Study on Improving Sludge Dewatering Efficiency by Addition of Conditioning Aids
Date Issued
2000-07-31
Date
2000-07-31
Author(s)
李公哲
DOI
892211E002022
Abstract
Fly ash from coal-fired power plant can
be used as filter aid in sludge conditioning.
The scope of this research includes the
dewatering characteristics and the
rheological properties of conditioning sludge
with fly ash / polymer.
Physical conditioning with fly ash
addition can improve the dewaterability of
inorganic sludge, but there is no profound
influence on activated sludge. The effect of
dual conditioning with fly ash and polymer
comparing to a sole chemical conditioning
with polymer is investigated. According to
the experiment with centrifugation and belt
filter press, dual conditioning for inorganic
sludge can reduce the dosage of polymer,
improve the dewaterability, and produce
higher cake solid concentration. However,
when comparing dual conditioning to a sole
chemical conditioning, fly ash addition
shows no significant effect in activatedsludge dewatering, and cake solid
concentration just increases as adding fly ash.
Capillary suction time (CST) and
specific resistance to filtration (SRF)are
better criteria for optimal dosage of polymer
in dewatering process of centrifuge. However,
dosage of polymer is usually insufficient in
dewatering process of belt filter press when
using CST, SRF, and coefficient of
compressibility as operational parameters.
In the measurement of the rheological
behaviors of sludge, optimal fly ash addition
can reduce yield stress, apparent viscosity of
inorganic sludge and improve the dewatering
characteristic. However, the behavior is not
observed in activated sludge conditioning
with fly ash addition. As addition of polymer
for chemical conditioning or dual
conditioning, the relationship between shear
rate and shear stress of inorganic sludge
changes from straight line to curve with an
obvious peak by flocculating the small
particles into large and stronger aggregates,
but this relationship remains linear for
activated sludge. Furthermore, when sludge
is treated by chemical or dual conditioning
process, both of yield stress and apparent
viscosity are increased in underdosing which
is attributed to the floc volume and floc
strength: The increases are also happened
made the condition of overdosing which is
due to the polymer residual in the water.
According to the experimental result, the
turning point showed in yield stress and
apparent viscosity curves could be used as
operational criterion for optimal dosage of
polymer.
Subjects
fly ash
polymer
dual
conditioning
conditioning
capillary suction time
specific
resistance to filtration
resistance to filtration
coefficient of
compressibility
compressibility
rheology
centrifuge
belt
filter press
filter press
Publisher
臺北市：國立臺灣大學環境工程學研究所
Type
report
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