Filtration

Filtration OutlineFilters galoreRange of applicabilityParticle Capture theoryTransportDimensional Analysis Model predictionsFiltersRapidSlowBioSandPotsRoughingMultistage Filtration

Filters GaloreBio SandRapid SandCartridgeBagPotCandleDiatomaceous earth filterSlow SandRough

Categorizing FiltersStrainingParticles to be removed are larger than the pore sizeClog rapidlyDepth FiltrationParticles to be removed may be much smaller than the pore sizeRequire attachmentCan handle more solids before developing excessive head lossFiltration model comingAll filters remove more particles near the filter inlet

The if it is dirty, filter it MythThe common misconception is that if the water is dirty then you should filter it to clean itBut filters cant handle very dirty water without clogging quickly

Filter range of applicabilitySSFCartridgeBagRSF+PotCandleDE

Developing a Filtration ModelIwasaki (1937) developed relationships describing the performance of deep bed filters.C is the particle concentration [number/L3]l0 is the initial filter coefficient [1/L]z is the media depth [L]The particles chances of being caught are the same at all depths in the filter; pC* is proportional to depth

Graphing Filter PerformanceThis graph gives the impression that you can reach 100% removalWhere is 99.9% removal?

Particle Removal Mechanisms in FiltersTransport to a surfaceAttachmentMolecular diffusionInertiaGravityInterceptionStrainingLondon van der Waalscollector

Filtration Performance: Dimensional AnalysisWhat is the parameter we are interested in measuring? _________________How could we make performance dimensionless? ____________What are the important forces?

Effluent concentrationC/C0 or pC*InertiaLondon van der WaalsElectrostaticViscousNeed to create dimensionless force ratios!GravitationalThermal

Dimensionless Force RatiosReynolds NumberFroude NumberWeber NumberMach NumberPressure/Drag Coefficients(dependent parameters that we measure experimentally)

What is the Reynolds number for filtration flow?What are the possible length scales?Void size (collector size) max of 0.7 mm in RSFParticle sizeVelocitiesV0 varies between 0.1 m/hr (SSF) and 10 m/hr (RSF)Take the largest length scale and highest velocity to find max Re

For particle transport the length scale is the particle size and that is much smaller than the collector size

Choose viscosity!In Fluid Mechanics inertia is a significant force for most problemsIn porous media filtration viscosity is more important that inertia.We will use viscosity as the repeating parameter and get a different set of dimensionless force ratiosInertia

GravityvporeGravity only helps when the streamline has a _________ component.horizontalvelocitiesforces Use this definition

Diffusion (Brownian Motion)kB=1.38 x 10-23 J/KT = absolute temperaturevporedc is diameter of the collectorDiffusion velocity is high when the particle diameter is ________.small

London van der WaalsThe London Group is a measure of the attractive forceIt is only effective at extremely short range (less than 1 nm) and thus is NOT responsible for transport to the collectorH is the Hamakers constant

Van der Waals forceViscous force

What about Electrostatic repulsion/attraction?Modelers have not succeeded in describing filter performance when electrostatic repulsion is significantModels tend to predict no particle removal if electrostatic repulsion is significant.Electrostatic repulsion/attraction is only effective at very short distances and thus is involved in attachment, not transport

Geometric ParametersWhat are the length scales that are related to particle capture by a filter?______________________________________________________Porosity (void volume/filter volume) (e)Create dimensionless groupsChoose the repeating length ________

Filter depth (z)Collector diameter (media size) (dc)Particle diameter (dp)(dc)Number of collectors!Definition used in model

Write the functional relationshipLength ratiosForce ratiosIf we double depth of filter what does pC* do? ___________doublesHow do we get more detail on this functional relationship?Empirical measurementsNumerical models

Numerical ModelsTrajectory analysisA series of modeling attempts with refinements over the past decadesBegan with a single collector model that modeled London and electrostatic forces as an attachment efficiency term (a)InterceptionSedimentationDiffusiona

Filtration ModelPorosityGeometryForce ratios

Transport EquationsBrownian motionInterceptionGravityTotal is sum of partsTransport is additive

Filtration TechnologiesSlow (FiltersEnglishSlow sandBiosand)First filters used for municipal water treatmentWere unable to treat the turbid waters of the Ohio and Mississippi RiversCan be used after Roughing filtersRapid (MechanicalAmericanRapid sand)Used in Conventional Water Treatment FacilitiesUsed after coagulation/flocculation/sedimentationHigh flow ratesclog dailyhydraulic cleaningCeramic

Rapid Sand Filter (Conventional US Treatment)SandGravelInfluentDrainEffluentWash waterAnthraciteSize(mm)0.70

0.45 - 0.55

5 - 60SpecificGravity1.6

2.65

2.65Depth(cm)30

45

45

Filter DesignFilter mediasilica sand and anthracite coalnon-uniform media will stratify with _______ particles at the topFlow rates60 - 240 m/dayBackwash ratesset to obtain a bed porosity of 0.65 to 0.70typically 1200 m/day

smallerCompare with sedimentation

SandGravelInfluentDrainEffluentWash waterAnthraciteBackwashWash water is treated water!WHY?Only clean water should ever be on bottom of filter!

Rapid Sand predicted performanceNot very good at removing particles that havent been flocculated

Slow Sand FiltrationFirst filters to be used on a widespread basisFine sand with an effective size of 0.2 mmLow flow rates (2.5-10 m/day)Schmutzdecke (_____ ____) forms on top of the filtercauses high head lossmust be removed periodicallyUsed without coagulation/flocculation!Turbidity should always be less than 50 NTU with a much lower average to prevent rapid cloggingfilter cakeCompare with sedimentation

Slow Sand Filtration MechanismsProtozoan predators (only effective for bacteria removal, not virus or protozoan removal)Aluminum (natural sticky coatings)Attachment to previously removed particlesNo evidence of removal by biofilms

Typical Performance of SSF Fed Cayuga Lake Water0.050.11012345Time (days)Fraction of influent E. coli remaining in the effluentFilter performance doesnt improve if the filter only receives distilled water(Daily samples)

Particle Removal by Size0.0010.010.110.8110Particle diameter (m)control3 mM azideFraction of influent particles remaining in the effluentEffect of the ChrysophyteWhat is the physical-chemical mechanism?

Techniques to Increase Particle Attachment EfficiencyMake the particles stickierThe technique used in conventional water treatment plantsControl coagulant dose and other coagulant aids (cationic polymers)Make the filter media stickierBiofilms in slow sand filters?Mystery sticky agent present in surface waters that is imported into slow sand filters?

Cayuga Lake Seston ExtractConcentrate particles from Cayuga LakeAcidify with 1 N HClCentrifugeCentrate contains polymerNeutralize to form flocs

Seston Extract AnalysisHow much Aluminum should be added to a filter?I discovered aluminum!

