trong bn v mc khy trn + T s C/N tt nht l 25 30/1 + pH ti u: 6,5- 7,5 + nh hng ca dng vi khun, chng loi vi khun, thi gian lu + Khng c cht c i vi vi khun - u im: Sinh t bn thi. * H ym kh - H su, oxy khng n c y, cc vi khun ym kh s phn hu cc cht hu c CO2, CH4 - ng dng ca phng php ym kh: X l cht hu c hm lng cao: Protein, m, khng cha cht c, c cht dinh dng.

- u im ca ym kh so vi hiu kh: Sinh ra t bn, khng cn thy sc kh, nhng phn hu khng trit , cn nhit cao (350C) thng ng dng x l tip. 4.3.3.2. C s l thuyt85

Qu trnh x l ym kh l qu trnh phn gii ym kh cc hp cht hu c, v c c th chuyn ha sinh nh vi khun h hp ym kh v h hp tu tin. Phng php ym kh ch p dng cho nc thi c hm lng BOD v cn l lng cao (BOD >1800mg/l; SS 300 400mg/l). Sn phm phn gii hon ton cc hp cht hu c cha ca qu trnh x l ym kh l kh sinh hc (Biogas), ch yu l CH4 v CO2 c th s dng lm kh t. a/. C ch phn gii ym kh. Qu trnh phn gii ym kh cc hp cht hu c l mt qu trnh phc tp gm nhiu giai on, c th tm tt theo s di y.

Giai on thy phn

Hp cht hu c phn t lng ln (gluxit, protein, lipit...)

Cht hu c phn t lng nh (ng, axit amin, axit bo...)

Giai on ln men

Ln men axit hu c v Cc cht trung tnh

Axit propionic, ru, andehit, axeton

Cc cht kh CO2, H2, NH3, H2S...

Axetic ha

Axit axetic

Decacboxyl ha 8H+ Ln men to metan CH4 + CO2

Kh CO2

S phn gii ym kh gm 4 giai on, trong mi giai on chc nng ca cc nhm khc nhau khng ging nhau. * Giai on 1: Giai on thy phn cc hp cht hu c:86

Cc hp cht hu c phn t lng ln nh protein, gluxit, lipit... b phn hy di tc dng ca cc enzim hydrolaza ca vi sinh vt thnh cc cht hu c phn t lng nh nh ng n gin, axit amin... Trong giai on thy phn, cc hp cht gluxit phn t lng nh c phn hy nhanh; cc hp cht hu c cha Nit c phn hy chm hn, trong khi cc hp cht hu c phn t lng ln nh tinh bt, cc axit bo phn t lng ln c phn hy chm, c bit zecelulo v liguo zenlulo c chuyn ho rt chm v khng trit do cu trc phc tp. Cc vi sinh vt tham gia vo qu trnh thu phn ph thuc vo cc cht nhim vo v cc c trng khc ca nc thi. *Giai on 2: Ln men cc axit hu c. Cc sn phm thu phn s c vi sinh vt hp th v chuyn ho. Trong iu kin ym kh, sn phm phn gii l cc axit hu c phn t lng nh nh axit propionic, axt butyric, axit lactic, cc cht trung tnh nh ru, andehit, axeton. Thnh phn ca cc sn phm trong giai on ln men ph thuc bn cht cc cht nhim, tc nhn sinh hc v iu kin mi trng. Ngoi ra trong giai on ny cc axit amin hnh thnh do thu phn protein cng c kh amin, mt phn gc amin c cc vi sinh vt s dng cho qu trnh sinh trng v pht trin, mt phn c kh. * Giai on 3: Giai on ln men to axit axetic. Cc sn phm ln men phn t lng ln nh axit bo, axit lactic s c chuyn ho n axit axetic. 3CH3 - CHOH- COOH 2CH3 CH2- COOH + CH3 COOH + CO2 + H2O a. Lactic a. Propionic a. Axetic *Giai on 4: Giai on Metan ho y l giai on quan trng nht trong ton b qu trnh x l ym kh thu biogas. Hiu qu x l s cao khi cc sn phm trung gian c kh ha hon ton. Qu trnh hnh thnh kh Metan thng xy ra theo 2 c ch ch yu sau: * S hnh thnh metan do decacboxyl ha: - CH4 c hnh thnh do decaboxyl axit axetic. CH3COOH CH4 + CO2. - CH4 hnh thnh do decacboxyl ha cc axit hu c khc4 CH3 CH2 - COOH 2 CH3 (CH2)2 - COOH2 H2O 2 H2O

7 CH4 + 5 CO2 5 CH4 +3 CO2

-

CH4 cng c th hnh thnh do Decacboxyl cc cht trung tnh:87

2C2H5OH CH3 CO CH3H2O

3CH4 + CO2 2 CH4 + CO2

* S hnh thnh CH4 theo c ch kh CO2: Hydro hnh thnh do qu trnh ln men cc axit hu c, trong iu kin ym kh s c cc vi khun Metanogene s dng nh l cht nhng Hydro kh CO 2. Qu trnh kh c th xy ra di 2 dng: - Kh bng Hydro phn t: CO2 + 4 H2 CH4 + 2H2O- Kh bng phn ng oxy ho kh:8 NADH+ 8 NAD

CO2

CH4 + 2H2O

b/. Tc nhn sinh hc. Trong phn gii ym kh cc qu trnh thy phn v ln men xy ra di tc dng ca nhiu loi vi khun khc nhau. Thnh phn ca khu h sinh vt trong phn gii ym kh ph thuc ch yu vo bn cht ca cc cht c trong nc thi. Vi sinh vt trong giai on thy phn v ln men axit hu c. + Vi khun Bacillus, Pseudomonas, Clostridium c nhiu trong mi trng giu Xenlulo. + Vi khun Micrococus, Lactobacilus, Clostridium... c trong mi trng giu tinh bt. + Vi khun Bacilus, Bacterium coli... c trong mi trng giu protein. + Vi khun Bacteroides, Bacillus... c trong mi trng giu lipit. Vi sinh vt trong giai on ln men to axit axetic. Mt s chng vi khun c hiu qu axetogen. + Syntrophobacter wolonii, Syntro.wolfei v Syntro.buswellii. Vi khun metan ha: gm 2 nhm chnh sau: + Nhm vi khun u m (Mesophyl): gm Methanococcus, Methanobacterium, Methanosarcina pht trin nhit ti u 35 37o v pH = 6,8 8,5. + Nhm vi khun a nng: (Thermophyl): Methanobacillus, Methanothrix, Methano spirllum. Nhit ti u 55 60oC 4.3.3.3. Cc yu t nh hng ti qu trnh phn hy ym kh a/. nh hng ca nhit : L mt trong