Search

In the tropics, cassava starch is produced at artisanal and industrial scales. This paper focuses on a new methodology enabling the technoeconomical comparison of small-scale cassava starch manufacturing process (1-5 t of starch/day) in two markedly different contexts (Colombia and Vietnam). Measurements were conducted during trial runs for each unit operation (washing/pealing, rasping, extraction and separation). Starch mass balance was calculated from sample composition (moisture, starch and crude fiber and ash content). Production capacity, water consumption, electric requirements and capital-labor costs were also measured. The manufacturing processes differed mainly on starch recovery from starch present in washed roots (65 vs. 76%), extraction capacity (0.3 vs. 0.9 t of washed roots/h), water consumption (45 vs. 21 m/t of dry starch), energy consumption (59 vs. 55 kWh/t of starch) and production costs (1,156 vs. 162 US$/t of starch) for Colombia and Vietnam, respectively. Moreover, the effectiveness of the starch extraction process could largely be attributed to the differences in the extent of root disintegration achieved with different rasping equipment. [ABSTRACT FROM AUTHOR]

Abstract: 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±0.11mequiv. H+/100g dry matter. [ABSTRACT FROM AUTHOR]