Chart2

0.558988764

0.170220345

0.1087730904

0.0075314233

0.0061913728

0.0060641528

0.0047749902

0.0023722287

0.003014308

0.1320693246

coliform analysis

Influent2

effluent2

total per filter4

total per filter24

sample MWF3

per week72

pumps

ismatec tubingID (mm)Area (mm^2)flow at 100 rpm (mL/min)rpm/flow (rpm/(mL/min))desired flow (mL/min)required rpm

org/org0.890.62211388525.418.51851851850.0541.08.6800827441

purp/wht2.796.1136178437323.1251340.6255.2342165994

org/red0.190.02835287370.32312.511.2863339145

org/ylw0.510.20428206232509.7903848115

flows

column diameter10cm

approach velocity10cm/hr

column area78.5cm^2

approach velocity0.17cm/min

flow rate13.1mL/min

pump rpm40.9rpm

column height20cm

porosity0.4

glass beads per column2.25kg

volume of water628mL

residence time48min

number of columns6

volume of column1571mL

glass bead height20cm

mass of beads2592g

volume of water for a week792L

desired E. coli conc2per mL

desired E. coli conc2.00E+06per liter

cryovial concentration2.00E+09per mL

E. coli dilution factor500

E. coli flow rate0.157mL/min

pump rpm2.909rpm

E. coli conc in fridge1.00E+09per liter

E. coli flow rate1583mL/week

volume of cryovial bacteria0.50mL/L

1 L will last4.42days

Fraquil dilution500

Azide dilution500

CLSE

actual CLSE conc2580mg/L

CLSE dilution400

flow rate0.0327mL/min

pump rpm1.64rpm

flow rate330mL/week

volume (two week supply)660mL18

Filter1 week (mg)2 weeks (mg)feed stock concentration (mg/L)CLSE concentrationmg/LCLSE fluxg/(m2/day)total CLSE appliedmgtotal CLSE appliedg/m2actually fed (mL)

434.068.1103low0.260.62486.2469

5170.2340.4516medium1.33.113717gives 1 m head loss266

6851.11702.12580high6.51514819gives 1 m head loss57

initial CLSE (mg)CLSE (g/m2)

2170mg22

3851mg108

sum3132mg

Stock concentration2580mg/L

stock volume1.21L

65.973mLneutralizedfor filter2

329.867mLneutralizedfor filter3

26.4mLdilute to660for filter4

132mLdilute to660for filter5

660mLdilute to660for filter6

total volume1213.9mL

TEP C rate20mg/cm2/day

TEP C rate1571mg/day

TEP C concentration83mg/L

TEP initial application

equal to7days

of2.5mg/L

therefore329.87mg

Dilution water

compounddilutionstock conc.stock volumemass for stockstock good for

mL/Lg/LLgL

KH2PO41.2534134

MgCL2 6H2O581.1181.1

Magnesium chloride solution: Add 81.1 g MgCl2*6H20 to 500 mL reagent grade water and then dilute to 1 L with reagent grade water

monroe:Requires about 180 mL of 1 N NaOH to titrate 1 L to pH 7.2

Fraquil

compoundmolecular weightfinal molarityfinal conc.dilutionstock conc.stockstock volumemass for stockstock good fordilution500 x concentrate500 x concentrate500x concentration of synthetic feed

g/molemole/Lg/LmL/100 Lg/LLgLmL/LmL/LmL/100 mLg/L

CaCl22H2O147.022.50E-040.03675510367.55a0.5183.775500010050518.38CaCl22H2O

NaNO384.991.00E-040.0084991084.99a0.542.49550001005054.25NaNO3

MgSO47H20246.471.50E-040.03697055073.941b173.94120005002502518.49MgSO47H20

NaHCO384.011.50E-040.01260155025.203b125.2032000500250256.30NaHCO3

K2HPO4174.181.00E-050.00174181174.18c0.117.41810000

Na2SiO39H2O284.21.25E-050.00355251355.25c0.135.52510000

CuSO45H2O249.681.00E-090.000000249710.024968d0.10.002496810000

Na2MoO42H2O241.951.50E-090.000000362910.0362925d0.10.0036292510000

CoCl26H2O237.952.50E-090.000000594910.0594875d0.10.0059487510000

MnCl24H2O197.912.30E-080.000004551910.455193d0.10.045519310000

ZnSO47H2O287.544.00E-090.000001150210.115016d0.10.011501610000

FeCl36H2O270.324.50E-080.000012164411.21644d0.10.12164410000

Na2C10H14O8N22H2O372.245.00E-060.00186121186.12d0.118.61210000

stocksvolumedilution

a0.110

b150

c0.11

d0.11

I tried to make a 200x concentrated combined stock of a,b,c. It precipated when I added stock C. So we won't use stock c for our experiment.

azide

Desired concentration3mM

molecular weight65.01

concentration195mg/L0.00019503g/g0.02%

dilution factor500

stock97.515g/L

42 g/100 g water @ 17C (63F)

total azide per week154.4016134379g/week

icp

ICP analysis

corrected for dilution with acid

IDmg/Lmg/LPercent Total Solids

Al401.4000439.16851442volatile solids56%

Na256.5000280.6346439Al17%

Fe17.760019.4311281Na11%

P14.600015.973719Fe0.8%

S14.300015.645516P0.6%

Si11.260012.319516S0.6%

Ca5.59406.120412Si0.5%

Cu2.63602.88406Ca0.2%

Zn1.15401.26268other metals0.3%

Mg1.08801.1904341other nonvolatile solids13%

Se0.86050.9415total2580

Pb0.52920.5790

Mn0.20340.2225

Mo0.15900.1740

Ni0.15100.1652

Cr0.12380.1354

Y0.09460.1035

B0.05170.0566

K0.02590.0283

Cd0.01610.0176

V0.01490.0163

Cobdbd

Asbdbd

Agnc

Nnr

total729797

0.8g/L

FSS1138mg/L

VSS1442

TSS2580

icp

0

0

0

0

0

0

0

0

0

0

polymer

TOC analysis on 6/8/00

blank26mV

standard751mV50mg TOC

standard739mV50mg TOC

scaling0.0695410292

Filtered polymer solution from CEE 453

volume0.1mL

signal336.9mV

335.45mV

351.3mV

average341.2166666667mV

minus blank315.2166666667mV

TOC21.9204914233mg Carbon

TOC con219.2049142327mg TOC/L

TOC analysis on 6/21/00

blank20.5

standard740.708

standard742.782

scaling0.0693245707

polymermVvolume (mL)mass Cconcentration (mg/L)

