basic principles of pre-treatment scheme in water treatment system

7/24/2019 Basic Principles of Pre-treatment Scheme in Water Treatment System

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BASIC PRINCIPLES OFBASIC PRINCIPLES OF

PRE-TREATMENT SCHEMEPRE-TREATMENT SCHEMEIN WATER TREATMENTIN WATER TREATMENT

SYSTEMSYSTEM


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INTRODUCTION

PRETREATMENT

The feed water, dependin !n it" "!#r$e, %a& $!ntain'ari!#" $!n$entrati!n" !f "#"pended "!(id" and di""!('ed%atter) S#"pended "!(id" %a& $!n"i"t !f in!rani$ parti$(e",$!((!id" and *i!(!i$a( de*ri" "#$h a" %i$r!!rani"%" anda(ae) +i""!('ed %atter %a& $!n"i"t" !f hih(& "!(#*(e "a(t","#$h a" $h(!ride", and "parin(& "!(#*(e "a(t", "#$h a"$ar*!nate", "#(fate", and "i(i$a) The different pr!$e"" f!r there%!'a( !f 'ari!#" $!n$entrati!n" !f "#"pended "!(id",

in!rani$ parti$(e", $!((!id" and *i!(!i$a( de*ri" i" $a((edPRETREATMENT.

WHY PRETREATMENT REQUIRED?

F!r re%!'a( !f the di""!('ed i%p#ritie" fr!% water%e%*rane "&"te% i" re#ired) S#"pended parti$(e" %a&

"ett(e !n the %e%*rane "#rfa$e, th#" *(!$in feed$hanne(" and in$rea"in fri$ti!n (!""e" .pre""#re dr!p/a$r!"" the "&"te%) soluble salts may precipitate from theconcentrate stream, create scale on the membrane surface,and result in lower water permeability through the ROmembranes (ux decline)


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WATER CHEMISTRY

WATER

INORGANICS ORGANICS

CATIONS ANIONS

BIOLOGICALCHEMICALPHYSICAL

SS

TurbidityO & G

Colour

OdourBOD

COD

TOC

Ca

Mg

Na

Fe

Cl

SO

NO!

HCO!

F

Si

Ba"teria

Algae


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PRETREATMENT PROCESS

Depending on the raw water quality, the pretreatment

process may consists of all or some of the followingtreatment steps:

Remo!al of large particles using a coarse strainer" #ater disinfection with chlorine"

$lari%cation with or without occulation" $lari%cation and hardness reduction using lime treatment" &edia %ltration" Reduction of al'alinity by p adustment" *ddition of scale inhibitor" Reduction of free chlorine using sodium bisul%te or

acti!ated carbon %lters" #ater sterili+ation using - radiation" .inal remo!al of suspended particles using cartridge %lters"


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Stilling Chamber Parshall Flume Flash Mier

!istributi"n Chamber

T" Main Clari#ier Water St"rage Tan$

Slu%ge Pit

Clear Water T" Flash Mier

Thi&$ener

Slu%ge Sum'

Centri#uge

S"li%s Ca$e

Clear Water t" Flash mier

Aerat"r

Slu%ge Trans#er Pum'

Centri#uge #ee% Pum'

Calri#ier()

Calri#ier(*

Thi&$ener+aOCl !"sing

+aOCl !"sing

Alum !"singP"l, !"sing

!e-atering

P"l, !"sing


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REMO#A$ OF S%SENDED ARTIC$ES

There are %i##erent meth"%s #"r rem".al "# sus'en%e% 'arti&les /TSS0 #r"m the

-ater be#"re it enters the main treatment 'lant /!M1RO1et&0

)2 Settling S,stems

/" .iltration 0ystems

0ettling 0ystems1" $lari%er

/" $larioculators

2" 3ube settlers

4" igh Rate 0olid $ontact $lari%er

Filtrati"n s,stem

3 Pressure san% #ilters

3 !ual Me%ia #ilters

3 A&ti.ate% &arb"n #ilters

3 Ir"n Rem".al Filter

3 Mi&r"n &artri%ge #ilters


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TSS AN+ T0RBI+ILY LIMIT FORTSS AN+ T0RBI+ILY LIMIT FOR

MEMBRANE SYSTEMMEMBRANE SYSTEM

3he quality of the feed water is de%ned in terms ofconcentration of suspended particles and saturation le!elsof the sparingly soluble salts" 3he common indicators ofsuspended particles used in the #ater 3reatment industry

are turbidity and 0ilt Density 5ndex (0D5)" 3he maximumlimits are: turbidity of 1 63 and 0D5 of 4"

$ontinuous operation of membrane system with feed waterwhich has turbidity or 0D5 !alues near the limits of these!alues may result in signi%cant membrane fouling"

.or long7term, reliable operation of the &embrane, thea!erage !alues of turbidity and 0D5 in the feed water shouldnot exceed 8"9 63 and /"9 0D5 units, respecti!ely"


