LI M U

LI M UNhu cu v nc ca con ngi khng ngng tng ln. hin ti ngun nc ang thiu v trong tng lai iu ny s ngy cng tr nn nghim trng hn, c bit cc quc gia ang pht trin v cc nc ngho c dn s ng th vn v nc sinh hot cha c quan tm y . Vit Nam l quc gia ang pht trin, nm trong khu vc nhit i gi ma chng ta khng phi l quc gia khan him v ngun nc nhng kh nng tr nc l khng cao do khng th phn b u theo thi gian trong nm.Hn na Vit Nam c hn 3260 km chiu di b bin vng bin c nhiu o v qun o, ng bng ven bin l ni tp trung dn c ng c nht, thi gian nh bt trn bin ca tu thuyn ngy cng ko di. ng thi, trn pht trin nhiu thnh ph ven bin s c mc ln. Do , nhu cu v nc cho sinh hot cc khu vc ny cn c quan tm gii quyt v nc bin v nc l khng th dng trc tip cho sinh hot.Trn th gii, t lu con ngi ngh n vic kh mn nc bin bng cch bay hi v ngng t nhng hiu qu cha cao. Mt gii php mang tnh t ph c a ra v ng dng thnh cng u tin M vo nhng nm 60 ca th k trc l lc nc bin v nc l s dng cho sinh hot bng cng ngh thm thu ngc RO. Cho n nay k thut ny ngy cng c hon thin . Tuy nhin, Vit Nam cha c nghin cu ng dng nhiu.Trong khun kh n tt nghip ny em tp trung tm hiu v cng ngh mng RO v ng dng trong lnh vc kh mn.Bo co ny l l nhng kt qu thu thp bc u cho ti tt nghip trn trong thi gian thc tp tt nghip.Kt thc li m u em xin chn thnh cm n thy ng Xun Hin, Ngi to iu kin v tn tnh gip chng em c c nhng bui tham quan cc cng trnh x l nc cp v nc thi rt thit thc.Sinh vin Nguyn nh Mi

Vin khoa hc v cng ngh mi trngBo co thc tp tt nghip

Nghin cu kh mn nc bin bng cng ngh mng thm thu ngcTrang 27

MC LCDANH MC CC HNH4DANH MC CC BNG6CHNG I: TNG QUAN V KH MUI V LA CHN CNG NGH KH MUI NC BIN7Cc vn v ngun nc trn tri t:7S cung ng v phn b nc trn hnh tinh:[2]7Vai tr ca nc: [2]8Thnh phn v tnh cht ca nc v nc bin:8Nhng c tnh chung ca nc tinh khit:[1]8Thnh phn ca nc bin:[1]9Cn bng ca nc bin:[1]10Cc cch biu th mn nc bin:[7]10S cn thit phi kh mn nc bin:11Khi qut v tnh hnh kh mn nc bin trn th gii:12Cc cng ngh kh mn nc bin:[3]14Phn loi cc bin php kh mui:14Cc phng php nhit:15Bay hi nhanh nhiu bc (Multi Stage Flash - MSF):15Bay hi a hiu ng (Multiple Effect Evaporlation - MEE):18Bay hi n hiu ng (Single Effect Evaporlation - SEE)20Mt s qa trnh kh mui s dng nng lng nhit khc21Cng ngh mng:21Mng in thm (Electro Dialysis - ED):21Mng thm thu ngc (Reverse Osmosis - RO)22I.6. La chn cng ngh kh mui ph hp: ...................................................................I.7. Vn mi trng ny sinh t cc nh my kh mui:2526CHNG II: C S L THUYT CA CNG NGH THM THU NGC RO 27S lt v cc loi mng v qu trnh mng:27Cc loi mng chnh:[4]27Cc qu trnh mng:27Cc khi nim lin quan: [5]27Gii thiu qu trnh lc mng:27Hin tng thm thu v thm thu ngc:30M hnh p sut thm thu:31Tnh ton p sut thm thu:31Cc c ch vn chuyn:[ 4]32Gii thiu hai c ch vn chuyn chnh:32M hnh khuch tn:34Gradient v Gradient p sut trong mng:34p dng m hnh khuch tn cho thm thu ngc39

.. 24

Cc yu t nh hng n qu trnh thm thu ngc:[ 7]42nh hng ca cu trc dung dch:42nh hng ca cht in ly43nh hng ca p sut lm vic:43nh hng ca nng dung dch:44nh hng ca cu trc mng:45Hin tng phn cc nng :45ng dng thm thu ngc trong kh mn nc bin:[ 4]46C s l thuyt ca qu trnh kh mui46nh hng ca p sut dng, nng mui (NaCl) v nhit ca nc cn x l n qu trnh lm vic ca mng thm thu ngc:[4]47nh hng ca p sut t vo:47nh hng ca nng mui:47nh hng ca nhit :48nh hng ca mt s yu t khc:49CHNG III: GII THIU MT S TRM X L NC CP V NC THI THAM QUAN50Cc trm x l nc cp v kh khong50Trm x l nc cp cho khu cng nghip Bc Thng Long:50Trm x l nc cp cho nh my m km - M mu LiLaMa:54Trm kh khong cho nh my m km - Mu LiLaMa:55H thng lc nc RO cp cho h thng sn xut Hir ca nh my m km - m mu LiLaMa:55Cc trm x l nc thi57Trm x l nc thi sinh hot cho khu cng nghip Bc Thng Long:57Trm x l nc thi ca nh my giy Bi Bng:59TI LIU THAM KHO67

DANH MC CC HNHChng IHnh I.1 T l cc loi nc trn tri tHnh I.2 Thnh phn cc nguyn t c bn trong nc binHnh I.3 Nh my bin nc bin thnh nc ngt ti vnh Tampa, M.Hnh I.4 Nh my bin nc bin thnh nc ngt vi cng sut 800m3/ngy Israel, s dng cng ngh thm thu ngcHnh I.5 Farasan - nh my bin nc bin thnh nc ngt ln nht trn th gii nm ti -Rp X-t.Hnh I.6 Nh my kh mui Tuas. Cng trnh u tin Singapore - N cung cp 10% nhu cu nc cho nc nyHnh I.7 S nguyn tc qu trnh kh muiHnh I.8 S phn loi cc qu trnh kh muiHnh I.9 H thng kh mui bay hi nhanh nhiu bc - tun hon dung dch mui (MSF - BR)Hnh I.10 H thng bay hi nhanh nhiu bc - dng i qua mt ln ( MSF-OT)Hnh I.11 H thng bay hi a bc - trn dng (MSF M)Hnh I.12 H thng bay hi a bc - nn hi (MSF VC)Hnh I.13 H thng chng a hiu ng vi dng vo song song (MED - PF) Hnh I.14 Qu trnh bay hi n hiu ng nn hi c hc (SEE - MVC) Hnh I.15 S loi b cc ion trong qu trnh in thmHnh I.16 S di chuyn cc ion trong qu mng in thmHnh I.17 S quy trnh kh mn bng mng thm thu ngc ROHnh I.18 th biu din lng nc c kh mn bng cng ngh thm thu ngc mt s ncChng IIHnh II. 1 Cc loi mng c bn

Hnh II.2 Cc qu trnh mng c bn v kch thc l cc mngHnh II.3 M t qu trnh mngHnh II.4 Hai cch t p sut vn hnh trong qu trnh mngHnh II.5 Qu trnh thu v thm thu ngcHnh II.6 M t s vn chuyn dung mi qua mng xp v mng chtHnh II.7 Kch thc mao qun v l thuyt p dng tt nht cho cc qu trnh mng c bnHnh II.8 S xuyn thm cng bc ca dung dch mt thnh phn theo m hnh khuch tnHnh II.9 Th ho hc, p sut v hot ho dung mi qua mng thm thu theo c ch khuch tnHnh II.10 D liu v s loi b mui v dng nc i qua khi cho thm thu mt dung dch mui (3.5 % NaCl) qua mt mng thm thu ngc cht lng cao. Dng mui th tng thch vi cng thc II. s gi li l mt hng s v khng ph thuc vo p sut.Cn dng nc trong cng thc II. tng ln theo p sut v dng bng 0 p sut 350 psi ca nc binHnh II.11 Hin tng phn cc nng Hnh II.12 Biu nh hng ca p sut n qu trnh tch mui bng mng RO Hnh II.13 Biu nh hng ca nng n qu trnh tch mui bng mng RO Hnh II.14 nh hng ca nhit n qu trnh kh muiChng IIIHnh III.1 S qui trnh cng ngh trm x l nc cp cho khu cng nghip Bc Thng LongHnh III.2 Mt bng trm x l nc cp cho khu cng nghip Bc Thng Long Hnh III.3 S quy trnh x l nc cp cho cng ty m km m mu - LiLaMa Hnh III.4 S nguyn l ca h thng kh khong nc cp cho dy chuyn mHnh III.5 S nguyn l h thng lc nc bng cng ngh RO cp nc cho h thng sn xut hirHnh III.6 S quy trnh cng ngh x l nc thi sinh hot khu cng nghipBc Thng LongHnh III.7 Mt bng trm x l nc thi sinh hot cho khu cng nghip Bc Thng LongHnh III.8 S quy trnh cng ngh x l nc thi nh my giy Bi Bng

Hnh III.9 C cu co rcHnh III.10 Khuy trn ho chtHnh III.11 Ngn phn ngHnh III.12 B lng ngang v c cu ht bnHnh III. 13 S iu khin h thng cho b cn bng, thp lm mt v b tip xc sinh hcHnh III.14 S iu khin v kim sot cho b tip xc sinh hc v aerotenHnh III.15 S iu khin v kim sot thp kh kh, b lng th cp v bm bnHnh III.16 S iu khin cho b cha bn, v h thng p bn bng tiHnh III.17 Bn tn ng cui b lng ngangDANH MC CC BNGBng I.1 Tnh hnh sn xut nc ngt t nc bin mt s nc trn th giiBng I.2 So snh phng php kh mui bng phng php nhit v mngBng II. 1 Th hin kch thc mao qun v p sut cn t vo cho mt s qu trnh mng

CHNG I: TNG QUAN V KH MUI V LA CHN CNG NGH KH MUI NC BINCc vn v ngun nc trn tri t:S cung ng v phn b nc trn hnh tinh:[2]Nc bao ph 71% din tch ca qu t trong c 97% l nc mn, cn li l nc ngt. Trong 3% lng nc ngt c trn qu t th c khong hn 3/4 lng nc m con ngi khng s dng c v n nm qu su trong lng t, b ng bng, dng hi trong kh quyn v dng tuyt trn lc i, ch c 0,3% nc ngt hin din trong sng, sui, ao, h m con ngi v ang s dng. Tuy nhin, nu ta tr phn nc b nhim ra th ch c khong 0,003% l nc ngt sch m con ngi c th s dng c v nu tnh ra trung bnh mi ngi c cung cp 879.000 lt nc ngt s dng (Miller, 1988).Hnh I.1 T l cc loi nc trn tri tNgun: Gleick, P. H, S.H Scheneide, Ti nguyn nc. Bch khoa t in v kh hu v thi tit.Quyn II, Nh xut bn i hc OXford, New york, 1996Hn na xt v mt a l, s phn b ca nc l khng ng u. 15% lng nc ngt ton cu c gi ti khu vc Amazon. Ngay trong khu vc a trung hi, cc nc giu v ti nguyn nc (Php, , Th Nh K, Nam T c) chim ti 2/3 lng nc ton khu vc. Tnh trng ny dn n s phn ha nhng nc giu v ngho tnh theo t l ti nguyn nc trn u ngi: Giao ng t cha n 100m3/nm n 10.000m3/nm. Di ngng 1000m3/nm/u ngi nhng cng thng bt u xut hin v ngng thiu nc c xc nh mc 500m3/nm. Khng nhng th lng nc li c s phn b khng ng u theo thi gian. C mt s mt cn i v lng nc gia ma kh hn v ma ma v gia cc nm.

