EVALUATION OF CHROMIUM REMOVAL FROM A
HIGHLY VARIABLE WASTEWATER STREAM
H. J. Campbell, Jr., Senior Engineer
N. C. Scrivner, Consultant
K. Batzar, Senior Research Chemist
R. F. White, Research Engineer
E. I. du Pont de Nemours & Company
Wilmington, Delaware 19898
INTRODUCTION
The significance of hexavalent chromium (CrVI) toxicity and the need for treatment
of industrial wastewaters for CrVI removal prior to discharge to our waterways remains
unquestioned.   Numerous articles in the literature have been devoted to various aspects of
CrVI toxicity and treatability [1].   The 1972 Federal Water Pollution Control Act Amendments (PL 92-500) were a most significant commitment by Congress to provide for the
protection and upgrading of our navigable waters.   As mandated in this federal legislation,
guidelines for various industrial categories are to be established and be complied with for
Best Practicable Control Technology Currently Available (BPCTCA) by July 1, 1977, and
Best Available Technology Economically Achievable (BATEA) by July 1, 1983 [2].   The
Environmental Protection Agency (EPA), as the Administrator of the Act, set about to
establish national technology-based guidelines for the various specific pollutants being discharged from industrial point sources.   Faced with the unrealistic time frame mandated
in the law, EPA, in its first attempt at guideline promulgation, met with a barrage of law
suits.   Among other issues, industrial suits claimed, in certain instances, an inadequate
technical basis for the proposed guideline levels.   As a result, guidelines were remanded
by EPA for further study to establish an adequate technical basis for future promulgation.
Due to the lack of adequate technical data for the Chrome Pigments Subcategory [3],
EPA's initial guideline development for this subcategory was unsuccessful.   To provide
EPA more meaningful information for restudy of this subcategory, studies were initiated
concerning the various aspects of waste treatment at a multiproduct pigments site.   A review of the site's existing wastewater treatment facilities indicated that the resultant effluent quality was, at best, extremely erratic and most probably could not consistently
comply with future federal guideline levels for CrVI.   The major difficulties with the existing waste treatment facility concerned continuous sulfur dioxide (S02) reduction of
CrVI in a highly variable, unequalized wastewater stream.
The purpose of these studies was threefold:   first, to review the literature for demonstrated technology to establish treatment alternatives; second, to perform appropriate
laboratory and pilot studies on the most likely treatment alternatives; and third, to select
the most economical site approach for yielding an acceptable effluent quality.   It was
anticipated that the submission of the detailed study results to EPA would assist in establishing a sound technical basis for future guideline promulgation.
LITERATURE REVIEW
A detailed literature review was conducted to gather information relating to the removal
of chromium from industrial wastewaters and, in addition, information relating to the
toxicity of chromium to living species.   A full discussion of these topics is contained elsewhere [ 1 ], and in the interest of space, our main conclusions are listed below:
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