Transcript File - Midwest Water Analysts Association

Adventures with O21N
(and other filaments)
Bob Moser and Jeff MacDonald
Midwest Water Analysts Annual Expo
January 27, 2017
Jones Island (Milw.) WRF
• Rehab & expansion – 1982-1996
• 200 MGD increased to 330 MGD
• 1987; primary sludge to primary effluent
channels
• SVI increase
• Filaments O21N and Thiothrix noted as
cause of poor settling – both can be
promoted by septic conditions
Jones Island (Milw.) WRF
• Mid-1987 – plant returns to old primary
facilities
• Permit violation for BOD & TSS avoided
• Primary sludge confirmed to be settling
in PE effluent channels
Actions Taken to Improve
Settling
• Primary sludge piped to location where
RAS and PE mixed
Actions Taken to Improve
Settling
• Primary sludge piped to location where
RAS and PE mixed
• RAS chlorination facilities commisioned
• Polymer addition to clarifiers
• New primary facilities restarted in late
1987
Ongoing Settling Issues
• O21N and Thiothrix dominant
alternately, seasonally
• RAS chlorination, through experience,
found to be effective control – proper
dose & application critical
• Polymer addition also fine tuned
• RAS chlorination SOP developed, based
on historical data & plant performance
Filaments of Concern
• O21N (Meganema perideroedes)
• Thiothrix
• Nostocoida limicola
Variability of O21N
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Gram positive and/or negative?
Cell shape
Cell size
Bulbous nodules
Bifurcations and later ‘rejoining’
Filament width & taper
Low level, continuous addition of chlorine at point of good mixing.
A dose of 4 – 6 lbs Cl2/1000 lbs MLVSS proved effective.
That’s it Folks!