The control and optimization of belt filter presses in the wastewater treatment industry is still largely dependent on operator intervention. This is mainly due to the lack of predictive models for belt filter press performance. This paper presents correlations determined via a factorial trial for the determination of filtrate suspended solids and solids capture as a function of individual process parameters as well as their interactions. A Box-Behnken experimental based design methodology was used to examine the relationship between the operating parameters and the response variables. The process parameters investigated were polymer concentration, polymer dosing, sludge flow rate and the belt speed. The measured responses were the filtrate suspended solids and sludge cake solids. The measured responses obeyed a second order polynomial relationship and their respective interaction effects of the operating parameters were illustrated on three-dimensional surface graphs. The sludge cake solids concentration was found to be constant over the wide range of experimental conditions. The interaction between the sludge flow rate and polymer dosing rate was the second most influential operating parameter on the filtrate suspended solids following sludge flow rate. The belt speed had an insignificant influence on the filtrate suspended solids and solids capture. The correlation is useful to determine the optimum amount of polymer required if the sludge flow rate changes due to production requirements for constant feed solids concentrations and can be used to develop automated control systems for a particular WWTP. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.