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+ESCRIPTION OF CLARIFIER+ESCRIPTION OF CLARIFIER

C(arifier wi(( *e "!(id $!nta$t rea$t!r t&pe with intera( 'aria*(e "peedC(arifier wi(( *e "!(id $!nta$t rea$t!r t&pe with intera( 'aria*(e "peed

i%pe((er t! interna((& re$a($#(ate "(#de water at ad1#"ta*(e rate t!i%pe((er t! interna((& re$a($#(ate "(#de water at ad1#"ta*(e rate t!pr!d#$e $!n"i"tent water #a(it&) The $(arifier #nit wi(( *e $ir$#(ar,pr!d#$e $!n"i"tent water #a(it&) The $(arifier #nit wi(( *e $ir$#(ar,$entra( feed t&pe with rea$ti!n 2!ne 3 $(arifi$ati!n 2!ne in R)C)C)$entra( feed t&pe with rea$ti!n 2!ne 3 $(arifi$ati!n 2!ne in R)C)C)Bride t&pe ar% ra$ %e$hani"% wi(( *e pr!'ided f!r interna( "(#deBride t&pe ar% ra$ %e$hani"% wi(( *e pr!'ided f!r interna( "(#dere$ir$#(ati!n) The *!tt!% !f C(arifier wi(( *e "(!ped t!ward" the $enterre$ir$#(ati!n) The *!tt!% !f C(arifier wi(( *e "(!ped t!ward" the $enter3 %e$hani$a((& dri'en "(#de "$raper and $!((e$t!r "ha(( *e #"ed t!3 %e$hani$a((& dri'en "(#de "$raper and $!((e$t!r "ha(( *e #"ed t!re%!'e the "ett(ed "(#de d!wn "(!ppin *!tt!% t! $enter "(#de area)re%!'e the "ett(ed "(#de d!wn "(!ppin *!tt!% t! $enter "(#de area)The "#ffi$ient detenti!n ti%e and area wi(( pr!'ide t! re%!'eThe "#ffi$ient detenti!n ti%e and area wi(( pr!'ide t! re%!'e

"#"pended "!(id)"#"pended "!(id)

0nderf(!w "(#de fr!% HRSCC, "ti((in $ha%*er and $he%i$a( h!#"e0nderf(!w "(#de fr!% HRSCC, "ti((in $ha%*er and $he%i$a( h!#"ewi(( *e (ed t! $!%%!n "(#de we(() S(#de fr!% HRSCC wi(( *e di"p!"edwi(( *e (ed t! $!%%!n "(#de we(() S(#de fr!% HRSCC wi(( *e di"p!"ed!f *& p#%p t! %e$hani$a( "(#de dewaterin "&"te%)!f *& p#%p t! %e$hani$a( "(#de dewaterin "&"te%)

C(arified water fr!% HRSCC wi(( *e $!((e$ted in $(arified water tan *&C(arified water fr!% HRSCC wi(( *e $!((e$ted in $(arified water tan *&ra'it&)ra'it&)


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+OSIN4 SYSTEM FOR PRETREATMENT+OSIN4 SYSTEM FOR PRETREATMENT

5 C!a#(ati!n +!"in "&"te% 6The Water $!ntain" "#"pended

%atter", $!((!ida( "i(i$a 3 t#r*idit& in 'ar&in pr!p!rti!n) A$!a#(ant (ie Ferri$ $h(!ride, A(#% !r e#i'a(ent i" d!"ed f!r$!a#(ati!n p#rp!"e) +#e t! effe$t !f $!a#(ant, hea'& f(!$"are f!r%ed whi$h trap the %in#te t#r*id parti$(e" and#ndi""!('ed "#"pended parti$(e" whi$h !therwi"e w!#(d ha'e

pa""ed thr!#h the fi(terin %edia) Th#" $!a#(ant" aid in*etter fi(trati!n) +!"ae rate !f C!a#(ant +!"in i" de$idedafter $!nd#$tin 7ar te"t at "ite)

.locculation Dosing system :olyelectrolyte helps in better

.locculation due to its special characteristic of absorbingmicron si+e particle and to form a hea!y oc" urpose ofpro!iding polyelectrolyte dosing after coagulant dosing is toachie!e better .iltration to ma'e e;uent as clear as possible"


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5 Ch(!rinati!n +!"in "&"te% 6Sin$e the water %a& $!ntain!rani$", (i'in %i$r! !rani"% and ir!n whi$h are %!"t#nde"ira*(e a" it %a& $a#"e ir!n f!#(in, *i!-!rani$ f!#(inin re"in" and RO %e%*rane")T! !8idi2e the ir!n, di"infe$tthe raw water and t! *rea the !rani$", "!di#%h&p!$h(!rite "!(#ti!n d!"ed in the rane !f 9): - ;): pp%)It f!r%" h&p!$h(!r!#" a$id 3 (i*erate" free $h(!rine whi$h!8idi2e" the di'a(ent Fe i!n", i((" %i$r! !rani"%" and*rea" (!n $hain p!(&%er" !f !rani$")

