Mc lcA.TNG QUAN21.Tng quan v nc22.Phn loi nc23.Cc thng s, ch tiu nh gi cht lng nc sch.33.1Ch tiu l hc33.2Ch tiu ha hc43.3Ch tiu vi sinh7B.CC PHNG PHP X L NC81.PHNG PHP X L L HC (C HC)81.1Phng php lng81.2Phng php lc101.3Phng php phn ring bng mng (membrane)121.4Phng php nhit151.5Phng php x l bng UV152.PHNG PHP HO HC V HA L172.1Phng php x l ho cht gim cng ca nc172.2Phng php trung ha182.3Phng php oxy ha v kh182.4Tch st bng phng php ho hc192.5Phng php kt lng202.6Phng php hp ph212.7Phng php trao i ion222.8c ch vi sinh vt bng ho cht243.PHNG PHP SINH HC25C.TI LIU THAM KHO28

A. TNG QUAN1. Tng quan v ncNc l mt nhu cu khng th thiu c trong cuc sng hng ngy cng nh trong qu trnh sn xut cng nghip. Trong sinh hot, nc dng cho nhu cu n ung, v sinh, cc hot ng gii tr, phun nc ti cy,Trong hot ng sn xut cng nghip, nc cp cho qu trnh lm lnh, sn xut cc loi thc phm hp, nc gii kht, ru, bia,..Tuy nhin, t s gia tng dn s qu mc, bin i kh hu, lm nhanh chng cn kit ngun ti nguyn nc ngt trn hnh tinh. Nc bt u b nhim, nhim phn, nhim nhiu kim loi nh: Fe, Ca, Mg,.gy nh hng xu n sc kho cng nh cc ngnh cng nghip lin quan n nc.Nc trong t nhin th by gi t nhiu cng b nhim bn, khng tp cht ny th cng l tp cht kia. Bt ngun t nguyn nhn trn, c nhiu bin php thc hin x l nc cung cp nc sch phc v cho n ung, sinh hot con ngi cng nh cc ngnh cng nghip ch bin khc c bit l ngnh cng nghip sn xut nc gii kht.Ni n cng nghip sn xut nc gii kht, th nc l mt thnh phn v cng quan trng v nc l nguyn liu chim t l cao nht (>80%). V vy, nc cn phi x l tht sch trc khi em sn xut thnh nc gii kht, nu khng s gy nh hng rt ln n cht lng, cm quan ca sn phm cng nh n sc kho ngi tiu dng.Nc dng trong cng nghip sn xut nc gii kht ch yu l ngun nc mt v ngun nc ngm.Thnh phn ha hc ca nc mt ph thuc vo tnh cht t ai ni m dng nc chy qua n cc thy vc, cht lng nc mt cn chu nh hng bi cc qu trnh t nhin( ma l, hot ng sng v cht i ca h sinh vt nc,) cng nh hot ng ca con ngi. Trn cng mt con sng, cht lng nc thng xuyn thay i ng k theo thi gian v khng gian.2. Phn loi nc+ Nc mtTrong nc thng xuyn c cc cht kh ha tan, ch yu l xy. xy ha tan trong nc c ngha quan trng i vi i sng ca cc thy sinh vt.Nc mt thng c hm lng cht rn l lng ng k vi cc kch thc khc nhau, mt s trong chng c kh nng lng t nhin, cht l lng c kch thc ht keo thng gy ra c ca nc sng, h. C nhiu cht hu c do sinh vt b phn hy C nhiu rong to, thc vt ni, ng vt ni Cht lng nc thay i theo ma B nh hng mnh m bi hot ng hai bn b ca con ngi( cng nghip, nng nghip)+ Nc ngmNgun nc ngm th thm qu nhiu lp ct, ,..nn cc vi sinh vt d dng li trong nc, nn hm lng khong trong nc rt cao t nc c cng cao.nh hng ca cc cht trong nc i vi cht lng v sc kho con ngi.3.Cc thng s, ch tiu nh gi cht lng nc sch.3.1 Ch tiu l hc Nhit Nhit nc l i lng ph thuc vo iu kin mi trng v kh hu.Nhit c nh hng khng nh n cc qu trnh x l nc. Nc mt c nhit thay i theo nhit mi trng. mu mu thng do cc cht bn trong nc to nn: hp cht st, mangan khng ha tan lm nc c mu ; cc cht mn humic gy ra mu vng; nc b nhim bn bi nc sinh hot hay cng nghip thng c mu xanh hoc en.Mu vng ca hp cht st v mangan.Mu xanh ca to, hp cht hu c.Nc c mu cao thng gy kh chu v mt cm quan. Vi cc quy trnh x l nh sc kh Ozone, clo ha s b, keo t, lng lc c th lm gim mu ca nc. Cn lu khi ngun nc c mu do hp cht hu c, vic s dng clo c th to ra cht mi l Trihalomethane c kh nng gy ung th. Tiu chun nc sinh hot quy nh mu ca nc.n v o mu thng dng l theo mu Platin - Coban.Nc thin nhin c mu thp hn 200 . mu biu kin trong nc thng do cc cht l lng trong nc to ra v d dng loi b bng phng php lc. loi b mu thc ca nc (do cc cht ha tan to nn) phi dng cc bin php ha l kt hp. c c l i lng o hm lng cht l lng trong nc, thng do s hin din ca cht keo, st, to v vi sinh vt.Nc c gy kh chu v mt cm quan, ngoi ra cn c kh nng nhim vi sinh.. Cc quy trnh x l nh keo t, lng, lc gp phn lm gim c ca nc.Nc c c ln chng t nc c nhiu cn bn. n v o c thng l mgSiO2/l, NTU, FTU.Nc c thng c c 20-100 NTU. Nc dng n ung thng c c khng vt qu 5 NTU. Hm lng cht rn l lng cng l mt i lng tng quan n c ca nc. Mi vMi trong nc thng do cc hp cht ha hc ch yu l cc hp cht hu c hay sn phm t qu trnh phn hy vt cht gy nn. Nc thin nhin thng c mi t, mi tanh, mi thi. Nc sau khi kh trng thng nhim mi clo hay clophenol. Ty theo thnh phn v hm lng cc mui khong ha tan nc c th c cc v mn, ngt, cht ,ng. nht nht l i lng biu th s ma st ni, sinh ra trong qu trnh dch chuyn gia cc lp cht lng vi nhau. y l yu t chnh gy nn tn tht p lc v do vy n ng vai tr quan trng trong qu trnh x l nc. nht tng khi hm lng cc mui ho tan trong nc tng v gim khi nhit tng. dn inNc c dn in km. Nc tinh khit 200C c dn in l 4,2 S/m (tng ng in tr 23,8M/cm). dn in ca nc tng theo hm lng cc cht khong ho tan trong nc v dao ng theo nhit . Thng s ny thng c dng nh gi tng hm lng cht khong ho tan trong nc. Tnh phng xTnh phng x ca nc l do s phn hu cc cht phng x trong nc to nn. Nc ngm thng nhim cc cht phng x t nhin, cc cht ny c thi gian bn phn hu rt ngn nn nc thng v hi. Tuy nhin khi b nhim bn phng x t nc v khng kh th tnh phng x ca nc c th vt qu gii hn cho php.Hai thng s tng hot phng x v thng c dng xc nh tnh phng x ca nc. Cc ht bao gm 2 proton v 2 ntron c nng lng xuyn thu nh, nhng c th xuyn vo c th sng qua ng h hp hoc tiu ho, gy tc hi cho c th do tnh ion ho mnh. Cc ht c kh nng xuyn thu mnh hn, nhng d b ngn li bi cc lp nc v cng gy tc hi cho c th.3.2 Ch tiu ha hc pH pH l ch s c trng cho nng ion H+ c trong dung dch thng c dng biu th tnh axit v tnh kim ca nc. pH = 7 nc c tnh trung tnh. pH < 7 nc c tnh axit. pH > 7 nc c tnh kim. pH ca nc c lin quan n s hin din ca mt s kim loi v kh ho tan trong nc. pH < 5, tu thuc vo iu kin a cht, trong mt s ngun nc c th cha st, mangan, nhm dng ho tan v mt s loi kh nh CO2, H2S tn ti dng t do trong nc. pH c ng dng kh cc hp cht sunfua v cacbonat c trong nc bng bin php lm thong. Ngoi ra khi tng pH v c thm tc nhn oxy ho, cc kim loi ho tan trong nc chuyn thnh dng kt ta v d dng tch ra khi nc bng bin php lng lc.Ngun nc c pH > 7 thng cha nhiu Ion nhm carbonate v bicarbonate (do chy qua nhiu tng t ). Ngun nc c pH thpc th gy h men rng.Hin nay, cha c bng chng c th no lin quan gia PH v sc khe ca ngi s dng. Theo tiu chun, pH ca nc s dng cho sinh hot l 6.0 - 8.5 v nc ung pH 6.5 - 8.5. Tuy nhin cc loi nc ngt c gas c pH t 2.0 - 4.0. Cc loi thc phm thng c pH 2.9 - 3.3.Gi tr pH ca nc c lin quan n tnh n mn thit b, ng ng dn nc v dng c cha nc. c bit trong mi trng pH thp, kh nng kh trng ca clo s mnh hn. Tuy nhin khi pH > 8.5, nu trong nc c hp cht hu c th vic kh trng bng Clo d to thnh hp cht Trihalomethane gy ung th. kim kim ton phn l tng hm lng ca cc ion hydrocacbonat (HCO3- ), hyroxyl (OH -) v ion mui ca cc axit yu khc. nhit nht nh, kim ph thuc vo pH v hm lng kh CO2 t do c trong nc kim l mt ch tiu quan trng trong cng ngh x l nc. xc nh kim thng dng phng php chun mu nc th bng axit clohydric ( HCl ) hay axit sunfuric (H2SO4) v theo di theo cht ch th mu, u tin l phenolphatalein sau d l metylloran. cng cng ca nc l i lng biu th hm lng cc ion canxi v magi c trong nc. Trong k thut x l nc s dng ba loi khi nim cng: cng ca nc l i lng biu th hm lng cc ion canxi v magi c trong nc. cng ton phn biu th tng hm lng cc ion canxi v magi c trong nc. cng tm thi biu th tng hm lng cc ion Ca2+, Mg2+ trong cc mui cacbonat v hydrocacbonat canxi, hydrocacbonat magi c trong nc. cng vnh cu biu th tng hm lng cc ion Ca2+, Mg2+ trong cc mui axit mnh ca canxi v magie.C