Multicomponent models containing both substrate and biomass have an advantage over conventional models in seeking better understanding of activated sludge systems. Such models are also useful in the characterization of wastewater. Studies in recent years have shown that most of the soluble organic matter in the effluent of treatment systems consists of soluble microbial products that arise during biological treatment. In order to support experimental studies, mathematical models have also been developed to explain microbial product formation. In connection with the approaches in the literature, a mathematical model for estimating chemical oxygen demand in effluent in dispersed media has been developed in this study. The death-regeneration approach - an approach of multicomponent activated sludge models containing the formation of soluble inert organic matter with together carbon oxidation was used. Because the differential equations developed for dispersed media have no analytical solutions, the system was represented with the in-series reactor approach, with the death-regeneration and hydrolysis concepts advised in the IAWPRC Task Group Model.