Analysis of the efficiency of sludge dewatering using Moringa oleifera as natural phytocoagulant
In order to evaluate the efficiency of sludge dewatering, specific parameters such as settling velocity (Vs) and sludge volume index (SVI) have to be measured. However, problems arise when these parameters are used for the evaluation of efficiency using M. oleifera as natu...
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Main Authors: | , , , |
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Format: | Conference or Workshop Item |
Language: | English |
Published: |
2015
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Subjects: | |
Online Access: | http://irep.iium.edu.my/46440/1/46440.pdf http://irep.iium.edu.my/46440/ |
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Summary: | In order to evaluate the efficiency of sludge
dewatering, specific parameters such as settling velocity (Vs) and
sludge volume index (SVI) have to be measured. However, problems
arise when these parameters are used for the evaluation of efficiency
using M. oleifera as natural phytocoagulant or sludge conditioner.
Using statistical optimization, it was found that despite good results
of Vs and SVI, the concentration of residual suspended solids in
supernatant liquid or turbidity was very high. Thus, turbidity of
supernatant liquid was selected as a criteria to evaluate the efficiency
of dewatering process. In this research, two optimization steps were
run under two factors for each optimization; i.e., mixing time and
concentration of M. oleifera seeds extract with NaCl (1 M). The
range of these factors was (100 – 1000 mg/L) for M. oleifera seeds
extract concentration, and (5 – 30 min) for mixing time. In the first
optimization, Vs and turbidity were used as responses. While in the
second optimization SVI and turbidity were used as response
parameters. Both optimization steps were run under (pH = 7), mixing
speed (120 rpm) for the first minute, and (40 rpm) during the rest
period of experiment. By using Design-Expert software v9, for the
first optimization of settling velocity, the optimum Vs was found to
be (1 cm/min) and the turbidity of the supernatant was (350.7 NTU).
Whereas in the optimization of the sludge volume index (SVI), the
optimum value was (24.7 mL/g), corresponding turbidity value of
suspended solids in supernatant liquid was (341.5 NTU). Since the
turbidity was very high, second optimization by redesigning the
factors was conducted resulting in optimum values of dosage of
(462.8 mg/L), mixing time of (13.4 min), turbidity of (67.2 NTU)
(further (80.2 %) reduction compared to the (350.7 NTU) of the first
optimization) and settling velocity of (0.93 cm/min) were obtained.
For the optimization of SVI, dosage of (447.5 mg/L) and mixing time
of (8.3 min) gave (33.5 mL/g) of SVI with (67.2 NTU). These
optimized dewatering parameters can be used to improve the
efficiency of sludge dewatering. |
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