Fly Ash Sbt

REMOVAL OF FLUORIDE IN WATER USING ALUM TREATED FLYASH S. B. Thakare1, Dr. S.M. Bhoyar2, A.V. Parwate3, Dr. M. Rao4 ABSTRACT India is among the 23 nations of the world, which confront with the problem of fluorosis due to intake of high fluoride contaminated water. Ground water in many parts of India contains fluoride in the range of 1.0 mg/l to 15 mg/l. Fluoride is a salt of an element called fluorine and fluorine is 17th most abundant element constituting about 0.065% of the earth’s crust. It is a devastating report from recent survey conducted by Water Technology Mission of Ministry of Rural Development, Government of India that around 62 million peoples including 6 million children below the age of 14 years in 20 states of the country are affected with dental, skeletal and non-skeletal fluorosis and therefore is a cause of concern in most of the developed and developing countries. A study was conducted to investigate the possibility of removing fluoride in water using Alum Treated Flyash, a low cost absorbent. Alum Treated Flyash (ATF) is better adsorbent with good adsorption capacity and higher adsorption potential. Near equilibrium is attended at 330 minutes at optimum conditions. Maximum fluoride removal observed to be 87% for the initial fluoride concentration of 10 mg/l. This technique is going to be simple low cost for rural and urban population and also of great relief to those water supply systems where fluoride ion concentration is reported to be very high. INTRODUCTION Water is a prime natural resource & physiological necessity to mankind. Safe potable water is no longer a ‘God given gift’ in a modern industrialised world. The rural water supply in our country suffers from inadequacies in terms of quantity as well as the quality. India is among the 23 nations of the world, which confront with the problem of fluorosis due to intake of high fluoride contaminated water. In the country 20 states are affected with dental, skeletal & non-skeletal fluorosis (Susheela, 2001). In Maharashtra 14 districts out of 35 districts are affected with the fluoride as the

1. 2. 3. 4.

Lecturer, Department of Civil Engineering, College of Engineering & Technology, Akola (M.S.). Asst. Professor, Department of Agricultural Chemistry and Soil Science, Dr. P.D.K.V. Akola (M.S.). Principal, A.V.C. Engineering college, Mayiladuthurai Dist. Nagai, (Tamilnadu) Principal, P.R. Engineering College, Vallam, Thanjavur (Tamilnadu)

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concentration in the ground water is above 1.5 mgl-1 (Thakare et. al. 2003). It is a devastating report from recent survey conducted by water technology mission of ministry of rural development, Government of India that over 30 million people living in 8700 villages are affected by fluorosis of which 6 millions are children below the age of 14 years and therefore is a cause of concern in most of the developed & developing countries. There is no permanent cure available till today for this ailment & hence preventive measures should be contemplated. In India the extent of fluoride contamination in ground water varies from 1.0 to 15 mgl-1. Fluoride enters in to the body through a variety of sources viz; water, food, air, medicaments & cosmetics. Fluoride is a salt of an element called fluorine. In India fluoride commonly occurs in earth’s crust as Fluospar (Sedimentary rocks), apatite and rock phosphate and phosphorites and cryolite in igneous rocks. Fluoride present in the rock & soil when comes in contact with water of high alkalinity, will release fluoride into ground water. Fluoride contain in mineral soil is shown in Table 1 (Peng et al., 1996). Tea has the highest fluoride content of 112 mgkg-1 among the various food items (Azbar et. al., 2000). Consumption of water having fluoride content more than 1.5 mgl -1 may have multi dimensional health manifestations most common being dental, skeletal & soft tissue fluorosis. Fluoride & fluorosis mitigation is possible through the provision of safe drinking water, with fluoride as low as possible, not to exceed 1.5 mgl -1. To overcome the above situation, it is very essential to adopt any appropriate deep fluoridation technique considering the local conditions, economic status & viability of the treatment method, literacy of the community, easy availability of media and reuse of exhausted media for treatment purpose. The object of present study is to evaluate the feasibility of fluoride removal using alum treated flyash i.e. ATF. MATERIAL AND METHODS The flyash was obtained from Thermal Power Plant at Paras, district Akola (Maharashtra). It was first soaked in 1 percent NaOH, washed with distilled water and then dried it at 115 ± 5 0C in an Oven for half an hour. The dried matter was mixed with 2 percent Al2 (SO4)3 solution and allowed to stand for half an hour. The white precipitate of Al (OH)3 so appeared was dissolved by adding 1:1 HCl till a clear solution was obtained. The solution left over night. The flyash then separated, washed until free from Al3+ and sundried for six hours. This is referred here as Alum Treated Flyash (ATF). Experimental Techniques Reaction mixture for all batch sorption studies consisted of 100 ml. Synthetic fluoride samples were prepared by spiking distilled water with NaF. Batch sorption tests were carried out in stopper reagent bottles and rotated at 150 rpm in a rotatory shaker. At the end of the desired contact time, bottles were removed and allowed to settle for 5 minutes. The samples were filtered using gravimetric filter paper (Whatman 42 filter) and fluoride concentration was determined using SPADNS method as per standard procedure. The initial fluoride concentration chosen for study was 15 mg/l, as ground

