removal of fluoride in waste waters by using calcium phosphate (dcpd) proceedings of the 2012...
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Removal of fluoride in waste waters by using calcium phosphate (DCPD)
Proceedings of the 2012 Japan-Taiwan Symposium on intelligent Green and Orange (iGO) Technology
Toyama National College of Technology
Yukina CHUJO
Fluoride Wastewater treatment 1/12
Fluoride > 10000 mg/L 20 – 30 mg/L > 10 mg/L
Sludge
CaF2M (OH)x
Ca salts (ex Ca(OH)2)
Al or Fe salts
And NaOHEffluent
Effluent
WasteWater
1st step
2nd step
Conventional Method
Problems of Conventional Method 2/12
Fluoride > 10000 mg/L 20 – 30 mg/L > 10 mg/LSludge
CaF2M (OH)x
Ca Salts (ex Ca(OH)2)
Al or Fe salts
And NaOHEffluent
Effluent
WasteWater
1st step
2nd step
unsuitable foragricultureAl and Na
damage soil
huge amount of wet sludge
impact to landfill
not remove fluoride efficiently
not to meet environmental
standard 8mg/L
Reaction of DCPD 3/12
DCPD(CaHPO4 ・ 2H2O)
Environmental reparation technique using DCPD
acid proof,hardly soluble
( Ca10(PO4)6F2 )
FApHA(Ca10(PO4)6(OH)2)
+ Acid + Fluoride
hint : anticarious fluoride application
F-
F-
F-
- immobilize small amount of fluoride in water by forming Fap
- No addition of excess chemicals are needed.
Problem of DCPD 4/12
0
5
10
15
20
0 100 200 300 400 500 時間 / min
フッ化
物イ
オン
濃
度/
mg dm
-3
lag time
lag time
product B
product A
Fig.1 Difference of DCPD’s reactivity with fluoride ion
fluor
ide
ion
mg
/ L
time / min
Reactivity of each DCPD is quite different by the kinds
100 μm
25 μm
Nano-Etching DPCD 5/12
Before After
1 mm1 mm
10mm10mm
TreatmentIn
Hot Water
1.2 m3/g 4.8 m3/g
by-product DCPDfrom food industry
nano surface structure→Nano-Etching DCPD
Fig.2 SEM images of DCPD particles
Difference in DCPD
Fig.8 Reaction of DCPD
0
5
10
15
20
0 100 200 300 400 500 時間 / min
3 hours lag time
By-Product DCPD(before treatment)Nano-Etching DCPD
(after treatment)
no lag time
6/12
Flu
orid
e m
g /
L
time / min
Method Comparison
Nano-EtchingDCPD
Nano-EtchingDCPD
By-ProductDCPD
By-ProductDCPD
able to remove fluoride ion efficientlybecause of having no lag time
ConventionalFluoride Treatment
ConventionalFluoride Treatment
- treatment performance- amount of generated sludge- cost efficacy
?
7/12
cheaper but inefficient
Experiment 8/12
Fluoride Ion Solution500ml
Mix for 1hr Add Flocculant
DCPD 0.03 ~ 0.09gor
Al2(SO4)3 0.2 ~ 0.35g
Fluoride Analysis
pH adjustin
Al precipitation
・ Gas Chromatography・ Ion Selective Electrode
Fluoride Ion Solution500ml
Mix for 1hr Add Flocculant
DCPD 0.05gor
Al2(SO4)3 0.25g
Observation
pH adjustin
Al precipitation
Weight measurementof Sludge
Decantation
Fig.3 Experimental Procedure
Result
0
2
4
6
8
10
12
0 1 2 3
時間 / h
NE- DCPD 0.09g
硫酸 アルミニウム 0.3g
time / hour
9/12
Flu
orid
e io
n m
g/L
Fig.4 Changes of fluoride ion
aluminum sulfate 0.3g
Property of Sludge 10/12
NE-DCPD Aluminum salt(gel like precipitate)
Size (mm)F
ract
ion
(%)
Large particle size= easy to filtration !!
NE-DCPD
Time (min)
Filt
ratio
n ra
tio (
-)
ConclusionTable1 Comparison between NE-DCPD and Aluminum
11/12
Nano-EtchingDCPD
AluminumSulfate
RemovalControl
- Additive-Time Time
ChemicalsAmount 0.1 kg/m3 0.5 kg/m3
pH Adjustment No Need NaOH : 0.1 kg/m3
Sludge Amount 0.09 kg/m3 0.3 kg/m3
Filtration Good Bad
Final Evaluation ○ △
Summary 12/12
In this study, we applied the reaction of DCPD to fluoride solution treatment. The results of the research were summarized as follow;By using nano-activated DCPD, the particle size was not changed after water treatment. If suitable particle of DCPD is applied, obtained sludge seems to be separated by conventional filtrations.
By using the DCPD, fluoride in waste water was easily removed, and a less amount of chemicals is needed than conventional method using aluminium sulphate.
Thank you for your attention