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


Location map

Location Map


Southeast awwa district meeting

Distribution System Map


Water quality 2008

Water Quality 2008


Thm 2008

THM 2008


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


2008 thm reduction via aeration opflow article

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 Cell60 minutes

    • Aeration Cell75 minutes

    • Effluent Cell60 minutes

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


Pilot1

Pilot


Test pipe arrangement

Test Pipe Arrangement


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


Pilot results

Pilot Results


Pilot results1

Pilot Results


Other pilot results

Other Pilot Results


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)


    Maximum residence time running annual average

    Maximum Residence Time Running Annual Average


    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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