Comparative evaluation of mass oxygen transfer in existing aeration systems with advance oxidation techniques for treatment agro based pulp and paper mill effluents

Abstract

Mass Oxygen Transfer is a molecular diffusion of gas in a liquid depending upon its characteristics, concentration and cross-sectional area across which diffusion occurs and is accomplished in aerobic digestion of organics through different aeration equipment. Accordingly the comparative evaluation of mass transfer oxygen by different aeration equipment were conducted in existing aeration tanks of Agro Based Pulp and Paper Mill by studying the effect during pre and post injection of liquid oxygen through submerged and floating turbine systems coupled with fine bubble replacing existing coarse bubble diffuser. The dissolved oxygen levels in the second aeration tank (AT2) equipped with submerged turbine has further improved in the range of 2 to 2.5 comparison to lower values up to 1.5 mg/l observed in first aeration tank (AT1) with floating turbine systems. It was further studied that if fine bubble diffuser replacing existing pipe in both the aeration tanks are further coupled with liquid oxygen injection through submersible turbine system in both the aeration tanks shall increase dissolved oxygen levels up to 3-3.5 mg/l besides reduction in energy consumption up to 25% thus lowering overall treatment cost and further improve the treatment efficiencies for reduction a of BOD and COD at the final out let well below compliance level.