Recovery of Undissolved Solids
From Rubber Plant Wastewater
STANFORD E. GROVES, Director of Engineering
Copolymer Rubber and Chemical Corporation
Baton Rouge, Louisiana 70821
HANS E. LUNDGREN, Marketing Specialist
The Permutit Company
Paramus, New Jersey 07652
INTRODUCTION
The Copolymer rubber and latex plant in Baton Rouge, Louisiana is one of a
number of nearly identical rubber plants in this country built by the Government
during World War II to provide an uninterrupted supply of synthetic rubber as the
natural supply diminished. Today the plant produces about 1 million pounds per
day of finished rubber products, 97 percent of which are of the SBR (Styrene Butadiene) type, the rest being of the nitrile type. Only a fraction of the production is
sold in the basic latex form.
Four of the five production lines at Copolymer produce black master batch
which contains extenders such as carbon black and oil while the fifth line produces
unpigmented rubber. The plant makes its own butadiene and purchases the other
raw materials.
The waste stream from this operation amounted to about 5 mgd and a total of
about 6 million pounds of suspended materials such as carbon black, oil latex and
rubber were discharged yearly into the Monto Sano Bauou, a tributary of the
Mississippi River.
Four years ago when interest in ecology was first indicated, the plant management responded by initiating a program of recovering materials right at the source
of discharge in order to minimize the solids losses. It soon became apparent that
the equipment installed for that purpose, a styrene butadiene and oil recovery
system, screens and hydrocyclones accomplished their purpose but did not bring
Copolymer's effluent into compliance with EPA standards. Again without external
pressure but in close cooperation with the Louisiana Stream Control Commission,
the plant initiated its phase II program focusing on a primary effluent treatment/
recovery system.
Although effluent discharge standards had not been set at that time, Copolymer
elected to proceed on its own, primarily to keep one step ahead of the regulatory
agencies thus having the option of evaluating and selecting the most efficient
and economical system for the particular conditions at Baton Rouge.
A literature search indicated a dearth of information on latex waste treatment
and a subsequent evaluation of common waste treatment processes quickly eliminated: 1) the filtration process because of the extreme expenses; 2) the sedimentation process because of the wide specific gravity range of the waste solids (0.6
to 2.0); and 3) others, such as the centrifugation and microscreening, because of
the sheer volume to be processed.
The dissolved air flotation process (DAF) was finally selected for further investigation because of its already proven ability to remove both light and heavy materials and
also because of promising initial flotation bench scale tests.
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