UPGRADING FOUNDRY WASTEWATER TREATMENT
Richard Osantowski, Unit Manager Rexnord, Inc.
EnviroEnergy Technology Center
Milwaukee, Wisconsin 53214
John Ruppersberger, Project Officer
U.S. Environmental Protection Agency
Industrial Environmental Research Laboratory
Research Triangle Park, North Carolina 27711
INTRODUCTION
There are approximately 1600 ferrous foundries located through the United States. Approximately
half operate manufacturing processes which result in process wastewater estimated at 4.0 x 10* m'
(106 x 10* gallons) each year. Seventy-five percent of this wastewater is recycled, with the remainder
being discharged to either navigable waters (23 percent) or publicly owned treatment works (POTW)
(2 percent) [1].
Primary wastewater generating operations in the ferrous foundry industry include:
1. Dust Collection—2.0 X  10" m'/yr (52.8 x  10* gal/yr)
2. Melting Furnace Scrubber—1.2 x 10" m'/yr (31.4 x  10' gal/yr)
3. Slag Quenching—0.43 x  10s mVyr (11.4 x  10* gal/yr)
4. Casting Quench and Mold Cooling—0.18 x 10" m'/yr (4.87 x 10'gal/yr)
5. Sand Washing—0.09 x 10" m'/yr (2.61  x  10'gal/yr)
The objective of this project was to determine the quality of treated iron foundry wastewater that
could be achieved using chemical clarification and filtration technology. The project did not include
evaluation of the technical feasibility of reusing wastewater of the quality produced by the pilot
treatment system. The research work was performed at a large gray iron foundry with an average
daily gross melt of 667 Mg (734 tons) and a wastewater flow of 8607 m'/day (2.27 mgd). The typical
water application rate during the 6 week investigation was 13 m' of wastewater per 1000 kg of gross
melt (3105 gal/ton).
The study was performed on a pilot scale using the U.S. Environmental Protection Agency's
(EPA's) mobile physical/chemical treatment system. This pilot plant is housed in a semi-trailer van
as shown in Figure 1. Treatment processes evaluated during the study included lime softening, lime/
soda ash softening, flocculation/sedimentation, and dual media filtration. The process treatment
train schematic is illustrated in Figure 2.
PROJECT RESULTS
Raw Wastewater
Plant wastewater discharged to the receiving stream during the production week averaged 454
1 /min (120 gal/min). The amount of water recycled during the production week averaged 92.2 percent
of the incoming wastewater and ranged from 85 to 95.9 percent.
A summary of raw wastewater quality is shown in Table I. Dissolved solids average 535 mg/1.
Principal cations of interest included lead (59 mg/I), zinc (72 mg/1), calcium (60 mg/1-), and aluminum
(60.3 mg/1). The foundry wastewater also contained substantial concentrations of suspended solids
(640 mg/1) and COD (315 mg/1).
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