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water fluoride concentration in fluorosis endemic areas of India, rarely exceeded this limit. RESULTS & DISCUSSION Effect of pH The pH value of the aqueous solution is an important controlling factor in the adsorption process thus the role of hydrogen ion concentration was examined for different pH values. The extent of removal was investigated at solution ion concentration of 15 mg/l fluoride and is shown in Figure 1. In case of ATF, the plot revealed that, the percent removal falls as pH decreases below 4.0 & rises above 8.0. The optimum pH for fluoride removal was found to be 6.5 where removal was 54.80 percent. Thus the aquo groups (-M-OH2-) and hydro groups (-M-OH)7 on the surface of sorbent may be responsible for adsorption of fluoride. Al2O3 is the major constituent of flyash. As the pH decreased below 4, Al2O3 will be dissolved as Al3+ and subsequently positively charged strong Aluminum complexes such as AlF2+ & AlF3+ are formed. The surface of Al2O3 will be further positively charged with decrease in pH. Therefore a decrease in adsorption at low pH is probably a result of the formation of positively charged aluminum complexes and positively charged surface. Conversely as the pH increases above 8 the hydro group (-M-OH)7 will gradually disappear forming increasingly negatively charged surface. In addition, OH will also compete for the available sites left on the surface. These findings are in conformation with the observations of Mehrotra, R. et. al. (1999). Effect of Contact Time . From the plot of percentage adsorption versus contact time as shown in Figure 2, it is found that the rate of removal of fluoride ions increases with increase in agitation time to some extent. Further increase in contact time dose not increase the uptake due to deposition of fluoride ions on the available adsorption sites on adsorbent material. The rate of uptake of fluoride ions by ATF at the optimum pH value indicates that the process is quite rapid. This initial rapid adsorption subsequently gives way to a very slow approach to equilibrium & saturation. The ultimate adsorption of 54.80 percent occurs within the first hour of the agitation with an initial concentration of 15 mgl -1. This initial rapid rate of adsorption is subsequently followed by slow rate of adsorption. Equilibrium & saturation is reached in 330 min & max. removal of fluoride is 69.40 percent. Effect of Adsorbent Dose Fluoride uptake by ATF as a function of sorbent dose is shown in Figure 3. it is obvious from the plot that if sorbent dose increased, percentage fluoride removal also increased. There is substantial increase in the adsorption when the dose of adsorbent was increased from 200 mgl-1 to 30000 mgl-1 and an additional amount of adsorbent did not influence the further removal of fluoride ions. The maximum removal in case of

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fluoride was found to be 85 percent with an adsorbent dose of 20000 mgl-1. These observations were in conformity with the earlier report of Singh, R.P. et. al. (2000). The plot of unit adsorption versus dose reveals that unit adsorption was high at low dosages than at high dosages. As the sorbent dose was increased, there was less commensurate increase in adsorption resulting from lower adsorptive capacity utilization of sorbent. Unit adsorption decreases significantly with decreasing mass of sorbent per unit volume. This effect has been termed as “Solid concentration effect” meaning overcrowding of particles. Effect of Initial Fluoride Concentration The effect of initial fluoride ion concentration on the adsorption efficiency by ATF has been systematically investigated by varying the initial concentration between 2 – 30 mgl-1. and a plot of percentage adsorption versus initial fluoride concentration is shown in Figure 4. It is a well-known fact that the rate of exchange adsorption is controlled by diffusion through a hydrostatic boundary layer called film diffusion control or through the pores of the resin matrix called particle diffusion control. The rate of exchange adsorption is mainly controlled by film diffusion under the conditions of small resin particle, dilute solution and mild stirring and vice versa in case of pore or particle diffusion. More practically, both processes control it. As the initial concentration of fluoride increases, percentage removal decreased. By using ATF the maximum removal for initial concentration of 15 mgl-1 is 85 percent, which is 2.25 mgl-1. In India the permissible limit for the fluoride ion in the drinking water is 1.5 mg/l thus if the initial concentration of fluoride in the water is about 10mg/l-1 then with the optimum conditions the ATF will remove the fluoride up to 87 percent and the concentration of fluoride remained will be 1.3 mgl-1. which is well below the prescribe limit of 1.5 mgl-1. Thus for the further studies the initial fluoride concentration is considered to be 10 mgl-1. Effect of Adsorbent Particle Size The effect of sorbent particle sizes having geometrical mean diameter of 0.45mm to <0.075 mm on the removal of fluoride and concentration was investigated for an initial fluoride concentration of 10 mgl-1. and are shown in Figure 5. It was observed that the adsorbent particle size has significant influence on the kinetics of absorption due to change in number of adsorption sites. The removal of fluoride ions at different particle sizes showed that the uptake of fluoride ion increases with decreasing particle diameter. The presence of larger number of smaller particles for a given weight provides, the sorption system with a grater surface area available for fluoride ion removal and it also reduces the external mass transfer resistance. The maximum removal of fluoride ion is at particle size < 0.075 mm i.e. 92.10 percent and the reduction in the percentage removal is with the particle size 0.45 mm that is 86.30 percent.

