SULFUR REMOVAL OF POLYSULFIDE RUBBER
MANUFACTURING WASTEWATERS BY ANAEROBIC TREATMENT
Bernard J. Obarsky, Graduate Student
John Cirello, Assistant Professor
Department of Environmental Science
Cook College, Rutgers University
New Brunswick, New Jersey 08903
Albert R. Roy, Manager
Engineering and Environmental Services
Van Note-Harvey Associates Consulting Engineers
Princeton, New Jersey 08540
INTRODUCTION
A bench scale treatability study was performed on the wastewater from a major
manufacturer of polysulfide rubber.   The study was undertaken to investigate the feasibility of removing sulfur through anaerobic biological treatment.   Although, aerobic
treatment of wastewaters by activated sludge can effect the oxidation of reduced forms
of sulfur it fails to remove sulfur, converting reduced forms to oxidized forms (the
mineral acid H2S04).   Furthermore the use of a neutralizing agent such as lime becomes
necessary to maintain the system pH within tolerable levels.   The result is a voluminous
quantity of sludge as calcium sulfate (gypsum) precipitate, which must be collected, de-
watered and disposed of.
Wastewater from polysulfide rubber manufacturing contain sodium sulfate, sodium
thiosulfate (Na2S203), sodium tetrathionate (Na2H2S406), sodium polysulfide, chlorinated hydrocarbons and low-molecular-weight polymer.   The use of anaerobic digestion
to reduce the above sulfur species to hydrogen sulfide was veiwed as a possible first
step of sulfur removal.
There are reports that sulfate and sulfide may act as inhibitors to the anaerobic process [1,2,3,4,5,6,7]. Rudolfs and Zeller [1] reported decreased gas production as one
of the effects of sulfate salts on the digestion of fresh solids. Rudolf and Amberg [2]
found that sulfide levels in excess of 200 mg/1 could decrease gas production and subsequent activity by 70%. Lawrence et al. [3] confirmed that sulfide levels above 200
mg/1 produce severe toxic effects.
More recently, United States Environmental Protection Agency Guidelines [4]  suggest
that sulfate levels as low as 500 mg/1 will inhibit anaerobic digestion-as reported by
Gosh [5], Pohland and Kang [6].   Further the early findings of Rudolfs and Amberg
[7]  reported an upper limit of 2,400 mg/1 of SO4.
In view of this, and because the polysulfide rubber manufacturing plant might produce wastewaters with sulfur levels similar to those mentioned above, a treatability
study was considered appropriate.
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