nhiu n v o cng khc nhau: c (o dH): 1 o dH = 10 mg CaO/l nc Php (o dH ): 1 o dH = 10 mg CaCO3/0,7 l nc Anh (oe ): 1 oe = 10 mg CaCO3/0,7 l nc ng u ( mgl/ l): 1 mgl/l = 2,8 o dH.Tu theo gi tr cng, nc c phn loi thnh: cng < 50 mg CaCO3/l : nc mm. cng 50 150 mg CaCO3/l : nc trung bnh. cng 150 300 mg CaCO3/l : nc cng. cng > 300 mg CaCO3/l : nc rt cng.Vit Nam dng dn v o d cng l mili dng lng trong 1 lit (mlg/l) khi o cng < 0.001 mlg/l dng micro dng lng gam trong lit mlg/l. i 1 mglg/l =1.8 o dH. oxy ho c bng permanganat oxy ho l mt i lng nh gi s b mc nhim bn ca ngun nc. l lng oxy cn c oxy ho ht cc hp cht hu c trong nc.Cht oxy ha thng dng xc nh ch tiu ny l pecmanganat kali (KMnO4).Trong thc t, ngun nc c oxy ho ln hn 10 mgO2/l c th b nhim bn. Nu trong qu trnh x l c dng clo dng clo t do hay hp cht hypoclorit s to thnh cc hp cht clo hu c [trihalomentan(THM)] c kh nng gy ung th. T chc Y t th gii quy nh mc ti a ca THM trong nc ung l 0,1mg/l. Ngoi ra, nh gi kh nng nhim ngun nc, cn cn nhc thm cc yu t sau y oxy ho trong nc mt, c bit nc c mu c th cao hn nc ngm. Khi ngun nc c hin tng nhum mu do rong to pht trin, hm lng oxy ho tan trong nc s cao nn oxy ho c th thp hn thc t S thay i oxy ho theo dng chy: Nu thay i chm, lng cht hu c c trong ngun nc ch yu l cc axit humic. Nu oxy ho gim nhanh, chng t ngun nhim l do cc dng nc t bn ngoi vo ngun nc. Cn kt hp vi cc ch tiu khc nh hm lng ion clorua, sunfat, photphat, oxy ho tan, cc hp cht nit, hm lng vi sinh vt gy bnh c th nh gi tng qut v mc nhim bn ca ngun nc. Cc hp cht nitQu trnh phn hu cc cht hu c to ra amoniac (NH4+), nitrit (NO2-) v nitrat (NO3-).Do cc hp cht ny thng c xem l nhng cht ch th dng nhn bit mc nhim bn ca ngun nc. Khi mi b nhim bn, ngoi cc ch tiu c gi tr cao nh oxy ho, amoniac, trong nc cn c mt t nitrit v nitrat. Sau mt thi gian NH4+, NO2- b oxy ho thnh NO3- . Phn tch s tng quan gi tr cc i lng ny c th d on mc nhim ngun nc. Vic s dng rng ri cc loi phn bn cng lm cho hm lng nitrat trong nc t nhin tng cao. Ngoi ra do cu trc a tng tng mt s m ly, nc thng nhim nitrat. Nng NO3- cao l mi trng dinh dng tt cho to, rong pht trin, gy nh hng n cht lng nc dng trong sinh hot. Cc hp cht SilicTrong nc thin nhin thng c cc hp cht silic. pH < 8, silic tn ti dng H2SiO3. Khi pH = 8-11, silic chuyn sang HSiO3-. pH > 11, silic tn ti dng HSiO3 v SiO32- .Do vy trong nc ngm, hm lng silic thng khng vt qu 60mg/l, ch c nhng ngun nc c pH > 9,0 hm lng silic i khi cao n 300mg/l. Trong nc cp cho cc ni hi p lc cao, s tn ti ca cc hp cht silic rt nguy him do cn silic ng li trn thnh ni, thnh ng lm gim kh nng truyn nhit v gy tc ng. Trong qu trnh x l nc, silic c th c loi b mt phn khi dng cc ho cht keo t lm trong nc. Clorua Clorua lm cho nc c v mn. Ion ny thm nhp vo nc qua s ho tan cc mui khong hoc b nh hng t qu trnh nhim mn cc tng cha nc ngm hay on sng gn bin. Vic dng nc c hm lng clorua cc mui khong hoc b nh hng t qu trnh nhim mn cc tng cha nc ngm hay on sng gn bin. Vic dng nc c hm lng clorua cao c th gy ra bnh v thn. Ngoi ra, nc cha nhiu clorua c tnh xm thc i vi b tng. SunfatIon sunfat thng c trong nc c ngun gc khong cht hoc ngun gc hu c. Vi hm lng sunfat cao hn 400mg/l, c th gy mt nc trong c th. FloruaNc ngm t cc vng t cha qung apatit, alkalic, granit thng c hm lng florua cao n 10mg/l. Trong nc thin nhin, cc hp cht ca florua kh bn vng v kh loi b trong qu trnh x l thng thng Hp cht stTrong nc ngm, st thng tn ti di dng ion Fe2+, kt hp vi cc gc bicacbonat, sunfat, clorua i khi tn ti di keo ca axit humic hoc keo silic. Khi tip xc vi oxy hoc cc tc nhn oxy ho, ion Fe2+ b oxy ha thnh ion Fe2+ v kt hp ta thnh cc bng cn Fe(OH)3 c mu nu .Nc mt thng cha st (Fe3+), tn ti dng keo hu c hoc cn huyn ph. Trong nc thin nhin, ch yu l nc ngm, c th cha st vi hm lng n 40 mg/l hoc cao hn. Vi hm lng st cao hn 0,5mg/l, nc c mi tanh. Cc cn st kt ta c th lm tc hoc gim kh nng vn chuyn ca cc ng dn nc. Cc hp cht mangan.Cng nh st, mangan thng c trong nc ngm di dng ion Mn2+ nhng vi hm lng tng i thp, t khi vt qu 5mg/l. Tuy nhin, vi hm lng mangan trong nc ln hn 0,1mg/l s gy nguy hi trong vic s dng, ging nh trng hp nc cha st vi hm lng cao. NhmVo ma ma, nhng vng t phn, t trong iu kin kh khng c oxy, nn cc cht nh Fe2O3 v jarosite tc ng qua li, ly oxy ca nhau vo to thnh st, nhm sunfat ho tan vo nc. Do , nc mt vng ny thng rt chua, pH = 2,5 4,5, st tn ti ch yu l Fe2+(c khi cao n 300mg/l), nhm ho tan dng ion Al3+ ( 5 7mg/l). Khi cha nhiu nhm ho tan, nc thng c mu trong xanh v v rt chua. Nhm c c tnh i vi sc kho con ngi. Kh ho tanCc loi kh ho tan thng thy trong nc thin nhin l kh cacbonic (CO2), kh oxy (O2) v sunfua huyro (H2S). Nc ngm khng c oxy. Khi pH < 5,5 trong nc ngm thng cha nhiu kh CO2. y l kh c tnh n mn kim loi v ngn cn vic tng pH ca nc. Cc bin php lm thong c th ui kh CO2, ng thi thu nhn oxy h tr cho cc qu trnh kh st v mangan.Ngoi ra, trong nc ngm c th cha kh H2S c hm lng n vi chc mg/l. y l sn phm ca qu trnh phn hu k kh cc cht hu c c trong nc. Trong nc mt, cc hp cht sunfua thng c oxy ho thnh dng sunfat. Do vy, s c mt ca kh H2S trong cc ngun nc mt, chng t ngun nc b nhim bn v c qu tha cht hu c cha phn hu, tch t y cc vc nc. Khi pH tng, H2S chuyn sang cc dng khc l HS- v S-. Thy ngn (Hg):c bit c hi l methyl thy ngn. Thy ngn d bay hi nhit thng nu ht phi s rt c n h thn kinh, h tiu ha, phi, thn c th gy t vong. Tr em khi b ng c s b co git, phn lit Hm lng thy ngn cho php trong nc ung ng chai l 6g/L (QCVN 6-1:2010/BYT), trong nc ngm l 1g/L (QCVN 09:2008/BTNMT). Ch (Pb):Cc hp cht ch hu c rt bn vng c hi i vi con ngi, c th dn n cht ngi. Nhng biu hin ca ng c ch cp tnh nh nhc u, d b kch thch, v nhiu biu hin khc nhau lin quan n h thn kinh. Khi b nhim c lu di i vi con ngi c th b gim tr nh, gim kh nng hiu, gim ch s IQ, thiu mu, ch cng c bit l tc nhn gy ung th phi, d dy v u thn kinh m. Nhim c ch c th gy tc hi i vi kh nng sinh sn, gy sy thai Hm lng cho php trong nc ung ng chai l 10g/L (QCVN 6-1:2010/BYT), trong nc ngm l 10g/L (QCVN 09:2008/BTNMT). Crm (Cr):Tn ti 2 dng ha tr 3 v 6 tuy nhin ha tr 6 crm gy nh hng xu n con ngi. Gy lot d dy, rut non, vim gan, vim thn , ung th phi Hm lng cho php trong nc ung ng chai l 50g/L (QCVN 6-1:2010/BYT) , trong nc ngm l 50g/L (QCVN 09:2008/BTNMT). Caimi (Cd):Caimi c bit gy tn hi i thn v xng liu lng cao, gy xng au nhc tr nn gin v d gy Hm lng cho php trong nc ung ng chai l 3g/L (QCVN 6-1:2010/BYT), trong nc ngm l 5g/L (QCVN 09:2008/BTNMT). Nhm (Al)Nhm l thnh phn chnh trong cc loi khong, t st. Nhm c dng trong cc nghnh cng nghip sn xut bn dn, thuc nhum, sn v c bit l ha cht keo t trong x l nc. Nc khai thc t vng t nhim phn thng c pH thp v hm lng nhm cao. Theo nghin cu, nhm sunfat Al2(SO4)3s lm tr tu km pht trin. St (Fe)Do Ion st 2 (Fe2+) d b oxy ha thnh hydroxit st 3 (Fe(OH)3), t kt ta v lng nn st t tn ti trong ngun nc mt. i vi nc ngm trong iu kin thiu kh, st thng tn ti dng ion Fe2+v ha tan trong nc. Khi c lm thong, st 2 (Fe2+) s chuyn ha thnh st 3 (Fe3+), xut hin kt ta hydroxit st 3(Fe(OH)3)c mu vng, d lng. Trong trng hp ngun nc c nhiu cht hu c, st c th tn ti dng keo (phc hu c) rt kh x l. Ngoi ra, khi nc c PH thp s gy hin tng n mn ng ng v dng c cha, lm tng hm lng st trong nc.St khng gy c hi nhiu cho c th. Khi hm lng st cao s gy nn cc bnh vim ng rut, d dy, tiu chy ng thi nc c v tanh, mu vng, c v mu tng nn kh s dng. Tiu chun nc ung v nc sch u quy nh hm lng st nh hn 0.5mg/L.

