Schroeter et al. (1982) operated four pairs of aerobic lab-scale systems at temperatures of 12 and 20°C. The systems were operated at sludge ages of 3, 8 and 20 days; two systems were operated at the 3 day sludge age for reasons discussed later. The influent consisted of domestic wastewater, diluted with tap water to a concentration of 500 mgCOD/I.
All systems were single reactor systems as shown in Fig. 1. The results of mass balances for COD and N for the Schroeter et al. (1982) systems are listed in Table I. The results are very good for all systems, regardless of whether nitrification was occurring (systems at the 3 day sludge age and 12'~C were not nitrifying; all other systems nitrified fully). As the
nitrogen balances are close to 100%, it is unlikely that aerobic denitrification occurred in these systems to a significant extent.