Skimmer With Rolling Stand Helps Prevent Oily Water Discharge

Avedon Engineering is a customized plastic parts manufacturer molding telephone, computer and other electronic equipment components in ABS, polycarbonate, polypropylene and foam-filled ABS. With production in two Longmont, CO buildings, the company operates 27 heavily used injection molding machines.

Despite continuous replacement and upgrading of fittings, it is difficult to entirely eliminate hydraulic and lubricating oil coming from machines during normal operations and maintenance activities. This oil ends up in different pits through wasterwater recycling throughout the plant.

Because of high oil content, city officials would not allow plant wastewater to enter the Longmont sanitary sewer system. This meant that Avedon had to disconnect collection pits from sewer lines and contract with a hazardous waste disposal company to have wastewater hauled away at 32¢/gallon. Prior to pumping water out of the pits, a sample would be taken to determine if any solvent was present. If it was, the disposal cost jumped to $575/barrel.

Faced with these high costs of wastewater recycling, Jerry Speckeen, Avedon’s Maintenance Manager, started looking for alternatives. The goal was to make the wastewater sewerable with a reasonable investment in equipment and operating costs. He found a solution in the PetroXtractor oil skimming unit made by Abanaki Corp., Chagrin Falls, OH.

Abanaki’s oil skimming unit was originally designed for monitoring and remediation wells. It utilizes a continuous one inch wide oil skimming belt that fits into small openings on the collection pit covers. In operation, the skimmer removes up to three gallons of oil per hour.

Oil skimming makes use of the differences in specific gravity and surface tension between oil and water. These physical characteristics allow the continuous oleophillic belt of the skimmer to attract oil from the surface of the water. Speckeen also devised a rolling stand (which he calls the “I-V” stand because of its resemblance to those seen in the hospitals) in order for the unit to be used in more than one collection pit.

The skimmer is rolled to each collection pit where the belt assembly is inserted through the small opening in the steel lid and lowered into the water. The belt length is customized for the application.

The unit can operate anywhere there is a source of 115 VAC power for the fan-cooled fractional horsepower gear motor. The belt runs on pulleys with the head pulley attached to the drive motor and the tail pulley immersed in water.

During operation, the belt travels over the head pulley and through tandem wiper blades where oil is scraped off both sides of the belt. This oil flows through a discharge channel that can be connected to a hose. Speckeen designed the I-V stand so that it would straddle a 55-gallon drum used to collect the skimmed oil.

Although skimmed oil usually can be handled in the same fashion as automotive drain oil, Avedon is currently storing it with the intent to recycle. Samples have been sent to a testing lab to identify the type of contaminants present. Their findings will be used to determine the type of equipment required to process the oil and make it suitable for reuse in the hydraulic systems.

Published in Water & Waste Digest