Filtration

Filtration Theory On removing little particle !ith big  particle

School of Civil and

Filtration O"tline  Filter

galore

 #ange

 $article

of applicability

Capt"re

 Filter  #apid  Slo!  '(ioSand)

theory  Tranport

 $ot

 %imenional &nalyi

 #o"ghing

 Model

 M"ltitage

prediction

Filtration

Filtration O"tline  Filter

galore

 #ange

 $article

of applicability

Capt"re

 Filter  #apid  Slo!  '(ioSand)

theory  Tranport

 $ot

 %imenional &nalyi

 #o"ghing

 Model

 M"ltitage

prediction

Filtration

Filter *alore Slo! Sand #apid Sand

Cartridge

(ag

$ot '(io) Sand

%iatomaceo" earth filter  Candle

#o"gh

Categori+ing Filter  Straining  $article

to be removed are larger than the pore i+e  Clog rapidly  %epth

Filtration

 $article

to be removed may be m"ch maller than the

 pore i+e  #e,"ire attachment  Can handle more olid before developing eceive head lo  Filtration model coming

&ll filter remove more particle near the filter inlet

The 'if it i dirty/ filter it) Myth  The

common miconception i that if the !ater i dirty then yo" y o" ho"ld filter it to clean it

 ("t

filter can0t handle very dirty !ater !itho"t clogging ,"ickly

Filter range of applicability 1

1

12  3T4 122

SSF

12

122 1k  people

#SF5 %E

12k

  122k 

Cartridge (ag

$ot Candle

%eveloping a Filtration Model  6!aaki

7189:; developed relationhip decribing the performance of deep bed filter. C z  dC   C   dC  dC  λ  < − dz  < − λ 2C  − ln    attractionG  Modeler

have not "cceeded in decribing filter performance !hen electrotatic rep"lion i ignificant  Model tend to predict no particle removal if electrotatic rep"lion i ignificant.  Electrotatic rep"lion>attraction i only effective at very hort ditance and th" i involved in attachment/ not tranport

*eometric $arameter  What

are the length cale that are related to  particle capt"re by a filterG  HHHHHHHHHHHHHH  Filter depth 7+;  HHHHHHHHHHHHHHHHHHHHHHHHHH  Collector diameter 7media i+e; 7d c;  HHHHHHHHHHHHHH  $article diameter 7d p; $oroity

 Create

dimenionle gro"p

Chooe

Π " =

d  p d 

7void vol"me>filter vol"me; 7 ε;

7dc; the repeating length HHHHHHHH 

Π z  =

 z  d 

 3"mber of collectorK

Π .+ :=

9 ⋅( 1 − ε ) B ⋅ln7 12;

⋅

+ d.c

 

Write the f"nctional relationhip     o     i   o  t   i   a  t  r  a  r   h  t  e  r c  n g   e  o   F   L  pC A = f  ( Π " / Π z / ε / Π g / Π (r  )

do"ble 6f !e do"ble depth of filter !hat doe pC* doG HHHHHHHHHHH   pC A = Π z f  ( Π " / ε / Π g / Π (r  )

Io! do !e get more detail on thi f"nctional relationhipG Empirical mea"rement  3"merical model

 3"merical Model  TraPectory

analyi

&

erie of modeling attempt !ith refinement over the pat decade

 (egan

!ith a 'ingle collector) model that modeled London and electrotatic force a an attachment efficiency term 7 α;

 pC A

 n  n   o   i   o  t  t  i  n t a  o n  p  e   i  c   i m e    "    r   e   6 n t  S e d   %  i ff

Π f  ( Π Π Π

)

Filtration Model 1 9

&.

