Treatment of Chromium Wastes
by Ion Exchange
RICHARD G.   TYLER
Professor of Sanitary Engineering
WILLIAM   MASKE,   MILTON   J.   WESTIN
Research Chemist, Research Fellow
University of Washington
Seattle, Washington
The sanitary engineering staff of the University of Washington
has been engaged in cooperative research with the State Stream Pollution
Control Commission for the past two years during which time it has
investigated several of the industrial waste problems that are of interest
to the Commission. One of the projects suggested for study by E. F.
Eldridge, Director and Chief Engineer of the Commission, was to
investigate the treatment by ion exchange of chromium wastes from
metal plating plants.
Don E. Bloodgood's paper on this subject had just been published
and the complexity of chromium in its manifold combinations, together
with its peculiar behavior in ion exchangers as discussed therein, made
it an interesting problem for further study. An investigation was there¬
fore initiated as to its behavior, first in a cation exchanger and later
with activated carbon. The present paper will deal with two aspects
of the observed reactions. The first or major problem has to do with
what takes place in the exchanger; the second is confined to a brief
comment on the effect of this treatment on controlling stream pollution.
Zeo-Karb H was selected for the first part of this study because
Zeo-Karb Na had proven very satisfactory on an earlier study by the
major author on sulfite waste liquor, a strong, acid waste from the pulp
and paper industry. It was hoped that Zeo-Karb H would be equally
rugged and effective with chromium wastes. This turned out to be a
happy choice since a few runs on a styrene base exchanger later produced
a heavy color throw indicating that a breakdown of the exchanger was
taking place.
There was nothing unusual in the method of operating the exchanger
except that it was soon realized that better results were obtained by
acidifying the Zeo-Karb before applying the chromium.   The full sig-
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