Using Particle Counters In Combination With Turbidimeters .
Using Particle Counters incombination with Turbidimetersto obtain a better understandingof coagulation and filtrationperformance.Presented By: John Clark
Topics Coagulation & Filtration Theoryo Nephelometric (90 Light Scatter) Turbidimeter Light Blocking Particle Counter Particle Volume Distribution – Why It Matters, Interpreting NTU & PC Data
Which Has Higher Turbidity?ABBoth samples contain mixture of water and iron oxide (hematite)
Which Has Higher Solids?ABBoth samples contain mixture of water and iron oxide (hematite)
Particle Size SpectrumMicron(Log ble10Near IR100Far IRH2OMetal IonDissolved OrganicsRelativeSize ofMaterialVirusesColloidal SilicaClaySiltFine ngTechnologyROMembrane FiltrationNFUFMFConventional FiltrationDynamic Light ScatteringLaser DiffractionSmall Angle X-RayImaging AnalysisScatteringLight BlockingTDA / TEM / SEM(a.k.a. Particle Counter)
Coagulation MechanismsRaw WaterDissolved OrganicsColloidsAlum Raw WaterSoluble CationicSpecies Al(OH)2 Colloidal HydroxidePrecipitate Al(OH)3(s)Amorphous HydroxidePrecipitate Al(OH)3NOMNOMNOMNOMNeutralization / l-NOMAl-NOMAl-NOMAl-NOMEnmeshment / OMAl-NOMAl-NOMAl-NOMAl-NOMAl-NOM
Turbidimeters(Light Scatter)
Turbidity Definition Turbidity is a measure of water clarity, howmuch the material suspended in waterdecreases the passage of light through thewater. - EPA Turbidity is the measure of relative clarity ofa liquid. - US Geological Survey (USGS)
Turbidimeter DefinitionOxford Dictionary An instrument for measuring the turbidity ofa liquid suspension, usually as a means ofdetermining the surface area of thesuspended particles.
Nephelometric Turbidimeter(90 Degree Light Scatter)LensLight90o0.00 NTU0.20Photo Detector
Light Scatter BehaviorRayleigh ScatteringSmall Particles ( 100 nm): Somewhat Symmetric Light ScatterMie ScatteringMedium Particles (100 to 500 nm): Increased Light Scatter inForward DirectionLarger Particles ( 500 nm): Extreme Scatter in Forward Direction
NTU Relationship To Solids? NTU? NTU
Iron Oxide - Nanoparticles
Impact of Particle Size On Turbidity
Demosntrating Impact Particle SizeHas On TurbidityPrior to UltrasonicationSample contains largeagglomerations of ironparticles, many largerthan 10 micron10 Seconds After Going Into BathAs discrete iron particlesare disbursed, moresurface area is exposed,increasing light scatter.Initial Moment After Going Into BathThe agglomerationsof iron particles beginto break apart.After UltrasonicationIron particles now disbursedas discrete submicronparticles which dramaticallyincreases turbidity.
Magnetite & Hematite
PC vs NTU Response
Turbidity (Light Scatter) Summary A qualitative measurement that determines clarity ofthe water, which is impacted by both number andsize of particles. 10 ppb of 5 micron particles will have a lower NTUthan 10 ppb of 0.5 micron particles. Does not reliably correlate to suspended solids postcoagulation due to changing distribution ofparticulate (post coagulation). Offers affordable means of submicron particledetection.
Particle Counters(Light Obscuration)
The Rise of Particle Counters Two major crypto outbreaks in the US occurred in the early90’s which led to intense interest in particle counters in thedrinking water industry as a way to hep guard against futureoutbreaks.Photo Credit: H.D.A Lindquist, U.S. EPA
Particle Counter (Light Blocking)ParticlesLight BeamLaser DiodePhoto DiodeWater Flow
Particle SizingmV10 Micron
Particle Counts Multi-Size channel view showing counts in eachsize bin.
Coincidence ErrorParticlesLight BeamLaser DiodeOr LEDPhoto DiodeWater Flow
What Is More Important?Particle Count (How Many?)Particle Volume (How Much?)
Idealized Size DistributionThis size distribution model statesthat for every 10 µm particle therewill be one million 0.1 µm particles inthe sample.A single 10 µm particle hasthe same volume as onemillion 0.1 µm particles.
Particle Size vs Volume0.1 micron 0.0005 µm³0.0005 ppt*2 micron 4.2 µm³10 micron 524 µm³4.2 ppt*524 ppt** At concentration of 1 count per mL
Real World Filter Effluent Data94.5%0.35% of counts 5 um5.1%0.28%0.04%0.02%0.007%80% of volume 5 um18%7%12%20%23%20%
Particle Volume Readout An important feature of some online particlecounters is a volumetric concentration readout
Biologically Active Filters
Total Counts with PPB
Before Chlorine AdditionBefore
After Chlorine AdditionAfterFilterBackwashes(120 hr)
Particle Detachment
Surface Removal (Straining)Top of filterFilter media Large floc particles lead to rapid head loss, shorterfilter run times.