Mangan (Mn)Mangan thng tn ti trong nc cng vi st nhng vi hm lng t hn. Khi trong nc c mangan thng to lp cn mu en ng bm vo thnh v y bn cha.Mangan c c tnh rt thp v khng gy ung th. hm lng cao hn 0,15mg/l c th to ra v kh chu, lm hoen qun o. Tiu chun nc ung v nc sch u quy nh hm lng mangan nh hn 0,5mg/l. ng (Cu)ng hin din trong nc do hin tng n mn trn ng ng v cc dng c thit b lm bng ng hoc ng thau. Cc loi ha cht dit to c s dng rng ri trn ao h cng lm tng hm lng ng trong ngun nc. Nc thi t nh my luyn kim, xi m, thuc da, sn xut thuc tr su, dit c hay phim nh cng gp phn lm tng lng ng trong ngun nc.ng khng tch ly trong c th nhiu n mc gy c nhng vi hm lng oxit ng cng gy i ma, n n, vim thn, suy gim chc nng. hm lng 1-2mg/l lm cho nc c v kh chu, v khng th ung c khi nng cao 5 - 8mg/l. Tiu chun nc ung v nc sch u quy nh hm lng ng nh hn 2mg/l. Km (Zn)Km t khi c trong nc, ngoi tr nhim t ngun nc thi ca cc khu khai thc qung. Cha pht hin km gy c cho c th ngi, nhng hm lng > 5mg/l lm cho nc c mu trng sa. Tiu chun nc ung v nc sch u quy nh hm lng km < 3mg/l. Niken (Ni)Niken t khi hin din trong nc, ngoi tr b nhim t ngun nc thi ca ngnh in t, gm s, c quy, sn xut thp.Niken c c tnh thp v khng tch ly trong cc m. Tiu chun nc ung v nc sch u quy nh hm lng niken < 0,02 mg/l. AMONI (NH3)- NITRIT(NO2-)- NITRATE (NO3-)Cc dng thng gp trong nc ca hp cht nit l amoni, nitrit, nitrat. Kt qu ca qu trnh phn hy cc cht hu c do nhim t nc thi. Trong , amoni l cht gy c nhiu nht cho c v cc loi thy sinh. Nitrit c hnh thnh t phn ng phn hy nito hu c v amoni v vi s tham gia ca vi khun. Sau nitrit s c oxy ha thnh nitrat. Ngoi ra, nitrat cn c mt trong ngun nc l do nc thi cc nghnh ha cht, t ng rung c s dng phn ha hc, nc r bi rc, nc ma chy trn. S c mt hp cht nito trong thnh phn ha hc ca nc cho thy du hiu nhim ngun nc.Tiu chun nc sch quy nh amoni < 3mg/l. Tiu chun nc ung quy nh amoni < 1,5mg/l.Tiu chun nc sch v nc ung u quy nh nitrit < 3mg/l.Tiu chun nc sch v nc ung u quy nh nitrat < 50mg/l.

