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Proceedings of the 2012 Japan-Taiwan Symposium on intelligent Green and Orange (iGO) Technology. Removal of fluoride in waste waters by using calcium phosphate (DCPD ). Toyama National College of Technology Yukina CHUJO. Sludge. CaF2 M (OH)x. Fluoride Wastewater treatment. 1/12.

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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

Removal of fluoride in waste waters by using calcium phosphate (DCPD)

Toyama National College of TechnologyYukina CHUJO

slide2

Sludge

CaF2

M (OH)x

Fluoride Wastewater treatment

1/12

Conventional Method

Ca salts (ex Ca(OH)2)

Waste

Water

Al or Fe salts

And NaOH

Effluent

Effluent

1st step

2nd step

Fluoride > 10000 mg/L 20 – 30 mg/L > 10 mg/L

problems of conventional method

CaF2

M (OH)x

Sludge

Problems of Conventional Method

2/12

unsuitable foragricultureAl and Na damage soil

Ca Salts (ex Ca(OH)2)

Al or Fe salts

And NaOH

Waste

Water

Effluent

not remove fluoride efficientlynot to meet environmental standard 8mg/L

Effluent

1st step

huge amount of wet sludgeimpact to landfill

2nd step

Fluoride > 10000 mg/L 20 – 30 mg/L > 10 mg/L

reaction of dcpd
Reaction of DCPD

3/12

hint:anticarious fluoride application

acid proof,hardly soluble

+Acid

+Fluoride

F-

F-

F-

HA

FAp

DCPD

( Ca10(PO4)6F2 )

(Ca10(PO4)6(OH)2)

(CaHPO4・2H2O)

- immobilize small amount of fluoride in water by forming Fap- No addition of excess chemicals are needed.

Environmental reparation technique using DCPD

problem of dcpd
Problem of DCPD

4/12

Reactivity of each DCPD is quite different by the kinds

lag time

lag time

fluoride ion mg / L

25 μm

product B

100 μm

product A

time / min

Fig.1 Difference of DCPD’s reactivity with fluoride ion

nano etching dpcd
Nano-Etching DPCD

5/12

Before

After

nano surface structure

→Nano-Etching DCPD

by-product DCPDfrom food industry

Treatment

In

Hot Water

10mm

10mm

1 mm

1 mm

1.2 m3/g

4.8 m3/g

Fig.2 SEM images of DCPD particles

difference in dcpd
Difference in DCPD

6/12

3 hours lag time

no lag time

Fluoride mg / L

By-Product DCPD(before treatment)

Nano-Etching DCPD(after treatment)

time / min

Fig.8Reaction of DCPD

method comparison
Method Comparison

7/12

able to remove fluoride ion efficiently

because of having no lag time

cheaper but inefficient

Nano-EtchingDCPD

By-ProductDCPD

ConventionalFluoride Treatment

  • treatment performance
  • amount of generated sludge
  • cost efficacy
experiment

pHadjustin

Al precipitation

Experiment

8/12

Fluoride Ion Solution500ml

Fluoride Ion Solution500ml

DCPD 0.03~0.09g

or

Al2(SO4)3 0.2~0.35g

DCPD 0.05g

or

Al2(SO4)3 0.25g

pHadjustin

Al precipitation

Mix for 1hr

Add Flocculant

Mix for 1hr

Add Flocculant

Observation

Decantation

・Gas Chromatography

・Ion Selective Electrode

Weight measurementof Sludge

Fluoride Analysis

Fig.3 Experimental Procedure

result
Result

9/12

aluminum sulfate 0.3g

Fluoride ion mg/L

time / hour

Fig.4Changes of fluoride ion

property of sludge
Property of Sludge

10/12

NE-DCPD

Fraction (%)

NE-DCPD

Aluminum salt

(gel like precipitate)

Size (mm)

Filtration ratio (-)

Large particle size

= easy to filtration !!

Time (min)

conclusion
Conclusion

11/12

Table1 Comparison between NE-DCPD and Aluminum

summary
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.