Attachment FiltrationTop of filterFilter media Smaller floc particles allow more of the filter mediato be utilized, allowing for longer filter run times
Attachment Filtration Mechanism Particles attach to filter media by way ofelectrostatic forces / van der Waals forces Enhanced with metal hydroxide (coagulant) orpolymer (filter aid). Particles are “stored” and not “trapped”. Probability of detachment & breakthroughincreases as solids loading and internal porevelocity increases.
DetachmentInternalPoreFLOW
Impact Of Flow Rate ChangesCombined FilterParticle CountsFilter #1 Particle CountsFiltration RateFilter #1 TurbidityHead Loss
End of Filter RuntimeParticle Breakthrough
Filtration Stagese.g. 120 HoursBackwashes Often PerformedMany Hours Before InitialBreakthrough OccursRipeningStageWorking age
End of Filter Run BreakthroughgEnd of run filter breakthrough trends for particle count and turbidityPaticle count 2-10 micron (particles per mL)450.1Particle CounterParticleCount (2-10 um)Laser Diode TurbidimeterF4 FT660scTungsten LampTurbidimeterF4 50.03100.0250.0101/2/2013 6:00:00 AM1/2/2013 9:00:00 AM1/2/2013 12:00:00 PMDateTime01/2/2013 3:00:00 PMTurbidity NTU50
Filter Integrity
Early Warning Of Filter Problems
Depression in media caused bydamaged underdrain
Coagulation Upsets
Coagulation UpsetsBackwash solids accidentallyrecycled at too high of aconcentrationCoagulant Feed Temporarily Lost.
Getting The Full PictureTurbidityParticleCountsTSSBaseline0.04 NTU10 cnts/ml 1 ppb#1Event0.30 NTU30 cnts/ml30 ppb#2Event0.10 NTU120 cnts/ml60 ppb
Getting The Full PictureTurbidityParticleCountsTSSBaseline0.04 NTU10 cnts/ml 1 ppb#1Event0.30 NTU30 cnts/ml30 ppb#2Event0.10 NTU120 cnts/ml60 ppb
The Takeaway Turbidimeters offer affordable detection ofsubmicron particulate, very informative in terms ofcoagulation performance. But the reduced responseto larger particles has potential implications inregards to early detection of filter performanceissues. Particle Counters offer affordable, very sensitivedetection of larger particles. These larger particlescan signal the beginning of the end of a filter run, adeveloping filter integrity issue, or excessivebiological shedding. Only when particle counters and turbidimeters areused together do we have the most complete pictureof coagulation & filtration performance.
Questions?
References Turbidity Science, Michael J. Sadar, Hach Monitor Water Filtration Processes For Optimum Particle Removal,John Gregory, University College London Particles Contributing To Turbidity, EPA Guidance Manual TurbidityProvisions http://www.hielscher.com/nano 01.htm; Ultrasonic Devices ToDisperse Nanomaterials Deep Bed Filtration: Modeling Theory and Practice, G. Keir; V.Jegatheesan; S. Vigneswaran Particle Counting In Real World Water Treatment Plant Operations,Thomas M. Ginn,Jr., P.E.; G. Ricky Bennett; Gregory D. Wheatley;Cobb County-Marietta Water Authority
10 ppb of 5 micron particles will have a lower NTU . The Rise of Particle Counters Two major crypto outbreaks in the US occurred in the early 90’s which led to intense interest in particle counters in the drinking water industry as a way to hep guard against future . Rapid. Incline. End
Introduction – COUNTERS A counter is a register that goes through a predetermined sequence of states upon the application of clock pulses. Asynchronous counters Synchronous counters Asynchronous CountersAsAsynchronous Countersynchronous Counters (or Ripple counters) the clock signal (CLK) is only used to clock th
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the need for ISO 21501-4 compliant particle counters in cleanroom certification and monitoring applications. Section B.2.2 of the previous standard, ISO 14644-1:1999, required particle counting to be performed using . The Lasair III Aerosol Particle Counter and the IsoAir 310P Aerosol Particle Sensor use a sophisticated system described .
1 Elec 326 1 Registers & Counters Registers & Counters Objectives This section deals with some simple and useful sequential circuits. Its objectives are to: Introduce registers as multi-bit storage devices. Introduce counters by adding logic to registers implementing the functional capability to increment and/or
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