EXPERIMENTAL ASSESSMENT OF DEPTH OF CONTACT MEDIA AND RATE OF FLOW OF SEWAGE FOR SELECTED MATERIAL IN SOIL BIOTECHNOLOGYM.V.S. RAJUAbstract Soil Biotechnology (SBT) is one of the emerging decentralized wastewater treatment technologies for small communities with several advantages. The establishment of treatment process involves experimental evaluation of its components, with locally available material for required degree of treatment. In this connection, an attempt has been made to study the required depth of contact media for different rates of application of domestic sewage for a chosen local material for Soil biotechnology treatment process. For which a column experimental study was conducted for sewage flow rates of 0.50, 1.00, 1.50, 2.00, 2.50 l/hr using dosing pump, after clarification in settling tank. The fabricated column setup consists of 100 mm diameter pvc pipe filled with locally available over burnt brickbats as contact media, culture catalyst and appropriate Inlet and outlets. The investigation was carried out at designated depths of 1.50 m, 2.00 m, 2.50 m and 3.0 m. The percentage removal of Biochemical Oxygen Demand (BOD) & Chemical Oxygen Demand (COD) was observed at each depth for a selected rate of sewage flow. It is found that 81.2 â 94.2% of BOD and 78.4 - 90.7% of COD removal were observed at 3.0 m depth for all discharges considered in the present study. While 69.1 â 82.5% of BOD and 67.9 - 79% of COD were removed at 2.5 m depth for all discharges. The rate of removal of BOD and COD are increasing with increase in depth of contact media because of more contact time between sewage and contact media. Further, the rate of removal of BOD & COD is decreasing with increase in rate of application of sewage, since the rate of flow is inversely proportional to the contact time. |