Crisafulli Case
History - Rotomite Application
Decatur, Arkansas
As reported in WaterWorld, Serving the Municipal Water/Wastewater Industry
"The Town of Decatur, Ark., is
using a self-propelled dredging system as part of a new biosolids
management program designed to reduce the cost of sludge disposal and
increase solids detention time in-plant. While less than 1,000 people live
in Decatur, the town’s wastewater treatment plant handles flows
equivalent to a population of 40,000. The primary contributor to these
flows is a poultry processing plant.
Over the last several years, the town’s Utility Manager, Rick McClain,
has been laying the groundwork for planned land application of Class B
biosolids. Until early 1996, Decatur had contracted for the removal of
pond wastes, which were dredged up by a private firm and hauled away for
land application.
The total throughput of Decatur’s plant is 2 million gallons per day.
The plant accepts combined storm and sanitary flows, as well as the
industrial processing wastes of its primary customer. While certain types
of trash and solids are more prevalent during storm water events, the
plant typically handles high amounts of solids due to the industrial
nature of the poultry waste.
To remove trash and large solids, flows are screened as they enter the
plant. Material then goes through another four-stage process including a
primary lagoon where settling occurs, an activated aeration cell, then a
secondary lagoon (polishing pond), ending in a sludge handling pond from
which the biosolids are extracted. The town also has two equalization
ponds and a waste holding pond.
The city’s goal is to land apply an estimated 1 million gallons of
biosolids each summer season. To accomplish this, the town needed a means
of producing consistent solids flow from the final sludge handling pond.
In early 1996, Decatur purchased a Rotomite TM dredge from SRS
Crisafulli. The dredge is equipped with an auger/cutterhead and is capable
of transferring approximately 800 to 1,000 gallons per minute of biosolids
with its 6 inch J-Series sludge pump. The ponds are lined with clay, so
Decatur elected to have the dredge fitted with a depth indicator which
allows the operator to control the depth of the dredge cut.
The dredge is powered by a 180 hp Isuzu diesel engine. It is approximately
27 feet long and eight feet wide. While it is designed to be operated by
one person, it can carry two people safely. It can excavate to a depth of
15 feet and at a speed of up to 10 feet per minute.
The dredge is used to help keep all of the town’s lagoons cleaned out.
Biosolids are dredged up for land disposal only about once a quarter, but
the dredge is used about once a week in the other ponds. The dredge is
propelled by an outboard hydraulic drive and has hydraulically controlled
steering. It doesn’t need a cabling traverse system. The town uses a
crane to move the 12,000 pound dredge from pond to pond.
When pumping from the final sludge handling pond, the dredge pumps the
biosolids ashore through a floating 8-inch discharge line. With an
experienced operator, the dredging operation is capable of producing a
consistent percentage of solids at the shoreline. It is not uncommon for
the equipment to produce sludge of up to 10 percent solids by weight, or
60 to 80 percent solids by volume.
At the shoreline, the biosolids are fed to a waiting truck, from which
they will be land applied (surface spread) on nearby farms. One truck
equipped with a vacuum pump is being used in the operation. There is no
surge tank at the shoreline; rather, any overflow is contained and
returned to the pond.
Decatur expects to save approximately $50,000 a year with a fully
operational biosolids management plan."
Double click photo to enlarge it.
Crisafulli
Rotomite dredge
Double click photo to enlarge it.
Crisafulli
stainless steel custom Rotomite dredge
After 40 years, customers still say "Crisafulli is
the best." Crisafulli Pumps, Dredges, and Power Units are customizable - Choose
special materials of construction, power source, bearings and
suction.
Each
Crisafulli Pump has a Crisafulli Impeller Inside - your assurance
of quality, performance, reliability and long useful life.
Contact
us today at the factory or through one of our dealers or reps to order
your Crisafulli Pump, Dredge, and Power Unit or to discuss your special applications to
enable us to custom design your Crisafulli equipment.
The wide range of performance and application capabilities of the rugged,
reliable Crisafulli Pump, Dredge, and Power Unit product line, each model
of which can be customized to our customer's special requirements,
provides our customers with what we call "The Crisafulli
Advantage."
