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The management of taste & odor�compounds and cyanotoxins in lakes and reservoirs

Byran Fuhrmann, PhD, MBA

Environmental Chemist

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Problem

SUPER Potent:

  • < 10 parts per trillion can make “nasty”
  • Very expensive to test for
  • Very expensive to remove enough to matter

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Not very predictable

  • Not much data due to analysis expense

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Source Water Concentration �

↑

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Degradation

Settling to Sediment

Input from tributaries

Production

Release from sediment

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Source Water Concentration �

↑

↔

Degradation

Settling to Sediment

Input from tributaries

Production

Release from sediment

↓

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  • High Nutrients
  • Stagnant surface water
  • Anoxic bottom water
  • Low N to P ratio
  • High ammonium to nitrate ratio
  • Limited littoral aquatic plant community

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Characteristics of High Geosmin & MIB Lakes

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  1. Cyanobacteria
    • If they’re present it’s likely their fault

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  • Bacteria (Actinomycetes)
    • Typically need oxygen
    • Not the problem if lake is green

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  • Everyone else combined is distant 3rd
    • Not really in source water
    • Probably only in infrastructure

Production of Geosmin & MIB

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Cyanobacteria

Major Characteristic

Managing Them

Anabaena/

Dolichospermum

Like the Surface

Nitrogen-fixers

Sediment Phosphorus

Mixing

Aphanizomenon

Planktothrix

Like the Middle

Sediment Phosphorus

Oscillatoria/

Lyngbya

Like the bottom

(shallow)

Establish aquatic plants

Algaecides (harsh)

Worst of the Worst

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Degradation is mostly bacteria (not UV or chemistry)

  • VERY chemically stable
  • Stored internally

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Degradation enhanced by:

  • High temp
  • Oxygen
  • Mixing

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Degradation of Geosmin & MIB

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Bloom crashes encourage accumulation

  • Normal growth-death cycles not as bad
  • Anoxic water/sediment allows it to persist

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Mucky anoxic sediment can be big source

  • Organic-rich sediment will hold it
  • Gassy, anoxic sediment can send it into water

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Sediment and Geosmin & MIB

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Malaysia Geosmin & MIB

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Malaysia Geosmin & MIB

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Malaysia Geosmin & MIB

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Malaysia Geosmin & MIB

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Anoxic bottom water is a problem

  • Source of nutrients (P & Ammonium)
  • Stagnant water above
  • Slow degradation rates

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Accumulation >> production

  • Cyanos have short lives
  • Need a larger sink (oxygen)
  • Or need better control (limit nutrients)

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Sediment storage can be significant

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Malaysia Takeaways

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In order of priority:

  1. Avoid high phosphorus
    • Watershed or wastewater
    • Alum/ACH, LMB, Oxygen
  2. Do your research - find the source
    • Organism AND location
    • Different control for benthic vs planktonic
  3. Avoid anoxic bottom water (planktonic)
  4. Avoid plant-devoid littoral areas (benthic)

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Management Takeaways

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Questions?

impact@cleanwaterhelp.org

cleanwaterhelp.org

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Time

Sediment

Organic Matter

Tipping Point

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Root of the Root

  • Too much dead algae

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  • Changes with season
    • Bacteria remove it
    • Blooms add it

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  • SPRING content is critical!