TREATMENT OF ZINC PLATING AND OIL BEARING
WASHER WASTEWATER
William C. Kreye, Vice President of Engineering
John W. Olver, President
Helen C. Sutton, Laboratory Director
Van Note-Harvey Associates
Blacksburg, Virginia 24060
Fred R. Voreh, Engineering and Materials Manager
American Screw Company, Camcar Division of Textron, Inc.
Wytheville, Virginia 24382
INTRODUCTION
Adequate treatment of heavy metal bearing wastewater is extremely important if the
quality of the environment is to be protected.    Discharge of most heavy metals in significant concentrations has an extremely harmful effect on aquatic organisms.   This fact
was recognized by state and federal regulatory agencies many years ago.   A concerted
effort by federal and state agencies has encouraged many industries to improve their
plating waste treatment systems to provide the best practical wastewater treatment
systems.   Unfortunately, improving the treatment of plating waste can be very expensive and has placed a heavy economic burden on the electroplating industry.
The wastewater treatment system described in this paper was designed for the
plating wastes and   washer   wastes for a major screw manufacturer.    The manufacturer's
existing wastewater treatment system was inadequate to provide treatment for the
plating and washer wastes.    The waste from the screw manufacturing facility is discharged to a municipal sewer system.   The town had previously used a primary treatment plant with anaerobic digestion for sludge stabilization.    In  1976, the town started
construction of a new secondary wastewater treatment plant using the activated sludge
process with anaerobic digestion.   Previous problems with heavy metals in the existing
anaerobic digester caused the town to enact a strict pretreatment ordinance to prevent
heavy metal problems at the new wastewater treatment plant.   The town indicated that
they would require pretreatment consistent with EPA's electroplating point source category pretreatment standards.   At the time the town's ordinance was enacted, EPA had
not promulgated the pretreatment standards for the electroplating industry.   The industry recognized that a major upgrading of their existing wastewater treatment would
be required to meet the new pretreatment requirements when they were finally
promulgated.
PRETREATMENT REQUIREMENTS
The first step in the design of the new treatment facility was to establish the required level of treatment.   At the beginning of this project, EPA's pretreatment standards
for the electroplating industry were not available.   All available literature was reviewed
to establish probable pretretreatment requirements and the probable performance of
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