XYANUAXyanua c mt trong ngun nc do nhim t cc loi nc thi nghnh nha, xi m, luyn kim, ha cht, si tng hp.Xyanua rt c, thng tn cng cc c quan nh phi, da, ng tiu ha. Tiu chun nc ung v nc sch u quy nh hm lng xyanua 0 mg/l. COLIFORMVi khun Coliform (ph bin l Eschrichia Coli) thng c trong h tiu ha ca ngi. S pht hin vi khun Coli cho thy ngun nc c du hiu nhim. Tiu chun nc ung v nc sch u quy nh hm lng E.coliform = 0. Ring Coliform tng trong nc sch c cho php 50 vi khun/100ml.Vi khun Coliform gy ra cc bnh vim ng rut, tiu chy, vv...3.3 Ch tiu vi sinh Vi khunVi khun thng dng n bo. T bo c cu trc n gin sao vi cc sinh vt khc. Vi khun trong nc ung c th gy nn cc bnh ng rut. VirutVirut khng c h thng trao i cht nn khng sng c lp c.Virut trong nc c th gy bnh vim gan vim ng rut. Nguyn sinh ng vtNguyn sinh ng vt l nhng c th n bo chuyn ng c trong nc. Ch nht l Giardia lamblia gy bnh giardiase. ToTo dn bo thuc loi quang t dng.Chng tng hp cc cht cn cho c th t cht v c n gin nh nh sng mt tri. To khng trc tip gy bnh cho ngi nhng sn sinh c t.

B. CC PHNG PHP X L NCC rt nhiu phng php x l nc c ra i, tu theo ngun nc v mc ch s dng m c cc bin php cng nh thit b khc nhau.Nc ni chung c cha nhiu cht nhim khc nhau, i hi phi x l bng nhng phng php thch hp khc nhau. Sau y l tng quan cc phng php x l nc .Cc phng php x l c chia thnh cc loi sau: + Phng php x l l hc; + Phng php x l ha hc v ha l; + Phng php sinh hc;1. PHNG PHP X L L HC (C HC)1.1 Phng php lngNgun nc u vo nu c cha mt s tp cht khng tan c th c xem nh l mt h huyn ph. Ta c th tch cc cu t thuc pha rn ra khi pha lng (pha lin tc) bng phng php lng.Lng l mt phng php phn ring da trn vo s khc nhau v khi lng ring ca cc cu t trong h huyn ph. ng lc ca qu trnh phn ring c th l trng lc, lc ly tm hoc lc tnh in. Tuy nhin trong cng nghip sn xut nc ung ngi ta thng s dng trng lc lm ng lc cho qu trnh lng. B lng ngNguyn l hot ngTrong b lng ng nc chuyn ng theo phng thng ng t di ln trn, cn cc ht ri ngc chiu vi chiu chuyn ng ca dng nc t trn xung. Khi x l nc khng dng cht keo t, cc ht cn c tc ri ln hn tc dng ca dng nc s lng xung c. Cn cc ht c tc ri nh hn hoc bng tc dng ca dng nc s ch l lng hoc b cun theo dng nc ln pha trn b. Khi s dng nc c cht keo t, tc l trong nc cha cc ht kt dnh, th ngoi cc ht cn c tc ri ban u ln hn tc ri ca dng nc lng xung c, cn cc ht cn khc cng lng xung c. Tuy nhin hiu qu trong lng ng khng ch ph thuc vo cht keo t, m cn ph thuc vo s phn b u ca dng nc i ln v chiu cao vng lng phi ln thi cc ht cn mi kt dnh vi nhau c.

Hnh 1: B lng ngB lng lp mng c cu to ging nh b lng ngang thng thng, nhng khc vi b lng ngang l trong vng lng ca b lng lp mng c t thm cc bn vch ngn bng thp khng g hoc bng nha. Cc bn vch ngn ny nghing mt gc 450 600 so vi mt phng nm ngang v song song vi nhau. Do c cu to thm cc bn vch ngn nghing, nn b lng lp mng c hiu sut cao hn so vi b lng ngang. Din tch b lng lp mng gim 5,26 ln so vi b lng ngang thun ty. B lng trong c lp cn l lng c u im l khng cn xy dng b phn ng, bi v qu trnh phn ng v to bng kt ta xy ra trong iu kin keo t tip xc, ngay trong lp cn l lng ca b lng. Hiu qu x l cao hn cc b lng khc v tn t din tch xy dng hn. Tuy nhin, b lng trong c cu to phc tp, k thut vn hnh cao. Vn tc nc i t di ln vng lng nh hn hoc bng 0,85 mm/s v thi gian lu nc khong 1,5 2 gi.

B lng ngangNguyn l hot ngNc vo h thng phn phi cc ht cn ln lng xung, nc s i qua vch hng dng ngn chuyn ng ri ca nc vo vng lng ti y cc ht cn nh s lng xung t t. Nc trn b mt l nc sch s c thu li qua ng thu nc b mt

Hnh 2: B lng ngang B lng ly tmNguyn l hot ngNc cn x l theo ng trung tm vo gia ngn phn phi, ri c phn phi vo vng lng. Trong vng lng nc chuyn ng chm dn t tm b ra ngoi. y cn c lng xung y nc trong th c thu vo mng vng v theo ng ng sang b lc. thu bn c thit b gt gm dm chuyn ng theo ray vng trn dm reo gin co bng thp c cc bn gt pha di. nh nhng bn gt ny, cn lng y c dn vo phu v x ra ngoi theo ng cn

Hnh 3: B lng ly tm1.2 Phng php lc tch cc cu t khng tan ra khi nc, chng ta c th s dng phng php lc ngoi phng php lng. Khi cho mt huyn ph i qua mt mng lc, cc cu t rn khng tan s b gi li, pha lin tc s chui qua mng lc v to nn dch lc.Sau mt thi gian lm vic, mng lc b cht li, lm tng tn tht p lc, tc lc gim dn. khi phc li kh nng lm vic ca b lc, phi thi ra b lc bng nc hoc gi, nc kt hp loi b cn bn ra khi lp vt liu lc. Tc lc l lng nc c lc qua mt n v din tch b mt ca b lc trong mt n v thi gian (m/h). Chu k lc l khong thi gian gia hai ln ra b lc T (h)C 2 phng php lc: lc b mt v lc b su.+ Trong phng php lc b mt: cc cu t rn c kch thc ln hn ng knh mao qun ca mng lc s b gi li trn mng v to nn lp b lc. Chiu cao ca lp b lc s tang theo thi gian v lm cho tr lc ca lp b lc tang theo.+ Trong phng php lc b su: cc cu t khng tan ca dung dch huyn ph c kch thc ln hn ng knh mao qun ca mng lc. Chng s khch tn vo bn trong cc mao qun ca mng v b lc c hnh thnh trong cc mao qun.Trong cng ngh sn xut nc gii kht, ty vo cht lng ca ngun nc u vo m ngi ta c th s dng phng php lc b mt hay lc b su.

Trong cc h thng x l nc cng sut ln khng cn s dng cc thit b lc p sut cao m dng cc b lc vi vt liu lc dng ht. Vt liu lc c th s dng l ct thch anh, than cc, hoc si nghin, thm ch c than nu hoc than g. Vic la chn vt liu lc ty thuc vo loi nc v iu kin a phng. Qu trnh lc xy ra theo nhng c ch sau: Sng lc tch cc ht rn hon ton bng nguyn l c hc; Lng trng lc; Gi ht rn theo qun tnh; Hp ph ha hc; Hp ph vt l; Qu trnh dnh bm; Qu trnh lng to bngThit b lc vi lp ht c th c phn loi thnh thit b lc chm, thit b lc nhanh, thit b lc h v thit b lc kn. Chiu cao lp vt liu lc trong thit b lc h dao ng trong khong 1-2 m v trong thit b lc kn t 0,5 1 m.Phng php mng lcPhng php mng lc thm thu ngc RO (Reverse Osmosis): L mt trong nhng phng php mng lc thng dng nht. Phng php RO l mt h thng p lc nn thng c bit tiu hao nng lng hn bt c phng php mng lc no do phi d dng in nng v c nng duy tr p lc cn thit trong h thng. Do c p lc trong h thng nn cc l xp trn mng lc c th c kch thc nh hn cc loi mng lc khc cho php loi b phn ln cc cht bn c trong nc.Mng lc thm thu ngc (mng RO) c lm bng Cellulose acetate, polyamide hoc mng TFC c l lc siu nh ( 0,001m).Nguyn l hot ng ca phng php lc thm thu ngc: s dng p lc ln dng nc vt qua mng thm thu. Ti y cc mui ha tan c gi li v loi b khi dng nc.Lc thm thu ngc l phng php hu hiu gip loi b cc ion v cc mui ha tan c trong nc. Tuy nhin, y l phng php t tin do i hi phi tiu tn nng lng duy tr p lc bn trong h thng.

