Section 10. METAL WASTES
OZONE OXIDATION OF CONCENTRATED CYANIDE WASTEWATER
FROM ELECTROPLATING OPERATIONS
Leale E. Streebin, Professor
Herbert M. Schornick, Assistant Professor
School of Engineering
University of Oklahoma
Norman, Oklahoma 73019
Anthony M. Wachinski, Research Engineer
Engineering and Services Laboratory
Tyndall Air Force Base, Florida 32401
Chemical oxidation with ozone can be an effective method for treating organic and
inorganic constituents of industrial waste streams. Many refractory materials resistant
to other treatment methods can be oxidized by ozone. One application of chemical oxidation using ozone is treatment of cyanide waste [1,2]. When highly complexed metal
cyanide wastes are present, ultraviolet (UV) radiation can be used successfully to breakdown many of the complexes and speed the reaction with ozone [ 3].
This paper summarizes research on the use of ozone and UV radiation in the treatment
of cyanide and complexed, metal-cyanide wastes generated from electroplating operations
at Tinker Air Force Base (AFB), Oklahoma City, Oklahoma. This paper presents data on
treatment efficiencies, capabdities and reaction-rate relationships obtained whde treating
concentrated cyanide wastes in a modified ozonation system in comparison with the alkaline
chlorination system presently in use at Tinker AFB.
A full-scale demonstration plant utilizing chemical oxidation with ozone was designed
and constructed at the test site to treat 3,000 gallons per month of primarily nickel-strip
wastes having total cyanide concentrations of up to 50,000 mdligrams per liter (mg/1).
The plant was designed to operate 24 hours a day five days per week at a flow of 6.25
gallons per hour (gph).
The original design goal for the system was to reduce cyanides to below detection.
However, the ozone-cyanide plant never achieved appreciable cyanide removal. Following
start-up, the plant was plagued with operational and maintenance problems, and subsequently, was shut down.
In August 1976, a study was performed to determine the efficiency and reliabdity of
the system. Upon plant start-up, several operational problems prevented evaluation of the
treatment process. Principal problems included compressor breakdown, od carry-over
into the air stream, inefficient prefdter operation, defective dryer operation, erratic functioning of the ozone generation system, ineffective mixing and transfer, diffuser plugging,
excessive foaming, inoperative monitoring equipment and inadequate ventilation.
Subsequently, in August of 1978 work was initiated to correct these and other problems,
to redesign and optimize the system, and to test the modified system. The authors reported
the results of the redesign and start-up of the full scale system in a previous paper |4).
OZONE CYANIDE PLANT DESCRIPTION
A flow diagram of the redesigned ozone plant is shown in Figure 1. The system consists
of three completely mixed flow reactors in series and ancillary equipment consisting of an
air-preparation system, ozone-generation system, and a waste-handling system.
The air preparation system consists of compressors, dryers and fdters. Compressed
air flows from the dryer through a cartridge-type fdter to remove desiccant dust, through
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