I.1.2.Vai tr ca nc: [2]Nc gi cho kh hu tng i n nh v pha long cc yu t gy nhim mi trng.Nc l thnh phn cu to chnh yu trong c th sinh vt, chim t 50% - 97% trng lng ca c th, chng hn nh ngi nc chim 70% trng lng c th v Sa bin nc chim ti 97%.Trong lnh vc nng nghip th nc li cng khng th thiu, khng c nc s khng c lng thc nui sng con ngi v cung cp nng lng cho s vn ng ca cc h sinh thi trong t nhin. Mt nghin cu ton cu gn y do cc nh nghin cu Vin Qun l Nc Quc t cho thy t nht 30% cc dng chy ca sng ngi trn th gii cn c s dng duy tr iu kin ca cc h sinh thi nc ngt.Tuy khng s dng nc nhiu nh nng nghip nhng nc cng khng th thiu trong hu ht cc hot ng cng nghip.Ngy nay dch v v du lch ngy cng c ch trng pht trin v y cng l lnh vc tiu tn nhiu nc.I.2.Thnh phn v tnh cht ca nc v nc bin: I.2.1.Nhng c tnh chung ca nc tinh khit:[1]Nc tnh khit c cng thc ho hc l H2O, trong phn t nc c hai phn t hyro v mt nguyn t xy. Cc phn t nc khng tn ti ring r m to thnh tng nhm phn t nh cc lin kt hyro.Nc c th tn ti th rn, lng hoc hi. p sut kh quyn 1at, nc ng c nhit 0 oC, si nhit 100 oC. nhit thng nc tn ti th lng. Phnt nc c mmen lng cc cao, hng s in mi cao, t trng 1kg/l, nhit dung ring 1cal/goC , nhit bay hi cao (540 cal/g), sc cng b mt ca nc bng 73 dyn/cm3 v nht bng 0.01 poise 20 oC.Nc c mt s tnh cht c bit sau:Nc c kh nng ho tan mt s cht rn, n l dung dch in ly vi anion, cation v cc cht khng in ly c cc c th ho tan trong nc vi nng cao. Khi nng cht tan cng ln th nhit si ca dung dch cng cao v nhit ng bng cng thp ho tan ca kh vo nc ph thuc vo nhit v p sut. Thng th ho tan tng khi nhit gim v p sut tng. Gi tr ca cc thng s ho tan c th xc nh theo nh lut Henry.Sc cng b mt ca nc ln hn sc cng b mt ca nhiu cht khc, tnh cht ny gip ta kim tra cc yu t v mt vt l, iu chnh git v hin tng b mt

Nc khng c mu, trong sut, cho nh sng v sng di i qua.Nc c t trng ti a 4 oC cho nn bng ni trn mt nc.Nhit bay hi ca nc ln hn nhit bay hi ca cc cht lng khc cho nn n thng c s dng trong cc qu trnh truyn nhit.Nhit ho tan ca nc cao hn cc cht lng khc v to iu kin gi nhit n nh im tinh khit ca nc.Nhit dung ring ca nc cao hn nhit dung ring ca cc cht lng khc.I.2.2.Thnh phn ca nc bin:[1]Nc bin l sn phm kt hp gia nhng khi lng khng l cc axit v baz t nhng giai on u ca s hnh thnh tri t. Cc axit HCl, H2SO4 v CO2 sinh ra t trong lng t do s hot ng ca ni la kt hp vi cc baz sinh ra do qu trnh phong ho cc thi nguyn thu v to thnh mui v nc.Thnh phn ch yu ca nc bin l cc anion nh Cl-, SO4-2, CO -2, SiO -2,v cc33cation nh Na+, Ca+2,Nng mui trong nc bin ln hn nc ngt 2000 ln. V bin v cc i dng thng nhau nn thnh phn cc cht trong nc bin tng i ng nht. Hm lng mui ( mn) c th khc bit nhng t l v nhng thnh phn chnh th hu nh khng i.Trong nc bin ngoi H2 v O2 ra th Na, Cl2, Mg chim 90%;K, Ca, S (Di dng SO4-2) chim 7% tng lng cc cht. i Ty dng t l Na/Cl = 0.55 0.56. Thi Bnh Dng v i Trung Hi t l Mg/Cl = 0.06 0.07 v K/Cl = 0.02i dng l ni lng ng cui cng ca nhiu vt th, sn phm cu nhiu qu trnh ho a cng nh cc cht thi do hot ng ca con ngi thi vo. i dng chp nhn qu trnh tun hon li t cc lc a, s ho tan v bay hi ca nhiu sinh vt trn tri t.Din t theo ngn ng ho hc th Nc bin l dung dch ca 0.5 mol NaCl, 0.05 mol MgSO4 v vi lng ca tt c cc nguyn t c mt trong ton cu

Hnh I.2 Thnh phn cc nguyn t c bn trong nc binNgun: http://en.wikipedia.org/wiki/Image:Sea_salt-e_hg.svgCn bng ca nc bin:[1]Ngi ta c on rng trong khong 500 triu nm , i dng tri qua 5 triu ln quay vng, ngha l chu k 1 vng quay l 1000 nm v do pha lng b xo trn mnh.Cn bng nc bin rt phc tp v l hn hp ca mt h thng cc nguyn t vi nhng thng s c o nh: Nhit trung bnh: 5oC (0 30 oC); p sut trung bnh: 200 at (1 at b mt v 1000 at di y) pH trong nc bin dao ng n nh trong khong 8.10.2. pE trong nc bin dao ng trong khong 12.5 0.2Cc cch biu th mn nc bin:[7] xc nh thnh phn nc bin ngi ta thng s dng cc thng s: Clo; mui ( mn); tng lng mui; nng Bm. Clo ca nc bin l tng s gam bc cn c lm Clo, Brom, iot c trong 0.328523 kg nc bin kt ta hon ton. n v o Clo l (phn nghn). K hiu Clo l Cl mui ( mn) ca nc bin l tng s gam mui ho tan trong 1000 gam nc bin, trong cc mui cacbonat, bromua, iotdua, c thay th bng cc oxyt tng ng v k c oxyt ca cc cht hu c. mui tnh bng v k hiu S Gia mui v Clo ca nc bin c h thc lin h sau:S % = 0.030 + 1.8050Cl Tng lng mui ca nc bin l tng s gam cc li mui c trong 1000 gam nc bin. Tng lng mui cng c tnh bng v k hiu

H thc lin h gia Clo v tng lng mui qua h thc sau = 0.073 + 1.811Cl - Nc bin cha cng nhiu mui ho tan th cng c v ngc li. biu th mc c, long ca nc bin, ngi ta dng mt thut ng nng . Nng nc bin o bng Bm k c gi l nng Bm (oB). Nc bin cha cng nhiu cc mui ho tan th Bm cng ln.Quan h gia nng Bm v t trng nc bin 15oC

o144.3

Trong :

d15 =

144.3

Be15

d15 : T trng ca nc bin 15oCoB: Nng Bm ca nc bin 15oCQuan h gia nng Bm v nhit ca nc bin:oBt = (0.00002748 oB15 0.00007837)t2 (0.00158oB15 + 0.00326)t (1.01675oB15 + 0.2242)Trong :oBt : Nng Bm ca nc bin 15oC t : Nhit nc thi.oB15 : Nng Bm ca nc bin 15oCPhm vi p dng cng thc trn trong khong t 0 40oC

I.3.S cn thit phi kh mn nc bin:Trn Tri t, nc bin ngy cng ng vai tr quan trng trong vic cung cp nc ung do vic pht trin cc ngun nc ngt t nhin b hn ch. Nh ni n trn, khong 97% nc trn tri t l nc bin. Nc m con ngi c th s dng d dng chng hn nh nc trong sng v h ch chim 0,01% tng lng nc ngt. Trong khi , dn s ton cu tng ti su t ngi vo nm 2000 v s t tm t vo nm 2025. 3,5 t ngi trong s ny chc chn s i mt vi tnh trng thiu nc.[9]Nhng con s thng k gn y ang thc s lm chng ta lo ngi. C 6 ngi, c 1 ngi khng thng xuyn c c ngun nc ung an ton. Hn 1/3 dn s, tc khong 2,4 t ngi khng c cc iu kin v sinh y . C mi 8 giy li c mt tr em cht v cc bnh lin quan n nc, v cc bnh ny gy ra 80% bnh tt v ci cht cc nc ang pht trin- tht s l bi kch i vi loi ngi khi t lu chng ta nhn ra rng cc cn bnh ny d dng phng trnh c [9]

i vi Vit Nam chng ta khng thiu nc n mc trm trng nhng din tch t nc tri di dc theo 3260 km dc theo b bin, ng nghip l ngnh pht trin theo hng nh bt xa b phi lu lu ngy ngoi bin, ngnh vn ti bin ang trn pht trin mnh m, nhng chin tu ch hng i trn bin rt di ngy. c bit dn c trn cc o ca Vit Nam vn cha c nc sinh hot. Ngun nc sinh hot cho c dn trn o ch yu l nc ma hoc nc c ch t t lin ra, tuy nhin nc c ch t t lin ra vi chi ph tng i cao v khng phi l cch gii quyt tt nht. ng thi t nc ta ang trong qu trnh cng nghip ho mnh m, cc thnh ph du lch ven bin, cc thnh ph cng s mc ln nhanh chng v ti cc th ny ngun nc ngt cng khng d dng g c c.T nhng nhn nhn nh vy ta thy kh mn nc bin l vic lm cn thit gii quyt phn no ngun nc sinh hot cho cng ng.I.4.Khi qut v tnh hnh kh mn nc bin trn th gii:Ngy nay, trn th gii c nhiu nh my bin nc bin thnh nc ngt ti Trung ng (Israel, rp Xt), a Trung Hi (Malta), chu M, Nam u, Caribbean, Nht Bn, qun o Channel, o Tenerife v Gran Canaria - ni ngun nc t nhin rt him do lng ma thp. Israel v -Rp X-t phi ph thuc nhiu vo nhng nh my nh vy cp nc cho ngi dn trong khi cc bang Florida v California ca M cng bt u xy dng nh my lc nc bin. 18 nh my kiu ny ang c xem xt xy dng ti California.Trong nhng thp k 1960-1970, cu tr li cho tnh trng thiu nc l xy dng nhiu h cha hn. Tuy nhin, gi t gia tng lm cho cc cng ty nc thng mi khng th la chn gii php ny. Kh mui trong nc bin l mt gii php tngi mi. N bt ngun t Trung ng vo nhng nm 1980 v 1990. Trong tng s hn7.500 nh my kh mui ang hot ng trn ton th gii, 60% nm ti Trung ng vi tng cng sut 16 t lt nc mi ngy.Nh my lc nc bin ln nht Tri t -Rp X-t sn xut 128 triu galon mi ngy (tng ng 581 triu lt). -Rp X-t l nc sn xut nc ngt t nc bin ln nht th gii, p ng 70% nhu cu nc ung hin nay ca t nc cng nh cung cp cho cc trung tm th v cng nghip thng qua mng li ng ng di hn 3.700km. Nhiu nh my mi ang c trin khai v s a tng s nh bin nc bin thnh nc ngt ln gn 30.Trong khi , 12% nc c kh mui ca th gii c sn xut chu M vi phn ln nh my nm ti Caribbean v Florida.Bng I.1 Tnh hnh sn xut nc ngt t nc bin mt s nc trn th gii

NcS t myCng sut (m3/ngy)

Cc tiu vng quc Rp thng nht3825.465.784

Bahrain1561.151.204

rp Xt2.07411.656.043

Oman102845.507

Qatar941.223.000

Kuwait1783.129.588

Llibya4311.620.652

Iraq207418.102

Ai Cp230236.865

Israel?149.594

Algeria174301.363

Tunisia64148.882

Yemen66132.897

Ngun: http://vietnamnet.vn/khoahoc/hoso/2004/06/160869/

Hnh nh mt s nh my kh mui trn th gii

Hnh I.4 Nh my bin nc bin Hnh I.5 Farasan - nh my HnhI.3 Nh my bin nc bin thnh nc ngt vi cng sut bin nc bin thnh nc ngt thnh nc ngt ti vnh Tampa, 800m3/ngy Israel, s dng cng ln nht trn th gii nm ti M.ngh thm thu ngc.-Rp X-t.

