DYNAMIC SIMULATION OF SHOCK-LOADING EFFECTS ON THE TREATMENT OF CORN-SWEETENER MANUFACTURING WASTEWATER

Casco Inc., a subsidiary of Corn Products International Inc., processes corn to manufacture corn derived products at three facilities across Ontario. The wastewater treatment systems at these facilities are subject to loading fluctuations. This paper reports on a dynamic simulation used to examine the potential effects of these fluctuating loads on the biological treatment process at one facility.Intensive full-scale operating data was collected from one facility during a two-week period. This data was then used to calibrate a dynamic model of the extended aeration activated sludge treatment process. The treatment process was simulated using the Mantis model, an extension of the IAWPRC Activated Sludge Model No. 1, as implemented using the commercially available GPS-X simulation software from Hydromantis Inc.The calibrated model was used to study the dynamic effects of various sizes of releases to the treatment process. A 30% glucose solution, with a chemical oxygen demand of approximately 594,000 mg/L, was used in the simulations as the shock loading stream.No significant effect on the soluble components of the treatment system effluent was noted. However, the observed rapid growth of heterotrophic biomass following such a release may cause upsets in the clarification process and result in high effluent suspended solids concentrations. Also, as expected, a temporary reduction in the dissolved oxygen concentration in the aeration basin was observed which could result in filamentous bulking problems and a corresponding decrease in effluent quality.A key result of the simulation work is the identification of nutrient deficiencies as a potential operating problem associated with the release of refined sugar streams. Nitrogen deficiency was apparent in the simulation results, as indicated by the observation of aerobic denitrification.