Hnh4:My lc nc RO - quy m h gia nh

Cc phng php mng lc khc nh lc nano (NF - nanofiltration), siu lc (UF - ultrafiltration), siu vi lc (MF - microfiltration) v thm tch in (ED - electrodialysis).

1.3 Phng php phn ring bng mng (membrane)Phn ring bng mng (membrane) l mt phng php mi ng dng trong cng nghip sn xut nc gii kht. Ngy nay nhiu nh my thc phm s dng membrane x l nc cng nghip trc khi a vo nh my sn xut.Ngi ta chia membrane thnh 4 loi ch yu: vi lc (microfiltration), siu lc (ultrafiltration), lc nano (nanofiltration), thm thu ngc (reverseosmosis) da theo kch thc mao qun.Membrane c kch thc nh nn d b tc nghn trong qu trnh x l nc. khc phc hin tng ny, ngun nc ti cc nh my phi c x l s b bng cc phng php khc tch bt tp cht th trc khi em qua x l bng membrane.

Bng so snh gia cc loi mng

Vi lcMc ch: l tch cc t bo vi sinh vt. ng knh ca mao qun ca membrane vi lc dao ng trong khong t 0,1m n 0,5m.Vi kch thc ny membrane vi lc c th gi li cc t bo vi khun, nm men v nm mc trn b mt membrane, ngoi tr cc virus c th chui qua membrane vi lc. Nu so snh vi cc phng php x l vi sinh khc th phng php vi lc th s to ra ngun nc t cht lng vi sinh vt rt tt v m bo an ton cho ngi s dng.n nay, phng php vi lc c p dng rng ri trong cc quy trnh x l nc ung ca quy m ln. Cu hnh thit b membrane dng si rng (hollow fibre) c s dng ph bin nht. Kch thc mao qun membrane thng l 0,1m hoc 0,2m. hn ch hin tng tch nghn mao qun membrane trong qu trnh s dng ngi ta thng s dng kh nn (p sut 90 100Psi) thi ngc nh k, kt hp vi qu trnh ra ngc (backwash) nhm tch b cc cu t bm trn b mt ca membrane. Ngoi ra, sau mi 4 6 tun s dng, ngi ta s dng ha cht v sinh membrane, ng thi c ch vi sinh vt bm trn membrane. Siu lcS dng membrane vi kch thc mao qun xp x 0,01m hoc thp hn cho cc vi sinh vt c kch thc nh nht nh virus cng s c loi b.Ngoi ra, phng php siu lc c th tch c mt s i phn t ra khi nc, ng ch nht l pyrogen. Hu ht cc pyrogen l lipolysaccharide c ngun gc t thnh t bo vi khun. Phn t lng ca chng c th xp x 20.000Da. Chng khng b bin i trong qu trnh x l nhit. Vic tch pyrogen ra khi nc bng phng php siu lc s m bo s an ton ca ngun nc cho ngi s dng.Ngy nay, thit b siu lc nc dng si rng ang c p dng ph bin trong thc tin sn xut.

H thng siu lc

Lc nanoPhng php lc nano c th loi b c cc mui ha tan ra khi nc, do s lm gim cng ca nc cn x l. Hm lng mui trong dng permeate s gim i 50 70% so vi nc nguyn liu, ring hm lng cc mui ha tr II gim n 95%. Hin nay, nhiu nc trn th gii s dng phng php lc nano x l nc cng v tch cc mui ha tan.Hu ht cc nh my x l nc s dng thit b nano vi cu hnh dng si rng, kch thc mao qun c th dao ng t 200 300Da n 400 600Da.

H thng lc nano

Thm thu ngcPhng php thm thu ngc ch cho dung mi (nc) i qua membrane v to nn dng permeate, ton b cu t tan v khng tan s b gi li trn b mt membrane v to nn dng retentate.Nu hiu qu phn ring trong phng php thm thu ngc l tuyt i th sn phm thu c dng permeate l nc khng b ln bt k tp cht no khc (nc tinh khit). Trong cc phng th nghim hin nay, ngi ta s dng phng php thm thu ngc thu nhn nc tinh khit, t ng dng trong phn tch nh lng i hi chnh xc cao.

H thng thm thu ngc s dng kh mui trong nc ung.1.4 Phng php nhitCc mui bicarbonate calcium v magnesium to nn cng tm thi cho nc. Di tc dng ca nhit, chng s b phn hy, chuyn sang dng kt ta v c th c tch b nh qu trnh lng hoc lc.i vi mui bicarbonate calcium, qu trnh un nng c th phn hy mui to thnh carbonate calcium khng tan trong nc, kh carbon dioxide v nc. Ca(HCO3)2 = CaCO3 + CO2 + H2Oi vi mui bicarbonate magnesium, s phn hy ch xy ra khi un si nc trong khong mt thi gian di, sn phm to ra l magnesium hydroxide v kh carbon dioxide, magnesium hydroxide c ha tan km. Mg(HCO3)2 = Mg(OH)2 + 2CO2Cn lu l phn ng phn hy mui bicarbonate magnesium xy ra chm v khng hon ton. Trong thc t, thi gian x l nhit s c xc nh bng phng php thc nghim ty theo hm lng cc mui bicarbonate c trong nc. Ngoi chc nng tch cc mui bicarbonate, phng php nhit cng c tc dng c ch hoc tiu dit mt s loi vi sinh vt c trong nc.Nhn chung phng php x l nhit tiu tn kh l nhiu nng lng. v vy phng php x l nhit ny t c s dng trong cng nghip sn xut nc gii kht.1.5 Phng php x l bng UVTia UV (Ultra- Violet) c kh nng c ch v tiu dit vi sinh vt. Kh nng tit trng l cao nht khi bc sng dao ng trong khong 260- 270nm. Hin nay, ngi ta s sng tia UV kh trng nc trong sn xut nc gii kht.Mt vn lu l tia UV c m xuyn rt km. Do tng cng kh nng kh trng ca tia UV, ngi ta thit k h thng chy mng v ngun nc cn x l phi trong sut. S c mt ca cc cu t rn khng tan hoc cc cht mu trong nc s lm gim i ng k v kh nng c ch v tiu dit vi sinh vt ca tia UV .C ch hot ng ca tia UV ln t bo vi sinh vt c th c gii thch nh sau: u tin, cc electron s b nh hng, chng s thay i qu o chuyn ng trong m my in t ca nguyn t hoc b bn ra khi cu trc ca nguyn t. Khi , nguyn t s b kch thch hoc ion ho. Nhng bin i ni trn cp nguyn t s lm nh hng n cc i phn t nh acid nucleic hoc protein trong t bo vi sinh vt. Nhng i phn t ny c th b phn hu hoc bin tnh. Tu theo mc bin i ca i phn t m t bo vi sinh vt c th b c ch hay tiu dit. Trong mt s trng hp c th lm xut hin mt s t bo b t bin di tc dng x l ca tia UV.

1.Ca vo ca ngun nc cn x l.2.Thn thit b3.Hp thu tinh cha n UV4.n UV5.Ca ra tho nc x l

S nguyn l thit b x l nc bng tia UV

Thit b x l nc bng tia UVTrong qu trnh x l nc, cc thng s cng ngh cn quan tm l cng sut hot ng ca n UV, dy ca lp nc chy qua thit b v thi gian tip xc ca nc vi tia UV. Tu theo cht lng vi sinh ca ngun nc cn x l m thng s cng ngh s thay i v c xc nh bng phng php thc nghim. Nu chng ta lc chn cc thng s cng ngh khng ph hp th hiu qu c ch vi sinh vt ca tia UV l khng ng k.

