USING BATCH REACTORS TO INVESTIGATE OXYGEN-CONSUMPTION AND ORGANICS DECOMPOSITION IN DRAINAGE SYSTEMS WITH ATTACHED BIOFILM

Oxygen consumption and organics decomposition in drainage systems with attached biofilm were investigated using a batch reactor. In order to distinguish the relative contribution of suspended biomass and biofil m parallel experiments were performed. The reactors with low and high glucose concentrations simulated lightly polluted rivers and sewers. T he dynamic behaviour was different for the systems dominated by biofil m and the systems with only suspended biomass due to different control ling mechanisms. The biofilm played a major role for the biodegradatio n only when the suspended biomass concentration was below a certain va lue. The ratio of wetted area on which biofilm grows over the water vo lume (WA/V) is closely correlated with the biofilm oxygen consumption rate, is also important to respirometer design. The relative contribut ion of the suspended biomass and biofilm was not sensitive to the chan ge of initial glucose concentration.