METAL FORGING AND PROCESSING WASTEWATER TREATMENT:
A CASE HISTORY
Melvin R. Hockenbury, Project Manager
James M. Bower, Design Manager
Andrew W. Loven, Vice President
Engineering-Science, Inc.
Atlanta, Georgia 30329
INTRODUCTION
An engineering study was carried out at a large metal forging and processing facility
regarding treatment of the wastewaters resulting from the various production processes.
Four types of wastewaters with widely varying characteristics are generated at this facility,
and in order to develop the most cost-effective treatment system for the total facility, a
carefully planned and executed study following sound engineering principles was required.
This chapter is a description of the systematic approach used to solve a rather complex
industrial wastewater problem and includes:   (a) detailed characterization of each type of
wastewater in terms of quantity and quality; (b) planning and conducting treatability
studies designed to evaluate the feasibility of alternative treatment processes for the various wastewaters, and (c) evaluating the results of the treatability studies, determining the
optimum treatment system and designing on a conceptual basis the recommended process.   Some of the technology involved in this particular situation includes gravity oil/water
separation, coagulation, flocculation, dissolved-air flotation, equalization, emulsion splitting, heavy metal precipitation and removal, fluoride precipitation and removal, clarification, sludge thickening and sludge dewatering.   One of the primary objectives of this
chapter, in addition to identifying processes used to treat these specific types of wastewaters, is to present a systematic and rational engineering approach to investigating and
solving similar industrial wastewater treatment problems.
WASTEWATER CHARACTERIZATION
One of the initial tasks in any engineering study is to characterize the wastewaters
which result from the various production processes with respect to quantity and quality.
Comprehensive characterization data are necessary to properly plan treatability studies as
well as to design wastewater treatment systems.
Forge Shop Wastewater
Wastewater from the forging process is collected by open floor drains and contains
varying quantities of suspended solids, oil and grease.   This wastewater is carried by a
process sewer to an API-type separator where free, floatable oil and grease are removed.
From there it flows to an oil retention lagoon where further oil, grease and suspended
solids are removed prior to discharge.
The characteristics of the influent to and effluent from the existing oil retention lagoon
are shown in Table I.
The parameters which appear in this facility's NPDES permit include pH, suspended
solids, oil and grease and heavy metals.   Other parameters were evaluated in addition to
those shown in order to fully characterize the wastewater, but none were found to be
significant and are therefore not reported here.
Emulsified Oily Wastewater
Emulsified oily wastewater has as its source the hydraulic power system used to furnish power to the forging presses.   A mineral-type oil is solubilized in water through the
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