Документ взят из кэша поисковой машины. Адрес оригинального документа : http://chem.msu.ru/rus/journals/membranes/17/html/mb_174.pdf Дата изменения: Mon Feb 13 17:55:22 2006 Дата индексирования: Mon Apr 11 05:31:52 2016 Кодировка:

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, , . , . . - . . , . , .. , , , - . , : Silt Density Index (SDI) - - , ; Permanganate Demand (PD) - , . , LSI SDSI ­ . . , 1,13. . : , , , , SDI, PD, LSI, SDSI ­ . One of main factors of the efficiency of membrane water purification systems is a feedwater quality. This factor is used for calculation of pretreatment and membrane unites, and operational parameters of water purification systems. Poor feedwater quality is a main cause of membrane fouling. Membrane fouling is a complex phenomenon. Gel layer formation or dissolved substances accumulation increase osmotic pressure and decrease permeate stream. Therefore the important factor of designing membrane installations is development of the authentic correlations, determining decrease of membranes capacity during operation. These correlations have been determined experimentally, since mathematical modelling of fouling formation is impossible because multifactor of the reasons. In practice of membrane water purification systems designing the greatest application was received two ways of feedwater testing with purpose of determines prerequisite for scale formation. Silt Density Index (SDI) the index of density weighed particles in unit of volume of water - determines decrease of membranes capacity due to formation on their surface weighed and colloid particles; Permanganate Demand (PD) - an index permanganate oxidability, determining influence of organics in feedwater on membranes fouling. One more reason of membranes fouling is calcium carbonate scale formationon on membrane surface, which can be supervised by means of LSI and SDSI - indexis Concentration polarization also is the reason of scaling and membrane fouling. It is experimentally determined, that oncentration polarization value for last membranes module should not exceed 1,13. Unique reliable way of minimization or exception of membranes fouling is careful pretreatment of feedwater. Key words: water, reverse osmosis, membranes fouling, oncentration polarization, SDI, PD, LSI, SDSI ­ indexis.

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, , . , . , , , .. , , «». , . , , , . , , . : : , , , ( ); , , ( );

( ); , , , ( ). - , .. , , . - . . 10 ( ) . , , , .. , . , . , .. , , - . , : Silt Density Index (SDI) - 23

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, ; Permanganate Demand (PD) - . SDI ­ , , . ASTM D-418982 /1/, 0,45 2 (30 psi). 0,45 , 0,45 . SDI- : ­ (c.) 500 (t1); ­ () 500 (t2), 5 - 15 , .
t - 100 в 1 - 1 t 2 SDI = T

, ; ; 30 psi.
SDI - : SDI 5 175 SDI 2 5

T - . 0,45 500 . ( 5 ) . (1 ­ t1/t2) 0,75, , T . , : , , ; 24

SDI ­ 500. SDI . SDI . SDI , , . , , SDI . , 1 ppm. SDI . SDI : ­ 5; ­ 18. SDI , .. SDI. SDI . PD ­ . PD - . PD - . . © , 2003

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..

- = 522 nm, - = 426 nm, 100 /. Mn04-, , , . . , PD- . :

, R. 2++32-=3; R=(2+)(32-); , , , ~ 0,05%. 2+2=2
3

= mx+b
m -
m = - 0 , 01191 - 2 , 6 x в 104 P

: 23=++3-; 3-=++32

k

D1

=

(H )(HCO )
+ - 3

H 2 CO

3
-

P - PD (/); Y - (/ 2 ); - , Y (); b - (/2 ). , . : ; , PD ­ ; = 275 nm - . LSI ­ (Langelier Saturatuion Index; ) /1,2/. , ,
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k

D

2

=

(H )(CO )
+ 2 3

HCO

2 3

-

: 2/3 : 3+2+2=(3)2; : 3++=2++3 :

KP =

(Ca )(HCO )
2
+

- 3

H

+

3 : KP=KR/kD2 , : (+)=(2+)(3-)вkD2/R , : log(H+) = -log(2+) ­ log(3-) - log(kD2/R) ; ; Alk: = -log(+); = - log(2+); 25

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: ps=+Alk+log(R/kD2); Alk = - log(3-); LSI ­ : LSI = pH. ­
.

, , . ; , ( ­ ) . pH , - ; , , ; , . . LSI - TDS ( ) 10 /. LSI TDS, , , pH, . LSI - , . - , , C2. , , .

LSI - , .. kD2. LSI - , , , , , , , , . LSI - - . LSI - . LSI , ­ , . , LSI ­ 0,5. LSI - , LSI 0,5 2,0 10 - 20 . , , /2/: 2++23-+2++SO42-=2H2O+2CO2+SO42 : 26

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LSI , : ; . pH , TDS ; (HCl, H2SO4). TDS . LSI ­ , . LSI ­ TDS 4000 /, SDSI . SDSI (Stiff and Davis) ­ , /1/. SDSI = pH.-pH
.

. 1.

, -, lk , . 2.

H. ­ ( ); pH. ­ ; H.=+lk+k = - log(2+), 2+ ­ ppm 3 lk = - log(3-), 3- ­ ppm 3-; k ­ , . H. , .1, .

. 2. lk : 2+ 3- ppm ppm CaCO3. : 3 + 3 = в 2 (2+)=470 ppm:



(

)



­ . (2+) ppm 3: 3=2,5в470=1,175 (3-)=126 ppm:

3 =





3 - 3

2

в 3-

(

)



(3-) ppm 3: 3=100/122в126=103.

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: I = 1/2mizi
2

I ­ ; mi ­ (1-/1000 ); zi ­ i- . :

mi =

Ci 106 - TDS 1000 M Wi в 106



. 3. SDSI ­


i ­ i- , ppm (ppm / , ); MWi ­ i- ; TDSf ­ , ppm. ppm ­ ; /, ; , , ; : I


= I/(1­Y),

I I ­ , ; Y ­ . I SDSI - , . 3. : SDSI=+lk+k. R- 28

. , . . , . , . , . . - ( ), , . . . , , , . ( ), . , , - . , .
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, , . , , , . , , . .. , ­ , . , , , . (). :

, ; R , . , , . R ; R 1,13. , . . . SDI PD - . . pH LSI ­ . . - . , , .
1. 2. ASTM.D-3739-94; D-4189-94. The American Society for Tasting and Materials, USA, (1994) . 116 - 134. ., .., .. . // , .14, 9, (1992), . 700 ­ 706.

2Q p R = eвk в Q f + Qb
k - , ( ); Qp - ; Qf - ; Qb - , . / ( ), R , .. , . R : R , . , -

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