Nestle USA
Morton, Illinois
Sean Westropp
Purdue University, West Lafayette, Indiana
The Nestle USA facility in Morton produces over 70 million pounds of Libby’s
solid pack pumpkin and pumpkin pie mix every year. The plant operates 24-hours
a day during production from mid-August to early November. The maintenance
department spends the rest of the year conducting preventive maintenance,
making process improvements and preparing systems for the next production
run.
Wastewater flow during production reaches 800,000 gallons per day. The
wastewater treatment plant (WWTP) consists of four lagoons and two spray
fields. The main goal of the WWTP is to lower the BOD5 and the TSS to meet
its permit conditions prior to discharge to a nearby stream. The intern
investigated various projects dealing with improving the operability of
the WWTP as well as conducting an energy efficiency audit.
Results:
The intern arranged to have two filter companies test a new gravity filter
and mesh filter centrifuge system during the upcoming production
run. If more insolubles can be separated from the process wastewater and
more
of the sugars and pumpkin meat solids recycled, this will generate
higher production efficiencies and reduce the BOD loadings going to the
WWTP.
If the TSS, which is a result of algae blooms, can be reduced, the WWTP
could discharge directly to the creek. The intern suggested that the WWTP
operator apply a liquid-based algaecide to treat the plactonic (suspended)
algae to the final stage of the lagoons. This will cost $8,500 but should
save over $20,000 in reduced treatment costs charged by the city.
If the Dissolved Oxygen (DO) content of the lagoons drops below 4%, the
lagoons can turn septic and emit bad odors. The intern recommended installing
DO probes to automatically turn the aerators on and off. This should maintain
a more constant DO level and save on electricity since they will not need
to be run all the time.
An energy efficiency audit was conducted and the following recommendations
were made:
- Utilize programmable thermostats with a remote control system
on the HVAC equipment so there is less employee tampering of the settings.
The
annual gas savings is expected to be approximately $6,000.
- Replace the motor for the compressed air system with a much
smaller horsepower motor. This could save over $3,000 per year in electricity
costs.
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