Pittsburgh Water

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• Pittsburgh Water
• and Sewer Authority
• Pilot-Scale
• Drinking Water Treatment Plant

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Unit Process Overview
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Unit Process Summary

• Design Flow Rate 4 gal/min (15 L/min)
• Three-stage Flocculation
• G Values 25, 17 and 9.2 s-1
• Primary Sedimentation
• Loading Rate 0.24 gpm/ft2
• Dual Media Filtration
• Filtration Rate 1 gal/ft2/min
• Ozonation (Pre and Intermediate Ozonation)
• Chlorine Dioxine (Batch Feed)

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Pilot-Scale Process Schematic
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Available Water Sources

• Raw Water (P)
• Primary Clarifier Effluent (P)
• Secondary Sedimentation Effluent (G)
• Filter Influent
• Filter Effluent (G)
• Filter Backwashing

Note
P Pumped G Gravity Feed
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SCADA System

• System Control And Data Acquisition System

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Instrumentation

• Turbidimeters
• Hach 1720D Low Range Process Turbidimeter
• pH meters
• GF Signet pH/Orp Electrode Model No. 2714/2716
• Particle Counters
• Two Chemtrac 2400D digital on-line particle
  counters. Chemtrac Systems Inc. each instrument
  dedicated to two filters.

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Conventional Train For SCADA
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Experimental Train Screen For SCADA
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Combined Train Screen For SCADA
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Flow Splitting Box

• 15-gallon acrylic basin
• Design Flow 8 gpm.
• Each train will only use 4 gpm.
• Detention Time 1.9 minutes.

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Flow Splitting Box
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Flow Splitting Box
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Pretreatment Basin

• A 22 gallon acrylic, baffled basin.
• Provides the necessary chemical contact time
• e.g., potassium permanganate or chlorine dioxide
• 5.6 minutes of detention time at 4 gpm.

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Pretreatment Basin
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Pretreatment Basin
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Rapid Mix Basins

• Design Flow 4 gpm
• Detention Time per cell 23 seconds.
• Each Cell Volume 1.5 gallons.
• Flow is baffled in an over/under configuration.
• Chemicals are delivered to each rapid mix cell
  immediately below the mixer impeller through a
  stainless steel tube.
• Each mixer has a range of 0 to 1,000 sec-1 .

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Rapid Mix Basins
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Rapid Mix Basins
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Flocculation Basins

• Three Acrlyic Flocculation Basins
• Total Volume 28 gallons
• Detention Time 21 minutes at design flow of 4
  gpm
• Detention Time 7 minutes per zone
• Flocculator Paddle Boards
• Zone 1 4 sets of 4 paddle boards (1.3 ft2 total
  area)
• Zone 2 3 sets of 4 paddle boards (1.0 ft2 total
  area)
• Zone 3 2 sets of 4 paddle boards (0.7 ft2 total
  area)
• Each paddle board is 0.5 inch wide by 2 feet
  long.
• Flocculation Mixing Range 10 to 70 sec-1.

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Zone 1 Flocculator
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Flocculation Basins
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Flocculation Basins
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Primary Clarifier

• Counter-Current Flow Lamella Plate Settler
• Settled water exits the top of the unit.
• Flocculated solids drop to the bottom.
• Sedimentation Basin is an Acrylic Tank with Seven
  Stainless Steel Plates
• Each plate is 1.5 feet wide by 3 feet deep.
• The plates are spaced 3 inches apart and inclined
  at a 60? angle.
• Area available for settling is 16 square feet.
• The design flowrate is 4 gpm.
• The projected loading rate is between 0.22 to
  0.44 gpm/ft2.

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Primary Clarifier
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Primary Clarifier (Plate Settling)
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Secondary Sedimentation Basin

• Flow Rate Reduced from 4 gpm to 1 gpm. Simulates
  the Full-Scale Facility.
• The Design Detention Time at 1 gpm is
  Approximately 20 hours.

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Secondary Sedimentation Basin
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Secondary Sedimentation Basin
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Filters

• 6-inch Acrylic Columns Approximately 16 Feet in
  Total Height.
• Each Pilot-Scale Filter Contains
• 18-inches of anthracite on top of 12-inches of
  filter sand.
• All media was taken from existing filters in the
  full-scale treatment plant. Media was aged for 6
  years.
• A ¾ inch thick Leopold Integral Media Support
  (IMS) cap is used in the pilot scale filter to
  support these granular layers.
• Maximum Allowable Filter Media Depth is 6 feet.
• Water Depth Above the Filter Media Can Range from
  6.5 to 9.5 feet.

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Filters

• 2 filters are supplied water from the
  conventional train.
• 2 filters are fed water from the experimental
  train.
• The flow rate can be varied from 0.2 gpm to 1
  gpm.
• The filter loading rate range is between 1
  gpm/ft2 to 5 gpm/ft2.

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Filters
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Filter Appurtenances
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Filter
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Ozone Generator

• The generator is an OSMONICS OREC Ozone Generator
  SP 19-O-1059, with a capacity of 1 pound/day of
  ozone.
• Ozone dosing can be accomplished by using of an
  in-line injector (eductor) or a fine bubble
  diffuser.

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Ozone Generator
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Ozone Feed Gas Offgas Monitors
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Ozone Eductor System
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Ozone Diffuser
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Ozone Offgas Destruction Unit
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Ozone Offgas Destruction
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Ozone Contactors

• Each contactor is made of glass, 6 inches in
  diameter, and 18 feet tall with 2 feet of
  freeboard.
• The water height in the contactors in operation
  is 16 feet in preozonation mode and 14 feet in
  intermediate ozonation mode.
• The design contact time at a flow of 4 gpm is
  5.9 minutes per contactor for preozonation and
  5.1 minutes per contactor for intermediate
  ozonation.

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Ozone Contactors
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Ozone Contactor
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Ozone and Chlorine Dioxide Generators in a Fume
Hood
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Chlorine Dioxide Generation

• A CDG Technologies Model MB-1000R pilot-scale
  generator.
• Can produce a stock solution of 1,000 to 3,000
  mg/L.
• Chlorine dioxide is generated by combining
  chlorine gas with sodium chlorite.

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Chlorine Dioxide Generator
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Chemical Feed System
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SCADA Filter Screen
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SCADA Data Screen
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SCADA pH Trend Screen
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SCADA Flow Trend Screen
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SCADA Turbidity Trend Screen
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SCADA Ozone Trend Screen
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SCADA Particle Trend Screen