Presentation on theme: "Removal of fluoride in waste waters by using calcium phosphate (DCPD) Proceedings of the 2012 Japan-Taiwan Symposium on intelligent Green and Orange (iGO)"— Presentation transcript:
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 SludgeCaF2 M (OH)x Ca salts (ex Ca(OH) 2 ) Al or Fe salts And NaOH Effluent Waste Water 1st step 2nd step Conventional Method
Problems of Conventional Method 2/12 Fluoride > 10000 mg/L 20 – 30 mg/L > 10 mg/L Sludge CaF2 M (OH)x Ca Salts (ex Ca(OH) 2 ) Al or Fe salts And NaOH Effluent Waste Water 1st step 2nd step unsuitable for agriculture Al 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 (CaHPO 4 2H 2 O) Environmental reparation technique using DCPD acid proof, hardly soluble ( Ca 10 (PO 4 ) 6 F 2 ) FAp HA (Ca 10 (PO 4 ) 6 (OH) 2 ) Acid Fluoride hint anticarious fluoride application F-F- F-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 lag time product B product A Fig.1 Difference of DCPDs reactivity with fluoride ion fluoride ion mg / L time / min Reactivity of each DCPD is quite different by the kinds 100 μm 25 μm
Nano-Etching DPCD 5/12 BeforeAfter 1 m 10 m Treatment In Hot Water 1.2 m 3 /g 4.8 m 3 /g by-product DCPD from food industry nano surface structure Nano-Etching DCPD Fig.2 SEM images of DCPD particles
Difference in DCPD Fig.8 Reaction of DCPD 3 hours lag time By-Product DCPD (before treatment) Nano-Etching DCPD (after treatment) no lag time 6/12 Fluoride mg / L time / min
Method Comparison Nano-Etching DCPD By-Product DCPD able to remove fluoride ion efficiently because of having no lag time Conventional Fluoride Treatment -treatment performance -amount of generated sludge -cost efficacy 7/12 cheaper but inefficient
Experiment 8/12 Fluoride Ion Solution 500ml Mix for 1hr Add Flocculant Mix for 1hr Add Flocculant DCPD 0.03 0.09g or Al 2 (SO 4 ) 3 0.2 0.35g DCPD 0.03 0.09g or Al 2 (SO 4 ) 3 0.2 0.35g Fluoride Analysis pH adjust in Al precipitation pH adjust in Al precipitation Gas Chromatography Ion Selective Electrode Fluoride Ion Solution 500ml Mix for 1hr Add Flocculant DCPD 0.05g or Al 2 (SO 4 ) 3 0.25g Observation pH adjust in Al precipitation Weight measurement of Sludge Decantation Fig.3 Experimental Procedure
Result time / hour 9/12 Fluoride ion mg/L Fig.4 Changes of fluoride ion aluminum sulfate 0.3g
Property of Sludge 10/12 NE-DCPDAluminum salt (gel like precipitate) Size ( m) Fraction ( ) Large particle size = easy to filtration !! NE-DCPD Time (min) Filtration ratio (-)
Conclusion Table1 Comparison between NE-DCPD and Aluminum 11/12 Nano-Etching DCPD Aluminum Sulfate Removal Control - Additive -Time Time Chemicals Amount 0.1 kg/m 3 0.5 kg/m 3 pH AdjustmentNo Need NaOH 0.1 kg/m 3 Sludge Amount0.09 kg/m30.3 kg/m3 FiltrationGoodBad 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.