348.4035022.7455

570.8910038.2382

573.38710038.3383

355.8165023.2465

575.62310038.5385

Gravimetric analysisVolatile solids

stock volume100mLdish1.0611

dish 1dish + dry solids1.0967

tare1.0587gdish + nonvolatile1.0768

dish + polymer1.3136gvolatile0.0199

dish 2nonvolatile0.0157

tare1.0584total0.03560.0356

dish + polymer1.0615fraction volatile56%

polymer0.258g/100 mL

polymer2.58g/Lpolymer nameCLSE

by measuring wet mass of gel and assuming density of 1Full nameCayuga Lake Seston Extract

volume of gel5.5mL/100 mL

55mL/L

FSS1.14g/L

VSS1.44g/L

TSS2.58g/L

schedule

Eventdatetime

begin pumping distilled water

begin pumping azide/Fraquil,Coliforms6/155:00 PMThursday

Sample coliforms6/16Friday

Begin feeding polymer6/19Monday

New azide, Fraquil, E. coli6/19Monday

E. coli Removal as a Function of Time and Al Application Rate pC* is proportional to accumulated mass of Aluminum in filterNo E. coli detected20 cm deep filter columns

Chart1

0.43702873890.4582180380.4582180380.54617320830.010.030.05-1

0.18336476111.13982387130.68750.68750.010.030.051

0.36362655383.16160439594.41657469595.73745769890.01

0.46765595424.63896441514.97891247684.85059399950.01

0.16536739373.86169730185.3729120034.0338582673

0.28437008246.3497630442.31633928853.3825555574

0.38958793436.28583849681.26464919772.8008919045

0.31931878146.3089910291.26661243092.0729578819

Horizontal bars indicate when polymer feed was operational for each filter.

control

4

20

100

low polymer feed

end polymer

end polymer

end azide

time (days)

E. coli remaining (pC*)

print

DateTime

Filter123456

head loss (cm)

flow rate (mL/min)

sectioninoutinoutinoutinoutinoutinout

est. conc. (#/mL)

sample volume (mL)000000000000

count

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)0.00.00.00.00.00.00.00.00.00.00.00.0

C/Co000000

const

start time6/19/005:30 PM6/19/00 17:30

headloss

Filter123456mg/m^2

datetimetimeadjusted timecontrolmed initial dosehigh initial dose3.9201003.9020.00100.00

6/16/003:30 PM6/16/000.000.010.0120.0150.0140.0110.016000

20-Jun1:26 PM6/20/000.830.0090.0120.0150.020.040.1043.239166666716.611111111183.0555555556

20-Jun4:05 PM6/20/000.940.0090.0160.0150.0140.0450.1653.669791666718.819444444594.0972222226

21-Jun9:05 AM6/21/001.650.0090.0130.0150.0140.0990.8056.432291666732.9861111111164.9305555555

6/21/003:30 PM6/21/001.920.010.0180.0170.01750.12551.0317.47538.3333333334191.6666666672

6/22/003:00 PM6/22/002.900.0090.0120.0150.0250.2651.04511.2937557.9166666667289.5833333336

6/23/007:46 AM6/23/003.590.0090.0130.0160.0330.3630.77514.018333333371.8888888889359.4444444447

6/23/002:55 PM6/23/003.890.0090.0120.0150.0360.4610.7715.180208333477.8472222223389.2361111117

6/24/004:21 PM6/24/004.950.0090.0120.0150.0330.7020.82519.31312599.0416666667495.2083333337

6/25/0011:00 AM6/25/005.730.0090.0130.0150.0510.9650.96822.34375114.5833333334572.9166666672

6/26/004:23 PM6/26/006.950.0090.0130.0150.0960.96527.1185416667139.0694444445695.3472222223

6/27/003:30 PM6/27/007.920.0090.0140.0150.1591.09430.875158.3333333334791.6666666672

6/28/004:15 PM6/28/008.950.0090.0130.0150.20334.896875178.9583333334894.7916666672

headloss

00000.010.030.05-1

00000.010.030.051

00000.01

00000.01

0000

0000

0000

0000

0000

0000

0000

0000

0000

control

3.9

20

100

4

20

100

end azide

time (days)

head loss (m)

coli sum

00

00

00

00

00

00

00

00

00

00

0

0

0

3.9

20

Total Al applied

head loss (m)

coli

Filter123456145646/29/00 16:2556/25/00 11:006/20/00 9:006/21/00 15:306/23/00 7:40total Al (mmol/m2)pC*adjusted (pC*-pC*0)

timecontrolmed initial dosehigh initial dose420100control420100timelow polymer feedtimeend polymertimeend polymertimeend azide00.4582180380

00.36557059960.60928433270.76595744680.34816247580.34816247580.28433268860.43702873890.4582180380.4582180380.546173208300.0100.030.650.053.6-12.681251.13982387130.6816058333

0.68750.65559440560.10680228860.07247298160.07247298160.18336476111.13982387131/3/00 10:300.015.730.031.920.053.617.393753.16160439592.7033863579

1.89583333330.4328859060.08053691280.01510067110.00068927990.000038320.00000183040.36362655383.16160439594.41657469595.73745769891/3/00 22:300.0111.293754.63896441514.1807463771

2.89583333330.34067796610.07389830510.00864406780.00002296340.00001049750.00001410610.46765595424.63896441514.97891247684.85059399959.950.0115.18020833343.86169730183.4034792638

3.89236111110.68333333330.0450.20.00013750.00000423730.00009250.16536739373.86169730185.3729120034.033858267326.94791666676.3497630445.891545006

6.90972222220.51955307260.05720670390.00000044690.00482681560.00041442360.28437008246.3497630442.31633928853.382555557430.8756.28583849685.8276204588

7.91666666670.40776699030.14291262140.00000051780.0543689320.00158164170.38958793436.28583849681.26464919772.80089190456/23/00 16:00replace leaking tube

8.91666666670.47938144330.18556701034.59231490160.00000049090.05412371130.00845360820.31931878146.3089910291.26661243092.0729578819

average50%10%90%

90%

AMP (Al) fluxmmol/(m2/day)

coli

0.36557059960.34816247580.34816247580.28433268860000

0.65559440560.07247298160.68750.68750000

0.4328859060.00068927990.000038320.00000183040

0.34067796610.00002296340.00001049750.00001410610

0.68333333330.00013750.00000423730.0000925

0.51955307260.00000044690.00482681560.0004144236

0.40776699030.00000051780.0543689320.0015816417

0.47938144330.00000049090.05412371130.0084536082

control

4

20

100

low polymer feed

end polymer

end polymer

end azide

time (days)

coli (1)

0.36557059960.60928433270.7659574468

0.65559440560.10680228860.0724729816

0.4328859060.08053691280.0151006711

0.34067796610.07389830510.0086440678

0.68333333330.0450.2

0.51955307260.05720670396.9097222222

0.40776699030.14291262147.9166666667

0.47938144330.18556701034.5923149016

control

med initial dose

high initial dose

time (days)

coli (2)

