Pure Oxygen Activated Sludge Treatment
of a Petrochemical Waste
R. E. RIEMER, Process Engineer
Chemicals and Plastics
Union Carbide Corporation
Hahnville, Louisiana
R. A. CONWAY, Group Leader
Research and Development Department
J. F. KUKURA, Project Engineer
Engineering Department
Union Carbide Corporation
South Charleston, West Virginia
E. A. WILCOX, Field Operations Manager
Linde Division
Union Carbide Corporation
Tonawanda, New York
INTRODUCTION
The Taft Plant of Union Carbide Corporation is a petrochemical complex located on
the Mississippi River about 30 miles above New Orleans, Louisiana. Over 50 products are
made at this plant, including various olefins, several aromatics, ethylene oxide, ethylene
glycol, ethyleneamines, alkylamines, acrylic esters, peracetic acid and its derivatives, epoxy
resins, and glyoxal. The Taft Plant has a production rate of several 100 million pounds of
chemicals per month.
Plans are being implemented toward efficient secondary treatment of process
wastewaters associated with the production of these petrochemicals. This paper describes
the wastewater characteristics, laboratory and pilot treatment studies, and preliminary
design of the selected system of anaerobic pretreatment followed by a UNOX System
oxygenated activated sludge facility.
The use of oxygen was considered for activated sludge treatment of the Taft Plant
waste since it would enable carrying higher mixed liquor biomass concentrations and thus
achieve the required treatment in a much lower retention time than would be needed with a
conventional aerated system, while also providing the many other advantages of a closed,
covered aeration system. Laboratory and pilot plant programs were conducted for both air
and oxygen systems to determine design conditions for treating the Taft wastewater. The
results of these pilot plant studies verified the expected reduction in retention time
achievable with the use of oxygen, and, consequently, oxygen was selected for use in the
full-scale design.
WASTEWATER CHARACTERISTICS
The process wastewaters at the Taft Plant are collected in sumps located at each
manufacturing unit and are pumped in elevated sewer lines to the waste treatment area. The
combined waste stream currently is subjected to pH adjustment, clarification, and
equalization/anaerobic lagooning before being discharged to the Mississippi River. By
keeping a minimum amount of water from being contaminated with process wastes, the
hydraulic load to the sewer has been reduced to approximately 2500 gpm (3.6 mgd). This
water conservation results in a relatively concentrated waste stream of 2500 to 3500 mg/1
BOD5. The temperature of the combined wastewater stream before primary treatment is
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