Modeling small-scale cassava starch extraction. Simulation of the reduction of water consumption through a recycling process

The purpose of this study was to model the extraction unit operation of the cassava starch manufacturing process and to propose a realistic recycling simulation in order to reduce the volumes of effluents. The model was developed from reactors which are commonly used for cassava starch extraction at a household scale in Vietnam. The reactors were tested using inflow starch as a marker at the beginning of the batch process. The experimental residence time distribution (RTDexp) was calculated by the outflow of the starch concentration. Using Matlab®, the RTDexp was compared to the theoretical residence time distribution (RTDth). The dynamic model obtained was built up on Simulink® and tested with four different strategies of recycling methods. Sedimented starch was collected from the different types of processes; the pH value and the titratable acidity of starch were then measured. The results showed a good correlation between RTDexp and RTDth. The reactors were described by a model of two mixed tanks in series. The simulation of the recycling process revealed a reduction in quantity of water used up to 43%; however, the recycling process increased significantly the titratable acidity of starch up to 6.48 ± 0.11 mequiv. H+/100 g dry matter.