EFFECT OF AGITATION ON ORGANIC LOADING REMOVAL KINETICS

Abstract

All aerobic wastewater treatment processes need free oxygen to sustain aerobic microorganism responsible for the stabilization of the organic matter in the wastewater. The oxygen requireMent of the aerobic treatment units are fulfilled by supplying oxygen to the wastewater from atmospherib air either by purging air from bottom through diffusion or by increasing air to liquid interfacial aera for oxygen transfer by creating turbulence in the water by mechanical agitation. In the present study experiments have been carried out to asses the effect of turbulence on the COD of the reactor. The 11 intensities of turbulence was varied by varying impeller submergence and speed. The experimental results shows that at the upper zone the reduction in COD decreases with increase in submergence at a faster rate than at lower part of the tank. With increase in impeller speed, turbulence increases proportionally and always there is increase in COD reduction with increase in impeller speed. At zero submergence and 100 rpm impeller speed for wastewater with 3200 mg/1 , 79.69% reduction in COD isobtained in 8 hrs of agitation. The effect of initial COD of the wastewater on the COD reduction with time has also been studied. Results shows that at low initial substrate concentration the COD reduction is higher than that at higher concentration.