0

0.6816058333

2.7033863579

4.1807463771

Horizontal bars indicate when CLSE feed was operational for each filter.


control

4

20

100

low polymer feed

end polymer

end polymer

end azide

time (days)


0

0

0

0

0

0

0

0

0.6875

0.6875

0.6875

0.6875

0

0

0

0

1.8958333333

1.8958333333

1.8958333333

1.8958333333

0

2.8958333333

2.8958333333

2.8958333333

2.8958333333

0

3.8923611111

3.8923611111

3.8923611111

3.8923611111

6.9097222222

6.9097222222

6.9097222222

6.9097222222

7.9166666667

7.9166666667

7.9166666667

7.9166666667

8.9166666667

8.9166666667

8.9166666667

8.9166666667

0.4370287389

0.458218038

0.458218038

0.5461732083

0

0

0

0

0.1833647611

1.1398238713

0

0

0

0

0.3636265538

3.1616043959

4.4165746959

5.7374576989

0

0.4676559542

4.6389644151

4.9789124768

4.8505939995

0

0.1653673937

3.8616973018

5.372912003

4.0338582673

0.2843700824

6.349763044

2.3163392885

3.3825555574

0.3895879343

6.2858384968

1.2646491977

2.8008919045

0.3193187814

6.308991029

1.2666124309

2.0729578819

adjusted (pC*-pC*0)

Total Al (mmol/m2)

E. coli remaining (pC*-pC*clean sand)

coli (3)

DateTimeTime12/31/99 0:00

Filter123456


sample volume (mL)

count

sample volume (mL)

count

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)000000000000

C/Co000000

Co (#/mL)0

coli (4)

Date6/16/00Time3:30 PMTime6/16/00 15:30

Filter123456


sample volume (mL)0.0200.0200.0200.0200.0200.0200.0200.0200.0200.0200.0200.020

count93.035.090.062.082.058.074.027.088.023.090.019.0

sample volume (mL)0.0200.0200.0200.0200.0200.020

count28.043.074.033.037.030.0

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)4650.01575.04500.02625.04100.03300.03700.01500.04400.01500.04500.01225.0

C/Co0.365570.609280.765960.348160.348160.28433

Co (#/mL)4308.3333333333

coli (5)

Date6/20/00Time10:00 AMTime6/20/00 10:00

Filter123456


sample volume (mL)0.0400.0800.0400.0800.0400.0800.0400.0800.0400.0800.0400.080

count60.067.053.016.041.05.044.07.050.00.038.00.0

sample volume (mL)0.0800.8000.8000.8000.8000.800

count58.096.071.069.00.00.0

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)1500.0781.31325.0127.31025.086.41100.086.41250.00.0950.00.0

C/Co0.655590.106800.072470.072470.000000.00000

Co (#/mL)1191.6666666667

coli (6)

Date6/21/00Time3:00 PMTime6/21/00 15:00

Filter123456


sample volume (mL)0.050.100.050.500.050.800.051.000.05100.000.05100.00

count64.048.052.040.058.012.051.01.056.03.017.00.0

sample volume (mL)0.1000.80010.00010001000

count38.012.08.044.02.0

sample volume (mL)100.02000.0

count67.071.0

sample volume (mL)

count

measured conc. (#/mL)1280.0430.01040.080.01160.015.01020.00.71120.00.0340.00.0

C/Co0.432890.080540.015100.000690.000040.0000018

Co (#/mL)993.3333333333

coli (7)

Date6/22/00Time3:00 PMTime6/22/00 15:00

Filter123456


sample volume (mL)0.050.10.050.50.0510.051000.051000.05100

count5739503450105211441423

sample volume (mL)0.111100010001000

count28757591114


count2026

sample volume (mL)

count

measured conc. (#/mL)1140.0335.01000.072.71000.08.51040.00.0880.00.0840.00.0

C/Co0.340680.073900.008640.000020.000010.00001

Co (#/mL)983.3333333333

coli (8)

Date6/23/00Time2:55 PMTime6/23/00 14:55

Filter123456


sample volume (mL)0.050.150.0510.0510.051000.0510000.051000

count509239373316041104033774


count72351117

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)1000.0546.7780.036.0660.0160.0820.00.1800.00.0740.00.1

C/Co0.683330.045000.200000.000140.000000.00009

Co (#/mL)800

Date6/26/00Time3:20 PMTime6/26/00 15:20

Filter123456


sample volume (mL)0.080.120.080.50.080.10.0810000.081000.0810

count4449591762063069360613


count44470131

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)550387.5737.542.66666666677750787.50.0003333333862.53.6762.50.3090909091

C/Co0.51955307260.057206703900.00000044690.00482681560.0004144236

Co (#/mL)745.8333333333

Date6/27/00Time3:30 PMTime6/27/00 15:30

Filter123456


sample volume (mL)0.080.120.080.250.080.10.0810000.0810.0810

count72274519463706535449


count36271103

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)900262.5562.5925750462.50.0003333333812.5355501.0181818182

C/Co0.40776699030.142912621400.00000051780.0543689320.0015816417

Co (#/mL)643.75

Monroe Weber-Shirk 2:Was zero!!! Put 1 here to get reasonable plot

Date6/28/00Time3:30 PMTime6/28/00 15:30

Filter123456


sample volume (mL)0.050.10.050.250.050.010.051000.0510.0510

count44485245564735046545882

sample volume (mL)0.10.250.00120001

count45452151

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)880465104018011204454.54545454547000.000476190592052.511608.2

C/Co0.47938144330.18556701034.59231490160.00000049090.05412371130.0084536082

Co (#/mL)970

Monroe Weber-Shirk 2:count was zero, but 1 here to get reasonable plot

MBD0077BC16.unknown

MBD04311B1E.unknown

MBD0430FE9B.unknown

MBD005149BB.unknown

Slow Sand Filtration Predictions

How deep must a filter (SSF) be to remove 99.9999% of bacteria?Assume a is 1 and dc is 0.2 mm, V0 = 10 cm/hrpC* is ____z is ________________What does this mean?23 cm for pC* of 66Suggests that the 20 cm deep experimental filter was operating at theoretical limitfor z of 1 mTypical SSF performance is 95% bacteria removal Only about 5 cm of the filters are doing anything!