5 +e-$h(!rinati!n +!"in "&"te% 6Free $h(!rine if pre"ent inthe water %a& pr!'e t! *e in1#ri!#" t! the RO %e%*rane")Hen$e it i" 'er& e""entia( t! +e-$h(!rinate the water in thepretreat%ent !f RO S&"te%)


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FILTRATION SYSTEM

Fi(trati!n !f water f!r re%!'a( !f "#"pended i%p#ritie" i" a intera( "tep in the treat%ent"$he%e f!r 'ari!#" app(i$ati!n) Fi(trati!n i" a("! an i%p!rtant pretreat%ent "tep f!r"!ftener", de%inera(i2ati!n and re'er"e !"%!"i" "&"te%) F!r pr!te$tin the i!n e8$hanere"in, $artride fi(ter 3 re'er"e !"%!"i" %e%*rane d#e t! "#"pended i%p#ritie" pre"ent inwater 3 "&"te% effe$ti'ene"" f!r "#$h ind !f pretreat%ent)

PSF (Pressure Sand Fi!er" # 0"ed f!r re%!'a( !f "#"pended parti$(e" 3 S+I) The %i8ed"and 3 different rade !f pe**(e" i" #"ed f!r thi" fi(trati!n) PSF re#ire" peri!di$*a$wa"hin t! e(i%inate a$$#%#(ate "#"pended %atter" and rerade the fi(ter *ed) Whenthe fi(ter *ed (!""e" the $apa$it& t! re%!'e the "#"pended parti$(e", the *ed %#"t *ere#ire *a$wa"hin) The end pr!d#$t i" $(ean water with n! !*1e$ti!na*(e "#"pended%atter)

)? @ 9 Media 6 4raded "and Pe**(e"

DMF (Dua Media Fi!er" #Thi" "&"te% i" #"ed f!r Hiher "#"pended %atter", ta"te, and!d!r, ) The end pr!d#$t i" $(ean water with n! !*1e$ti!na*(e ta"te 3 "#"pended %atter")


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IRF (Ir'n re'%a Fi!er" # 0"ed f!r Ir!n re%!'a( 3 "#"pendedparti$(e" ) The %i8ed "and 3 different rade !f pe**(e" MnO9i"

#"ed f!r thi" fi(trati!n)

-elocity (m2


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SOME WATER PROBLEMS, CAUSES AND CURESRO@AB&RO@AB& 0C&3O&0C&3O& $*0B$*0B 3RB*3&B633RB*3&B63

ardnessardness 0oap curd lime scum0oap curd lime scum

in bathy, white scale inin bathy, white scale in

pipespipes

Bxcessi!eBxcessi!e

magnesium magnesium

calcium saltscalcium salts

#ater softener (cationic#ater softener (cationic

ion exchanger)ion exchanger)

OdorOdor

>rassy or musty>rassy or musty Organic matterOrganic matter *cti!ated carbon*cti!ated carbon

$hlorine$hlorine Bxcessi!eBxcessi!e

chlorinationchlorination*cti!ated carbon*cti!ated carbon

Rotten eggRotten egg ydrogen sul%deydrogen sul%de &anganese greensand,&anganese greensand,

chlorination, aerationchlorination, aeration0ulfate bacteria0ulfate bacteria Disinfect pipe systemDisinfect pipe system

$hemical (phenol)$hemical (phenol) 5ndustrial waste5ndustrial waste

seeping intoseeping intowater supplywater supply

0top seepage, use0top seepage, use

acti!ated carbonacti!ated carbon

3aste3aste

0alty or brac'ish0alty or brac'ish igh sodium origh sodium or

magnesiummagnesiumcontentcontent

$ation


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RO@AB&RO@AB& 0C&3O&0C&3O& $*0B$*0B 3RB*3&B633RB*3&B63

3urbidity3urbidity &ud, silt clay&ud, silt clay 0uspended matter in0uspended matter in

water supplywater supply.iltration.iltration

*cid water*cid water >reen stains on>reen stains on

plumbing %xturesplumbing %xturesAow p reacting withAow p reacting with

copper brasscopper brass

piping, %ttingspiping, %ttings

*cid neutrali+ation*cid neutrali+ation

Red waterRed water

0trains dishes and0trains dishes andlaundrylaundry

Dissol!ed ironDissol!ed iron Oxidation and %ltrationOxidation and %ltration

Red sedimentRed sedimentwhen water is leftwhen water is leftstandingstanding

recipitated ironrecipitated iron .iltration.iltration

Red color e!enRed color e!en

after standing forafter standing for

/4 hours/4 hours

$olloidal iron$olloidal iron Oxidation %ltrationOxidation %ltration

ea!y metalsea!y metals 6o color, taste or6o color, taste orodor signs"odor signs"

ossible healthossible health

eEectseEects

5ndustrial waste5ndustrial wastepollution, corrosionpollution, corrosion

productsproducts

0oftening, deioni+ation,0oftening, deioni+ation,re!erse osmosisre!erse osmosis

SOME WATER PRO*LEMS+ CAUSES AND CURES


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3*6F CO3*6F CO

basic principles of pre-treatment scheme in water treatment system

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