STUDIES ON TRANSITION PHASE FROM ACTIVATED SLUDGE PROCESS TO AEROBIC HYBRID REACTOR

Abstract

Activated sludge process is widely used for wastewater treatment throughout the world with various needful modifications. The hybrid modification of activated sludge process facilitates incorporating media which can be floating or fixed into aeration basin and serves as carrier material for growing active organisms on its surface. As a result the carrier media allows the biological reactor to operate at high biomass concentration than that of conventional activated sludge process. The present work consists of fitting plastic nets vertically inside the aeration tank of conventional activated sludge process in a laboratory scale model. The addition of nets resulted in improvements m COD and ammonium nitrogen removal efficiency. Initially model was operated as activated sludge unit and once it attained steady state, system was changed into hybrid modification by incorporating plastic nets in aeration tank. When Pseudo steady was reached removal efficiencies for Activated sludge process and hybrid reactor were 70% and 84% respectively. When kinetics of reactor stabilization was studied, it revealed that, activated sludge unit took 40 days for 90% of maximum removal efficiency, which is typically a start up period. In such case which is very large and rate coefficient found was 0.043d" . But when the system was modified into hybrid reactor, for same maximum removal efficiency it requires only 7 days. The process stabilization kinetics was established. When the unit was modified into hybrid reactor, the MLSS concentration was reduced due to no recycling of sludge without any affect on COD removal efficiency. The study demonstrates that the existing plants can be upgraded by fitting plastic nets in the aeration tanks to high efficiency AS-Biofilm systems.