Head Loss Produced by Aluminum

Chart2

0.0140.011

0.020.04

0.0140.045

0.0140.099

0.01750.1255

0.0250.265

0.0330.363

0.0360.461

0.0330.702

0.0510.965

0.096

0.159

0.203

3.9

20

Total Al applied

head loss (m)

print

DateTime

Filter123456

head loss (cm)

flow rate (mL/min)


est. conc. (#/mL)


count

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)0.00.00.00.00.00.00.00.00.00.00.00.0

C/Co000000

const

start time6/19/005:30 PM6/19/00 17:30

headloss

Filter123456mg/m^2


6/16/003:30 PM6/16/000.000.010.0120.0150.0140.0110.016000

20-Jun1:26 PM6/20/000.830.0090.0120.0150.020.040.1043.239166666716.611111111183.0555555556

20-Jun4:05 PM6/20/000.940.0090.0160.0150.0140.0450.1653.669791666718.819444444594.0972222226

21-Jun9:05 AM6/21/001.650.0090.0130.0150.0140.0990.8056.432291666732.9861111111164.9305555555

6/21/003:30 PM6/21/001.920.010.0180.0170.01750.12551.0317.47538.3333333334191.6666666672

6/22/003:00 PM6/22/002.900.0090.0120.0150.0250.2651.04511.2937557.9166666667289.5833333336

6/23/007:46 AM6/23/003.590.0090.0130.0160.0330.3630.77514.018333333371.8888888889359.4444444447

6/23/002:55 PM6/23/003.890.0090.0120.0150.0360.4610.7715.180208333477.8472222223389.2361111117

6/24/004:21 PM6/24/004.950.0090.0120.0150.0330.7020.82519.31312599.0416666667495.2083333337

6/25/0011:00 AM6/25/005.730.0090.0130.0150.0510.9650.96822.34375114.5833333334572.9166666672

6/26/004:23 PM6/26/006.950.0090.0130.0150.0960.96527.1185416667139.0694444445695.3472222223

6/27/003:30 PM6/27/007.920.0090.0140.0150.1591.09430.875158.3333333334791.6666666672

6/28/004:15 PM6/28/008.950.0090.0130.0150.20334.896875178.9583333334894.7916666672

headloss

0.010.0140.0110.0160.010.030.05-1

0.0090.020.040.1040.010.030.051

0.0090.0140.0450.1650.01

0.0090.0140.0990.8050.01

0.010.01750.12551.031

0.0090.0250.2651.045

0.0090.0330.3630.775

0.0090.0360.4610.77

0.0090.0330.7020.825

0.0090.0510.9650.968

0.0090.0960.9656.9534722222

0.0090.1591.0947.9166666667

0.0090.2038.94791666678.9479166667

control

3.9

20

100

4

20

100

end azide

time (days)

head loss (m)

coli sum

3.9

20

Total Al applied

head loss (m)

coli



00.36557059960.60928433270.76595744680.34816247580.34816247580.28433268860.43702873890.4582180380.4582180380.546173208300.0100.030.650.053.6-12.681251.13982387130.6816058333

0.68750.65559440560.10680228860.07247298160.07247298160.18336476111.13982387131/3/00 10:300.015.730.031.920.053.617.393753.16160439592.7033863579

1.89583333330.4328859060.08053691280.01510067110.00068927990.000038320.00000183040.36362655383.16160439594.41657469595.73745769891/3/00 22:300.0111.293754.63896441514.1807463771

2.89583333330.34067796610.07389830510.00864406780.00002296340.00001049750.00001410610.46765595424.63896441514.97891247684.85059399959.950.0115.18020833343.86169730183.4034792638

3.89236111110.68333333330.0450.20.00013750.00000423730.00009250.16536739373.86169730185.3729120034.033858267326.94791666676.3497630445.891545006

6.90972222220.51955307260.05720670390.00000044690.00482681560.00041442360.28437008246.3497630442.31633928853.382555557430.8756.28583849685.8276204588


8.91666666670.47938144330.18556701034.59231490160.00000049090.05412371130.00845360820.31931878146.3089910291.26661243092.0729578819

average50%10%90%

90%


coli

0.36557059960.34816247580.34816247580.28433268860000

0.65559440560.07247298160.68750.68750000

0.4328859060.00068927990.000038320.00000183040

0.34067796610.00002296340.00001049750.00001410610

0.68333333330.00013750.00000423730.0000925

0.51955307260.00000044690.00482681560.0004144236

0.40776699030.00000051780.0543689320.0015816417

0.47938144330.00000049090.05412371130.0084536082

control

4

20

100

low polymer feed

end polymer

end polymer

end azide

time (days)

coli (1)

0.36557059960.60928433270.7659574468

0.65559440560.10680228860.0724729816

0.4328859060.08053691280.0151006711

0.34067796610.07389830510.0086440678

0.68333333330.0450.2

0.51955307260.05720670396.9097222222

0.40776699030.14291262147.9166666667

0.47938144330.18556701034.5923149016

control

med initial dose

high initial dose

time (days)

coli (2)

0

0.6816058333

2.7033863579

4.1807463771



control

4

20

100

low polymer feed

end polymer

end polymer

end azide

time (days)


0

0

0

0

0

0

0.6458333333

0

0.6875

0.6875

0.6875

0.6875

3.4375

0

1.9166666667

0

1.8958333333

1.8958333333

1.8958333333

1.8958333333

3.9375

2.8958333333

2.8958333333

2.8958333333

2.8958333333

9.9548611111

3.8923611111

3.8923611111

3.8923611111

3.8923611111

6.9097222222

6.9097222222

6.9097222222

6.9097222222

7.9166666667

7.9166666667

7.9166666667

7.9166666667

8.9166666667

8.9166666667

8.9166666667

8.9166666667

0.4370287389

0.458218038

0.458218038

0.5461732083

0

0

0

0

0.1833647611

1.1398238713

0

0

0

0

0.3636265538

3.1616043959

4.4165746959

5.7374576989

0

0.4676559542

4.6389644151

4.9789124768

4.8505939995

0

0.1653673937

3.8616973018

5.372912003

4.0338582673

0.2843700824

6.349763044

2.3163392885

3.3825555574

0.3895879343

6.2858384968

1.2646491977

2.8008919045

0.3193187814

6.308991029

1.2666124309

2.0729578819

adjusted (pC*-pC*0)

Total Al (mmol/m2)


coli (3)


Filter123456


sample volume (mL)

count

sample volume (mL)

count

sample volume (mL)

count

sample volume (mL)

count


C/Co000000

Co (#/mL)0

coli (4)

Date6/16/00Time3:30 PMTime6/16/00 15:30

Filter123456


sample volume (mL)0.0200.0200.0200.0200.0200.0200.0200.0200.0200.0200.0200.020

count93.035.090.062.082.058.074.027.088.023.090.019.0

sample volume (mL)0.0200.0200.0200.0200.0200.020

count28.043.074.033.037.030.0

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)4650.01575.04500.02625.04100.03300.03700.01500.04400.01500.04500.01225.0

C/Co0.365570.609280.765960.348160.348160.28433

Co (#/mL)4308.3333333333

coli (5)

Date6/20/00Time10:00 AMTime6/20/00 10:00

Filter123456


sample volume (mL)0.0400.0800.0400.0800.0400.0800.0400.0800.0400.0800.0400.080

count60.067.053.016.041.05.044.07.050.00.038.00.0

sample volume (mL)0.0800.8000.8000.8000.8000.800

count58.096.071.069.00.00.0

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)1500.0781.31325.0127.31025.086.41100.086.41250.00.0950.00.0

