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Guaranteeing Accuracy and Safety in Wastewater Filtration
Team implements the automated dosing of dry treatment chemical with a flexible screw conveyor to improve the filtration process
‘This precludes cross contamination if multiple chemical agents are used.’
Editor’s Note: Jeff Koepnick, the project manager at Oberlin Filter Co., says
introducing chemicals precisely is key to a successful filtration process. In
the following article, he shares how he and David Boger, a technical expert on
flexible screw conveyor technology at Flexicon Corp., worked together on a tough
wastewater filtration problem.
By Jeff Koepnick and David Boger
Important Facts about Filtration Process
• A specific amount of dry treatment chemical is automatically transported by the flexible screw conveyor from the chemical hopper to the working tank.
• The working tank contains colloidal rinse water from the manufacturing process.
• The dirty water and chemical mixture is agitated for a preset time and then automatically discharged into the pressure filter.
• The pressure filter removes the solids and discharges liquids into the clean tank.
• An equal volume of clean rinse water is pumped from the clean tank to the process tank to maintain liquid levels. |
The key to dropping out heavy metals and separating resins from colloidal suspensions
is to introduce exactly the right dry ingredient into the wastewater — consistently
and in large volumes. This cannot be accomplished satisfactorily with a manual
dry chemical delivery system.
Oberlin Filter Co., a global leader in high-pressure flatbed liquid-solid filtration
systems for such demanding applications as filtering heavy metals and resins from
colloidal suspensions, uses its DMax filtration system to clean “impregnation
resin” wastewater. Such a tough application requires a dry chemical delivery system
that provides particularly precise, clean and safe dosing.
To get the precision, cleanliness and safety it requires, Oberlin uses a flexible
screw conveyor to introduce measured amounts of dry chemicals into wastewater.
Its DMax system integrates pressure filter technology with a pre-treatment process
that uses the flexible screw conveyor to deliver dry chemicals into the wastewater
without the spillage or dust associated with manual dumping. The chemicals cause
minute waste products to clump together as larger solids, called flocculate, which
can be filtered out for discharge or disposal as dry cake. The cleaned wastewater
can be continuously re-used in the original application or discharged as cleaned
and permitted water.
Tough applications such as wastewater
filtration require a dry chemical delivery system that provides particularly
precise, clean and safe dosing. |
Oberlin’s engineers researched numerous systems before determining that a flexible
screw conveyor would be the best way to achieve consistent delivery of a variety
of large quantities of dry chemicals. They chose this particular flexible screw
conveyor because it conveys vertically as well as horizontally, can accommodate
small configurations, requires little or no maintenance and is built tough. Flexicon
Corp. in Bethlehem, PA, makes the unit, called the Model 1250. Flexicon, which
specializes in the design and manufacture of bulk handling equipment, ran Oberlin’s
DMax process in its test lab to demonstrate that the conveyor would deliver dry
ingredients according to specifications and then repeated the process at Oberlin’s
plant in Waukesha, WI. The conveyor has a 3-inch (76 mm) diameter, 10-foot (305
cm) long tube. Combined in-line with a very small filter and tanks, it results
in a machine train that is 6 feet (1,829 mm) wide and 27 feet (823 cm) long. When
treatment of large (8-feet or 244 cm) tanks of water is required, a bulk bag discharger
is added to the DMax filter system to deliver large quantities of dry chemicals.
The DMax filtration system has an
automated dry chemical delivery system for precise dosing.
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The conveyor has one moving part that contacts the dry chemicals — a durable,
replaceable, flexible screw that is driven by an electric motor. As the screw
rotates, the chemical is propelled forward, and the screw self-centers within
the conveyor tube. A removable clean-out cap at the intake end of the conveyor
tube allows the tube to be emptied, flushed, disassembled and washed. This precludes
cross contamination if multiple chemical agents are used. The working tank is
equipped with high- and low-level sensors that signal a PLC to automatically control
the material feed, thereby delivering the correct amount of dry chemicals while
eliminating the need for manual dumping and the risk of spillage and dust. Some
cleaning systems require up to 50 pounds of dry chemicals per day, which means
workers have to lift heavy bags of material overhead for dumping into small hoppers
atop large tanks, creating dust and spillage. The Model 1250’s hopper, with a
dump height of less than 4 feet (122 cm), eliminates this problem.
Although Oberlin does not use treatment chemicals that are toxic or hazardous, the company is pleased its wastewater clarification system does not incur a dust problem. Most companies discharge cleaning water at the end of the day, but the addition of automated conveying to the DMax system, which is being used to treat heavy metal, emulsified, vibratory and color dye wastewater, enables the re-use of wastewater and the discharge of cleaner wastewater, reducing both cost and environmental impact.
Additional information is available by contacting Flexicon Corp., 2400 Emrick
Blvd., Bethlehem, PA 18020, at 888-353-9426 or by visiting www.flexicon.com
and www.oberlinfilter.com.
Advantage Business Media
Rockaway, NJ, 07866
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