DEVELOPMENT OF A BIOLOGICAL DENITRIFICATION PROCESS
FOR A HIGH-STRENGTH INDUSTRIAL WASTE
Cyron T. Lawson, Developmental Scientist
Research and Development Department
Union Carbide Corporation
South Charleston, West Virginia 25303
The addition of a new manufacturing unit under consideration for one of Union Carbide's plants would result in a particularly high-strength aqueous waste. At the developmental
stage, the waste composition was defined, in terms of conventional wastewater parameters:
• BODs     = 34,000-63,000 mg/1
•COD      = 135,000-240,000 mg/1
• TOC      = 26,000-55,000 mg/1
•N03-N= 9,600-12,000 mg (as N)/l
in terms of specific chemicals:
•NaN03 = 6-10.7% by wt.
• Alcohols, glycols, sodium salts, and polyglycols = 5.3-11.0% by wt.
• Other organics =  1.0-2.1% by wt.
" pH  =  3.0-5.6 or "^ 12.0 (depending on final process equipment design)
At the anticipated process waste flow, the daily organic load from the process would be
about equal to the existing raw waste load from all other sources at the existing plant site
chosen for process installation. The new process could constitute a serious treatment plant
overload. Furthermore, the nitrate content required treatment to meet an anticipated
discharge limite of 20-25 mg NO3-N/I in the effluent (about 100 mg/1 of NOJ ion).
Literature reviews and consultation with personnel at the Oak Ridge National Laboratory
[1-3] showed that anaerobic biological denitrification had considerable potential for simultaneously removing both the nitrates and a large fraction of the organics from this process
waste. In fact, a full-scale denitrification facility was in operation at the Oak Ridge Y-12
Plant [3).
Whde ORNL researchers had demonstrated successful denitrification processes in both
stirred reactors (analogous to the aerobic activated sludge process) and packed-bed reactors,
we chose to pursue the stirred reactor configuration for three reasons.
1. Since the packed-bed process had not yet been demonstrated on a large scale, many scale-up
questions remained.
2. With the process waste not yet well-defined, and potentially quite variable in composition,
the completely mixed stirred reactor seemed to offer more inherent process stability.
3. Biomass management in a packed-bed treating a high-strength waste at high reaction rates,
with a potential for sloughing of excess bio-growth, seemed to be a particularly troublesome
consideration at full-scale operation.
DEVELOPMENT OF THE DENITRIFICATION PROCESS
Biological Culture Development
Dr. Alicia Compere and Dr. William Griffiths at ORNL were very helpful in providing
frozen cultures of denitrifiers and in defining optimum culturing procedures. Because of
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