EFFECT OF DISSOLVED OXYGEN CONCENTRATION ON THE AEROBIC STABILIZATIONOF SWINE WASTE

Most aerobic waste treatment system designs recommend that the dissolved oxygen concentration be maintained at 0.5 - 2.0 mg//. This design parameter may not be applicable to high strength wastes. Swine wastes (initial chemical oxygen demand (COD), 30,000 mg//) werebatch-digested at three levels of dissolved oxygen (0.5-2.0 mg//; 5-8mg//; and 15-20 mg//) over 14-day treatment periods. The results indicate that dissolved oxygen concentrations greater than 2 mg/ / produce a significant increase in the rate of aerobic stabilization of the waste. For this waste, the bacteriawereable to removethe organiccompoundsresponsible for the soluble COD from solution within2 daysat all oxygen levels buttheywere ableto oxidizethesechemicals morerapidlyat the higher oxygen concentrations. This increase in the rate of stabilization with oxygen concentration could have a direct effect on the design of waste treatment systems for other high strength animal and food processing wastes.