C/Co0.655590.106800.072470.072470.000000.00000

Co (#/mL)1191.6666666667

coli (6)

Date6/21/00Time3:00 PMTime6/21/00 15:00

Filter123456


sample volume (mL)0.050.100.050.500.050.800.051.000.05100.000.05100.00

count64.048.052.040.058.012.051.01.056.03.017.00.0

sample volume (mL)0.1000.80010.00010001000

count38.012.08.044.02.0


count67.071.0

sample volume (mL)

count

measured conc. (#/mL)1280.0430.01040.080.01160.015.01020.00.71120.00.0340.00.0

C/Co0.432890.080540.015100.000690.000040.0000018

Co (#/mL)993.3333333333

coli (7)

Date6/22/00Time3:00 PMTime6/22/00 15:00

Filter123456


sample volume (mL)0.050.10.050.50.0510.051000.051000.05100

count5739503450105211441423


count28757591114


count2026

sample volume (mL)

count

measured conc. (#/mL)1140.0335.01000.072.71000.08.51040.00.0880.00.0840.00.0

C/Co0.340680.073900.008640.000020.000010.00001

Co (#/mL)983.3333333333

coli (8)

Date6/23/00Time2:55 PMTime6/23/00 14:55

Filter123456


sample volume (mL)0.050.150.0510.0510.051000.0510000.051000

count509239373316041104033774


count72351117

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)1000.0546.7780.036.0660.0160.0820.00.1800.00.0740.00.1

C/Co0.683330.045000.200000.000140.000000.00009

Co (#/mL)800

Date6/26/00Time3:20 PMTime6/26/00 15:20

Filter123456


sample volume (mL)0.080.120.080.50.080.10.0810000.081000.0810

count4449591762063069360613


count44470131

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)550387.5737.542.66666666677750787.50.0003333333862.53.6762.50.3090909091

C/Co0.51955307260.057206703900.00000044690.00482681560.0004144236

Co (#/mL)745.8333333333

Date6/27/00Time3:30 PMTime6/27/00 15:30

Filter123456


sample volume (mL)0.080.120.080.250.080.10.0810000.0810.0810

count72274519463706535449


count36271103

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)900262.5562.5925750462.50.0003333333812.5355501.0181818182

C/Co0.40776699030.142912621400.00000051780.0543689320.0015816417

Co (#/mL)643.75


Date6/28/00Time3:30 PMTime6/28/00 15:30

Filter123456


sample volume (mL)0.050.10.050.250.050.010.051000.0510.0510

count44485245564735046545882


count45452151

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)880465104018011204454.54545454547000.000476190592052.511608.2

C/Co0.47938144330.18556701034.59231490160.00000049090.05412371130.0084536082

Co (#/mL)970


MBD0430FE9B.unknown

MBD04311B1E.unknown

MBD005149BB.unknown

MBD0077BC16.unknown

Aluminum feed methodsAlum must be dissolved until it is blended with the main filter feed above the filter columnAlum flocs are ineffective at enhancing filter performanceThe diffusion dilemma (alum microflocs will diffuse efficiently and be removed at the top of the filter)

Performance Deterioration after Al feed stops?HypothesesDecays with timeSites are used upWashes out of filterResearch resultsNot yet clear which mechanism is responsible further testing required

Chart1

0.43702873890.4582180380.4582180380.54617320830.010.030.05-1

0.18336476111.13982387130.68750.68750.010.030.051

0.36362655383.16160439594.41657469595.73745769890.01

0.46765595424.63896441514.97891247684.85059399950.01

0.16536739373.86169730185.3729120034.0338582673

0.28437008246.3497630442.31633928853.3825555574

0.38958793436.28583849681.26464919772.8008919045

0.31931878146.3089910291.26661243092.0729578819


control

4

20

100

low polymer feed

end polymer

end polymer

end azide

time (days)


print

DateTime

Filter123456

head loss (cm)

flow rate (mL/min)


est. conc. (#/mL)


count

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)0.00.00.00.00.00.00.00.00.00.00.00.0

C/Co000000

const

start time6/19/005:30 PM6/19/00 17:30

headloss

Filter123456mg/m^2


6/16/003:30 PM6/16/000.000.010.0120.0150.0140.0110.016000

20-Jun1:26 PM6/20/000.830.0090.0120.0150.020.040.1043.239166666716.611111111183.0555555556

20-Jun4:05 PM6/20/000.940.0090.0160.0150.0140.0450.1653.669791666718.819444444594.0972222226

21-Jun9:05 AM6/21/001.650.0090.0130.0150.0140.0990.8056.432291666732.9861111111164.9305555555

6/21/003:30 PM6/21/001.920.010.0180.0170.01750.12551.0317.47538.3333333334191.6666666672

6/22/003:00 PM6/22/002.900.0090.0120.0150.0250.2651.04511.2937557.9166666667289.5833333336

6/23/007:46 AM6/23/003.590.0090.0130.0160.0330.3630.77514.018333333371.8888888889359.4444444447

6/23/002:55 PM6/23/003.890.0090.0120.0150.0360.4610.7715.180208333477.8472222223389.2361111117

6/24/004:21 PM6/24/004.950.0090.0120.0150.0330.7020.82519.31312599.0416666667495.2083333337

6/25/0011:00 AM6/25/005.730.0090.0130.0150.0510.9650.96822.34375114.5833333334572.9166666672

6/26/004:23 PM6/26/006.950.0090.0130.0150.0960.96527.1185416667139.0694444445695.3472222223

6/27/003:30 PM6/27/007.920.0090.0140.0150.1591.09430.875158.3333333334791.6666666672

6/28/004:15 PM6/28/008.950.0090.0130.0150.20334.896875178.9583333334894.7916666672

headloss

00000.010.030.05-1

00000.010.030.051

00000.01

00000.01

0000

0000

0000

0000

0000

0000

0000

0000

0000

control

3.9

20

100

4

20

100

end azide

time (days)

head loss (m)

coli sum

00

00

00

00

00

00

00

00

00

00

0

0

0

3.9

20

Total Al applied

head loss (m)

coli



00.36557059960.60928433270.76595744680.34816247580.34816247580.28433268860.43702873890.4582180380.4582180380.546173208300.0100.030.650.053.6-12.681251.13982387130.6816058333

0.68750.65559440560.10680228860.07247298160.07247298160.18336476111.13982387131/3/00 10:300.015.730.031.920.053.617.393753.16160439592.7033863579

1.89583333330.4328859060.08053691280.01510067110.00068927990.000038320.00000183040.36362655383.16160439594.41657469595.73745769891/3/00 22:300.0111.293754.63896441514.1807463771

