Halfway through a sugar beet processing campaign
(September through May) a Midwest refinery noticed
something was wrong with their wastewater processing
system. The plant discharge was within limits for their NPDES
permit parameters, but the chemical oxygen demand (COD)
readings from their 8.9 million-gallon anaerobic digester
were very different at the top, center, and bottom of the
digester. The system engineer suspected the mixers were
not operating properly.
Without functional mixing, the digester was unable to
process the high COD wastewater from the refinery. To fix
the problem, the facility’s processing and engineering team
decided to repair the mixing blades in the digester at the
end of the campaign. The digester was emptied and cleaned
in the process, which removed all active biology in the tank.
After maintenance was completed, the anaerobic digester
needed to be reseeded to begin properly processing high
COD wastewater.
Initially, using activated sludge from a neighboring sugar
refinery’s anaerobic digester was suggested to seed the
repaired digester. This process would involve hauling
thousands of gallons of activated sludge, an expense ranging
between $70,000 and $100,000. In addition to cost, seeding
with activated sludge from another facility would be highly
time consuming and risky. The sludge could introduce
unknown foreign contaminates to the newly cleaned and
repaired system.
This could cause unpredictable treatment issues in the
future. The plant was seeking alternative options, which lead
them to BioLynceus®. The team at BioLynceus® suggested
reseeding with Probiotic Scrubber® II (PBII). This live culture
treatment would supply the digester with a diverse microbial
community and give the company a more cost-effective,
easier to transport, and more reliable solution.
PBII was added to the digestor in addition to the facility’s
high strength COD wastewater to restart the digester.
After four days of implementing PBII of product, consistent
methane was being produced by the digester; indicating
the microbiology was properly processing the influent COD.
Seeding the digester with PBII saved the refinery time and
money, because sludge hauling was not necessary to restart
the system.
Figure 1. Cumulative biogas produced per 1000 pounds influent
COD was calculated for an anaerobic digester at an industrial
wastewater plant from November to March during three sugar
refinery production campaigns. PBII was used to seed the anaerobic
digester at the end of campaign 1. Treatment continued through
campaigns two and three. The values displayed were calculated by
summing the biogas produced divided by the COD loading.
An additional benefit of treating with PBII, was the quantity of
methane produced was much higher than before treatment
(Figure1). The average increase in biogas produced during
the second and third campaign was 13 cfs per 1000 lbs
COD. These results were also attributed to cleaning out
the digester and repairing the mixers before implementing
the product. The methane produced was used as a cleaner
energy source to help operate the drying kilns.
With BioLynceus®, the anaerobic digester was started with
less financial burden than using activated sludge, and the
biogas produced from the digester provides the refinery
with a stable energy source.
BioLynceus® ProBiotic Scrubber®II is a cost-effective program for digestor start-up.