2. PHNG PHP HO HC V HA L2.1 Phng php x l ho cht gim cng ca nc chuyn cc mui calcium v magnesium t dng ho tan trong nc ;sang dng kt ta, ngi ta s dng calcium hydroxide v sodium carbonate. Calsium hydroxide tc dng vi mui bicarbonate calcium v magnesium s lm gim cng tm thi ca nc. Phng trnh phn ng nh sau:Ca(HCO3)2 + Ca(OH)2 = 2CaCO3 + 2H2OMg(HCO3)2 + Ca(OH)2 = MgCO3 + CaCO3 + H2OMgCO3 +Ca(OH)2 = Mg(OH)2 +CaCO3 Ngoi ra, calcium hydroxide cng c th phn ng vi mt s loi mui ho tan khc ca magnesium v lm gim cng vnh cu ca nc.MgCl2 + Ca(OH)2 = Mg(OH)2 + CaCl2MgSO4 + Ca(OH)2 =Mg(OH)2 + CaSO4Cc phn ng trn s tch c Mg2+ ra khi nc. Tuy nhin nng Ca2+ trong nc s gia tng. tch chng ta cn s dng sodium carbonate (sodium carbonate).Sodium carbonate tc dng vi cc mui ho tan ca calcium di dng chloride, sulphate v lm gim cng vnh cu ca nc.CaCl2 + Na2CO3 = CaCO3 + 2NaClHm lng calcium hydroxide v sodium carbonate cn s dng s ph thuc vo nng ca cc mui calcium v magnesium c trong ngun nc cn x l. Bit c nng ca cc mui calcium v magnesium c trong nc, ta s tnh c lng ho cht cn s dng.Trong thc t, qu trnh lm gim cng ca nc bng phng php s dng ho cht s chia lm hai giai on. u tin l x l nc vi calcium hydroxide, sau n x l vi sodium carbonate.

Qu trnh lm gim cng ca ncCc ho cht b sung vo thit b x l nc di dng dung dch. Cc thit b phn ng phi c cnh khuy hot ng phn b u dung dch ho cht trong nc. Trong trng hp s dng b phn ng c th tch ln, ngi ta thay cnh khuy bng cch sc khng kh vo b thng qua h thng dn kh thng c b tr trn y hoc b bm tun hon mt phn nc trong b o trn.

2.2 Phng php trung haTrung ha nc c thc hin bng nhiu cch khc nhau Trn ln nc vi axit hoc kim. B sung cc tc nhn ha hc. Lc nc axit quavt liu lcc tc dng trung ha. Hp th kh axit bng cht kim hoc hp th amonic bng nc axit.Trong qu trnh trung ha mt lng bn cn c to thnh. Lng bn ny ph thuc vo nng v thnh phn ca nc cng nh loi v lng cc tc nhn x dng cho qu trnh.2.3 Phng php oxy ha v kh lm sch nc c th dng cc cht oxy ha nh Clo dng kh v ha lng, dioxyt clo, clorat canxi, hypoclorit canxi v natri, pemanganat kali, bicromat kali, oxy khng kh, ozon...Trong qu trnh oxy ha, cc cht c hi trong nc c chuyn thnh cc cht t c hn v tch ra khi nc. Qu trnh ny tiu tn mt lng ln tc nhn ha hc, do qu trnh oxy ha hc ch c dng trong nhng trng hp khi cc tp cht gy nhim bn trong nc khng th tch bng nhng phng php khc.Oxy ha bng CloClo v cc cht c cha clo hot tnh l cht oxy ha thng dng nht. Ngi ta s dng chng tch H2S, hydrosunfit, cc hp cht cha metylsunfit, phenol, xyanua ra khi nc.Khi clo tc dng vi nc xy ra phn ngCl2 + H2O = HOCl + HClHOCl H+ + OCl-Tng clo, HOCl v OCl- c gi l clo t do hay clo hot tnh.Cc ngun cung cp clo hot tnh cn c clorat canxi (CaOCl2), hypoclorit, clorat, dioxyt clo, clorat canxi c nhn theo phn ngCa(OH)2 + Cl2 = CaOCl2 + H2OLng clo hot tnh cn thit cho mt n v th tch nc l: 10 g/m3 i vi nc sau x l c hc, 5 g/m3 sau x l sinh hc hon ton.Ozone (O3)Thi gian gn y, ti nhiu c s x l nc, ngi ta s dng ozone nh l mt tc nhn tiu dit vi sinh vt. Trong nc, ozone khng bn v s b phn gii to thnh oxygen phn t v oxygen nguyn t. Oxygen nguyn t c kh nng oxy ho rt mnh, tui th rt ngn ch vi mili giy trong iu kin thng.O3=O2+OKh ozne khng c mu nhng c mi hi tanh ging nh hin tng sau khi c st. Kh nng tiu dit vi sinh vt ca ozone ph thuc vo loi vi sinh vt, trng thi sinh l ca t bo, nng ozone trong nc, thi gian x l v mt s yu t khc.Ngoi chc nng c ch hoc tiu dit vi sinh vt th ozone c th phn ng vi mt s tp cht c trong nc, c bit l cc cht mu. Nc qua x l ozone s ci thin c mu v trong.Ozone c to ra bng cch m phng qu trnh to sm st trong t nhin. Ngi ta sn xut bng cch cho mt dng khng kh sch ( tch bi, vi sinh vt, m,) i qua gia hai in cc c t di mt in p xoay chiu. Khi , mt s phn t oxygen trong khng kh s c chuyn ho thnh ozone. Dng khng kh c cha ozone s theo ng ng thot ra ngoi v c sc vo b nc cn x l.

Hnh5:My Ozone

2.4 Tch st bng phng php ho hcTrong ngun nc thin nhin, st thng tn ti di dng mui ho tr II, ph bin nht l mui bicarbonate. Vic tch st trong qu trnh st trong qu trnh x l nc l rt quan trng. Vi hm lng st t 0,5mg/l tr ln, nc s c mi tanh.Ngoi ra, cc cn st bm trong h thng ng ng dn nc s lm gim lu lng dng chy v lu ngy c th tt nghn ng ng. tch st ra khi ngun nc, ngi ta thng dng phng php chuyn ho Fe2+ thnh Fe3+ trong iu kin c Oxygen:4Fe(HCO3)2 + 2H2O + O2 = 4Fe(OH)3 +8CO2Phn ng s to thnh Fe(OH)3 l kt ta c mu nu dng cn bng. Tip theo ngi ta s dng qu trnh lng hoc lc tch kt ta ra khi nc.Hin nay, thc hin qu trnh tch st, cc nh sn xut c th dng nhiu dng thit b khc nhau. Nguyn l hot ng chung ca cc thit b l nc s c phun thnh dng tia tng din tch b mt tip xc ca nc trong mi trng c thi khng kh lin tc cung cp oxygen. Nh , phn ng oxy ho s din ra nhanh v t hiu sut cao. Ti mt s nh my, trc khi vo thit b tch st, ngi ta b sung mt lng chlorine vo nc nh l mt cht xc tc cho phn ng oxy ho cc mui st.

