Procedures for determining influent COD fractions and the maximum specific growth rate of heterotrophs in activated sludge systems

The influent COD of municipal wastewaters has been categorised into fractions: readily (soluble) and slowly (particulate) biodegradable, and soluble and particulate unbiodegradable. Procedures are presented for determining the division into these four categories, as are experimental methods for determining the maximum specific growth rate of the heterotrophs within the IAWPRC Task Group model structure. Some of the procedures are dependant on knowledge of the heterotroph yield and endogenous mass loss rate constants; comment is made on suggested values.