UPGRADING BIOLOGICAL WASTEWATER TREATMENT
USING AN EQUALIZATION/DENITRIFICATION SYSTEM
Glen T. Daigger, Assistant Director for Wastewater Reclamation
Norman N. Hatch, Jr., Department Manager, Industrial Processes
CH2M Hill, Inc.
Denver, Colorado 80222
Fritz D. Bertz, Technical Manager
Daniel A. Skedsvold, Environmental Control Chemist
Columbia Nitrogen Corporation and Nipro, Inc.
Augusta, Georgia 30913
INTRODUCTION
The Columbia Nitrogen Corporation in Augusta, Georgia owns and operates a facility which
produces precursors for the manufacture of Nylon 6 and fertilizers from the byproducts of nylon
precursor manufacture. The 1 to 2 million gallons (MG) of wastewater generated at the facility daily
contains readily biodegradable, low molecular weight organics, organic nitrogen, and both ammonia
and nitrate nitrogen. Table 1 summarizes the characteristics of the Columbia Nitrogen wastewater.
Biological treatment is provided to this wastewater in an activated sludge system prior to discharge
to the receiving stream. The current discharge permit requires removal of organics (i.e., BOD) but
not of nitrogen or nitrogen species.
Historically, a number of factors have adversely affected the performance of the Columbia Nitrogen biological treatment system. The organic treatment capacity of the system, expressed as the
total chemical oxygen demand (TCOD), has been estimated to be approximately 30,000 to 50,000 lb
TCOD/day. However, as illustrated in Figure 1, historical loadings exceeded these values about half
the time with values as high as 150,000 lb TCOD/day observed on occasion.
The nature and strength of the wastewater is also quite variable due to variations in production
cycles, the use of batch processes, and process spills. The pH of the influent typically varied from 2
to 12 during the course of the day, as illustrated in Figure 2 for grab samples collected at 4-hour
intervals for a one-week period. The type and concentration of organic and nitrogen loadings also
varied significantly during the day and from day to day. Finally, since the influent tended to be acidic
and since nitrification in the biological treatment system tended to consume the available alkalinity,
the pH in the aeration basin at times was quite low.
Table I. Typical Characteristics of Columbia Nitrogen Wastewater*
Item
Meanb
Range'
BOD (mg/L)
TCOD (mg/L)
Total Kjeldahl Nitrogen (mg-N/L)
Ammonia Nitrogen (mg-N/L)
Nitrate Nitrogen (mg-N/L)
Total Phosphate (mg-P/L)
PH
1,860
2,880
275
150
420
115
900-4,090
1,500-8,180
177-445
67-372
210-780
31-550
3.5-9.7
"Data are for June 1981.
hMonthIy average.
'Range in daily values for month.
613