LABORATORY STUDY OF THE EFFECT OF TEMPERATURE CHANGES ON MIXING AND PERFORMANCE OF PONDS

Abstract

This work is an investigation of the eect of temperature changes on the mixing and performance of ponds. The parameters tested for were: biochemical oxygen demand, dissolved oxygen, coliform, suspended solid, temperature and pH. Three metallic tanks were fed simultaneously by a plastic container under gravity. This was achieved by systems of hoses and pipelines with one plastic container supplying sewage to another. Each tank measured 2 x 0.5 x 0.4m while each plastic container measured 300litres. Aerobic conditions prevailed in both the plastic containers and the metallic tanks. There was a lighting system over each tank. Two tanks contained heating coils at the bottoms, thermostatically controlled. One tank was the control (without heating coils). Each tank also had control taps at both inlet and outlet. There was a sampling device for collecting sewage at every 0.1m depth of each tank. The results showed that mixing causes general uctuations in dissolved oxygen, suspended solid, biochemical oxygen demand and coliform with
respect to depth, as the temperature varies.