2.89583333330.34067796610.07389830510.00864406780.00002296340.00001049750.00001410610.46765595424.63896441514.97891247684.85059399959.950.0115.18020833343.86169730183.4034792638

3.89236111110.68333333330.0450.20.00013750.00000423730.00009250.16536739373.86169730185.3729120034.033858267326.94791666676.3497630445.891545006

6.90972222220.51955307260.05720670390.00000044690.00482681560.00041442360.28437008246.3497630442.31633928853.382555557430.8756.28583849685.8276204588


8.91666666670.47938144330.18556701034.59231490160.00000049090.05412371130.00845360820.31931878146.3089910291.26661243092.0729578819

average50%10%90%

90%


coli

0.36557059960.34816247580.34816247580.28433268860000

0.65559440560.07247298160.68750.68750000

0.4328859060.00068927990.000038320.00000183040

0.34067796610.00002296340.00001049750.00001410610

0.68333333330.00013750.00000423730.0000925

0.51955307260.00000044690.00482681560.0004144236

0.40776699030.00000051780.0543689320.0015816417

0.47938144330.00000049090.05412371130.0084536082

control

4

20

100

low polymer feed

end polymer

end polymer

end azide

time (days)

coli (1)

0.36557059960.60928433270.7659574468

0.65559440560.10680228860.0724729816

0.4328859060.08053691280.0151006711

0.34067796610.07389830510.0086440678

0.68333333330.0450.2

0.51955307260.05720670396.9097222222

0.40776699030.14291262147.9166666667

0.47938144330.18556701034.5923149016

control

med initial dose

high initial dose

time (days)

coli (2)

0

0.6816058333

2.7033863579

4.1807463771



control

4

20

100

low polymer feed

end polymer

end polymer

end azide

time (days)


0

0

0

0

0

0

0.6458333333

0

0.6875

0.6875

0.6875

0.6875

3.4375

0

1.9166666667

0

1.8958333333

1.8958333333

1.8958333333

1.8958333333

3.9375

2.8958333333

2.8958333333

2.8958333333

2.8958333333

9.9548611111

3.8923611111

3.8923611111

3.8923611111

3.8923611111

6.9097222222

6.9097222222

6.9097222222

6.9097222222

7.9166666667

7.9166666667

7.9166666667

7.9166666667

8.9166666667

8.9166666667

8.9166666667

8.9166666667

0.4370287389

0.458218038

0.458218038

0.5461732083

0

0

0

0

0.1833647611

1.1398238713

0

0

0

0

0.3636265538

3.1616043959

4.4165746959

5.7374576989

0

0.4676559542

4.6389644151

4.9789124768

4.8505939995

0

0.1653673937

3.8616973018

5.372912003

4.0338582673

0.2843700824

6.349763044

2.3163392885

3.3825555574

0.3895879343

6.2858384968

1.2646491977

2.8008919045

0.3193187814

6.308991029

1.2666124309

2.0729578819

adjusted (pC*-pC*0)

Total Al (mmol/m2)


coli (3)


Filter123456


sample volume (mL)

count

sample volume (mL)

count

sample volume (mL)

count

sample volume (mL)

count


C/Co000000

Co (#/mL)0

coli (4)

Date6/16/00Time3:30 PMTime6/16/00 15:30

Filter123456


sample volume (mL)0.0200.0200.0200.0200.0200.0200.0200.0200.0200.0200.0200.020

count93.035.090.062.082.058.074.027.088.023.090.019.0

sample volume (mL)0.0200.0200.0200.0200.0200.020

count28.043.074.033.037.030.0

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)4650.01575.04500.02625.04100.03300.03700.01500.04400.01500.04500.01225.0

C/Co0.365570.609280.765960.348160.348160.28433

Co (#/mL)4308.3333333333

coli (5)

Date6/20/00Time10:00 AMTime6/20/00 10:00

Filter123456


sample volume (mL)0.0400.0800.0400.0800.0400.0800.0400.0800.0400.0800.0400.080

count60.067.053.016.041.05.044.07.050.00.038.00.0

sample volume (mL)0.0800.8000.8000.8000.8000.800

count58.096.071.069.00.00.0

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)1500.0781.31325.0127.31025.086.41100.086.41250.00.0950.00.0

C/Co0.655590.106800.072470.072470.000000.00000

Co (#/mL)1191.6666666667

coli (6)

Date6/21/00Time3:00 PMTime6/21/00 15:00

Filter123456


sample volume (mL)0.050.100.050.500.050.800.051.000.05100.000.05100.00

count64.048.052.040.058.012.051.01.056.03.017.00.0

sample volume (mL)0.1000.80010.00010001000

count38.012.08.044.02.0


count67.071.0

sample volume (mL)

count

measured conc. (#/mL)1280.0430.01040.080.01160.015.01020.00.71120.00.0340.00.0

C/Co0.432890.080540.015100.000690.000040.0000018

Co (#/mL)993.3333333333

coli (7)

Date6/22/00Time3:00 PMTime6/22/00 15:00

Filter123456


sample volume (mL)0.050.10.050.50.0510.051000.051000.05100

count5739503450105211441423


count28757591114


count2026

sample volume (mL)

count

measured conc. (#/mL)1140.0335.01000.072.71000.08.51040.00.0880.00.0840.00.0

C/Co0.340680.073900.008640.000020.000010.00001

Co (#/mL)983.3333333333

coli (8)

Date6/23/00Time2:55 PMTime6/23/00 14:55

Filter123456


sample volume (mL)0.050.150.0510.0510.051000.0510000.051000

count509239373316041104033774


count72351117

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)1000.0546.7780.036.0660.0160.0820.00.1800.00.0740.00.1

C/Co0.683330.045000.200000.000140.000000.00009

Co (#/mL)800

Date6/26/00Time3:20 PMTime6/26/00 15:20

Filter123456


sample volume (mL)0.080.120.080.50.080.10.0810000.081000.0810

count4449591762063069360613


count44470131

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)550387.5737.542.66666666677750787.50.0003333333862.53.6762.50.3090909091

C/Co0.51955307260.057206703900.00000044690.00482681560.0004144236

Co (#/mL)745.8333333333

Date6/27/00Time3:30 PMTime6/27/00 15:30

Filter123456


sample volume (mL)0.080.120.080.250.080.10.0810000.0810.0810

count72274519463706535449


count36271103

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)900262.5562.5925750462.50.0003333333812.5355501.0181818182

C/Co0.40776699030.142912621400.00000051780.0543689320.0015816417

Co (#/mL)643.75


Date6/28/00Time3:30 PMTime6/28/00 15:30

Filter123456


sample volume (mL)0.050.10.050.250.050.010.051000.0510.0510

count44485245564735046545882


count45452151

sample volume (mL)

count

sample volume (mL)

count

measured conc. (#/mL)880465104018011204454.54545454547000.000476190592052.511608.2

