Reducing THM via Aeration

25 Pages·2014·1.6 MB·English

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Reducing THM via
Aeration: A Case Study
August 28, 2014
by Gary Williams, P.E.
Jones & Henry Engineers
WEA-AWWA 2014 Technical Conference & Expo
Agenda
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Location

History

Pilot

Implementation

Take Away Information

Location Map
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Water Quality 2008
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Raw Water
Total Hardness 285 mg/L as CaCO
3
Total Alkalinity 133 mg/L as CaCO
3
pH 8.2
Turbidity 3.2
Total Organic Carbon 4.5 mg/L
Finished Water
Total Hardness 150 mg/L as CaCO
3
Total Alkalinity 36 mg/L as CaCO
3
pH 9.2
Total Organic Carbon (average) 2.1 mg/L
TOC Removal (average) 51%
THM 2008
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Total Trihalomethane & HAA5 2007/2008
Date of Sample Location Second MR002
HAA5
Sample Quarter 2007 Average RAA LRAA Average RAA
5/24/2007 RD002 38.9 13.4
RD003 40.8 14.4
MR002 50.2 43.3 47.8 59.3 11.8 13.2 17.8
Thrid Quarter 2007
7/10/2007 RD002 82.3 16.6
RD003 85.3 15.2
MR002 102.0 89.9 50.4 60.6 16.7 16.2 14.4
Fourth Quarter 2007
10/11/2007 RD002 54.1 17.3
RD003 58.3 16.4
MR002 81.7 64.7 58.1 69.3 22.0 18.6 15.9
First Quarter 2008
1/16/2008 RD002 40.6 19.3
RD003 40.7 20.8
MR002 54.9 45.4 60.8 72.2 20.4 20.2 17.0
Second Quarter 2008
4/2/2008 RD002 40.5 13.6
RD003 40.6 13.1
MR002 60.3 47.1 61.8 74.7 14.2 13.6 17.1
Third Quarter 2008
7/8/2008 RD002 85.1 33.1
RD003 85.3 32.1
MR002 131.0 100.5 64.4 82.0 34.7 33.3 21.4
Fourth Quarter 2008
10/9/2008 RD002 52.0 28.8
RD003 55.7 28.8
MR002 80.6 62.8 63.9 81.7 33.3 30.3 24.4
Water History
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1972 Water Treatment Plant, Low Head Dam, and

Reservoir Constructed
1993 Water Treatment Plant Study

1996 Reservoir Study
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1999-2000 Water Treatment Plant Expansion $3,000,000

2002 Second Reservoir $2,300,000
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2004 Water Distribution System DBP Reduction Study
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2005 Chlorine Dioxide Benchtop Study
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2005 MIEX Benchtop Study
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2006 RSSCT for GAC Benchtop Study
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2008 THM Reduction via Aeration Opflow Article

2008 THM Reduction via Aeration Opflow
Article
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Research
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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 hp Blower

Pilot
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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
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Calculated the Volume over the Diffusors
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Developed the Detention Times in the Three Celled
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Clearwell
Influent Cell 60 minutes

Aeration Cell 75 minutes
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Effluent Cell 60 minutes
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Scaled down the flows of air and water to match a 4-inch

PVC pipe
Pilot
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