Journal of Geoscience and Environment Protection
2013. Vol.1, No.2, 22-25
Published Online October 201 3 in SciRes (http://www.scirp.org/journal/gep) http://dx.doi.org/10.4236/gep.2013.12005
Copyright © 2013 SciRes.
Experimental Study on Fly Ash for Conditioning of Specific
Resistance of Sludge Water
Bingtao Liu, Pengju Ding
School of Environmental and Municipal Engineering, North China University of Water Resources and Electric
Power, Zhengzhou, C hina
Email: liubingtao@ncwu.edu.cn
Received August 2013
Discharge of sludge from water works into waters will result in the increased deterioration of water envi-
ronment. Therefore, an experimental study was conducted on the addition of conditioning agent to im-
prove sludge dewatering performance. The result shows that coagulation is inadaptable to the treatment of
sludge from water works and use of powdered coal ash from power plant as conditioning agent can great-
ly reduce the specific resistance of sludge and the dewatering performance can be improved. The optimal
dosage of fine powdered coal is 20 g/100 mL and coarse powdered coal is 30 g/100 mL. Powdered coal is
mixed with sludge to form filter cake, which is blended with coal in certain proportion to make into fuel.
So that incineration of sludge from water works can be realized.
Keywords: Fly Ash; Sludge Water; Sludge; Specif i c Resi s t ance
Introduction
The sludge water of waterworks includes sludge water of set-
tling tank and backwash wastewater of filter. After the simple
sedimentation and separation, the supernatant can be reused,
sediment forms so-called sludge of sludge water. At present,
most of the existing waterworks directly discharge sludge of
sludge water into natural water in China which will cause pol-
lution to water (Liu Hui & Xu Jianhua, 2001; Lu jiajuan, 2005).
In the 1970s, the United States, Japan and other developed
countries began to pay attention to the treatment and disposal of
sludge of waterworks (John T. Novak, 1999; J Kopp & N Dichtl,
2001). The treatment method is similar to sludge treatment me-
thod of municipal sewage plant (Xu Qiang , 2003). However, the
sludge from waterworks and sewage plant has different charac-
teristics, even if the sludge is all from waterworks. There are
significant differences in properties because of the different raw
water quality and the different production technology. We have
an experimental research on methods of treatment and disposal
of sludge from inclined tube sedimentation tank of water treat-
ment plant in Zhengzhou.
Experiment
Main Reagents and Mud Sample
PAC, light yellow powder, alumina content 31%, basicity
76%, confect concentration of 10 g∙L−1 when use i t.
Sludge samples, Activated sludge from Zhengzhou city se-
wage sludge treatment plant emissions, take underlayer preci-
pitation after standing.
Two kinds of fly ash that contains fly ash of coarse particle
and fine particle in the experiment are from Zhengzhou thermal
power plant. Its quality is shown in Table 1.
Experiment Method
Test is divided into two steps. First of all is test of coagula-
Table 1.
Quality index of powdered fly ash (%).
Items Finenes
(Remai ni ng amount of 45 µm screen)
loss
Fly ash of coarse particle 55.2 4.41
Fly ash of fine particle 12.9 3.13
tion, sedimentation and pre-concentration of waterworks sludge
is in progress and we can obtain settlement curve. Then specific
resistance of mud sample is measured (an important index of
sludge dewatering performance) and make optimization of the
sludge conditioner of specific resistance in order to achieve the
sludge dehydration and drying.
The purpose of adding 1 g PAC and 5 mg PAM coagulant to
per liter of sludge water is to destabilize colloids that inorganic
coagulant is the first dosing and PAM is dosing after 5 S. Oper-
ating parameters: in the mixing process, n = 300 r/min, T = 30
S; in the flocculation process, n1 = 150 r/min, T1 = 3 min, n2 =
30 r/min, T2 = 10 min. Static precipitation continues for 2 h
after coagulation, a decline height of muddy liquid level along
with time is recorded and subsidence curves is depicted.
Specific resistance has a special measuring device shown in
Figure 1. Including Büchner funnel, filter media, smoke filters,
cylinders, vacuum table and vacuum pump.
Test run at room temperature. Measure out 100 ml of sludge
in the beaker, stir in a certain pH by adding flocculents, stir in
medium-speed about 5 minutes and pour into the Büchner fun-
nel, the vacuum filtration dehydrat ion until no drop. Then record
at different times (t) and the corresponding filtrate volume (v),
with t/v as the vertical coordinate, v the horizontal mapping, t/v
and v is linear, the slope b, constant pressure filtration
Where