γ ( ε ) := ( 1 − ε )  O B ⋅( 1 − γ ( ε ) ) ( ) ε :=

⋅ ( ε) B − 9 γ

Π .# ( d.p) := Π

 D

+ 9 γ ⋅ ( ε ) − B γ ⋅ ( ε)

*eometry

d.p d.c

9 ⋅( 1 − ε ) .+ := B ⋅ln7 12;

Π .(r ( d.p) :=

 O

$oroity



+

⋅

 

d.c

k .b ⋅T 9 π ⋅ ⋅µ ⋅d.p ⋅J.a ⋅d.c

B

Π .g( d.p) :=

d.p

Force ratio ⋅( ρ .p − ρ .!) ⋅g 1 µ ⋅ ⋅J.a

Tranport E,"ation 1

9

9

η (r ( d p) := ⋅& ( ε ) ⋅Π # ( d p)

−



η # ( d p) :=

1 B1.

⋅& ( ε ) ⋅Π # ( d p)

1 D

B

⋅Π (r ( d p)

1.B

9

(ro!nian motion 6nterception

η g( d p) := 2.91 Π ⋅ g( d p)

*ravity

η ( d p) := η (r ( d p) + η # ( d p) + η g( d p) Tranport i additive

Total i "m of part

( ) := Π .+⋅ α ⋅η ( d.p)

 pC d.p

Filtration Technologie  Slo!

7FilterQEnglihQSlo! andQ'(ioand);

 Firt

filter "ed for m"nicipal !ater treatment  Were "nable to treat the t"rbid !ater of the Ohio and Miiippi #iver  Can be "ed after #o"ghing filter  #apid

7MechanicalQ&mericanQ#apid and;

 4ed

in Conventional Water Treatment Facilitie  4ed after coag"lation>flocc"lation>edimentation  Iigh flo! rateQclog dailyQhydra"lic cleaning  Ceramic

#apid Sand Filter 7Conventional 4S Treatment;

Size (mm)

Anthracite Infuent

Drain Euent

Sand Gravel

!"

S&eci'c De&th Gravit (cm) !%

+

!#$ - !$$ *!%$

#$

*!%$

#$

$ - %

Wash water

Filter %eign  Filter

media

 ilica

and and anthracite coal

 non-"niform

media !ill tratify !ith HHHHHHH maller particle

at the top  Flo!  D2

rate - B2 m>day

 (ack!ah  et

Compare !ith edimentation

rate

to obtain a bed poroity of 2.D to 2.:2

 typically

1B22 m>day

(ack!ah  Wah

!ater i treated !aterK

Anthracite Infuent

Drain Euent

Sand

 WIRG

Only clean !ater ho"ld ever be on  bottom of filterK

Gravel Wash water

#apid Sand predicted performance ρ p := 122 Ja

:= 

kg

(ro!nian 6nterception *ravity Total

9

m

m hr 

T := B89N   + := cm dc

122

:= 2.mm

   A    C   p      a    l   a   v   o   m   e   r   e    l   c    i    t   r   a    $

12

1

α := 1 ε := 2.

2.1 2.1

 3ot very good at removing particle that

1

12

$article %iameter 7µm;

122

Slo! Sand Filtration  Firt

filter to be "ed on a !idepread bai  Fine and !ith an effective i+e of 2.B mm  Lo! flo! rate 7B.-12 m>day; Compare !ith edimentation  Schm"t+decke 7HHHHH filter cake HHHH; form on top of the filter   ca"e

high head lo  m"t be removed periodically  4ed

!itho"t coag"lation>flocc"lationK  T"rbidity ho"ld al!ay be le than 2 3T4 !ith a m"ch lo!er average to prevent rapid clogging

Slo! Sand Filtration Mechanim  $roto+oan

predator 7only effective for bacteria removal/ not vir" or proto+oan removal;  &l"min"m 7nat"ral ticky coating;  &ttachment to previo"ly removed particle  3o evidence of removal by  biofilm

Typical $erformance of SSF Fed Cay"ga Lake Water     i    l   o   t   c   n  #   e   "    E   l

1

   t    f   n   f   e   e   "   e    l    f    h   n   t    i   n    f    i   o   g   n   n   i   o   n 2.1    i    t    i   c   a   a   r   m    F   e   r 2.2

2

1

B 9 Time 7day;



 7%aily ample;

Filter performance doen0t improve if the filter only receive ditilled !ater 

$article #emoval by Si+e 1 control      e    l   c   t    i    t   r   n   a   e   " 2.1   p   l    t    f   n   f   e   e   "   e    l    f    h   n   t    i   n    f    i   o   g   n 2.21   n   i   o   n    i    t    i   c   a   a   r   m    F   e   r

9 mM a+ide

Effect of the Chryophyte What i the phyicalchemical mechanimG

2.221 2.