Hnh I.6 Nh my kh mui Tuas. Cng trnh u tin Singapore - N cung cp 10% nhu cu nc cho nc ny.

Ngun: http://vietnamnet.vn/khoahoc/hoso/2004/06/160869/

I.5. Cc cng ngh kh mn nc bin:[3]

I.5.1. Phn loi cc bin php kh mui:Bn cht ca qu trnh kh mui l tch cc mui t do c trong nc bin hoc nc l, vi cc mui c trong dng nc u vo ca qu trnh kh mui s c nng cao nng trong dung dch ca dng nc thi b sau x l. C hai phng php nhit v lc mng c s dng trong lnh vc ny. Hnh I.7 m t khi nim ca qu trnh kh mui, hnh I.8 a ra cc loi cng ngh chnh trong hai qu trnh trn.Hnh I.7 S nguyn tc qu trnh kh mui

Ngun: H. El-Dessouky and H. Ettouny, Study on water desalination technologies, prepared forESCWA in January, 2001.

Hnh I.8 S phn loi cc qu trnh kh mui

Ngun: H. El-Dessouky and H. Ettouny, Study on water desalination technologies, prepared forESCWA in January, 2001.

Cc phng php nhit:Bay hi nhanh nhiu bc (Multi Stage Flash - MSF):Phng php ny c thng mi ho vo nhng nm 50 ca th k XX. H thng loi ny c nhng c trng sau:C t 15 n 25 bc Cng sut c th t c giao ng t 1 15 triu gallon/ngy Nhit ca dung dch mui trong h thng t 70 90 0CTrong cng ngh ny ngi ta pht trin thm nhng h thng khc nhau nng cao hiu qu ca qu trnh chng vi mt s cng ngh c bn thuc nhm ny nh: Tun hon dung dch mui, Nc i qua h thng 1 ln, Nn hi, hay khuy, trong s th h thng bay hi nhiu bc c tun hon dung dch c s dng rng ri nht H thng kh mui bay hi nhiu bc tun hon dung dch mui:i vi h thng ny, nc u vo c chia thnh hai dng. Dng th nht l dng lm mt (Mcw) sau c a tr li bin, dng th hai l dng nguyn liu vo h thng (Mf). Dng ny c kh kh v x l ho hc b phn thi nhit trc khi vo cc bc chng pha sau.Dng dung dch tun hon (Mr) c ly t b cha bc cui cng ca b phn thi nhit v c a vo cc ng ngng t bc cui cng ca b phn thu hi nhit. Dng ny c gia nhit nh s hp th n nhit ngng t. Dng hi nng (Ms) c ngng t bn ngoi b mt cc ng ngng t. Cn dng dung dch mui th hp th n nhit ca dng ngng t v nhit ca n tng ln n gi tr cc i, hay gi TBT (T0)Dung dch nc mui nng i vo cc bc bay hi nhanh b phn thu hi nhit sau i sang b phn thi nhit, ti y mt t hi nc c to thnh bi s bay hi dung dch mui trong mi bc. Nh m t dc hi c ly nh vo s gim p sut trong bcTrong mi bc bay hi th hi c ngng t bn ngoi cc ng ngng t, ti y dng dung dch mui tun hon (Mr) i bn trong ng lm lnh hi hi nng bn ngoi. B phn thu hi nhit c tc dng lm tng nhit ca dung dch muiHi nc ngng t bn ngoi cc ng ngng t c tch tr li qua cc bc v to thnh dng sn phm ct (Md), dng ny i qua nhiu bc theo hng t bc c nhit cao n bc c nhit thp hn v nc c loi mui c thu hi bc cui cng ca b phn thi nhitS bay hi v hi nc c hnh thnh b gii hn bi s gia tng th tch ring nhit thp cng nh nhng kh khn gp phi trong qu trnh vn hnh p sut tnh

thp. Theo kinh nghim chung th nhit bc cui cng khong 30 40 0C tng ng vi vn hnh trong ma ng v ma h.Nhi bc bay hi ca h thng MSF hot ng di 100 0C v p sut thp. Trong qu trnh hot ng dung dch nc mui c th gia tng cc kh ho tan di dng vt do s r r t ngoi vo, do s kh kh khng hon ton thp kh kh hay do phn gii CaHCO3, iu ny c th l nguyn nhn chnh l gim vn tc ti nhit gia cc bung bay hi vi nhau. Theo thi gian iu ny c th lm gia tng khuynh hng n mn v gim vn tc bay hi.Qu trnh tin x l nc bin trc khi a vo h thng (Mf + Mcw) thng ch l qu trnh lc s b v k hn l thm cng on kh kh v b sung cc ho cht gim s ng cn hay ko mng trong thit b.Hnh I.9 H thng kh mui bay hi nhanh nhiu bc - tun hon dung dch mui (MSF - BR)

Ngun: H. El-Dessouky and H. Ettouny, Study on water desalination technologies, prepared forESCWA in January, 2001. H thng kh mui bay hi nhiu bc cho dung dch i qua mt ln:H thng ny cng tng t nh h thng trn (Hnh) vi s bc tng ng nhau . Nhng khng c c b phn gii nhit nh h thng (Hnh ), nh vy dung dch mui thi ra cn mang mt nhit tng i cao iu ny c th lm nhim nhit i vi ngun tip nhn li n (thng th n c a li bin)

Hnh I.10 H thng bay hi nhanh nhiu bc - dng i qua mt ln ( MSF-OT)

Ngun: H. El-Dessouky and H. Ettouny, Study on water desalination technologies, prepared forESCWA in January, 2001. H thng kh mui bay hi nhiu bc khuy trn dung dch muiH thng ny cng c nguyn tc hot ng nh h thng MSF vi s bc tng ng, tuy nhin trc khi i vo dy bung chng th dng nc bin c trn vi mt phn ca dng dung dch mui x. B trn c tc dng gia nhit cho dung dch trc khi vo cc bng bc hi.Vi h thng ny ta tn dng c mt phn nhit thi a tr li h thng ng thi gim mt phn nhit thi ra mi trng.Hnh I.11 H thng bay hi a bc - trn dng (MSF M)

Ngun: H. El-Dessouky and H. Ettouny, Study on water desalination technologies, prepared forESCWA in January, 2001. H thng kh mui bay hi nhiu bc nn hiVi h thng ny th nc c gia nhit v lm bay hi u vo sau hi ny c ht v nn bng cc Ejecter v to thnh dng kh nng, nhit ny c a n

gia nhit cho cc bung bay hi theo bc pha sau. V dng dung dch mui sau khi ra khi dy bung chng c a li gia nhit bc hi nc u vo.Hnh I.12 H thng bay hi a bc - nn hi (MSF VC)

Ngun: H. El-Dessouky and H. Ettouny, Study on water desalination technologies, prepared forESCWA in January, 2001.

I.5.2.2. Bay hi a hiu ng (Multiple Effect Evaporlation - MEE):Bay hi a hiu ng hay cn gi l qu trnh chng a hiu ng (Multiple Effect Evaporlation - MED) v n c c s t qu trnh bay hi nhiu bc (MSF).MED l qu trnh chng ct cng nghip lu i nht c s dng trong kh mn nc bin. N l cng ngh chc chn, k thut hon ho, cht lng nc ct cao, v qu trnh hot ng theo di d dng. Hin ti khong 3.5 % lng nc kh mui trn th gii c to ra bng phng php ny.Phng php ny c th c phn thnh hai loi l MED nhit thp (LT - MED) v MED nhit cao (HT - MED). i vi h thng LT MED th nhit lm vic c th thp 600C 700C v nhit ra hiu ng cui cng c th 400C, qu trnh ny s dng nng lng hiu qu hn so vi h thng MSF v thi gian lm vic khong 23 nm. Cn HT MED th s dng dng kh nhit cao, qu trnh ng cn c kimsot trong sut qu trnh tin s l ca dng nc bin vo, HT MED c s dng nhiu hn LT MED v hiu sut ca qu trnh ny gp i HT MED. Sau y l mt qu trnh in hnh cho cng ngh ny Bay hi a hiu ng vi dng vo song song:H thng MED bao gm mt s thit b bay hi thng t 8 16, thit b ny lm vic theo nguyn tc trao i nhit gin tip, mt dy cc hp bc hi, cc b ngng t v h thng thng gi. Mt hiu ng ring r bao gm b phn trao i nhit, khng gian bay hi, b kh sng v cc ph kin khc. Trong thit b bay hi th dng nc c

phun t trn xung di dng cc ht nh li ti v tip xc vi cc ng c b tr nm ngang, cc ng ny c dng kh i qua bn trong.Trong h thng dng hi i t tri sang phi theo chiu gim p sut, cn dn nc bin hay dung dch mui i thng gc vi cc hiu , dng nc c dn t thit b bay hi th nht n b phn bay hi th hai, ti y dng nc c trn ln vi dng hi.Nc bin ht vo c a vo bnh ngng, ti y n hp th n nhit ca hi nc ngng t hiu ng cui cng, sau khi qua bnh ngng nhit ca nc u vo c tng ln, mt phn nc lm lnh th c a tr li ngun, phn kia th chia thnh nhiu dng c x l ho hc, c kh kh ri sau phun vo cc thit b bay hiTrong mi hiu ng, nhit tng ln n nhit si tng ng vi p sut trong khng gian bay hi trc mt lng nh hi nc c to thnh. Ngng t kim sot lng hi qu nhit i vo bn trong cc b ng hiu ng th nht cung cp nhu cu nhit cho gia nhit li v bay hiDng hi mang nhit i vo qu trnh c cp t mt ni hi bn ngoi, nc c sch cao thit b bay hi th nht c a tr li ni hi.Hnh I.13 H thng chng a hiu ng vi dng vo song song (MED - PF)

Ngun: H. El-Dessouky and H. Ettouny, Study on water desalination technologies, prepared forESCWA in January, 2001.Ngoi qu trnh trn i vi quy trnh bay hi nc bin a hiu ng cn mt s cng ngh khc nh: Bay hi a hiu ng dng vo ni tip Bay hi a hiu ng dng vo i theo hng thng ng

I.5.2.3. Bay hi n hiu ng (Single Effect Evaporlation - SEE):y cng l qu trnh bay hi nhng n gin hn so vi cc hiu ng trn v qu trnh ny ch i qua mt thit b chng. Sau y l quy trnh bay hi n hiu ng ph bin nht Qu trnh bay hi n hiu ng nn hi c hc. Qu trnh bay hi n hiu ng nn hi c hc:Trong qu trnh ny nc bin (Mf, Tcw) u tin c chia thnh hai dng v bm vo hai thit b trao i nhit gin tip. Mt dng trao i nhit vi sn phm (Md, Td)cn mt dng trao i nhit vi dung dch mui thi b (Mb, Tb). Dng nc bin vo i trong cc ng ca thit b cn dng sn phm v dng mui thi b i bn ngoi thit b ng chm. Nc bin vo sau khi trao i nhit vi hai dng trn s c gp li mt dng (Mf, tf) trc khi c a vo thit b bay hi, cn dng sn phm sau khi trao i nhit vi dng nc vo s thnh sn phm cui cng (Md,To) v dng mui thi l dng (Mb,To)Dng (Mf,tf) sau c dn vo thp chng bng cch phun iu vo tit din thp bng mt gin phun, nc sau khi c phun di dng cc ht nh li ti s tip xc vi b mt ngoi ca cc ng trao i nhit c xp ngang bn trong cc ng c dng hi nng i qua. Khi tip xc vi cc ng trao i nhit th nc hp th n nhit v tng nhit i n nhit bc hi hi ny i qua tm kh sng v sau c ngng t thnh dng sn phm (Md, Td), cn nc bin sau khi i qua gin bc hi s tng nng mui v i xung y thp to thnh dng dung dch thi (Mb,Tb).H thng ny l h thng chng c in v tng i n gin, hiu sut bay hi cha cao ng thi cht lng nc sn phm sau khi ct cng thp hn so vi cc h thng

c.Hnh I.14 Qu trnh bay hi n hiu ng nn hi c hc (SEE - MVC)kh

Ngun: H. El-Dessouky and H. Ettouny, Study on water desalination technologies, prepared for ESCWA in January, 2001.

