The BiO3 Service approach to concrete
pipe and structure corrosion control is to work on the cause
of the corrosion.
Cause: The underlying cause of concrete
corrosion is the dissolved sulfides in the wastewater. Dissolved
sulfides are created by anaerobic sulfate-reducing bacteria
(SRB’s) during their growth cycle – they take
an oxygen atom from sulfate in the wastewater thereby reducing
the sulfate to sulfide.
Effect: When the wastewater reaches an airspace
(force main air pocket, gravity main, wetwell or grit pit)
and conditions are right (pH and temperature) then the dissolved
sulfides in the wastewater form Hydrogen Sulfide (H2S) which
offgases into the headspace.
The H2S is then oxidized to sulfuric acid by aerobic bacteria
on the moist concrete surfaces. The sulfuric acid attacks
the concrete, causing the corrosion.
Control Approach : The BiO3
corrosion control approach is to work on the cause, i.e. to
reduce the dissolved sulfide levels in the wastewater thereby
reducing the corrosion precursors. This is accomplished with
BiO3 Bioaugmentation. For more information, click
on BiO3 Bioaugmentation.
Baton Rouge Corrosion Control Study
As a part of the contract with Baton Rouge, an engineering
firm, Chenevert, Songy, Rodi, Soderderg (CSRS), was commissioned
to perform a corrosion study.
The findings of their study were:
1. Microbial feed in the South Suburban Transportaation Network
will reduce corrosion at the South Treatment Plant headworks
by 80-90% as compared to an untreated waste stream.
2. The reduced corrosion rates resulting from microbial feed
will increase the concretes structures' useful life by a factor
of 4-6 times-possibly as much as 12 times if Dissolved Sulfide
levels stabilize at 2.0 mg/l.
3. Corrosion in pump station wet wells at the extremities
of the transportation network, while minimal to begin with,
can be reduced by a factor of 10, thus increasing the structural
life of the wet well by the same factor.
4. Provided that the Air Release Values on the force main
system are Maintained and no pockets of air are allowed to
accumulate, there should be little or no corrosion to the
interior of the force main piping.
To read the complete executive summary of this study, click
on (CSRS Study).
Contact Us: If you have questions and/or
want to discuss a specific problem, please contact
us . cliff@biothree.com
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