Process Engineering

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Browsing Process Engineering by Author "Agezegn, Gezahegn"

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    Investigations of Filtrate Clarification and Optimizations of Flocculant Dosages: A Case Study at Wonji Shoa Sugar Factory
    (Addis Ababa University, 2019-07) Agezegn, Gezahegn; Hundessa, Dessalegn (PhD)
    This study was found out the installed filtrate clarification plant by flotation system in the Wonji Shoa Sugar Factory was inapplicable and ineffective. The average juices Brix to carry out by floatation system are 65 0 Brix and above while the average Brix for the filtrate juice measured were 8.94. The only possible method investigated was by decanting the filtrate juice in a separate stream. This type of method of production system requires a number of processing parameters like flocculant dosages, phosphate and lime additions. The method as well accounts of optimum processing conditions for better juice purification system. Then, the only identified factors in this filtrate clarification system were lime additions and flocculant dosages because of the amounts of phosphate levels already found in the filtrate juice were 350 ppm which were sufficient for the next clarification process to be carried on. So the initial steps were the filtrated juice samples taken from the filtrate juice tank and then measurements of the parameters such as purity, pH, phosphate contents and calcium contents were analyzed before the clarification system carried out. Next flocculants were measured by weighing balance and they were prepared in solutions form at a temperature of 50-60 0 C. Then, the juices passed through a heating medium until the temperature reaches 70-75 0 C. When the temperatures reached at the required range, the filtered juices treated with limes at different pH levels. Then, the heating processes were also continued until the temperature reaches 95-100 0 C. Next the prepared samples were taken and poured into the 1000 ml graduated cylinders, and then different concentrations of flocculants (Separan) were added. Immediately, the parameters such as the settling rate, the height of muds formed in the cylinder, the colors, the turbidity, the percentage purity, the purity rise, calcium and magnesium contents of the clear juice were measured. Finally, the effect of milk of limes starting 6.8-7.4 pH and flocculants 4-8ppm within clear juices were optimized by using Design Expert software version of 6.0.8. By using this software the responses such as pH of clear juices, the turbidities and the colors were the significant while the calcium contents did not show any significant variations at 5% significance level. The optimal solutions obtained for flocculants dosages in the range of 4.05- 4.67 and limed filtrated juice pH at 6.84-7.01 combined respectively.