I.5.2.4. Mt s qa trnh kh mui s dng nng lng nhit khc:Trong quy trnh kh mui s dng nhit ngoi cc h thng c th p dng quy m cng nghio trn th ngy nay ngi ta pht trin thm mt s phng php mi cng s dng nng lng nhit nhng khng tiu tn nhiu nng lng nh vo vic tn dng cc ngun nng lng ti to nh nng lng gi, nng lng mt tri, nng lng sng hay tn hay tn dng qu trnh bay hi t nhin. Hoc da vo s chnh lch khi lng ring ca nc ngt v nc bin nhit ng c ng bng v thu hi nc ngt, tuy nhin trn thc t th bin php ny khng kh thi lm.

I.5.3. Cng ngh mng:

I.5.3.1. Mng in thm (Electro Dialysis - ED):Theo cng ngh ny nc bin hoc nc l c bm vo khong gia cc mng trao i ion vi p sut thp, s lng cc mng c th ln n hng trm mng t song song v xen k nhau, c mt mng trao i cation th n mt mng trao i anion thnh tng cm.Mng trao i cation l nhng mng ch cho php cc ion dng chuyn qua. Mng trao i anion ch cho php cc ion m i qua.Trong qu trnh mng in thm tch, tp cht c tch loi khi nc nh dng in. Dng in mt chiu chuyn cc ion qua mng to ra dng nc ngt v dng nc mui c nng cao hn. Mng s hnh thnh mt ro cn gia dung dch mui v nc ngt. Pha mng c nng mui cao hn gy ra hin tng phn cc nng , nhim bn hu c, to cn khong cht vi v cc kt ta khc.

Hnh I.15 S loi b cc ion trong qu trnh in thm

Hnh I.16 S di chuyn cc ion trong qu mng in thm

Ngun: H. El-Dessouky and H. Ettouny, Study on water desalination technologies, prepared forESCWA in January, 2001

I.5.3.2. Mng thm thu ngc (Reverse Osmosis - RO):Trong qu trnh thm thu ngc, nc t ngun dung dch mui p lc cao c tch mui ho tan bng cch thm qua mng bn thm. Dng cht lng thm qua mng c gi l dng lc (Permeate), n c sinh ra do chnh lch p sut gia dung dch mui c p sut ca dng sn phm xp x vi p sut kh quyn. Phn cn li ca dung dch cp vo tip tc chy qua mng bn pha c p sut cao v to ra dng c (C hm lng mui cao). y hon ton khng cn gia nhit v cng khng din ra qu trnh bin i pha. Do nng lng ch yu l cp cho qu trnh to p dng vo h thng RO.p sut lm vic ca h thng RO i vi nc l t 250400 psi, cn i vi nc bin t 800 1000 psi.Trn thc t, nc cp c bm vo bnh kn to ra p sut trn b mt mng. Mt phn nc thm qua mng, phn cn li s c nng mui cao hn nng mui cp vo. gim nng cc mui ho tan trong phn cn li ngi ta x bt mt phn ra khi bnh cha. Nu khng x th nng mui trong dung dch cp vo s khng ngng tng ln dn ti yu cu nng lng cp vo cng phi gia tng khc phc hin tng gia tng p sut thm thu.Hnh I. Biu din quy trnh kh mn ca mt h thng thm thu ngc gm cc giai on c bn sau:Ht nc t bin vo (Intank seawater):Cc nh my kh mui thng t gn b bin nhng v mc nc bn thp ng thi thng ly nc cch xa b t vi chc n vi trm mt do m phi tn nng lng cho bm ht nc t bin vo.-Tin x l (Pretreament):Nc trc khi cp vo cc module mng lc cn phi loi b cht rn l lng, iu chnh pH cho ph hp, b sung thm cc c ch kim sot thnh phn cc cht gy ra hin tng ng cn trn b mt mng nh CaSO4 , cng nh cc thnh phn c th ko mng sinh hc trn b mt mng.To p v phn tch bng mng RO (Reserve Osmosis Process):p sut c to ra nh h thng bm. Tu thuc vo tng loi mng cng nh thnh phn v nng trong nc m p lc c to ra khc nhau khi a vo h thng tch mngDo tnh cht c bit ca mng bn thm ngn chn cc mui ho tan nhng li cho php nc thm qua. Nn kt qu l sau khi i qua cc module mng, t dng nc bin ban u s to thnh hai dng: Dng nc tinh khit v dng dung dch mui m c.

Do mng khng hon ho nn cc mui ho tan vn c th thm qua n, kt qu l trong dng sn phm vn c th cha mt lng nh mui ho tan.Mng thm thu ngc thng c thit k di dng cc module vi cc dng khc nhau nh:+ Module dng cun xon+ Module dng si xp+ Module dng aNhng trong s th module dng xon c c s dng rng ri v hiu qu hn c. Trong hnh I.17 biu din mt module dng xon c in hnh X l b sung - n nh nc (Post - Treament)Nc sn phm sau khi ra khi h thng lc RO s c iu chnh pH v ui kh trc kh vo b cha v vo h thng phn phi Tr trong b cha (Freshwater storage):Thng thng th nc sau x l c x vo cc b cha trc khi a vo mng li phn phi.Hnh I.17 S quy trnh kh mn bng mng thm thu ngc RO

Ngun:http://www.awa.asn.au/Content/NavigationMenu2/AboutWaterandtheWat erIndustry/WaterFacts/FactSheets/Desalination/

I.6. La chn cng ngh kh mui ph hp: a ra s la chn ph hp nhm pht trin mt cng ngh thch ng vi xu hng pht trin cng ngh kh mn trn th gii ng thi thch hp vi iu kin Vit Nam ta phi c nhng so snh nht nh gia cc cng ngh khc nhau v nhiu mt.Bng I.2 So snh v mt s ch tiu gia hai cng ngh nhit v cng ngh mngBng I.2 So snh phng php kh mui bng phng php nhit v mngMSFMEDME-TVCMVCROED

Nhit lm vic (oC)< 120< 65< 65< 65< 45< 45

Dng nng lngSteamSteamSteamMechanical (Electrical) energyMechanical (Electrical) energyElectrical Energy

Tiu th nng lng (kWh/m3)average 3,5average 1,5average 1average 8-14 *average 5-7 *average 1-2*

Cht lng nc thnh phm (TDS)< 10 ppm< 10 ppm< 10 ppm< 10 ppm< 500 ppm (single stage)< 500ppm

Di cng5.000-500-500-50-10-1-

sut hin ti50.00020.00020.0003.00010.00010.000

(m3/ngy)

(*) : Ph thuc vo hm lng mui trong nc th

Ngun: Asia EcoBest Work Programme 2001, Sea water desalination in coastal areas of Central and South Vietnam, Synlift system, Trang 54

LNG NC BIN C KH BNG CNG NGHRO MT S NC350030002500200019962000150010005000Q uc gia1000m3/ngyHnh I.18 th biu din lng nc c kh mn bng cng ngh thm thu ngc mt s nc

Ngun: H. El-Dessouky and H. Ettouny, Study on water desalination technologies, prepared forESCWA in January, 2001

Qua phn tch bng s liu TRONG BNG I.2 Ta thy nhit lm vic ca h thng RO thp, thng th nhit mi trng. Nng lng s dng l nng lng in v mc tiut th l t 5- 7 kWh/m3 mc tiu th nng lng ny ch thp hn MVC cn cao hn so vi cc phng php cn li. ng thi nc sau x l c hm lng TDS cao hn so vi cc phng php cn li nu lc 1 bc. Di cng sut c th thit k l t 10 10000 m3/ngy. Nh vy da vo bng so snh trn ta thy RO khng phi l cng ngh chim u th.Tuy nhin nh trn hnh I.18 biu din th lng nc c kh mn bng cng ngh RO ngy cng tng ln c bit l nhng nc pht trin bi v cng ngh ny c nhng u im sau v ngy cng c hon thin.Nu cc qu trnh chng nc bin lun phi ch n vt liu khng b n mn nhm tng tui i ca nh my th i vi h thng RO khng cn xt nhiu n yu t n mn vt liu.Hiu sut kh mui rt cao, cc mng RO ngy nay c th loi b n 99% mui (Tu theo p sut lm vic v hm lng TDS trong nc ngun)Vi s pht trin ca cng ngh vt liu th ngy nay nhiu dng mng RO mi ra i c th p ng c iu kin lm vic tt hnTheo thi gian th cng ngh ny em li hiu qu kh mui tng lnQuy trnh cng ngh tng i n ginC th lp c nhiu quy m khc nhau, t cc my lc nc gia nh n quy m cng nghip trong khi mt s bin php chng ct khng th p dng quy m nhKhng i hi kinh ph lp c ln v thi gian lp c nhanh nh vo vic module ha cc mng lc.Cng ngh ny c th loi b gn nh ton b thnh phn hu c v v c trong ncCng ngh thm thu ngc khng gy nhim nhit ti mi trng v tiu tn t ho cht.Ngy nay ngun nng lng cung cp cho h thng RO c th s dng ngun nng lng ti to nh nng lng gi, nng lng mt tri. l nhng l do em chn phng php kh mui bng mng thm thu ngcROI.7.Vn mi trng ny sinh t cc nh my kh mui:Nhiu ngi lo ngi v tc ng tim nng ca nh my lc nc bin ti mi trng. Ti mt s nh my, c kh nng sinh vt bin b kt hoc b git cht trong cc mng

lc. Lo ngi chnh v mi trng l liu lng cn nc mui cn li sau qu trnh thm thu s lm tng mn cng vng bin ni t nh my v nh hng ti sinh vt bin. Hay nhit thi t cc h thng chng nc bin c lm tng nhit vng bin dn n nh hng n h sinh thi ven b ca khu vc .Cht thi lng: (cn nc mui cng vi ho cht c s dng lm sch cc thit b trong nh my) c th c ho vi nc lm mt nh my in hoc nc t nh my x l nc thi trc khi c ra bin. Do vy, mn ca nc bin khng tng. Mt gii php khc l dn nc thi vo h thng cng ti nh my x l nc thi hoc lm kh v chn ti bi. Cc thit b cng c th c lm sch bng sinh vt hoc nhit cao, trnh nhim.Vn nhit thi t cc h thng chng th ngy nay c thu hi tun hon li, do m lng nhit thi ra ngoi t cc h thng chng nc bin cng gim i ng k.Vn nng lng v pht thi kh nh knh: Trc y, cc nh my kh mui nc bin tiu tn mt lng nng lng rt ln. Nhng cc nh my thm thu nghch hin i tiu th mc nng lng ch bng 50% so vi cng ngh trc y nh vo nhng thit b phc hi nng lng. Ngoi ra, cng ngh RO cn gim thiu chi ph cng nh kh nh knh pht thi. Chi ph xy dng mt nh my kh mui t nc bin vi cng sut 100 triu lt mi ngy vo khong 100 triu USD hay ln hn. V gi nc c sn xut t cc nh my ny ch cn khong 1.5 USD cho 1000 LitCc nh my bin nc bin s gp phn ngn chn cc cuc chin tranh v nc trong tng lai. Ti Trung ng, nhiu cuc chin tranh, c bit l Cuc chin tranh 6 ngy vo nm 1967 gia Israel vi Ai Cp, Jordan, Syria, l nhng tranh chp v nc. Ngoi ra, chng cn gim thiu nn nhim ngun nc ngm. Chng hn, Syria hin c hn 16.000 ging khoan bt hp php nhm khai thc nc t tng ngp nc.Nu khng c qun l tt, chnh nhng ging ny c th lm tng nc ngm b nhim trm trng.

