These results reveal that even though extraction at 50 C gives
the maximum yield, it may not reflect the optimal extraction conditions.
One possible reason for this is the extracted active components
may not be those responsible for efficient flocculating and
dewatering properties. One study states that the extraction temperature
affects the polarity of water, which defines the type of
compounds that are extracted (Carr et al., 2011). For temperatures
between 60 and 90 C, the bio-flocculants exhibited more desirable
dewatering properties. The water recovery for AF and DF were
almost constant at 45e50% and the SS removal was more than 90%.
This indicates that the produced sludge flocs were stronger and
more compact than the ones at lower extraction temperatures, thus
promoting the dewaterability of the flocs with high removal of SS.
Despite this benefit it is noted that increasing temperature will also
lead to an increase in energy consumption and hence cost of the
extraction process, thus 70 C was adopted as the optimal extraction
temperature for the remainder of the parametric study.