Reducing thm via aeration a case study november 21 2013 by gary williams p e jones henry engineers
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Reducing THM via Aeration: A Case Study November 21, 2013 by Gary Williams, P.E. Jones & Henry Engineers. Southeast AWWA District Meeting. Agenda. Location History Pilot Implementation Take Away Information. Location Map. Distribution System Map. Water Quality 2008. THM 2008.

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Reducing thm via aeration a case study november 21 2013 by gary williams p e jones henry engineers

Reducing THM via Aeration: A Case StudyNovember 21, 2013by Gary Williams, P.E.Jones & Henry Engineers

Southeast AWWA District Meeting


Agenda
Agenda

  • Location

  • History

  • Pilot

  • Implementation

  • Take Away Information






Water history
Water History

  • 1972 Water Treatment Plant, Low Head Dam, and Reservoir Constructed

  • 1993 Water Treatment Plant Study

  • 1996 Reservoir Study

  • 1999-2000 Water Treatment Plant Expansion $3,000,000

  • 2002 Second Reservoir $2,300,000

  • 2004 Water Distribution System DBP Reduction Study

  • 2005 Chlorine Dioxide Benchtop Study

  • 2005 MIEXBenchtop Study

  • 2006 RSSCT for GACBenchtop Study

  • 2008 THM Reduction via Aeration Opflow Article



Research
Research

  • Limited Research Available for Dynamic System

  • One Company Marketed a System $$$$$$$$

  • Air : Water Ratios (cfm : gpm) 5 to 60

  • If A:W = 40 and processing water @ 700 gpm = 28,000 cfm blower

  • Approximately 200 hpBlower


Pilot
Pilot

  • Assumed 20:1 A:W ratio or 14,000 cfm

  • Determined Approximate Area Diffusors for 14,000 cfm in Clearwell 2

  • Assumed One/half Depth of Clearwell or 7 feet

  • Calculated the Volume over the Diffusors

  • Developed the Detention Times in the Three Celled Clearwell

    • Influent Cell 60 minutes

    • Aeration Cell 75 minutes

    • Effluent Cell 60 minutes

  • Scaled down the flows of air and water to match a 4-inch PVC pipe




Pilot protocol
Pilot Protocol

  • Two Pilot Steps

    • First Step Test Entire A:W Range

    • Second Step Optimize Results of the First Step

  • Goal was to Optimize Air Required

  • Parameters Tested

    • TOC

    • THM

    • HAA5

    • Chlorine Residual

    • Stability

      • pH

      • Total Alkalinity

      • Total Hardness

      • Calcium Hardness

      • TDS

      • Chlorides

      • Sulphates





Project costs
Project Costs

  • Aeration System

    • 5:1 A:W ratio 3,500 scfm Blower

    • Stainless Steel Diffusors

    • Caustic Soda Feed System to increase pH to 8.9

    • 12-inch Air Piping to Clearwell Diffusors

    • Electric and Controls

  • Project Cost - $401,700

  • Annual O&M - $73,000

  • GACSystem

    • Project Cost - $1,225,600

    • Annual O&M - $145,000


  • Brand x
    Brand X

    • 2011 SolarBee Aeration System Proposal

      • Two 15 HP Blowers 580 scfm Each

      • Three Submersible Mixers

      • 86 Diffusor Assemblies

      • Caustic Soda Feed System to increase pH to 8.9

      • 8-inch Air Piping to Clearwell Diffusors

      • Electric and Controls

    • Project Cost - $571,700

    • Annual O&M - $21,000

  • SolarBeeOffer

    • Install Clearwell Equipment

    • Provide Temporary Blower and Piping

    • 6-month Trial

    • If Satisfied, Purchase Price $360,000


  • Second thoughts
    Second Thoughts

    • April 1, 2012 SolarBee Oops

      • Further Testing Showed Spray Aeration Preferable

      • Highly Recommended Spray System

      • One GS-12 Submersible Mixer in Clearwell 1

      • Two SN-15 Floating 15 HP Pump/Mixer/Spray Systems

      • Two Ventilation 2HP Blowers 750 scfm Each

      • Caustic Soda Feed System to increase pH to 8.9

      • 12-inch Air Piping to Clearwell

      • Electric and Controls

    • Project Cost - $369,900

    • Annual O&M - $22,000

  • SolarBeeOffer

    • Provide In-Clearwell Equipment and Two Blowers

    • Install Clearwell Equipment

    • 6-month Trial

    • If Satisfied, Purchase Price $168,000


  • Schedule
    Schedule

    • Bid – October 2012

    • Preconstruction Meeting – November 2012

    • Substantial Completion – March 2013

    • Total Completion – June 2013


    Tthm summary
    TTHM Summary

    (all values TTHM in ppb, except where noted)



    Take away information
    Take Away Information

    • THMsHave to be Formed

      • Aeration Does Not Reduce Formation Potential

    • Chloroform is Typical Target THM

    • Powered Air Supply for Ventilation Probably Required

    • Check pH/Stability

    • Check Chlorine Residual


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