Operational History

The BOD of the high-rate oxidation pond ("small pond") at startup was 2420 ppm (mg/l), and the hexane soluble content was 2040 mg/l. Both ponds were covered with about 6 in of floating oil and grease (see Figure 8.2.8 for the rate of stabilization).

The system was set on a recirculation rate of 50 gpm. Three days later, when the pH showed no further erratic swings, dried bacterial cultures (special species of sapro-phytic and facultative bacteria that consume oil) were added to create a biomass specifically for oil and grease reduction. The initial dosage was 5 lb, followed by 1 lb/day addition for 14 days. After this initiation, the system was

FIG. 8.2.9 Polishing pond performance from startup. A = initial BOD of 2420 ppm (at startup ODI roughly equals BOD; later BOD is stabilized at 50 percent ODI for this waste); B =

FIG. 8.2.10 Theoretical vs actual performance. A. Rate of pollutant addition reducers; B. Standard theoretical curve for rate of pollutant reduction by biological treatment systems; C. Curve distortion due to exceptional load condition. System gave 97% reduction in 30 days.

FIG. 8.2.9 Polishing pond performance from startup. A = initial BOD of 2420 ppm (at startup ODI roughly equals BOD; later BOD is stabilized at 50 percent ODI for this waste); B =

FIG. 8.2.10 Theoretical vs actual performance. A. Rate of pollutant addition reducers; B. Standard theoretical curve for rate of pollutant reduction by biological treatment systems; C. Curve distortion due to exceptional load condition. System gave 97% reduction in 30 days.

maintained by the addition of Ate lb of the dried culture three times a week. Figure 8.2.9 illustrates initial reduction of the hexane soluble content and continuing control since the beginning of plant operation.

The effectiveness of a biological treatment to control oily wastewater is also shown in Figure 8.2.10 where theoretical and actual performances are compared.

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