1

$article diameter 7m;

12

Techni,"e to 6ncreae $article &ttachment Efficiency  Make

the particle tickier 

The

techni,"e "ed in conventional !ater treatment plant

Control

coag"lant doe and other coag"lant aid 7cationic polymer;

 Make

the filter media tickier 

(iofilm Mytery

in lo! and filterG

ticky agent preent in "rface !ater that i imported into lo! and filterG

Cay"ga Lake Seton Etract  Concentrate  &cidify

particle from Cay"ga Lake

!ith 1 3 ICl

 Centrif"ge  Centrate

contain polymer 

 3e"trali+e

to form floc

Seton Etract &nalyi I discovered aluminum!

carbon 1D

Io! m"ch &l"min"m ho"ld be added

filterG

 E# coli #emoval a a F"nction of Time and &l &pplication #ate 20 cm deep filter columns

 3o E. coli detected mmol Al  m B ×d

%$ pCA i proportional to acc"m"lated ma of &l"min"m in filter 

Slo! Sand Filtration $rediction ρ p := 122 Ja

:= 12

kg

hr 

+ := 122cm

(ro!nian 6nterception *ravity Total

9

m cm

T := B89N  

dc

1222

   A    C   p      a    l   a   v   o   m   e   r   e    l   c    i    t   r   a    $

122

:= 2.Bmm

α := 1 ε := 2.

12 2.1

1

12

$article %iameter 7µm;

122

Io! deep m"t a filter 7SSF; be to remove 88.8888 of bacteriaG  &"me

α i 1 and d c i 2.B

mm/ J2 < 12 cm>hr  D  pC ( 1µm)  pC * i HHHH  B9 cm for pCA of D  + i HHHHHHHHHHHHHHHH   What

=

B.:28 for  of 1 m

doe thi meanG

S"gget that the B2 cm deep eperimental filter !a operating at theoretical limit Typical SSF performance i 8 bacteria removal Only abo"t  cm of the filter are doing anythingK

Iead Lo $rod"ced by &l"min"m

mmol Al  m B ⋅ d

%$mmol Al  mB

&l"min"m feed method  &l"m

m"t be diolved "ntil it i blended !ith the main filter feed above the filter col"mn  &l"m floc are ineffective at enhancing filter performance  The diff"ion dilemma 7al"m microfloc !ill diff"e efficiently and be removed at the top of the filter; 122

   A    C  pC  d $e  p   p      a    l  pC#  d p   a   v   o   m pCg  d p   e   r   e  pC d    l   c  p    i    t   r   a    $

( )

( )

( )

12

( )

1 21

1

12

$erformance %eterioration after &l feed topG  Iypothee %ecay

!ith time Site are "ed "p Wahe o"t of filter   #eearch  3ot

re"lt

yet clear !hich mechanim i reponible U f"rther teting re,"ired

Sticky Media v. Sticky $article  Sticky

Media

 $otentially

treat filter media at the beginning of each filter r"n

 3o

need to add coag"lant to !ater for lo! t"rbidity !ater

 Filter

!ill capt"re  particle m"ch more efficiently

 Sticky

$article

 Eaier

to add coag"lant to !ater than to coat the filter media

The (ioSand Filter Cra+e  $atented

'ne! idea) of lo! and filtration !itho"t flo! control and called it '(ioSand)  Filter are being intalled aro"nd the !orld a $oint of 4e treatment device  Cot i ome!here bet!een VB and V12 per ho"ehold 7V19>peron baed on proPect near Copan #"in/ Iond"ra;  The per peron cot i comparable to the cot to  b"ild centrali+ed treatment "ing the &g"aClara model

