Activated Sludge Treatment of Petroleum Refinery Wastewater: Part 1 – Experimental Behaviour

Abstract

An experimental programme was conducted to provide an initial database for development of a dynamic simulation model for activated sludge systems treating petroleum refinery wastewater. A laboratory scale single reactor aerobic activated sludge system was first operated under constant loading conditions, receiving a feed of petroleum refinery wastewater of fixed COD concentration at a constant flow rate. The steady state system was operated at sludge ages of 10 and 20 days. Data on dynamic response behaviour were obtained by operating the system under a 24 hour cyclic square-wave loading pattern; the system received the same daily influent volume of fixed COD concentration at a constant rate, but over a 12 hour period with no feed over the remainder of the 24 hour cycle. The system was monitored intensively over 24 hour cycles when operated at sludge ages of 5 and 20 days. Batch tests were conducted off-line to establish the decay rate of microorganisms and the potential for volatilization of organics from the raw wastewater. All experimentation was conducted at 20°C.