Treatment of Wastewater from the
Manufacture of Polystyrene
WALLACE MASON, Environmental Control Manager
Foster Grant Company, Inc.
Leominster, Massachusetts 01453
GERALD S. ALLEN, Sanitary Engineer and President
SERCO Laboratories
Minneapolis, Minnesota 55406
BACKGROUND
The following information is offered to acquaint the reader with the Foster Grant Co.,
Inc. and some of its products, as an introduction to this paper. The Foster Grant Co., Inc.
was founded in 1919 in Leominster, Mass. From a modest beginning, manufacturing ladies
celluloid combs, the corporation has risen to the position of the world's largest producer of
sunglasses and the third largest producer of polystyrene resins in the United States.
The Company has facilities in Baton Rouge, Louisiana, with a capacity for the
production of 800 M M pounds/ year of monostyrene which is the basic raw material for its
three polystyrene plants located in Leominster, Mass., Peru, 111. and its latest addition in
Chesapeake, Va. The combined output of these three plants is in excess of 500 MM pounds
per year.
The company produces several varieties of polymer at the three locations, including
crystal polystyrene (a clear transparent product used in making drinking cups, etc.), various grades of impact (used where toughness is required, such as refrigerator liners, etc.)
and ABS (Acrylonitrile butadiene styrene), which is used where extreme toughness is a
requirement such as in automotive parts, etc. Several grades of foamed styrene product are
also manufactured. The product is made in two grades, one for packaging material and hot
drink cups and the other for self-extinguishing insulation use.
Chemically, styrene is vinyl benzene, which is a combination of ethylene and benzene.
After the combining of the ethylene and benzene molecules, a heat induced de-
hydrogenation process takes place with the styrene molecule being formed. This
monomolecular styrene is transported by barge, tanker, tank car and truck to the three
polystyrene plants where, in large agitated reactors in the presence of water, suspended
agents, trace chemicals and initiators, the monomer, in an exothermic reaction, becomes a
polymer. This polymer which in most instances has the consistency of a coarse powder or a
fine sugar is separated from the liquid suspending medium by centrifugation.
The liquid remaining after removal of the polymer is the aqueous effluent, or
wastewater, produced in the polystyrene manufacturing process. This effluent, along with
floor washing water, extruder vacuum seal water and an occasional in-plant spill,
essentially comprise the influent to the wastewater pretreatment plant. The physical and
chemical characteristics of this material are shown in Table I for the Leominster plant.
The wastewater contains a high level of suspended solids as noted in Table I. These
solids will not settle even if held in a quiescent state for several weeks. It also contains
significant concentrations of BOD and ortho-phosphate. Pretreatment of the wastewater at
the three Foster Grant polystyrene manufacturing facilities is required primarily to reduce
the suspended solids concentration and the turbidity level prior to discharge into the
municipal sewer system.
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