'(ioSand) $erformance

'(ioSand) $erformance  $ore

vol"me i 1 Liter

 Jol"me

of a b"cket i HHHHHHHHHHHH 

 Iighly

variable field performance even after initial ripening period

ield tests on " #T$ ater in the &' 

Field $erformance of '(ioSand)

Table B pI/ t"rbidity and E. coli level in in the field $arameter Mean pI 7n hr

filtration rate 7thro"gh 5 m of media; E,"ivalent "rface loading < 12 m>day  4age of I#F for large cheme ha been limited d"e to high capital cot and operational problem in cleaning the filter.

#o"ghing Filter 

Filtration thro"gh ro"ghing gravity filter at lo! filtration rate 71B- m>day; prod"ce !ater !ith lo! partic"late concentration/ !hich allo! for f"rther treatment in lo! and filter !itho"t the danger of olid overload.  6n large-cale hori+ontal-flo! filter plant/ the large pore enable particle to be mot efficiently tranported do!n!ard/ altho"gh particle tranport ca"e part of the agglomerated olid to move do!n to!ard the filter  bottom. Th"/ the pore pace at the bottom tart to act a a l"dge torage bain/ and the ro"ghing filter need to be drained periodically. F"rther development of drainage method i needed to improve efficiency in thi area.

#o"ghing Filter 



#o"ghing filter remove partic"late of colloidal i+e !itho"t addition of flocc"lant/ large olid torage capacity at lo! head lo/ and a imple technology. ("t there are only 11 article on the topic lited in



7ee article per year;



They have not devied a cleaning method that !ork

(ie comparison to floc)sed systems?

M"ltitage Filtration  The

'Other) lo! tech option for comm"nitie "ing "rface !ater

 4e

no coag"lant

 *ravel

ro"ghing filter

 $olihed  Large  3o

!ith lo! and filter

capital cot for contr"ction

chemical cot

 Labor

intenive operation

What i the tank area of a m"ltitage filtration

Concl"ion  Many

different filtration technologie are available/ epecially for $O4  Filter are !ell "ited for taking clean !ater and making it cleaner. They are not able to treat very t"rbid "rface !ater  $retreat "ing flocc"lation>edimentation 7&g"aClara; or ro"ghing filter 7high capital cot and maintenance problem;

Concl"ion  Filter

co"ld remove particle more efficiently if the attachment HHHHHHHHH efficiency !ere increaed  SSF remove particle by t!o mechanim $redation  HHHHHHHHHHHH  Sticky al"min"m polymer that coat the and  HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH  Completely

 We

at the mercy of the ra! !aterK

need to learn !hat i re,"ired to make &LL of the filter media 'ticky) in SSF and in #SF

#eference 









T"fenkPi/ 3. and M. Elimelech 7B22;. Correlation e,"ation for predicting ingle-collector efficiency in phyicochemical filtration in at"rated poro" media. Environmental-Science-and-Technology *"7B; B8-9D. C"hing/ #. S. and %. F. La!ler 7188;. %epth Filtration F"ndamental 6nvetigation thro"gh Three-%imenional TraPectory &nalyi. Environmental Science and Technology 9B7B9; 9:89 -921. Tobiaon/ . E. and C. #. OXMelia 718;. $hyicochemical &pect of $article #emoval in %epth Filtration. o"rnal &merican Water Work &ociation 271B; -D. Rao/ N.-M./ M. T. Iabibian/ et al. 718:1;. Water and Wate Water Filtration Concept and &pplication. Environmental Science and Technology 711; 112. M.&. ElliottA/ C.E. Sta"ber/ F. Nokal/ N.#. Liang/ %.N. I"lage/ F.&. %i*iano/ M.%. Sobey. 7B22D; The operation/ flo! condition and microbial red"ction of an intermittently operated/ ho"ehold-cale lo! and filter 

Contact $oint