INDUCED AERATION

Abstract

All the world over, as a result of population explosion and industrialization the quality of water resources has greatly deteriorated. In this situations the water and wastewater treatment has become important from public health, ecological and aesthetic point of view. Aeration is a process having many applications in water and waste water treatment. The three phase gas transfer phenomena involves sub-dividing of liquid in the gas phase or sub-dividing gas in the liquid phase by the two film concept. Several methods are in use for the aeration process. A new method known as "Induced Aeration" working on the principle of jet theory of aeration has been introduced here. This method is reported to be simple, compact and efficient as it requires little space, no moving pads, little operating and maintenance cost. The method essentially consists of subjecting the air water mixture temporarily to hydrostatic pressure thus increasing the value of saturation concentration of dissolved oxygen and therefore the dissolved oxygen deficit which is a driving force in aeration. Slip between air and water and hold-up of air bubbles increases the value of overall film transfer coefficient and surface renewal rate. For evaluating the performance of the proposed induced aerator, a study has been done on laboratory scale model with different air and water flow rates. The oxygen transfer efficiencies with different water and air flow rates are found to be quite comparable with other systems of aeration and fairly thatched with jet system of aeration. By the study the oxygen transfer efficiency is found to • be 26.16% (average) and 33.95% (max.) for constant air flow rate (20 1pm). So the induced aerator can also be proposed for the field use after further improvement.