CHNG II: C S L THUYT CA CNG NGH THM THU NGC ROII.1. S lt v cc loi mng v qu trnh mng: II.1.1.Cc loi mng chnh:[4]Hnh II. 1 Cc loi mng c bn

Ngun: Richard W.Baker, Membrane Technology and Application

II.1.2. Cc qu trnh mng:Hnh II.2 Cc qu trnh mng c bn v kch thc l cc mng

Ngun: Richard W.Baker, Membrane Technology and ApplicationII.2. Cc khi nim lin quan: [5] II.2.1.Gii thiu qu trnh lc mng:Cc qu trnh mng p lc c dng rng ri trong hu ht lnh vc ho hc, dc phm, thc phm v cc qu trnh cng nghip hng ngy. Yu t ct li ca qu trnh lc mng l cc mng cho php mt thnh phn bit i qua v gi li cc thnh

phn khc. Trc tin l mt vi yu t quan trng c dng trong k thut mng th hin trn hnh hnh II.3Hnh II.3 M t qu trnh mng

Ngun: Sren Prip Beier, Pressure Driven Membrane Processes, In Zusammenarbeit mit, May 2007Trong hnh II.3 Pha u vo thng l dung dch m c (bulk solution). Mt s thnh phn trong dung dch m s c gi li sau khi n i qua mng. Vi mt p lc c to ra sn gia hai bn mng th mt dng (flux) s xuyn qua mng t bn dung dch c sang bn thm, dng ny c k hiu bng ch ci J v n v thng dng cho n l [L/(m2.h)]. Dng cht lng xuyn qua mng c gi l dng thm (permeate)Mt qu trnh tch c hon thnh bng cch dng mt mng c kh nng sn sng cho mt thnh phn d i qua hn nhng thnh phn khc. Ni cch khc, mng cho thnh phn no thm i qua d dng hn so vi cc thnh phn cn li v s khc nhauv tnh cht ho hc v vt l gia mng v cu t i qua c mng.+ Khc nhau v kch thc: Trong nhiu qu trnh mng (Chng hn microfiltration and ultrafiltration) th cc l rng c phn b. Cho nn vi kch thc l cho, mt vi thnh phn s c g li bi s khc nhau v kch thc cn mt s thnh phn nh xuyn qua cc l trong mng.+ Khc nhau v s tch in: Vi mt s qu trnh mng (Chng hn qu trnh in thm tch - electrodialysis) khc nhau v kh nng tch in cc thnh phn c tch. iu ny c hon thnh bng cch s dng cc mng trao i anion v cation, cc mng ny ch cho php cc cation v anion vn chuyn tng i qua mng. Chng hn mng trao i cation l mng tch in m cho nn n s y cc anion v chuyn cc cation i qua

Trong hnh II.3 Ta thy ng lc to ra mt dng thm t bn dung dch c v pha bn dung dch thm. Cc ng lc khc nhau c ni n trong cc qu trnh mng l: Chnh lch p sut Chnh lch nng Chnh lch hiu in th Chnh lch nhit Tuy nhin trong cc qu trnh c quan tm trong n ny em th ch yu ng lc ca n l chnh lch p sut. Trong bng II.1 th hin kch thc l v p sut cn thit cho mt s qu trnh mng:Bng II. 1 Th hin kch thc mao qun v p sut cn t vo cho mt s qu trnh mng

Ngun: Sren Prip Beier, Pressure Driven Membrane Processes, In Zusammenarbeit mit, May 2007T l gia dng i qua mng v ng lc ca qu trnh c th biu din bng cng thc tng qut:J = - A. dX(2.1)dxDng J t l vi ng lc, n c biu din nh mt gradient ca X ( C th l p sut, nhit , nng , hay hiu in th) theo hng x vung gc vi b mt mng. A l hng s, n c gi l h s hin tng ln (phenomenological coefficient). V gradient gim theo phng x nn du (-) c t vo v phi cng thc. ng lc trong

qu trnh mng l s chnh lch p sut gia hai bn mng, do m h thc

dX trongdx

2.1 c th vit li thnh p. Khi cng thc 2.1 c vit li thnh nh lut Darcy:J = lp.p(2.2)H s hin tng c vit li lp, chnh l h s thm ca mng. dy ca cc lp mng chn lc c ghp vo h s thm trong 2.2 v y t c thm cao n mc c th, ngi ta dng mng bt i xng vi cc lp chn lc rt mng, dy ca cc lp chn lc trong mng bt i xng thng khong 1m. thm thng ph thuc vo h s nht ng hc ca cht lng di chuyn qua mng v tr lc theo hng

truyn cht. thm ca mng microfiltration ln hn so vi mng ultrafiltration, cn thm ca mng and nanofiltration / reverse osmosis membranes th thp hn rt nhiu so vi mng microfiltration. Thnh ra qu trnh RO cn p sut cao cho hn UF and MF, Th hin trong bng II.1Hai cch t p sut vn hnh cho qu trnh mngHnh II.4 Hai cch t p sut vn hnh trong qu trnh mng

Ngun: Sren Prip Beier, Pressure Driven Membrane Processes, In Zusammenarbeit mit, May 2007

II.2.2. Hin tng thm thu v thm thu ngc:Nu t mt mng bn thm vo gia dung mi hoc hai dung dch c nng khc nhau, ta s quan st thy hin tng chuyn dung mi vo dung dch hoc t dung dch c nng thp n dung dch c nng cao v c xu hng san bng nng . y l hin tng thm thu.Hnh II.5a v II.5b M t hin tng thm thu v cn bng nh sau: Dung mi chuyn vo dung dch lm cho p sut thu tnh ca dung dch tng ln n mt cao no th qu trnh t cn bng, tc l tc chuyn dung mi (A) vo dung dch bng tc chuyn dung mi (B). p sut ng vi qu trnh cn bng ny gi l p sut thm thu (), hay gi mt cch khc p sut thm thu bng p sut phi tc dng ln bmt dung dch hin tng thm thu ngng li.Hnh II.5c m t qu trnh thm thu ngc: Khi tip tc tng p sut trn dung dch th dng chy c xu hng chuyn ng ngc tc l dung mi t dung dch c s qua mng vo dung dch long hn. Khi p sut tng cng ln th vn tc dng chy ngc cng ln, nh vy dung dch cng m c hn. Hin tng ny gi l hin tng thm thu ngc

thmJA >JBDDlong-AJADD c- BJBJA =JBDD c- BDDlong-AJAJBJA > Dj

KL /l. y l mt gi

jthit tt cho cc mng thm thu ngc c s dng tch mui trong nc. Xt n dng nc u tin. mt im m ti c t vo mt p sut thu tnh cn bng vi gradient hot ho ca nc, im cn bng thm thu (Hnh 2.9 b). Khi dng nc qua mng bng 0 v cng thc 2.30 tr thnh:

Hay:

L

D KJi = 0 =iil

ci,o

ci,l .exp

i ()R.T

(2.31)

()ci,l = c .expi

(2.32)

i,l

R.T

p sut thu tnh cao hn , cng thc 2.30 v 2.32 hp li thnh:

Hay:

Ji =

D K cLi i i ,o 1l

exp

i ( po

pl )R.T

(2.33)

y:

Ji =

L

D K cii i,o 1l

exp

i p R.T

(2.34)

p: Hiu p sut thu tnh qua mng (po - pl). Mt tnh ton th cho biu thc: i (p )/RT th nh di iu kin chun ca thm thu ngc. V d, trong nc mui khi p = 1000atm, = 10 atm, and i = 18 cm3/mol, th thnh phn i (p )/RT khong 0.06

D K L .c . .( p)iii,o iCc iu kin khng , n gin 1 exp(x) x as x 0, cng thc 2. c vit li mt cch gn ng:

Ji =

l.R.T

(2.35)

Cng thc ny c th n gin thnh:Ji = A(p )(2.36)

i y, A l mt h s bng biu thc: Di KL cioi

/RT . Trong thm thu ngc, A

thng c gi l Hng s thm nc (water permeability constant).Mt cch tng t, n gin biu thc cho dng mui, Ji, xuyn qua mng c th c suy ra, bt u vi biu thc ng hng 2.30

D KLJi =iil

c j,o

c j,l

exp

i ( po R.T

pl )

(2.37)

V biu thc i (p )/RT rt nh v hm m trong biu thc 2.37 tin n 1 cho nn c th vit li:D K L

Ji =

ii (c l

j,o

c j,l )

(2.38)

Hoc Ji =

B(cj,o

c j,l )

(2.39)

y B thng gi l hng s thm ca mui v n c gi tr

D KLB =i il

(2.40)

Cc d bo v s vn chuyn ca nc v mui qua mt mng thm thu ngc p dng m hnh khuch tn (Bt ngun u tin bi Merten v Cc cng s). Ph hp vi cng thc 2.36 dng nc xuyn qua mt mng thm thu ngc nh mt p sut cho trc ca dung dch mui sau tng ln theo p sut t vo. Cng thc 2.39 tng hp vi dng mui b chn ch yu ph thuc vo p sut. Mt vi kt qu c biu hin nh hnh II.10 , nh th hin trong hnh th mt biu thc c gi l h s thu hi (gi li), R c nh ngha:

R = (1 -

c j ,lc j ,o

)100%(2.41)

H s thu hi (gi li) d on kh nng phn tch mui t dng dung dch voi vi mt mng chn lc hon ho th mui i qua, cjl = 0 v R = 100%, i vi mt mng khng chn lc th cj,l = cj,o v R = 0Trong hnh II.10 Ta thy R tng ln theo p sut t vo v dng nc th tng theo p sut nhng dng mui th khng.Hnh II.10 D liu v s loi b mui v dng nci qua khi cho thm thu mt dung dch mui (3.5 % NaCl) qua mt mng thm thu ngc cht lng cao.Dng mui th tng thch vi cng thc 2.36s gi li l mt hng s v khng ph thuc vo p sut. Cn dng nc trong cng thc I2.39 tng ln theo p sut v dng bng 0 p sut 350 psi ca nc bin

Ngun: Richard W.Baker, Membrane Technology and ApplicationII.4.Cc yu t nh hng n qu trnh thm thu ngc:[ 7] II.4.1.nh hng ca cu trc dung dch:Dung dch l mt hn hp ng th t nht l c hai cu t v c thnh phn thay i. V dung dch gm nhiu cu t nn c trng ch yu ca dung dch l nng , r rng s phn b cht tan, s lin kt gia cc phn t dung mi v phn t cht tan to thnh mt ng th s quyt nh tnh cht c trng ca dung dch, tt c c tnh cht trn ca dung dch iu ph thuc vo cu trc dung dch v nng dung dch m t ph thuc vo bn cht dung dch. gii thch r nh hng ca cu trc dung dch n qu trnh lm vic ca mng ngi ta da vo cc c trng Nhit ng v cu trc dung dchKhi ho tan mt cht tan trong mt dung mi no , th lp tc c s tng tc gia phn t dung mi v phn t cht tan ng thi sinh ra hiu ng nhit, hiu ng nhit ca qu trnh ho tan nhiu khi rt ln. V vy, c th cho rng: Qu trnh ho tan l kt qu ca mt phn ng c bit to ra mi lin kt gia dung mi v cht ta. Ngi ta gi

qu trnh ny l qu trnh solvat ho (Hay qu trnh Hyrt ho): qu trnh ny c nh ngha:Hyrat ho l s nh hng ca cc phn t nc xung quanh ion cht tan, chuyn ng cng vi chng v tc dng tng h ln nhau. Solvat ho l danh t ch qu trnh trn nhng dung mi khng phi l nc.

II.4.2 .nh hng ca cht in ly:Nhiu tc gi nghin cu qu trnh tch cc mui v c t dung dch nc bng phng php thm thu ngc ch ra rng vi cc ion khc nhau tin hnh trong cng mt iu kin nh nhau trn cng mt mng th cc c trng ca qu trnh tch cng khc nhau. Nh vy, qu trnh tch cn ph thuc vo bn cht ca cc cht in ly trong dung dch. Nh ni trn kh nng hyrt ho khc nhau ca cc ion c nh hng n tnh la chn v thm thu ca mng. Qua thc t nghin cu nhiu tc gi a n kt lun: la chn tng khi kh nng hydrat ho ca ion tng (Tng ng vi bn knh ion gim) v ngc li.Kh nng hydrat h o ca cc ion c sp xp nh sau: Ion ho tr 1: Li+ >Na+ >Rb+>Cs+Cl- >Br- >NO3->I- >CNS-Ion ho tr 2: Mg2+>Ca2+>Cr2+>Ba2+Ion ho tr 1&2: Sr2+> Ba2+>Li+>Na+>K+SO4->Cl->Br->NO3->I- bn ca v hydrat ho c nh gi nh sau:Z 2

Trong :

Q

ZA: in tch anion rA: bn knh ion (Ao)

ArA0,25

(2.42)

t nc.