C/Co0.47938144330.18556701034.59231490160.00000049090.05412371130.0084536082

Co (#/mL)970


MBD0077BC16.unknown

MBD04311B1E.unknown

MBD0430FE9B.unknown

MBD005149BB.unknown

Sticky Media vs. Sticky ParticlesSticky MediaPotentially treat filter media at the beginning of each filter runNo need to add coagulants to water for low turbidity watersFilter will capture particles much more efficiently

Sticky ParticlesEasier to add coagulant to water than to coat the filter media

The BioSand Filter CrazePatented new idea of slow sand filtration without flow control and called it BioSandFilters are being installed around the world as Point of Use treatment devicesCost is somewhere between $25 and $150 per household ($13/person based on project near Copan Ruins, Honduras)The per person cost is comparable to the cost to build centralized treatment using the AguaClara model

BioSand Performance

BioSand PerformancePore volume is 18 LitersVolume of a bucket is ____________Highly variable field performance even after initial ripening periodhttp://www.iwaponline.com/wst/05403/0001/054030001.pdfField tests on 8 NTU water in the DR

Field Performance of BioSand Table 2 pH, turbidity and E. coli levels in raw and BSF filter waters in the fieldParameter rawfilteredMean pH (n =47)7.48.0Mean turbidity (NTU) (n=47)8.11.3Mean log10 E. coli MPN/100mL (n=55)1.70.6http://www.iwaponline.com/wst/05403/0001/054030001.pdf

Potters for Peace PotsColloidal silver-enhanced ceramic water purifier (CWP)After firing the filter is coated with colloidal silver. This combination of fine pore size, and the bactericidal properties of colloidal silver produce an effective filterFilter units are sold for about $10-15 with the basic plastic receptacleReplacement filter elements cost about $4.00What is the turbidity range that these filters can handle?How do you wash the filter? What water do you use?

Horizontal Roughing Filters1m/hr filtration rate (through 5+ m of media)Usage of HRFs for large schemes has been limited due to high capital cost and operational problems in cleaning the filters.Equivalent surface loading = 10 m/day

Roughing FiltersFiltration through roughing gravity filters at low filtration rates (12-48 m/day) produces water with low particulate concentrations, which allow for further treatment in slow sand filters without the danger of solids overload. In large-scale horizontal-flow filter plants, the large pores enable particles to be most efficiently transported downward, although particle transport causes part of the agglomerated solids to move down towards the filter bottom. Thus, the pore space at the bottom starts to act as a sludge storage basin, and the roughing filters need to be drained periodically. Further development of drainage methods is needed to improve efficiency in this area.

Roughing FiltersRoughing filters remove particulate of colloidal size without addition of flocculants, large solids storage capacity at low head loss, and a simple technology. But there are only 11 articles on the topic listed in

(see articles per year)

They have not devised a cleaning method that works

Size comparison to floc/sed systems?

Multistage FiltrationThe Other low tech option for communities using surface watersUses no coagulantsGravel roughing filtersPolished with slow sand filtersLarge capital costs for constructionNo chemical costsLabor intensive operationWhat is the tank area of a multistage filtration plant in comparison with an AguaClara plant?

ConclusionsMany different filtration technologies are available, especially for POUFilters are well suited for taking clean water and making it cleaner. They are not able to treat very turbid surface watersPretreat using flocculation/sedimentation (AguaClara) or roughing filters (high capital cost and maintenance problems)

ConclusionsFilters could remove particles more efficiently if the _________ efficiency were increasedSSF remove particles by two mechanisms__________________________________________________Completely at the mercy of the raw water!We need to learn what is required to make ALL of the filter media sticky in SSF and in RSF

PredationSticky aluminum polymer that coats the sandattachment

ReferencesTufenkji, N. and M. Elimelech (2004). "Correlation equation for predicting single-collector efficiency in physicochemical filtration in saturated porous media." Environmental-Science-and-Technology 38(2): 529-536.Cushing, R. S. and D. F. Lawler (1998). "Depth Filtration: Fundamental Investigation through Three-Dimensional Trajectory Analysis." Environmental Science and Technology 32(23): 3793 -3801.Tobiason, J. E. and C. R. O'Melia (1988). "Physicochemical Aspects of Particle Removal in Depth Filtration." Journal American Water Works Association 80(12): 54-64.Yao, K.-M., M. T. Habibian, et al. (1971). "Water and Waste Water Filtration: Concepts and Applications." Environmental Science and Technology 5(11): 1105.M.A. Elliott*, C.E. Stauber, F. Koksal, K.R. Liang, D.K. Huslage, F.A. DiGiano, M.D. Sobsey. (2006) The operation, flow conditions and microbial reductions of an intermittently operated, household-scale slow sand filter

Contact Points

Polymer Accumulation in a Pore

******http://www.lenntech.com/cartridgefilter-bagfilter.htmhttp://www.nesc.wvu.edu/ndwc/pdf/OT/TB/OT_TB_su01.pdf on DE filters*Iwasaki, T. (1937). "Some Notes on Sand Filtration." Journal American Water Works Association 29: 1591.*************Yao, K.-M., M. T. Habibian, et al. (1971). "Water and Waste Water Filtration: Concepts and Applications." Environmental Science and Technology 5(11): 1105.*******Interception is very importantLousy at removing pathogens if they havent been flocculatedA 0.1mm particle has a pC* of 100!!!!!!!!!!Either particles havent been flocculated or attachment is poor****************The operation, flow conditions and microbial reductions of an intermittently operated, household-scale slow sand filter M.A. Elliott*, C.E. Stauber, F. Koksal, K.R. Liang, D.K. Huslage, F.A. DiGiano, M.D. Sobsey. *University of North Carolina, CB 7431, Chapel Hill, NC, 27514, USA.

Long ripening periodAfter pore volume is flushed has poor performance*http://www.iwaponline.com/wst/05403/0001/054030001.pdf***http://wedc.lboro.ac.uk/conferences/pdfs/22/Jayalat.pdfGravity roughing filter for pre-treatmentJ.M.J.C. Jayalath and J.P. Padmasiri, Sri Lanka

Picture from http://diglib.tums.ac.ir/pub/magmng/pdf/483.pdf

http://www.wrc.org.za/downloads/watersa/2006/Jan%2006/1728.pdf for filtration rate*Filter Mechanisms in Roughing Filters Boller, M Aqua AQUAAA, Vol. 42, No. 3, p 174-185, June 1993. 17 fig, 1 tab, 13 ref. *Filter Mechanisms in Roughing Filters Boller, M Aqua AQUAAA, Vol. 42, No. 3, p 174-185, June 1993. 17 fig, 1 tab, 13 ref. *http://www.atypon-link.com/TELF/doi/pdf/10.1680/wama.157.3.143.46664*****

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