FiltrationFiltrationat the Bloomington, ILat the Bloomington, ILWater Treatment PlantWater Treatment Plant
Old Plant FiltersOld Plant Filters1929, 1956, 19661929, 1956, 1966
Old Plant FiltersOld Plant Filters
• Filters #1-12: GAC-Capped Sand
• 435 square feet per filter (20’ x 21.75’)
• Operated at a flow rate of ~ 1 gpm/ft2
• Fixed surface wash nozzles
Old Plant Filters: Influent Trough Old Plant Filters: Influent Trough
Old Plant FiltersOld Plant FiltersAfter Pressure WashingAfter Pressure Washing
PVC Surfa
ce Wash P
ipin
g
Old Plant Filters:Old Plant Filters:Fixed Surface Wash NozzlesFixed Surface Wash Nozzles
PVC Pipe and Nozzles
Old Plant Filters: Media RemovedOld Plant Filters: Media Removed
ManifoldLa
tera
ls
Old Plant Filters: UnderdrainOld Plant Filters: Underdrain
Perforated Cast Iron Lateral Piping :
Uniform Distribution of Backwash Water
New Plant Filters - 1994New Plant Filters - 1994
New Plant Filters: GAC CapNew Plant Filters: GAC Cap
24” filter cap replaced with virgin GAC every two years
New Plant Filters: Influent TroughNew Plant Filters: Influent Trough
Wash Water Trough
Influent Channel and
Wash Water Gullet
New Plant Filters: Influent TroughNew Plant Filters: Influent Trough
• Filters #13-18
• Dual-cell filters
• 462 square feet per filter (10.75’ x 21.5’ x 2 cells)
• Operated at a flow rate of ~ 2 gpm/ft2
• Rotating surface wash
New Plant Filters:New Plant Filters:Rotating Surface WashRotating Surface Wash
Su
rfac
e W
ash
Hea
der
New Plant FiltersNew Plant Filters
GAC Removed
Sand Layer Exposed
Granular Activated CarbonGranular Activated Carbonand Silica Sandand Silica Sand
BackwashBackwash
Sand Grab SampleSand Grab Sample
Filter Core SampleFilter Core Sample
Silica Sand Granular Activated Carbon
Top / Bottom of Sand LayerTop / Bottom of Sand Layer
top bottom
New / Old SandNew / Old Sand
New sand is finer; more uniform
New / Old SandNew / Old Sand
D10 (new) = 0.52 mm D10 (old) = 0.58 mm
Examination of Old SandExamination of Old SandStereo MicroscopeStereo Microscope
Examination of Old SandExamination of Old Sand
Examination of Old SandExamination of Old Sand
Examination of Old SandExamination of Old Sand
Examination of Old SandExamination of Old Sand
Elution of Old SandElution of Old Sand
Organisms Rinsed from Old SandOrganisms Rinsed from Old Sand
GAC Grab SampleGAC Grab Sample
Chain of CustodyChain of Custody
New / Old CarbonNew / Old Carbon
new old
black grey
New / Old CarbonNew / Old CarbonOld GAC has lost both ‘fines’ & larger particlesOld GAC has lost both ‘fines’ & larger particles
Examination of Old CarbonExamination of Old Carbon
Examination of Old CarbonExamination of Old Carbon
Examination of Old CarbonExamination of Old Carbon
Examination of Old CarbonExamination of Old CarbonStalked, Epiphytic Bacteria extend from GAC surfaceStalked, Epiphytic Bacteria extend from GAC surface
Examination of Old CarbonExamination of Old CarbonBacteria fluoresce under UV illuminationBacteria fluoresce under UV illumination
Examination of Old CarbonExamination of Old CarbonMicrobial Colonization of GAC SurfaceMicrobial Colonization of GAC Surface
Examination of Old CarbonExamination of Old Carbon
Examination of Old CarbonExamination of Old Carbon
Examination of Old CarbonExamination of Old Carbon
Replacing Lost SandReplacing Lost Sand
The Changing of the CarbonThe Changing of the Carbon
Disinfection after GAC/Sand ReplacementDisinfection after GAC/Sand Replacement