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Prairie Farms Inc.
Carbondale, Illinois
Intern: Syed Jaffery
Southern Illinois University, Edwardsville
The Prairie Farms facility in Carbondale makes cottage cheese and sour cream. The
facility processes approximately 45,000 gallons of raw milk daily. It operates
24 hours a day, six days a week with an average monthly production of 1.8 million
pounds of cottage cheese, 1 million pounds of sour cream, and a quarter of a million
pounds of dip.
Primary tasks during the internship were to reduce organic waste load of the wastewater,
identify water conservation opportunities and perform an energy audit.
Results:
The intern made the following recommendations:
- Reuse post-rinse cleaning water for the pre-rinse phase of the subsequent
wash cycle, utilizing the existing CIP tanks. In addition to reducing the
time for post rinses, this project could reduce water use by 5,000 gallons
a day with an annual savings of over $23,000 and a pay back period of three
months.
- Wastewater from the curd wash operation was found to be over 18,000 gallons
per day that is discharged to the sanitary sewer with a significant surcharge
leading to an annual disposal fee of about $34,000. Additionally, acid
whey is generated at a rate of 33,000 gallons per day and is hauled to
a hog farm to be blended for feed at a cost over $411,000 per year. The
intern suggested implementing a three-stage reverse osmosis/nano filtration
(RO/NF) membrane filtration system with a RO polisher. The system would
generate 38,000 gallons per day of clean water for reuse and concentrated
whey for feed blending at the hog farm receiving the acid whey waste or
selling the concentrated whey to a feed manufacturer. The recommended technology
can be incorporated at three additional Prairie Farms plants.
- Utilizing a RO/NF system with RO polisher for hauling concentrated
whey to the hog farm would save an estimated $318,000 annually and
have a payback period of two and a half years.
- Implementing a RO/NF system with RO polisher for selling whey concentrate
to feed manufacturers would annually save the entire $444,000 associated
with the disposal of curd wash and acid whey while realizing a $29,000
profit from the sales of the whey concentrate. Selling the whey concentrate
reduces the payback period to 21 months.
- Sewer charges were billed to the plant based on sampling of the effluent
and water usage from the city. The intern noted water displacement to various
process, evaporation, and transport with acid whey waste. Implementing
an ultrasonic wastewater flow meter would save the company over $12,000
in excess flow charges and yield a payback of 4 months.
- A facility-wide energy audit was performed and the following recommendations
were made:
- Upgrading the T-12 fluorescent fixtures to T-8 fixtures in the office
and plant areas would yield over $2,800 savings per year with a payback
period less than 1 year.
- Replacing the 400W metal halide lamps with 250W high pressure sodium
lamps will save about $2,700 annually with a payback period less than two
years.
- Implementing motion sensors in various areas of the plant will save nearly
$2,000 per year with a payback of 5 months.
- Implementing a stack economizer on the boiler will annually save over
$14,000 with a payback period of 3 ½ years. Repairing the steam
leaks and insulating steam lines will save an additional $16,000 per year
with payback less than a year.
- Repairing the 62 identified compressed air leaks would save over $3,200
per year and yield a payback less than 1 month.
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