55    WASTEWATER FLUORIDE COMPLIANCE
UNDER METALS FORMING CATEGORICAL
PRETREATMENT STANDARDS
Brian J. Postale, Senior Environmental Engineer
John J. Ostrosky, Principal Engineer
Wyman-Gordon Company
North Grafton, Massachusetts 01536-8001
James O'Shaughnessy, Professor
Department of Civil and Environmental Engineering
Worcester Polytechnic Institute
Worcester, Massachusetts 01609
INTRODUCTION
The Wyman-Gordon Company is a manufacturer of large metal forgings. primarily for use in
the aerospace industry. At Wyman-Gordon's North Grafton Massachusetts Plant, current wastewater treatment uses metal hydroxide precipitation as the wastewater pretreatment process prior
to discharge to the Town of Grafton P.O.T.W. Metal hydroxide sludge from the pretreatment
process, as well as spent acids from manufacturing operations are collected and disposed offsite
as hazardous wastes. Oily wastewaters and stormwater runoff from the manufacturing site are
collected and treated. These treated waters are then recycled for use as process water in the various manufacturing operations.
Changing industrial wastewater pretreatment requirements required a process change in
Wyman-Gordon's wastewater pretreatment plant in order to achieve compliance. Alternate
process changes were evaluated with respect to treatment effectiveness and the cost of compliance. The evaluation focused on the modification of existing treatment methods and evaluation
of new waste minimization techniques (Figure 1).
New pretreatment criteria limits the effluent fluoride quantity to 7.4 lb/day based on the current level of manufacturing production. The existing treatment operations of metal hydroxide
precipitation were unsuccessful at reducing current fluoride loading to meet the permitted limits.
Evaluations were undertaken to determine the effectiveness of precipitation processes utilizing:
• calcium hydroxide
• calcium carbonate
• calcium chloride
• waste caustic (as a Al+++ cation)
• calcium hydroxide/waste caustic (as a Al+++ cation)
• calcium hydroxide/aluminum sulfate
• poly aluminum chloride
• aluminum chloride
This project established criteria for the Wyman-Gordon Company to meet current fluoride effluent discharge limits set by the U. S. Environmental Protection Agency's industrial pretreatment regulations.
51st Purdue Industrial Waste Conference Proceedings. 1996, Ann Arbor Press. Inc.. Chelsea, Michigan 48118.
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