Keo tu tao bong

7/31/2019 Keo tu tao bong

1/23

KEO T - TO BNG

Coagulation - Flocculation

Gii thiu chung loi b cht rn l lng (SS SuspendedSolid) trong nc/nc thi

Lng (Sedimentation)

S- khi lng ring ca ht (kg/m3)

L- khi lng ring ca cht lng (kg/m3)

d - kch thc ca ht (m)

- nht ng lc hc (kg/ms)

vg

dS S L= 18

2

( )


2/23

S lin h gia kch thc ht v thi gian lng

20 nmHt keo10-5

2 nmHt keo10-4

8 ngyVi khun10-3

2 git st10-2

2 phtCt mn10-1

10 giyCt1

1giySi10

Thi gian lng( su 1m)

Loi htKch thc ht(mm)

Gii thiu chung (tt) Tuyn ni (Flotation)

Bt kh c thm vo

Cc cht rn l lng s bm vo b mtca bt kh v ni ln

Lc (Filtration)

Ch hiu qu khi kch thc ht > 1m

Phi gim hm lng SS trnh nghnct lc

Keo t to bng (Coagulation Flocculation)


3/23

Keo t to bng

Mc ch: tch cc ht cn c kch thc0,001m < < 1m, kh tch loi c bngcc qu trnh l hc thng thng nh lng,lc, tuyn ni.

Ht keo: 2 dng chnh Keo k nc: t st, oxit kim loi,

Khng c i lc vi mt nc D keo t a s l nhng ht keo v c

Keo a nc: proteins, polymers,

Th hin i lc vi nc Hp th nc v lm chm qt keo t a s l nhng ht keo hu c

c tnh ca ht keo Kh nng lng rt chm (chuyn ng Brown

gy cn tr qt lng do trng lc)

L tc nhn gy nhim nc e.g tng c (turbidity)

c tnh b mt (in th ,) l yu t quantrng (surface properties)

C xu hng kt hp vi cc cht t mi trngxung quanh (t l din tch b mt:khi lng caohn)

C xu hng tng in tch


4/23

Cu to ht keo

Lc tng tc gia cc ht


5/23

H keo Khi cc ht keo tip xc vi nhau, chng to

thnh cc ht c kch thc ln hn, to bngv kt ta

Lc gia cc ht keo: lc ht v lc y tnhin hoc lc Van der Waals

ln: t l nghch vi khong cch gia ccht

Kh nng n nh ht keo l kt qu tng hp

Fh v F

in th zta < 0,03V Fh thng F. Khi 0th qu trnh keo t cng t hiu qu

S

n

nh h

keo v gi tr


6/23

Nng lng tng tc ca h keo

Cch qt keo t to bng Qt nn lp in tch kp, gim th in ng

zta nh ion tri du

Qu trnh keo t do hp ph ion tri du trnb mt, trung ha in tch to ra im ngin = 0

C ch hp ph - to cu ni

Cc polymer c th ion ha, nh cu trcmch di chng to cu ni gia cc ht keoqua cc bc: Phn tn polymer

Vn chuyn polymern b mt ht

Hp ph polymer ln b mt ht

Lk gia cc ht hp ph polymer vi nhau hoc vi cc ht khc

Qt keo t hp ph cng lng trong qt lng


7/23

Cch (tt)

Trung ha in tch S hp ph cc cht mang in tch tri du vi cc

ht keo

Gim th in th b mt v lm mt n nh h

keo

Hm lng cht keo t tng nng ht keo tng

Qu nhiu cht keo t ti n nh h keo

Qt keo t - hp ph cng lng trong qt lng

Phn nhmPhn st

pH Al(OH)3Fe(OH)3

Cch to cu ni Phn ng 1: phn t polymer kt dnh vi ht keo

(tch in tri du)

Phn ng 2: phn cn li ca polymer trn linkt vi nhng v tr hot tnh trn b mt cc htkeo khc


8/23

Cch to cu ni (tt) Phn ng 3: hin tng ti bn ht keo

Phn ng 4: nu qu tha polymer

C

ch

to c

u n

i (tt)

Phn ng 5: nu khuy trn qu mnhhoc qu lu, lk gia ht keo v polymers b ph v

Phn ng 6: ti bn ht keo


9/23

Cht keo t (Coagulant)

