Algae Control with Dissolved Air Flotation in Bellingham, WA

PNWS-AWWA Conference 2016

Joshua Kennedy/CH2M

Bill Evans/City of Bellingham

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Outline

• Algae in the Pacific Northwest

• Bellingham WTP background

• Alternatives and pilot study

• Chlorine gas conversion

• Conclusion

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Algae in the Pacific Northwest

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Climate change and algal blooms

• Increased temperatures result in rising lake temperatures

• Increased Proliferation of Algae & Algal Toxins

Lake Erie Algal Bloom, 2013, Source: NOAAWorldwide Lake Warming 2015, Source: NASA

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Algal blooms in Oregon

Source: https://public.health.oregon.gov/HealthyEnvironments/DrinkingWater/Operations/Treatment/Pages/algae.aspx

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Impacts of algae

Taste and odor events

Disruption of treatment equipment

Water quality issues

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Impacts of algae: Mitigation techniques

Source Management

Ozone

Chemical oxidation

Activated carbon (PAC,

GAC)

Dissolved Air Flotation

Operational Changes

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Bellingham WTP Background

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Whatcom Falls Treatment Plant background

Constructed in 1968

In-line Filtration Plant

Limited pre-treatment

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Whatcom Falls Treatment Plant background

Treatment

Plant

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Whatcom Falls Treatment Plant background

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Whatcom Falls Treatment Plant background:2009 algae event

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Alternatives and Pilot Study

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Treatment alternatives

No action

Relocation of the intake

Filter expansion

Construction of a pretreatment facility

Triple bottom line scoring was used for evaluation

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Chosen alternative

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Chosen alternative

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Pilot study

• Rented DAF unit, used existing pilot filter columns

• Tested loading rates of 10 to 20 gpm/sf

• Varied polymer dose and flocculation times

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Pilot study: Results

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Whatcom Falls Treatment Plant background

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Wat

er D

eman

d (

mgd

)

THM

in p

arts

per

bill

ion

Total Trihalomethane (THM) Averages and Water Demand 2003-2015

Farthest Sampling Site from Treatment Plant Average Water Used per Day (mgd)

The maximum THM allowed is 80 parts per billion

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Moving forward with DAF

• First DAF installation for drinking water in the NW

• One of the highest rate DAF units ever designed

• Climate considerations

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Chlorine gas conversion

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Chlorine gas conversion

Opportunistic time to consider conversion

Several associated risks

• Chlorine gas

• No scrubbers

• Outdoor storage

• Park Setting

• Operator space/parking nearby

• Supply chain issues

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Chlorine gas conversion: Alternatives Analysis

• Selected based on safety and O&M considerations

On-site generation

• Not selected due to potential environmental impacts and off-gassing

Bulk hypo

• Most familiar technology but not deemed safe for the City moving forward

Gas chlorine

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Chlorine gas conversion: Key benefits

Safety concerns

Environmental impacts

Supply issuesReduce no. of

deliveries

Chlorine gas

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Conclusion

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Bellingham project status

Going out to bid for

construction this year

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Bellingham project approach

Quickly and efficiently analyzing

alternatives

Early generation of 3D models

and site layouts

CH2M CPES™ Cost estimating

tool

30% deliverable drawings created in SketchUp

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Bellingham project approach

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Bellingham project approach

Thank You