0,25: Hng s c trng cho s khng i xng v tr lng cc ca phn

Nh vy khi bn hydrat ho tng th la chn tng v thm thu gim.

II.4.3 .nh hng ca p sut lm vic:Mt trong nhng yu t nh hng n qu trnh thm thu ngc c tnh cht quan trng l p sut lm vic. Mun qu trnh thm thu ngc xy ra ta phi to p sut ln hn p sut thm thu to ra ng lc ca qu trnh. R rng p sut cng tng th ng lc ca qu trnh (P-) cng ln, thm thu v chn lc cng tng , tuy nhin mc tng ca cc thng s ny trong tng vng p sut khng ging nhau.

Trong qu trnh lc mng th khng phi lm vic p sut cng cao th cng tt v khng nhng thm thu gim, chn lc khng tng c bao nhiu m cn do mng b nn qu ln dn ti mng b bin dng qu gii hn n hi, lm ph hu cu trc ca mng. Thng thng mi loi mng cc nh sn xut u a ra cc thng s lm vic nht nh.

II.4.4 .nh hng ca nng dung dch:Nng dung dch cng l mt yu t rt quan trng nh hng n qu trnh lm vic ca mng, khi nng thay i khng nhng ng lc ca qu trnh thm thu ngc thay i (do p sut thm thu ph thuc vo nng ) m cu trc ca dung dch cng thay i.Trong dung dch ngi ta thng chia thnh 3 vng nng sau: Vng nng long: L vng nng cng tn ti cc phn t nc trng thi t do trong dung dch. Vng nng gii hn: Ti cng ny khng cn tn ti cc phn t nc trng thi t do m n trong lp v htdrat gn v xa. Vng nng c c: Ti vng ny ton b nc chuyn vo lp v hydrat ho th nht.Theo mt s tc gi khi chuyn t vng nng cao sang vng nng ny sang vng nng khc th cu trc dung dch thay i t ngt.Vi dung dch long nh hng ca nng n chn lc v thm thu ca mng l khng ng k v trong dung dch lun tn ti cc phn t nc t do to thnh mt lp mng nc nguyn cht trn b mt mng. Nhng khi nng dung dchtng dn ln th s phn t nc t do trong dung dch gim i chng chuyn dn vo lp v hyrat th hai v th nht. Khi lc tng tc gia cc ion cht tanv dung mi rt ln, mi lin kt ny rt bn vng do b mt mng khng to thnh lp nc nguyn cht c v xy ra hin tng bt kn cc mao qun do chn lc v thm thu gim i rt nhanh.Theo Govindan v Souvirajan th quan h gia thm thu v nng c biu hin qua cng thc:

K1(KCn )P2G =(2.43)

Trong :P: ng lc ca qu trnh, kg/cm2: Khi lng ring ca dung dch, kg/m3

: nht ca dung dch, Ns/m2C: Nng dung dch, mol/L n: Hng s thc nghimK1,K2: Hng s ng vi tng h dung dch - mngII.4.5.nh hng ca cu trc mng:Trong qu trnh tch bng mng thm thu ngc, mng bn thm c nh hng quan trng n cht lng ca qu trnh. Cc mng thng c chn lc v thm thu rt khc nhau, ngay trong cng mt loi mng sn xut theo iu kin cng ngh nh nhau th cu trc ca mng cng khng ging nhau, khuyt tt ca mao qun trn tng vng ca mng c ng knh khc nhau nn ng knh mao qun cng rt khc nhau do m ng knh mao qun ch tnh trung bnh. Ni chung mng c ng knh mao qun cng nh th c kh nng gi ion cng tt. Nhng m bo qu trnh lm vic tt th cc mng phi tha mn cc yu cu sau:C thm thu ln vi nc v nh vi cht tan.C bn c hc ln, ng u v kch thc v cu trc.Cc mao qun ng nht t khuyt tt.D ch to, sn xut hng lot, d bo qun.II.4.6.Hin tng phn cc nng :Hnh II.6 biu din profin nng ti b mt mng trong qu trnh thm thu ngc, r rng s tch t cht tan trn b mt mng lm cho vn tc khuych tn qua mng chm hn vn tc chuyn cht tan t nhn pha n b mt mng nn gy ra s chnh lch nng (grad C) gia nhn pha v b mt mng chnh l hin tng phn cc nng Hin tng ny s lm tng dng cht tan i qua mng do lm gim chn lcca mngS tng nng trn lp bin c th t ti nng bo ho ca cu t no v to kt ta trn b mt mng, lm gim b mt lm vic ca mng (To thnh lp mng th hai) lm gim dng dung mi.Hin tng phn cc nng lm gim ng lc ca qu trnh do lm gia tng p sut thm thu. khc phc hin tng phn cc nng th nn tin hnh trong iu kin dung mi khng qu ln, to dng chy xoy mnh trn b mt mng.Hnh II.11 Hin tng phn cc nng

Cii,p = R.T.(Ci-Cp)b,p = R.T.(Ci-Cp)

Cs CvBin dngnng Cp

II.5.ng dng thm thu ngc trong kh mn nc bin:[ 4] II.5.1.C s l thuyt ca qu trnh kh mui:Mui v nc i qua mng thm thu ngc th ph hp vi c ch vn chuyn khuch tn nh trnh by mc II.3Dng nc, Ji lin h vi p sut qua mng bi cng thcJi = A(p - )(2.44)Trong :p: Hiu ca p sut qua mng. : p sut thm thu.A:Hng sKhi p < , nc s i t bn c nng mui long sang bn c nng mui cao hn, y l qu trnh thm thu thng thng.Khi p = , khi khng c s chuyn dch dng.Khi p >, Nc s i t bn dung dch c nng mui cao hn sng bn c nng mui thp hn.Dng mui, Jj, qua mng c m t bi biu thcJj = B(Cj,o - Cj,l)(2.45)Trong :B: H s thm ca mui.Cj,o:Nng mui trong nc cp vo h thng. Cj,l: Nng mui bn kia mng.Tuy nhin Cj,l nh hn rt nhiu so vi Cj,o cho nn h thc trn c th n gin nh sau:Jj = BCj,o(2.46)Theo di hai biu thc trn ta thy chuyn ng ca dng nc qua mng c mi lin h vi p sut t vo, nhng dng mui th khng ph thuc vo p sut. iu ny c ngha l mng c tnh chn lc hn khi p sut tng. Tnh chn lc c th xc nh theo

mt s cch, nhng thng thng, thng c xc nh da vo h s loi b mui R, c nh ngha nh sau:

R = [1 -

C j ,lC j ,0

]100 %(2.47)

Nng mui trong nc bn kia mng lc c lin h vi lu lng nc v dng mui qua mng bi h biu thc:

Trong :

Cj,l =

3

J j i(2.48)Ji

i : T trng ca nc (g/cm )

BiA ( p)T cc cng thc trn ta c kh nng loi b cc cht ca mng c biu th bi biu thc.

R = [1 -

]100%(2.49)

II.5.2 .nh hng ca p sut dng, nng mui (NaCl) v nhit ca nc cn x l n qu trnh lm vic ca mng thm thu ngc:[4]

II.5.2.1 .nh hng ca p sut t vo:

Hnh II.12 Biu nh hng ca p sut n qu trnh tch mui bng mng RO

Ngun: Richard W.Baker, Membrane Technology and Applicationnh hng ca p sut dng vo h c biu din nh hnh II.12 . th trn ta thy ti mt p sut bng p sut thm thu (350 psi) th dng qua mng bng 0, Sau nu p sut tng theo mt ng tuyn tnh th lng mui c loi b (ngoi suy) t 0 p sut 350 psi, nhng tng rt nhanh theo s tng p sut n kt qu t c l loi b hn 99 % mui p sut t vo 700 psi (Gp i p sut thm thu ca dung dch).

II.5.2.2 .nh hng ca nng mui:

Hnh II.13 Biu nh hng ca nng n qu trnh tch mui bng mng RO

Ngun: Richard W.Baker, Membrane Technology and Applicationnh hng ca s gia tng nng mui trong dung dch vo n hiu qu lm vic ca mng c biu th nh hnh II.13 S tng nng mui nh hng n s gia tng p sut thm thu. Do bi, p sut khng i 1000 psi dng nc qua mng bng 0 nng mui 10wt%, im p sut thm thu bng p sut thu tnh t vo th nng mui b loi b bng 0, nhng li tng rt nhanh theo s tng nng mui. Nng mui c gi li hi 99% c gii hn min nng di 6%. Tng ng vi p sut c vo khong 400 psi.

II.5.2.3 .nh hng ca nhit :Hnh II.14 nh hng ca nhit n qu trnh kh mui

Ngun: Richard W.Baker, Membrane Technology and Application

nh hng ca nhit nc u vo ln phn trm mui c loi b v dng nc c m t nh trn hnh II.14 Th phc tp hn hai yu t trn. L mt qu trnh ng, v c hai tng ln theo hm m vi s tng nhit . Trn biu cho thy nh hng ca nhit ln dng nc tng i nhy, lu lng dng qua mng tng gp i khi nhit tng t 20 ln 30oC. Tuy nhin, nh hng ca nhit ln dng mui th t hn. Thc ra dc ca ng nhit th tng i thp.Cc biu trn c a ra t mt h thng kim tra thng hot ng dung dch mui kim tra l 0.2 1% NaCl di p sut 150 600 psi.II.5.2.4.nh hng ca mt s yu t khc:Tnh cht ca mng v s phn cc nng .

CHNG III: GII THIU MT S TRM X L NC CP V NC THI THAM QUANII.6. Cc trm x l nc cp v kh khong:

II.6.1. Trm x l nc cp cho khu cng nghip Bc Thng Long: Gii thiu khu cng nghip Bc Thng Long:Din tch: 198haa im: ng Anh, H Ni (B Bc sng Hng Bn cu Thng Long) Ch u t: Cng ty c kh ng Anh v Tp on Sumitomo (Nht Bn)Khu cng nghip Thng Long: KCN Thng Long c pht trin bi Thng Long Industrial Park, mt cng ty lin doanh gia tp on Sumitomo (Nht Bn) v Cng ty c kh ng Anh (B Xy dng), c thnh lp theo Gip php u t s 1845/GP do B K hoch & u t Vit Nam cp ngy 22/2/1997. c cp chng ch qun l mi trng ISO-14001.Cp nc: Sau khi c x l ti nh my lc nc, nc tiu dng cng nghip c cung cp bi h thng ng nc bng st mm t ngm di lng t.Thng tin lin lc: H thng thng tin lin lc, cng c t ngm di lng t, s cho php m rng p ng nhu cu tng ln v truyn d liu tc cao.X l nc thi: Nc thi ca cc n v thu t s c thu hi bng h thng ng ngm v c x l trc khi cho chy vo knh chy qua cc khu cng nghip. ng thi cc nh my c thi ra cc loi nc thi c t trung ring bit phi c h thng x l cc b trc khi thi vo ng ng chung.Hin ti cc doanh nghip v cng ty c nh my t trong khu cng nghip l cc cng ty n t Nht Bn, sn xut v kinh doanh trong mt s lnh vc: in t, gms, Thp S quy trnh cng ngh:Hnh III.1 S qui trnh cng ngh trm x l nc cp cho khu cng nghip Bc Thng Long