Thng s dng trong x l nc v nc

thi: Fe(III) v Al(III)

FeCl3

Alum

R, ph thuc ln vo pH

Ha hc ca cht keo t C Al3+ v Fe3+ u p/ mnh vi nc

cc hydroxide kt ta

Al3+ + 3H2O Al(OH)3 + 3H+

Fe3+ + 3H2O Fe(OH)3 + 3H+

pH cao:

Al(OH)3 + OH- Al(OH)4-

Fe(OH)3 + OH- Fe(OH)4-


10/23

Cht keo t - Alum

To thnh t qung Bauxit ha tan trong

H2SO4

Dung dch to thnh c loi b tp cht,

trung ha, cho bay hi to thnh cc ming

Nhm Sulfate

C mu xm hoc trng vng (ty vo hm

lng tp cht)

Cng thc: Al2(SO4)3(H2O)n (n = 0,6,10,16,18

v 27)

Alum (tt)Alum ha tan v p/ vi kim trong nc

Al2(SO4)3(H2O)n + HCO3- Al(OH)3 + CO2

+ SO42- + H2O

Kt ta Al(OH)3 mu trng

CO2 to thnh dng bt kh trong nc v bm

trn thnh cc th nghim Jar Test

SO42- tn ti trong nc

1g Alum tiu th ht 0,5g kim


11/23

Alum (tt)

pH < 4

pH = 4,5 5

AlOH2+, Al8(OH)204+

pH > 9,5: Al(OH)4-

pH = 5 9: nhiu dng ktta, ch yu Al(OH)3

Alum (tt)

Nu s keo t (bng Alum) trong vng ti n nh(restabilization):

Tng hm lng Alum s dng thot khi mino ngc in tch

Tng nng SO42-

Thm dd vi tng pH, chuyn sang pha bn phivng ti n nh

Thm cht to bng kt bng cc keo mang in

dng Thm cht keo t mang in m (bentonite, silica

hot tnh) gim in tch dng ca ht keo to bng

trng lng ht keo tng tng vn tc lng


12/23

Hp cht Fe

3 dng mui st ch yu thng gp trongx l nc:

FeCl3.6H2O : Ferric chloride

Fe2(SO4)3(H2O)9 : Ferric sulfate

FeSO4(H2O)7 : Ferrous sulfate

Fe2+ thng kt ta di dng Fe(OH)2 vFeCO3

kim nc t nhin: ch yu HCO3-

thm vi voFe2+ + HCO3- + OH- FeCO3 + H2O

Hp ch

t Fe (III)

Fe2(SO4)3.nH2O OXH FeSO4 bng HNO3

n: 0, 3, 6, 7, 10 v 12

FeCl3.nH2O cho HCl p/ vi Fe, Fe2(CO3)2hoc Fe2O3.

n: 6 (ch yu); 2; 2,5 v 3,5

Cc dng khc Fe(OH)2+

Fe(OH)4-


13/23

M hnh Jar Test


14/23

Jar Test (tt)

Mc ch: xc nh hm lng cht keo t thch hp Tin trnh th nghim

Ly th tch mu xc nh

Thm vo cht keo t vi hm lng tng dn

Khuy trn nhanh trong (3 pht), sau khuychm trong (12 pht), lng

o c ca mu

nh gi hiu sut ca qu trnh keo t to bng

Vn tc lng c

Th tch phn cn lng

Jar Test (tt)Nu khng xy ra keo t, hoc bng cn to thnh

khng thch hp

S dng hm lng cht keo t ln hn

Kim tra kim ca nc thi u vo (thm Soda)

Nhit ca nc thp p/ keo t khng xy ra

Jar Test: nh gi hiu qu ca cc cht keo t khc

nhau

Kh nng x l mu, mi v sn phm phca qu trnh kh trng


15/23

Jar Test

Mt s cht keo t v c


16/23

ng hc qt keo t to bng

Qt keo t: l thuyt v s ph bn ht keo

Qt to bng: s tip xc gia cc ht keo bph bn, theo cc c ch sau

Tip xc do chuyn ng nhit

Chuyn ng Brown/s khuych tn, to thnh cc ht 1m

Perikinetic flocculation

Tip xc t s chuyn ng ca lu cht

Gy ra bi qt khuy trn lu cht

Orthokinetic flocculation

Tip xc do qu trnh lng ca cc ht

ng h

c qt keo t

to bng (tt)