2.5 Phng php kt lngMt s hp cht ha hc dng keo nh gum,acid silicic v cc mui ca n tn ti trong nc th. Cc hp cht dng keo c kch thc dao ng trong khong 10-4 -10-6 . v vy chng khng th tch c ra khi nc nh qu trnh lng thng thng (lng di tc dng ca trng lc). Do ta cn s dng cc cht tr lng, ph bin nht l phn nhm v phn st.Phn nhm c cng thc ha hc l Al2(SO4)3.18H2O. khi cho vo nc s xy ra cc phn ng sau:Al2(SO4)3 2Al3+ + 3SO4-Al3+ + 3H2O Al(OH)3 + 3H+Hydroxide nhm to thnh cc ha tan km v c dng bng. Nh , cc hp cht dng keo s hp ph ln b mt cc bnghydroxidde nhm, to nn nhng tp hp (aggregate) vi kch thc ln v nng hn. Chng ta c th tch chng ra khi nc d dng bng phng php lng hoc lc. Cc bng hydroxide nhm tch in dng. Do khng ch cc hp cht dng keo m nhng tp cht tch in m c trong nc cng s lin kt vi chng to kt ta v c tch ra khi nc. Cn lu l khi x l nc bng phn nhm th nc s xut hin mt lng nh acid sulfuric trong nc. Acid ny s phn ng vi mui CaCO3 to thnh mi calcium sulphate, kh CO2 v nc. Nh vy, mt phn cng tm thi s c chuyn sang cng vnh cu.Theo l thuyt, kch thc bng cng ln th qu trnh tch cc hp cht keo trong nc s t hiu qu cng cao. Khi gi tr pH ca nc nh hn 4,0 , cc bng hydroxide nhm c kch thc rt b. Ngc li, khi gi tr pH ca nc ln hn 4,0 , kch thc cc bng hydroxide nhm s ln hn. Gi tr pH ti u x l nc bng phn nhm dao ng trong khong 7.5-7.8. Khi gi tr pH ca nc ln hn 8,0 th s to thnh hydroxide, phn nhm s khng cn tc dng h tr s kt lng ca cc hp cht keo trong nc.Phn st c cng thc ha hc Fe2(SO4)3.9H2O. Tng t nh phn nhm, khi c phn st vo nc cng xy ra cc phn ng: Fe2(SO4)3 2Fe3+ + 3SO42-Fe3+ +3H2O Fe(OH)3 + 3H+Kt qu nghin cu thc nghim cho thy qu trnh x l nc bng phn st t hiu qu cao nht khi gi tr pH ca nc nm trong khong 8.2-8.5. tin hnh x l nc bng phn nhm hoc phn st ngi ta s dng b cha nc hnh tr, y cn hoc khi hp hnh ch nht, bn trong c cnh khuy hoc h thng ng ng sc kh o trn. Trc tin, ngi ta cho phn nhm hoc phn st vo nc to thnh dung dch c nng xp x bng 5% sao b sung dung dch ny vo b nc cn c x l. Cho cnh khuy hot ng hoc cho sc kh trong thi gian u phn b u ha cht trong nc. Tip theo tt cnh khuy hoc ngng sc kh qu trnh kt lng xy ra. Ti mt s c s sn xut thc ung, ngi ta c th chm dung dch phn nhm hoc phn st ngay trn ng ng dn nc ngm vo b lng. Khi chng ta khng cn s dng cnh khuy hoc h thng sc kh o trn. Thi gian cn thit xy ra s kt lng cc tp cht keo trong nc bi phn nhm hoc phn st c th ko di 6-8 gi.

2.6 Phng php hp ph tch mt s tp cht ra khi nc, ngi ta c th s dng hp ph bng than hot tnh. Than hot tnh l mt thut ng chung ch nhm vt liu carbon c xp cao. B mt ring ca than hot tnh c th dao ng trong khong 500-1.500m2/g. Nh , than hot tnh c th hp ph nhiu loi tp cht, t bit l cht mu v cht mi c trong nc.Khi ra s dng cc hp cht c cha chlore c ch vi sinh vt trong nc , sau khi x l nc thng c mi chlore. Cn cho ngun nc ny qua ct cha than hot tnh. Ngoi kh nng cht mi c hp ph trn b mt cc ht than, cn c th xy ra cc phn ng: C + 2Cl2 + H2O CO2 + 2HClNh vy vic kh mi mc s t hiu qu cao.Hiu qu ca qu trnh x l nc bng than hot tnh, ph thuc vo thnh phn ha hc ca ngun nc cn x l, nhng tnh cht ca loi than hot tnh s dng v cc thng s cng ngh ca qu trnh x l (chiu cao ca lp than trong thit b s l, lu lng nc i qua thit b).Trong thc t x l nc bng than hot tnh, ngi ta thng s dng thit b lc vi vt liu gm ba thnh phn nh si, ct, than hot tnh. Thit b ny c cu to tng t thit b lc s dng vt liu lc l ct v si. im khc bit ch yu l trong vt liu ny c n bn lp vt liu lc c ngn cch vi nhau bi bn tm . Di cng l lp si vi chiu cao 10cm. Pha trn lp si ln lt l lp ct (dy 35cm) ri n lp than hot tnh (dy 15cm). trn cng l lp si vi chiu cao 10cm. Lp si v ct c chc nng gi li mt s cu t khng tan trong nc. Cn lp than s hp ph mt s hp cht mu, mi..nh ci thin mt s tnh cht cm quan ca nc.

Thit b lc than hot tnh.

2.7 Phng php trao i ionTrong cng ngh x l nc, phng php trao i ion c s dng tch cc hp cht tch in ra khi nc. Nh vy, sau khi qua x l trao i ion, cng v nng cc anion v cation s gim xung.Bn cht ca phng php trao i ion l s tng tc gia nc vi pha rn c cha sn cc ion c th i ch vi cc ion c trong ngun nc cn x l. Cc cht to nn pha rn c gi l ionit (nha trao i ion) .Ionit c kh nng tham gia trao i vi cc ion dng c gi l cationit v ionit tham gia trao i vi cc ion m c gi l anionit. T , phng php trao i ion c th chia thnh hai nhm c bn l trao i cation v trao i anion.

Hnh 5: M hnh v thit b ca phng php ion gip lm mm nc

Gii thiu v cc ionitHin nay, c nhiu loi cationit v anionit khc nhau c s dng quy m cng nghip. Bn cht ha hc ca cc ionit l cc ht nha tng hp gn sn cc ion. Thng gp nht l nha polystyrene-divinylbenzene.Khi ta thc hin phn ng polymer ha tryrene s to ra sn phm l cc polystyrene mch thng. Nu ta thc hin phn ng polymer ha khi c mt c styrene v divinylbenzene th cc phn t divinyl benzene s to nn nhng cu ni lin kt cc mch polystyrene li vi nhau, t hnh thnh nn mng li khng gian ba chiu v to nn cu trc c trng cho nha polystyrene-divinylbenzene.T l hm lng divinylbenzene trong hn hp cc cht tham gia phn ng polymer ha s nh hng quyt nh n tnh cht ca nha polystyrene-divinylbenzene. Thng thng t l ny chim khong 6%-15%.Cationit: to nn cationit, ngi ta c th gn mt s cht ha hc ln cc nha polystyrene-divinylbenzene, v d nh acid sulfonic.Do acid sulfonic d dng b phn ly thnh SO32- v H+ nn kh nng trao i cation ca cationit l rt cao. Loi cationit ny thng c s dng trong x l nc tch ion kim loi nh Ca+ v Mg2+..Anionit: to nn anionit, ngi ta gn ln vng benzene ca cc ht nha polystyrene-divinylbenzene mt nhm amine. Trc tin, ta cn thc hin phn ng chloromethyl ha polystyrene-divinylbenzene, sau x l sn phm vi amine bc 1,2,3 hoc vi NH3. Di y l s phn ng s dng amine bc 3:Qu trnh x l nc bng phng php trao i ion.Khi cho nc qua ct trao i cationit, cc cation c trong nc s c gi li trn ct. S trao i ion ca cc mui ha tan calcium c biu din nh sau:CaCl2 + H2-Resin Ca-Resin + 2HClCaSO4 + H2-Resin Ca-Resin + H2SO4Ca(NO3)2 + HO-Resin NO3-Resin + 2HNO3Nh vy, th nng cc cation c trong nc sau khi x l s gim xung. Tuy nhin, trong nc s xut hin cc acid v pH ca nc gim xung. tch acid ra khi nc, ta s dng phng php trao i anion. S trao i nh sau:HCl + HO-Resin Cl-Resin + H2OH2SO4 + (HO)2-Resin SO4-Resin + 2H2OHNO3 + HO-Resin NO3-Resin + H2ONh vy, cc anino nh Cl-,NO3-,SO42-.s c tch khi nc sau khi cho nc qua ct anionit.Trong thc t sn xut, ngi ta s cho nc ln lt qua ct cationit ri anionit. Kt qu cui cng l s lm gim c cng v nng cc ion khc c trong ngun nc cn x l.Sau mt khong thi gian s dng, kh nng trao i ion ca cc ht nha trong ct cationit v anionit b gim xung nn cn phi ti sinh chng.i vi cationit dng H-Resin, ngi ta thng s dng acid ti sinh, nh dung dch HCl 5-6%. Trong qu trnh ti sinh s xy ra s trao i ion nh sau:Ca-Resin + 2HCl H2-Resin + CaCl2Ca-Resin + H2SO4 H2-Resin + CaSO4i vi anionit dng HO-Resin, ta s dng dung dch base, thng l dung dch NaOH 1% ti sinh:Cl-Resin + NaOH HO-Resin + CaCl2SO4-Resin + 2NaOH (HO)2-Resin + Na2SO4Cc mui NaCl,Na2SO4 ha tan c trong nc v s theo dng dung dch ti sinh thot ra ngoi ct ionit.u im ca phng php trao i ion l thit b c cu to n gin, quy trnh d vn hnh, khng tn km nhiu chi ph trong qu trnh x l, cc ionit c th s dng c trong mt khong thi gian di.

