HYPOLIMNETIC AERATORS - PREDICTING OXYGEN-TRANSFER AND HYDRODYNAMICS

A simple model that predicts oxygen transfer in hypolimnetic aerators is described. The model accounts for cocurrent flow of air and water, variation of the saturated aqueous oxygen concentration with depth, an d depletion of oxygen in the gas-phase. A correlation for water flow r ate is developed from literature data, while existing correlation equa tions are used to estimate the mass transfer coefficient. Published ex perimental data for water flow rate and oxygen transfer are used for m odel validation with most of the observed data being predicted to with in +/- 30%. Equations are provided for estimating the extent of the ox ygenated zone-of-influence for an aerator operating in relatively stag nant water or a uniform underflow current. The potential deterioration in aerator performance due to short-circuiting of oxygenated water is briefly discussed. The model represents a substantial improvement in understanding of oxygen transfer in hypolimnetic aerators. It should b e useful in the preliminary design and economic optimization of hypoli mnetic aeration systems, and in determining spacing requirements for a erators in a lake or reservoir when more than one aerator is installed .