Dewatering and Drying Characteristics of Water Hyacinth (Eichhornia Crassipes) Petiole. Part II. Drying Characteristics

I. C. O. Akendo, L. O. Gumbe, A. N. Gitau


The broad objective of the study was to identify and relate the parameters that are important
in drying of water hyacinth petiole. This involved identification of the pertinent properties
that influence drying of water hyacinth petiole and then developing predictive empirical
equations for the identified factors. Field work involved collection of samples from four
different locations within Nairobi dam. A series of experiments were carried out using a
standard oven to obtain the drying data and the subsequent drying curves. Mean drying rate
( mean k ) derived from the experimental data was used to develop predictive equation that
adequately described the effect of varying both drying temperature and current moisture
content of samples during the drying process. Mean drying rates, mean k were found to be 2.22,
2.71 and 3.39 h-1 for oven drying temperatures of 105, 130 and 150oC respectively. It was
evident that increasing the drying temperature resulted into an increase in drying rate whereas
a change in the moisture content of the sample before drying, did not affect the drying rate at
a constant drying temperature with a P-value of 0.97 at a significance level of 0.05. Mean
initial moisture content of water hyacinth petiole was found to be 91% (w.b.) for 16
determinations. Statistical investigation showed that there was no significant difference in the
means of the initial moisture content (P-value = 0.94) for the samples collected at the four
locations within Nairobi dam. A two paired t-test between predicted drying rates and mean
drying rates obtained from experiments gave a P-value of 0.99. The significance of this study
is seen in the role the results obtained will have in influencing the design of suitable drying

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