2.8 c ch vi sinh vt bng ho chtNhiu hp cht c kh nng c ch vi sinh vt. Trong x l nc, s dng ph bin nht l sodium hypochloride, calcium hypochloride v ozone.Sodium hypochloride (NaClO)NaClO thng mi dng lng cn gi l nc Javel. Thng thng nc Javel c chlore dao ng t 10-200 ( chlore l s t chlore c gii phng ra tnh trn 1kg sn phm). Khi cho NaClO vo nc s xy ra cc phn ng ch yu sau y:NaClO + H2O = HClO + NaOHHClO = HCl + OOxygen nguyn t c kh nng oxy ho rt mnh v l mt tc nhn dit khun. N s chui vo bn trong t bo vi sinh vt, tham gia phn ng vi mt nhm chc ca protein v lm ri lon qu trnh trao i cht cu t bo.Liu lng sodium hypochloride cn s dng v thi gian x l s thay i ph thuc vo nng t bo vi sinh vt c trong nc. tiu dit t bo vi khun, ta cn tng liu lng s dng v thi gian x l. Trong thc t sn xut, thi gian x l thng khng thp hn 1 gi.Calcium hypochloride (Ca(ClO)2)Ca(ClO)2 thng ma dng bt mu trng. Trc khi s dng cn ho Ca(ClO)2 vo nc, sau cho vo b nc cn x l. Cc phn ng ch yu gm c:Ca(ClO)2 + H20 =Ca(OH)2 + 2HClOHClO= HCl +OTng t nh NaClO, Ca(ClO)2 khi phn ng vi nc cng to ra oxygen nguyn t c tc dng tiu dit vi sinh vt. Ngoi ra cn c th xy ra cc phn ng:Ca(ClO)2+4HCl=CaCl2+2Cl2+2H2OCl2+H2O=HClO+HClHClO=HCl+OKh chlore s phn ng vi nc to ra acid hypochloride; acid ny b phn hu gii phng oxygen nguyn t, gp phn c ch h vi sinh vt c trong nc. Mt im cn lu l khi x l nc bng Ca(ClO)2 th cng vnh cu ca nc s tng ln.Nhn chung, u im ca phng php x l vi sinh vt trong nc bng cc hp cht c cha chlore l thit b s dng n gin, chi ph x l thp, hiu qu kh trng kh cao. Nhc im quan trng l sau x l nc c mi chlore. khc phc vn ny, ngi ta s s dng than hot tnh ci thit ch tiu cm quan (mi) ca nc.

3. PHNG PHP SINH HCPhng php sinh hc c ng dng x l cc cht hu c ha tan c trong nc thi cng nh mt s cht v c nh H2S, Sunfit, ammonia, Nito da trn c s hot ng ca vi sinh vt phn hy cc cht hu c gy nhim. Vi sinh vt s dng cht hu c v mt s khong cht lm thc n. Mt cch tng qut, phng php x l sinh hc c th phn thnh 2 loi:- Phng php k kh s dng nhm vi sinh vt k kh, hot ng trong iu kin khng c oxy.- Phng php hiu kh s dng nhm vi sinh vt hiu kh, hot ng trong iu kin cung cp oxy lin tc. Qu trnh phn hy cc cht hu c nh vi sinh vt gi l qu trnh oxy ha sinh ha. thc hin qu trnh ny, cc cht hu c ha tan, c cht keo v cht phn tn nh trong nc thi cn di chuyn vo bn trong t bo vi sinh vt theo 3 giai on chnh nh sau: Chuyn cc cht nhim t pha lng n b mt t bo vi sinh vt. Khuch tn t b mt t bo qua mng bn thm do s chnh lch nng bn trong v bn ngoi t bo. Chuyn ha cc cht trong t bo vi sinh vt, sn sinh nng lng v tng hp t bo mi.Tc qu trnh oxy ha sinh ha ph thc vo nng cht hu c, hm lng cc tp cht v mc n nh ca lu lng nc thi vo h thng x l. mi iu kin x l nht nh, cc yu t chnh nh hng n tc phn ng sinh ho l ch thy ng, hm lng oxy trong nc thi, nhit , pH, dinh dng v cc yu t vi lng. PHNG PHP SINH HC K KH Qu trnh phn hy k kh cc cht hu c l qu trnh sinh ha phc tp to ra hng trm sn phm trung gian v phn ng trung gian. Tuy nhin phng trnh phn ng sinh ha trong iu kin k kh c th biu din n gin nh sau:Vi sinh vtCht hu c > CH4 + CO2 + H2 + NH3 + H2S + T bo miMt cch tng qut qu trnh phn hy k kh xy ra theo 4 giai on:- Giai on 1: thy phn, ct mch cc hp cht cao phn t;- Giai on2: acid ha;- Giai on 3: acetate ha;- Giai don 4: methan ha. Cc cht thi hu c cha nhiu cht hu c cao phn t nh proteins, cht bo, carbohydrates, celluloses, lignin,trong giai on thy phn, s c ct mch to nhng phn t n gin hn, d phn hy hn. Cc phn ng thy phn s chuyn ha protein thnh amino acids, carbohydrate thnh ng n, v cht bo thnh cc acid bo. Trong giai on acid ha, cc cht hu c n gin li c tip tc chuyn ha thnh acetic acid, H2 v CO2. Cc acid bo d bay hi ch yu l acetic acid, propionic acid v lactic acid. Bn cnh , CO2 v H2, methanol, cc ru n gin khc cng c hnh thnh trong qu trnh ct mch carbohydrate. Vi sinh vt chuyn ha methan ch c th phn hy mt s loi c cht nht nh nh CO2 + H2, formate, acetate, methanol, methylamines, v CO. Ty theo trng thi ca bn, c th chia qu trnh x l k kh thnh:- Qu trnh x l k kh vi vi sinh vt sinh trng dng l lng nh qu trnh tip xc k kh (Anaerobic Contact Process), qu trnh x l bng lp bn k kh vi dng nc i t di ln (UASB);- Qa trnh x l k kh vi vi sinh vt sinh trng dng dnh bm nh qu trnh lc k kh (Anaerobic Filter Process). PHNG PHP X L SINH HC HIU KH TRONG X L NC THI Qu trnh x l sinh hc hiu kh nc thi gm ba giai on:- Oxy ha cc cht hu c;- Tng hp t bo mi;- Phn hy ni bo. Cc qu trnh x l sinh hc bng phng php hiu kh c th xy ra iu kin t nhin hoc nhn to. Trong cc cng trnh x l nhn to, ngi ta to iu kin ti u cho qu trnh oxy ha sinh ha nn qu trnh x l c tc v hiu sut cao hn rt nhiu. Ty theo trng thi tn ti ca vi sinh vt, qu trnh x l sinh hc hiu kh nhn to c th chia thnh:- X l sinh hc hiu kh vi vi sinh vt sinh trng dng l lng ch yu c s dng kh cht hu c cha carbon nh qu trnh bn hot tnh, h lm thong, b phn ng hot ng gin on, qu trnh ln men phn hy hiu kh. Trong s cc qu trnh ny, qu trnh bn hot tnh l qu trnh ph bin nht.- X l sinh hc hiu kh vi vi sinh vt sinh trng dng dnh bm nh qu trnh bn hot tnh dnh bm, b lc nh git, b lc cao ti, a sinh hc, b phn ng nitrate vi mng c nh.

C. TI LIU THAM KHO1) Gio trnh Cng Ngh Sn Xut Nc Gii Kht. Trng HCNTP.TPHCM.2) Trnh Xun Lai, X l nc cp cho sinh hot v cng nghip.3) www.luanvan.co

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