Investigations of Filtrate Clarification and Optimizations of Flocculant Dosages: A Case Study at Wonji Shoa Sugar Factory
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Date
2019-07
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Addis Ababa University
Abstract
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.
Description
Keywords
Filtrate, Lime, Flocculant, Phosphate, Color, Turbidity, pH