PACJavel

Tip nhn

B sung

Ngn phn Ngn phn

B lng ngang

B cha nc sau x l

Ging khoan

v lm thong

ho cht vkhuy trn

ng bc 1

ng bc 2

B lc ct

i nc

CH THCHng nc chnh ng Bn ng ho cht

ng nc ra lc ng nc ra lc c lng

B bn

ngBn

B cha nc ra lc

Sn phi bn

Ngun nc: Ngun nc cp cho h sinh hot ca khu cng nghip Bc Thng Long c ly t nc ging khoan gn sng Hng v c a vo trm x l trc khi a ln mng li phn phi nc. Cng sut ca trm: Trm c cng sut 4000 m3/ngy m vi 2 n nguyn mi n nguyn c cng sut 2000 m3/ngy m . Tuy nhin, thi gian hot ng ca h thng thng khong 20 h/ngy. Cng ngh v thit b ca h thng c cung cp t Nht Bn. Nh my chnh thc hot ng t 2004 v p ng mt phn nhu cu v nc sinh hot cho khu cng nghip. Thuyt minh s cng ngh: Ngn tip nhn: Nc t ging khoan c bm vo ngn tip nhn ng thi lm thong. Ti ngn ny c b tr mt thit b khuy trn b mt cng sut ln vi mc ch lm cho nc tip xc vi oxi kh st v mangan v trong nc ngm c hm lng st v mangan nht nh, ng thi tng th oxi ho ca nc, nu l nc mt th s tip xc oxi s kh CO2 nhm nng cao pH y nhanh qu trnh xi ho v thu phn st, mangan trong qu trnh kh chng. Ngn b sung ho cht v khuy trn: Sau khi qua b lm thong nc c a vo ngn khuy trn sau khi i qua ngn b sung ho cht. Ti ngn khuy trn c b tr b cnh khuy vi vn tc ln nhm phn tn nhanh, u PAC (Poly Aluminum Clorua) v Javel vo nc. PAC c rt nhiu u im so vi phn nhm trong qu trnh keo t: t tc ng pH, liu lng thp, t gy n mn thit b, c bit i vi nc c c v kim cao. Javel c b sung vo u dy chuyn ngoi ngha kh trng n cn ng vai tr l cht oxi ho st rt hiu qu.Qu trnh khuy trn s din ra v t hiu qu cao nht khi gradiel vn tc do cnh khuy to ra t 200 - 300 s-1 trong thi gian 2 n 3 pht v trn thc t th c th kim sot trong khong t 200 1000 s-1.Gradiel vn tc c tnh theo cng thc

Trong :G: Gradiel vn tc, s-1

G =P V

0.5

: nht ng lc ca nc (N.s/m2);ivi nc c nhit 20 0C ly bng 0,001Ns/m2 (N: niwtn, Kg.m/s2)P: Nng lng tiu hao tng cng, J/s V : Dung tch b trn, m3-Ngn phn ng keo t: Tip theo nc c a i qua hai ngn phn ng keo t. To iu kin v thc hin kt dnh cc ht keo phn tn thnh bng cn c kh nng

lng v lc vi tc kinh t cho php. Ti cc ngn phn ng th cn quan tm n gradien vn tc ca cnh khuy. Thng nm trong khong t 30 80 s-1 th t hiu qu cao. Tuy nhin i vi tng loi nc thi m cn nhng kinh nghim m nhng kinh nghim ny phi c a ra bi ngi vn hnh h thng .i vi qu trnh to bng th hiu qu to bng tt nht khi cnh khuy to ra gradiel vn tc trung bnh trong khong t 30 70 s-1B lng ngang: Sau qua cc b phn ng nc c a vo ngn phn phi n nh dng chy ri a vo b lng. Lng l qu trnh quan quan trng cn c kim sot cht ch trong cng ngh x l nc cp v y l qu trnh d quan st c hiu qu bng mt thng t c th iu chnh cc qu trnh pha trc nh keo t hiu qu lng cao hn. ng thi qu trnh lng tt s gim c ti cho b lc khi thi gian ra lc gim xung ng thi nng cao cht lng nc u ra. B lng ca h thng ny c thit k di dng b lng ngang mng phn phi nc t ngang b v nc c thu nh cc mng t dc theo chiu di b cui b ri c a qua b lng.B lc: B lc l cng on x l c hc cui cng trong trnh x l. Nc i qua lp ct lc nh p lc thu tnh. Vi cng sut 2000 m3/ngy m th b lc c thit k vi din tch khong 16m2 cao 5m v chiu cao lp ct lc khong 3m chnh lch p lc khong 1.5m nc. B c ra theo chu trnh vi ph thuc vo cht lng nc u ra. H thng ra lc c iu khin t ng trn c s cc van vn hnh t ng bng kh nn. Nc ra lc c dn qua mt b lng sau c bm li b tip nhn.Bn thi: Bn t b lng 2 c bm nh k 20 ting 1 ln vo b cha bn sau c bm sang sn phi bn. B tr mt bng trm x l:Cc cng trnh trong h thng c b tr hp khi trn nn t tng i bng phng v n nhNc i qua cc cng trnh chnh iu t chy nn khng tn nng lng cho bm, tit kim c chi ph vn hnh.Cc cng trnh chnh c xy ni trn mt t, ch co b cha nc ra lc v b cha bn c xy chm.Cch b tr nh vy tit kim c qu t cng nh chi ph xy dng v vn hnh ng thi tn dng kh nng t chy ca nc tn chi ph nng lng bm.Hnh III.2 Mt bng trm x l nc cp cho khu cng nghip Bc Thng Long

7645312B

T

N

Ch thch1 B tip nhn v lm thong2 Ngn b sung ho cht3 Ngn khuy trn ho cht4 Ngn phn ng bc 15 Ngn phn ng bc 2

6 Mng phn phi7 B lng ngang8 B lc ct9 B cha nc ra lc10 B cha bn11 B cha nc sau x l

12 i nc13 Trm bm14 Khu cha v ho ho cht15 Nh iu khin16 ng ni b17 Lang cang kim sot cccng trnh18 Cu thang

19 Cng chnh

n nguyn th hai c cng sut 2000m3/ngy

17

8

15

11

9

1410

18161312

19

nh gi cng ngh v cc yu t cn khc phc nng cao hiu qu lm vic ca trm: Vi cng ngh nh trn hon ton c th x l t tiu chun cho sinh hot i vi ngun nc ngm nh ca khu vc ny. Tuy nhin cch lm thong nh cng ngh trn tng i tn nng lng cho vic vn hnh cnh khuy, trong nhiu quy trnh khc ngi ta thng s dng gin phun ma. Khi quan st ta nhn thy trong b lng cn nhiu huyn ph l lng mng thu nc cui b. iu ny lm nh hng xu n qu trnh lc ct pha sau. Hin tng ny c th do cc nguyn nhn sau gy ra: Do h thng ang hot ng qu ti Do qu trnh keo t cha tt nn cc bng keo cha ln lng. khc phc hin tng ny c th tin hnh mt s iu chnh nh nh: B sung cht tr lng Kim tra li qu trnh keo t a ra mt s iu chnh thch hp

II.6.2. Trm x l nc cp cho nh my m km - M mu LiLaMa:S nguyn l:

Hnh III.3 S quy trnh x l nc cp cho cng ty m km m mu - LiLaMa

i ncGin phun lm thongMng phn phi v thu nc raB cha nc sau x lB cha nc sau lm thongB lc vt liu niLc ctCH THCHng nc chnh ng nc ra lc ng ho chtBm nc ra ngc Ging khoanThuyt minh s : Lm thong: Nc c bm t ging khoang ln thp lm thong bng ginphun. Nh tip xc t nhin vi oxi m qu trnh oxi ho st v mangan trong nc ngm c din ra. ng thi thot bt kh v hi trong lng t. Lc qua lp vt liu l lng: Lp vt liu ny dng ht xp (Polystyren) c gi trong b nh mt li thp cho nc i qua nc i qua. Khi b ny ging nhu mt b lng tip xc, cc ht cn nng va chm vi cc ht xp sau i xung dn y b khikhi lng ln ln. Lc ct: Nc sau khi i qua b lng tip xc c phn phi vo b lc ct loi b cc cn l lng khng th lng cng on trc. Mng phn phi nc cng chnh l mng thu nc ra lc. Kh trng: Clo c bm vo nc ngay trn ng n c bm t b lng v b cha.nh gi cng ngh:Quy trnh nh trn l quy trnh x l nc ngm n gin v c in c p dng x l nc cp cho sinh hot. Quy trnh ny ch yu l kh st v mangan trong nc vi hm lng thp. Khc vi cch kh st quy trnh ca nh my nc cp cho khu cng nghip Bc Thng Long y l cch lm thong t nhin bng gin phun ma.Trong quy trnh trn c th nc ra lc c thi ra b mt t m khng c lng tun hon li. V trong nc ra lc c cha hm lng st do nu c nu thi ra mt t trong thi gian di c th lm nhim lp t.

II.6.3.Trm kh khong cho nh my m km - Mu LiLaMa:S nguyn l:

Hnh III.4 S nguyn l ca h thng kh khong nc cp cho dy chuyn m

Mng lc UF kchCt than hot thc l 5mtnhNc sinh hotBn cha

Dng ra dung dch ra

Dung dch ra ct cationMng lc UF kchDung dch ra ct anionCt trao iCt trao ithc l 1mcationanion

Thuyt minh s : Lc s b: Nc ngun c ly t nc cp sinh hot v bm vo h cc module mng lc loi b cc cht c kch thc ln nhm gim ti cho cc h thng pha sau: Lc qua than hot tnh: Trc khi vo h thng trao i ion nc gn nh khng cn cc ht c kch thc ln do m n c tip tc a vo h thng lc than hot tnh. Ti y mu s c kh bt, ng thi gim ti cho thit b trao i ion v mnglc pha sau. Ct trao i cation: Nc i qua ct cation th cc ion m s c loi b Ct trao i anion: ln gim cng Lc cng on cui: Cc ion v vi khun cha c lm sch cc cng on trc s c loi b ti mng lc cui cng trc khi c cp cho dy chuyn m.

II.6.4.H thng lc nc RO cp cho h thng sn xut Hir ca nh my m km - m mu LiLaMa: S nguyn l:Hnh III.5 S nguyn l h thng lc nc bng cng ngh RO cp nc cho h thng sn xut hir

Ct lc a vt liuCt lc Cacbon hot tnhCt trao i ionDD axit axetic

Module mng RONc bn DD ra lc

Nc x lNc sinh hot

Thuyt minh s : Lc a vt liu (Multimedia Filter): Nc ngun c bm qua thit b lc Multimedia Filter . Ti y, cc cn th, cn l lng c gi li. Cc cn l lng khng ho tan c kch thc 20micron s b gi li. Cng dng ca qu trnh lc ny l bo v tng tui th cho thit b trao i ion v thit b lc thm thu ngc Lc qua than hot tnh (Activated carbon filter): Nc sau khi i qua thit b lc Multimedia Filter c y sang thit b lc than hot tnh. Cng dng ca cng on ny l: Kh mu, mi , cc cht hu c, Chlorine, Chloramin, phenol ng thi bo v tng tui th thit b trao i ion v mng lc thm thu ngc. Thit b trao i ion (Soften): Nc sau khi qua thit b lc than hot tnh c a sang thit b trao i ion. Ti y din ra qu trnh trao i ion, cc ion gy nn cng ca nc Ca2+, Mg2+s c thay th bng ion Na+. Nc sau khi i qua thit b lm mm nc c cng nh hn 17mg/lt. iu ny gim ti cho mng lc thm thu ngc pha sau. Thit b lc thm thu ngc (Reverse Osmosis): Trung tm ca h thng x l nc cng ngh cao ny l Thit b lc thm thu ngc RO. Thit b lc ny c chng minh l thit b tin cy, an ton v hiu qu nht trong vic x l nc cng ngh cao. Thit b ny c th loi b ti >99% cc mui ho tan, cc bacteria v pyrogens cng nh phn t hu c tan. H thng trn x l nc sinh hot cp cho nh my sn xut hir c cng sut 40 m3 H2/gi. Nc sau x l c dn thp hn 5 S/cm. Theo yu cu vn hnh th sau khi sn xut 6 tn nc phi ra mng mt ln bng dung dch CH3COOH.

