The interactive effect of cationic polymer additives, COD, and UFV was explored by Bhunia and Ghangrekar [51] who studied the influence of these parameters on biomass granulation and COD
removal efficiency in a UASB reactor treating low strength wastewater. They formulated statistical models based on these three variables to optimize the biomass granulation and COD removal efficiency in UASB reactors using a two-level factorial design. For the thick inoculums used in the study, having 80 g/l SS, and VSS to SS ratio of 0.3, catinic polymer additives in the inoculums showed adverse effect on biomass granulation and COD removal efficiency