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Case Study for Customer Location CO40:
Reservoir or Lake Use:
Municipal wastewater treatment system serving a population of about 740 people.
System Overview and Reservoir:
The existing treatment system consists of two ponds. Pond 1 (the primary pond) is 0.5 acres in area,
9 ft deep, 1 MG capacity, and the loading is about 281 lb BOD/acre/day. Pond 1 has a 40-hp grid
aeration system running 24 hrs/day. Pond 1 is semi-split by a partial curtain. Pond 2 (the secondary
pond) is 0.5 acres in area, 9 ft deep, 1 MG capacity, and has a 10-hp grid aeration running 24 hrs/day.
Flow rate to the system is about 0.07 MGD, with 100% going first to Pond 1, then to pond 2, then to
discharge. This system has periodic scheduled discharge. Total detention time is 28 days. Most
critical discharge permit limits are: 25/40mg/L CBOD, 75/110 mg/L TSS or 85% CBOD removal. There
are no current ammonia discharge limits.
Reported Problem Before Installation:
The main problems were high energy, operating and maintenance costs from the aeration systems,
unacceptable noise levels from the aeration system, sludge accumulation in the ponds, odors, and
maintaining acceptable water quality of the final effluent.
Installation:
Date: April 2000, installed two (2) units equal to SB2500*, with 24-hour electrical kits, one on each
side of the curtain in primary Pond 1.
Results:
By January 2003, sludge depth had been reduced about 2.5 ft in center of pond, and about 1 ft along
the pond’s edges. The units’ intake depths were lowered in 2004, which improved consistency and
enabled the plant to meet all discharge limits and maintain good sludge stabilization. Because of
efficient solar-powered circulation, customer had reduced run time of the 40-hp aerator to where the
financial saving essentially paid for the two circulators by 2005. In 2005, the customer replaced the 40-
hp aerator with a 15-hp aerator, achieving similar savings in power costs while maintaining/improving
effluent water quality and complying with CBOD and TSS discharge limits. And because SolarBees
run silently, reduced aeration also means reduced noise. The customer is very pleased with the
results.
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SolarBee
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