II.7. Cc trm x l nc thi:

II.7.1. Trm x l nc thi sinh hot cho khu cng nghip Bc Thng Long: S quy trnh cng ngh:

Hnh III.6 S quy trnh cng ngh x l nc thi sinh hot khu cng nghip Bc Thng Long

JavelSt cha rc

MngB lng th cplng ctB kh trngNc thiNc thivosau x lSong chnSongthchnB iuAeroten s dng thitBn sau khi phiCh thchtinhhob khuy trn b mtch i chn lpng nc chnhSn phi bnng bnng ho chtBn tun hon ng ng cp khBcha bn

Cng ngh s dng l cng ngh Aeroten khuy trn hon chnh. Cng sut hot ca trm l 5000 m3/ngy m, vi hai n nguyn hot ng song song. Nc thi c thu gom t nc thi sinh hot ca cng nhn v nhn vin cc c s sn xut trong khu cng nghip v c a vo h thng. Thuyt minh s cng ngh: Song chn rc: Nc thi u tin c a ln lt qua hai song chn rc loi b cc vt liu rc c kch thc trn 5mm. Gia hai song chc rc th v song chn rc tinh l mt on mng c sc kh. on mng ny c thit k vi mc ch lng ct v cc vt liu nng ng thi sc kh c ch s hot ng ca cc vi sinh vt h hp ym kh c trong cng dn v lm giu oxi cho nc trc khi vo h thng hiu kh. Hn na qu trnh sc kh s b nh th ny cng lm sch mt s cht bn trong nc nh qu trnh oxi ho. B iu ho: B iu ho c vai tr chnh l iu chnh lu lng v nc thi sinh hot thng nhiu v ban ngy nhng m li t. y khng b sung cht dinh dng v nc thi sinh hot l ngun nc giu dinh dng. Aeroten: Aeroten l h thng bn hot tnh khut trn hon chnh nh 3 b cnh khuy hai tng hot ng song song.

9B lng 2: B lng 2 l b lng Raial vi nc c a vo ng trung tm sau phn phi vo vng lng. B lng 2 c ng knh khong 15 m v cao 4m. Nc sau lng c thu ra bng mng hnh rng ca t theo chu vi b. B kh trng: Nc trc khi a ra ngun tip nhn c kh trng bng dung dch Javel. Nc i qua b kh trng theo cc ng dch zt tng thi gian tip xc vi dung dch kh trng trc khi i vo cng thi ra sng Hng. Bn tun hon: Bn t b lng 2 c bm ln mt b cha t trn np b iu ho nhm to ra cao trnh bn t chy v sn phi bn. Ti b cha bn c thit k 2 ngn c mng chy trn qua nhau , bn c bm vo ngn th nht tun hon cn lng d s chy sang ngn th 2 v tip tc chy ra sn phi. X l bn: Bn c phi cc sn phi v lu y khong 4 thng sau c ch i chn lp ti cc khu chn lp cht thi rn. B tr mt bng trm x l:Cc cng trnh: Song chn rc, b iu ho v aeroten c b tr hp khi cn b lng 2 v b kh trng c b tr ring r bn cnh.

Hnh III.7 Mt bng trm x l nc thi sinh hot cho khu cng nghip Bc Thng Long

T

12345

6

8910111213

14B

Ch thchCng chnh Song chn rc th Mng lng ctSong chn rc tinh B iu ho lu lngB aeroten s dng thit b khuy b mt

khi vo b lng B lng 2B kh trng Nh cha ho chtSn phi bnNh iu khinB cha bn (t trn b mt b iu ho)ng ni b

1

1

1114

2

2

4

3

13

7

8

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66 6

10

n nguyn th hai c cng sut 3000 m3/ngy

nh gi cng ngh v cc yu t cn khc phc nng cao hiu qu lm vic ca trm:Cng ngh aeroten l cng ngh x l nc thi vi sinh truyn thng thng c p dng x l cc loi nc thi n gin nh nc thi sinh hot vi chi ph r! H thng ang ni hot ng tt do m cht lng nc u ra c th t c cht lng mong mun. Tuy nhin cc thng s c bn cha c kim sot thng xuyn v trung tm cha c phng phn tch ti ch.

II.7.2.Trm x l nc thi ca nh my giy Bi Bng: S quy trnh cng ngh:(S quy trnh cng ngh x l nc thi ca nh my giy Bi Bng nh hnh III.8) Thuyt minh s cng ngh:Quy trnh x l nc thi sn xut giy ca nh my c x l qua hai cng on x l ho l v cng on tip theo l x l sinh hc.o Giai on 1: X l ho lV c trng ca nc thi sn xut giy l trong thnh phn ca n cha mt lng x si rt ln v lng x si ny hon ton c th thu hi s dng li. Chnh v vy m trong cng on u tin ca x l nc thi giy ngi ta thng s dng mt s bin php nh: ng keo t, tuyn ni thu hi lng x si ny. Trong cng ngh ny sdng phng php keo t.

- Song chn rc: Nc thi sn xut c dn thng vo h thng, trng hp c s c hoc tu s h thng th nc thi c a vo h d tr bn cnh, hoc trng hp lu

lng qu ln th mt phn nc thi s c bm vo h d tr. Song chn rc c nhim v loi b cc thnh phn chtHnh III.9 C cu co rc

rn c kch thc ln. Rc c co bng h thng c hc v

a vo b cha bng vt ti. on mng dn b sung ho cht: Sau khi qua song chn rc nc thi c dn qua mt on mng m ti y pH c iu chnh bng H2SO4 v NaOH a pH v vng pH ti u cho qu trnh keo t bng phn nhm Al2SO4 l khong 6,5 8 trc khi a vo ngn khuy trn. pH ca nc thi hin ti l 6,8. Khuy trn: Khuy trn bng b cnh khuy nhm phn tn iu ho cht vo nc thi sao cho to c s tipHnh III.10 Khuy trn ho cht

xc ln nht ca phn vi cht bn.

Hnh III.5 S quy trnh cng ngh trm x l nc thi nh my giy Bi BngAl2(SO4)2NaOH H2SO4UrH3PO4Anti foamPolymeNc ra bng tiH d tr

Lm giu bn

Nc Thi sx giy

Trng quay lm kh bn

H thng p bn bng ti

Song chn rc

MngdnKhuy trn

Ngn phn ng

B lng ngang

My nn khB cha bn

NT sau khi qua h thng x l ho l (Keo t)

B cn bng

CH THCH

ng nc

Thp lm mt

B tip xc sinh hc

B aeroten

Bn tun hon

Thp kh kh

B lng bc 2

Vin khoa hc v cng ngh mi trngBo co thc tp tt nghipNghin cu kh mn nc bin bng cng ngh mng thm thu ngcTrang 60 ng ho cht ng bn ng kh

-Phn ng: Nc thi qua ngn phn ngHnh III.11 Ngn phn ngc khuy trn bng b cnh khuy lng quay(theo thit k) nhng hin nay c thay bng b cnh khuy chn vt nhm to ra Gradien vn tc ph hp sao cho qu trnh to bng t hiu qu cao nht qu trnh lng din ra tt. Vch ngn gia b keo t v vng lng c ph b. iu ny c th nh hng khng tt n qu trnh lng v khng c s phn phi n nh dng nc trc khi vo b lng nn vn tc dng vo u b lngqu.Lng: B lng c thit k l b lngngang c h thng ht bn di chuyn dc theo chiu di b v bm ht bn di y b bm vo mng bn phi t trn thnh b. Nc c thu ra nh mng hnh rng ca t cui b.Lm giu v lm kh bn: Bn t mng thu ca b lng chy vo hai b lm giu sau c bm vo h thng lm kh bn bng trng quay. Bn sau khi c lm kh s chuyn sang sn chaHnh III.12 B lng ngang v c cu ht bn bn cho cc c s lm ba cactong. Nc p bnc bm li u vo.o Giai on th hai: X l sinh hcB cn bng: Nc sau khi qua cng on x l ho l c dn vo b cn bng qua mt mng dn c cc vch ngn di dng mng rng ca lm giu oxi. B cn bng c tc dng iu ho lu lng trc khi vo h thng x l sinh hc hiu kh ng thi trong b c b tr 3 Ejector cp kh cho b nhm lm tng DO.Thp lm mt: h nhit ca nc trong h thng s dng cc thp lm mt nh cc qut gi cng sut ln. Nc c bm t b cn bng ln cc mng phn phi i qua lp m bng nha tip xc vi gi c thi t di ln. Dng nc c a vo b cha di thp ri bm qua b tip sc sinh hc (B chn). Bt c hng v a li b cn bng.

rt ln dn n qu trnh lng c th khng hiu

Nghin cu kh mn nc bin bng cng ngh mng thm thu ngcTrang 67Hnh III. 13 S iu khin h thng cho b cn bng, thp lm mt v b tip xc sinh hc

B tip xc sinh hc: Tip xc sinh hc l cng on ht sc quan trng trong qu trnh x l sinh hc bng cng ngh aeroten. ng nh tn gi giai on ny to mi trng thun li nht cho vi sinh vt hot ng v din ra qu trnh oxi ho cng on tip theo (Aeroten). Ti b cn bng, nc c b sung N, P v anti foam (ph bt). ng thi ti y c cp kh nn sc t di y v dng bm khuy trn u nc trong b. Bn tun hon c cng c a vo b ny. S dng b tip xc sinh hc s to s hot ng an ton cho h thng x l sinh hc. B tip xc sinh hc s loib cc vi sinh vt ym kh ng thi to ra mt lng sinh khi tt nht. B aeroten: Sau khi qua b chn nc t chy qua aeroten v qu trnh xi ho sinh hc tip tc din ra. Ti y cc thnh phn c th oxi ho sinh hc c s c oxi ho n cc sn phm cui cng. H thng cp kh: hai b tip xc sinh hc v aeroten c cp kh bng h thng my nn m bo cho DO trong hai b ln hn hoc bng 1,5 mg/L. DO hin ti trong b chn l 1.6 mg/L v trong b aeroten l 1.5 mg/L. Ta thy h thng cp kh c kim sot cht ch v nu DO xung di 1.5 mg/L th vi sinh vt hiu kh b c ch hoc cht. Nhng nu cp kh qu ln s gy lng ph. Tuy nhin theo cc gi tr thc nghim cho thy h thng aeroten lm vic hiu qu th DO ti u thng t 2 4 mg/L.

Hnh III.14 S iu khin v kim sot cho b tip xc sinh hc v aeroten

Thp kh kh: Sau khi ra khi aeroten trong nc thi c c cc kh in hnh l CO2 v mt s kh khc. Cc kh ny cn phi kh v n c tc dng xu n qu trnh lng v bt kh s lm ni bn trong b lng 2. Thp kh kh c thit k nh mt lp m, nc i qua v kh thot ra ngoi. Sau khi qua thp kh kh nc i vo b cha v t chy vo ng trung tm ca b lng. B lng 2: L cng trnh c tnh ton v thit k ht sc cn thn bn lng hiu qu nht. B lng c thit k trong h thng l b lng raial nc t thp kh kh i vo ng phn phi trung tm sau i ra vng lng. Trn b c b tr hai lang cang quay trn quanh b. Bn c ht t y vng lng vo tm b nh s chnh lch p sut, s chnh lch p sut ny c to ra nh b to chn khng. Trn lang cang cn gng cc c cu ph bt. Nc c thu ra khi b lng nh cc ca c b tr theo chu vi b. Ti cc ca thu c b tr cc tm rng ca cho nc i qua nhm tng DO trc khi c bm ra ngun tip nhn. Nc ny c trn ln vi nc thi sinh hot c qua x l n gin bng lng v kh trng s b.

Hnh III.15 S iu khin v kim sot thp kh kh, b lng th cp v bm bn

H thng p bn bng ti: Hai bm ht bn tun hon v b tip xc sinh hc ng thi 1 bm c b tr bm bn vo b cha. Tip theo c bm qua h thng p bn bng ti. Bn sau p c th lm phn vi sinh. Trong qu trnh p bn lm khbn nhanh ngi ta b sung polyme.

Hnh III.16 S iu khin cho b cha bn, v h thng p bn bng ti

nh gi cng ngh v cc yu t cn khc phc nng cao hiu qu lm vic ca trm:-Cc s liu v th tch ca cc cng trnh trong h thng x l:B ng keo t: 7000m3 B cn bng: 6000m3 B chn:1500m3 Aeroten:13000m3B tch bt: 1200m3/hB lng:S = 2500m2 (h = 3.8 t mt nc) B bn V = 400m3-Cc thng s u vo:Lu lng u vo: 500 1000 m3/h Nc thi vo: pH 6 8T = 32 n 45 oCCOD