Ht c kch thc nh: ch yu l perikinetic

flocculation

Nu =1m v G=10s-1 th Jok=Jpk

Cc ht c xu hng kt hp to thnh ht

c kch thc 1m bng chuyn ng Brown

(perikinetic flocculation) khuy trn duy

tr tip tc s keo t to bng (orthokineticflocculation)

c tng gi tr G ti u gim


17/23

Perikinetic flocculation

Jpk - tc thay i nng cc ht keo theo thi gian doPerikinetic flocculation

N0 - nng cc ht l lng ti thi im t

- h s hiu qu ca s va chm (tip xc)

k - hng s Boltzman

T nhit tuyt i

- nht ca cht lng

Tc qu trnh Perikinetic flocculation khng ph thuckch thc ht

Jpk t l thun vi nng cc ht l lng

J dNdt

k T Npk = =0

02

43. . .

..( )

Orthokinetic flocculation

d - ng knh ca ht

G - gradient vn tc, ph thuc vo

Thnh phn ha hc ca nc

Bn cht v nng keo trong nc

J pk J d tok . 2

0

3

0 ).(3

...2N

dG

dt

dNJOK

==


18/23

Gi tr G v t G v t ti u ph thuc vo

Thnh phn ha hc ca nc

Bn cht v nng ca bng cn

G ti u gim khi c tng

G qu cao cn b v

t qu cao cn b n mn

Qu trnh to bng:

Ban u, bng cn c to thnh vi gi tr Gcao

Khi bng cn ln dn, gim dn G trnh lmv bng cn

Gi tr G v t


19/23

Cht to bng (Flocculant)

Nng cn thp:

Cn s dng cht keo t vi hm lng cao

Bng cn to thnh nh, d v v lng chm

Cht to bng

S dng tng c tnh ca bng cn (tnh bn,

kh nng lng,)

Silica hot tnh

Bentonite

Vi

polymers

Cht t

o bng vai tr

Thay i pH thay i in tch b mt htkeo

To kim thch hp cho qt keo t

Gim in tch b mt (bng cch hp phtrn b mt ht keo) thot khi vng tin nh ht keo

To cu ni gia cc ht keo to bngcn

Tng bn ca bng cn

Tng nng cc phn t trong dung dch

Tng trng lng ca bng cn


20/23

Polymers

Polymer hu c

Khi lng phn t ln, mch di

Polymer t nhin: hiu qu thp

Polymer tng hp: hiu qu cao hn

Polymer tng hp

C th cha cc nhm mang in Thng s dng trong cc nh my x l nc,

nc thi

Thit b ca qu trnh keo t Trung ha, lm mt n nh cc ht keo

Cht phn ng c khuch tn vo dungdch cng nhanh cng tt

Th tch cht phn ng c thm vo rtnh so vi th tch dung dch cn x l

Thit b khuy trn phi m bo: Gy xo trn thch hp

Phn tn nhanh cc cht phn ng vo dung dch


21/23

My trn tnh (Static Mixers)

My trn tnh (tt) Khng c cc phn linh ng d bo dng

v sa cha

Mng chn, li,c lp pha trong ngng to s xo trn cn thit khuch tncht keo t

Nhc im

Tn tht ct p ln

Khng ph hp khi lu lng dng chy gim


22/23

My trn kh nn (Pneumatic Mixers) Kh nn c s dng nh 1 thit

b khuy trn, c a vo thngqua my khuch tn

Khi bt kh ni ln gy s xotrn

Mc xo trn c iu chnhbi loi my khuch tn v p sut

Nhc im

Cc bng cn c th bm vo bt kh gycn tr qu trnh lng ca bng cn

My trn chc (Mechanical Mixers)

S xo trn c to ra do ng c turbin/chn vt/micho,quay

Tiu hao nhiu nng lng chi ph vn hnh v bodng cao

Lin tc hoc gin on


23/23

Quy trnh cng ngh x l nc thiKCN L Minh Xun

t

Screenings

p bn

To bng B keo t B chnhpH

Treated water

H thu

B iu ha

Song chn rc

B lng 1

B trung ha AerotankB lng 2

B kh trng

NaOHPACAnionic polymer

HCl

Cationicpolymer

Nc Javel

PAC

Anionic polymer

NaOH

HCl

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