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Sorption mechanism The sorption data for the removal of fluoride ions have been correlated with the Freundlich models, and the estimated values of the Freundlich parameters for the sorption of fluoride ions are presented in Table 3. The Freundlich equation have the general form of ; qe = Kf C1/n The linearized Freundlich adsorption isotherm is of the form: Log (qe) = log Kf + 1/n log Ce Where, qe is the amount of fluoride ions adsorbed per unit weight of adsorbents (mg/g). Kf and 1/n are the Freundlich constants related to sorption capacity and sorption intensity respectively. Linear plots of log (qe) vs log (Ce) at different adsorbent doses are applied to confirm the applicability of Freundlich model. The coefficient of correlation (Cc) values presented in Table 3 indicate the applicability of the Freundlich model using ATF for the removal of fluoride ions. The linearised rearranged Freundlich model for the removal of fluoride is shown in Figure 6. The isotherm constants derived from the linearized Freundlich model are presented in Table 3. The regression co-efficient (r2) values presented in Table 3, indicate that the adsorption data of fluoride ion is a better fit for freundlich isotherm. CONCLUSIONS Fly ash collected from the thermal power station is effective adsorbent after some treatment as compared to costlier conventional absorbent. Result showed that this low cost adsorbent can be fruitfully used for the removal of fluoride in wide range of concentrations. The exhausted alum treated fly ash can be easily disposed of. Fly is the waste product and require a small cost for transportation and pre-treatment. The authors are suggesting that there is no need to regenerate exhausted fly ash because it is easily, cheaply and locally available.

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BIOGRAPHY I have passed B.E. (Civil) in 1989 from Amravati University in first division. Later I completed M.E. (Environmental Engg.) in 2001, while working in College of Engineering and Technology, Akola as a Lecturer in Department of Civil Engineering. So far my total experience is about 12 years in the same college. During this time I became member of Institutions of Engineers (India), Indian Water Work Association, Indian Society for Earthquake Technology, IAEM and ISTE. I registered for Ph.D. in 2002 and I am in the position to submit it in December 2005. I have published 05 research papers in National Journals of repute and 10 research paper in National and International Conferences / Seminars. I have actively participated in arranging several functions at IWWA, IE(I), etc. under Amravati center. I have arranged rainwater harvesting workshop at my college in June 2005. REFERENCES APHA (1992). Standard methods for the examination & waste water 18 th edition, American Public Health Association, Washington, D.C. Azbar and A. Turkman (2000). Defluoridation of drinking water. J. of Water Science & Technology. 42 : 403 – 407. Mehrotra, R., B.S. Kapoor and B. Narayan (1999). Defluoridation of drinking water using low cost adsorbent. Indian J. Environmental Health. 41 (1) : 53 – 58. Peng, J. Qi Ching Gang and A.J. Rubin (1996). Use of fluorspar in water fluoridation. J. of Environmental Engineering. 3 : 132 – 140. Singh, R.P., Y. Singh and D. Swaroop (2000). Defluoridation of groundwater in Agra city using low cost adsorbents. J. environmental contamination and toxicology. 65 : 120 – 125. Susheela, A.K. (2001). Sound planning and implementation of fluoride and fluorosis mitigation programme in an endemic village. Proceeding of International workshop on fluoride in drinking water organized by Government of Madhyapradesh at Bhopal. January 2001 : 1 – 9. Thakare, S.B., A.V. Parwate and M. Rao (2003). Studies on fluoride removal using Low Cost Material. Proceeding of All India seminar on challenges in environmental protection and possible solution at Amravati (M.S.). January 2003 : 51 - 58

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Table 1. Concentration of fluoride ion in mineral soil. Minerals Meteorites Dunite Basalt High calcium Alkali rocks Shale Sand Stone Deep sea clays Granite

Fluoride (ppm) 28.30 12.00 100 520 1200 – 8500 740 270 1300 --

Table 2. Physical & Chemical Characteristics of Flyash Physical Characteristics Bulk Density kg/m3 = 925.6 Moisture (%) = 11.40 Ash Content (%) = 6.68 Porosity (%) = 0.39 Surface area (m2/gm) = 485 Loss on Drying (%) = 13.64 pH zpc = 2.40

Chemical Characteristics SiO2 (%) = 61.25 Al2O3 (%) = 23.45 CaO (%) = 2.10 Fe2O3 (%) = 4.00 MgO (%) = 1.30

Table 3 : Freundlich constants for the removal of fluoride ion using ATF as adsorbent. Freundlich constants K1

1/n

r2

0.0128

3.6322

0.9479

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Volume of Sample = 100 ml Initial Fluoride Concentration = 15mg/l Adsorbent dose = 1 gm/l Contact Time = 60 minutes

80.00 60.00 40.00 20.00

A TF

9. 0 10 .0

8. 5

8. 0

7. 5

7. 0

6. 5

6. 0

5. 0

4. 0

3. 0

0.00 2. 0

% Removal of Fluoride

100.00

pH Figure 1 : Effect of pH on the Removal of Fluoride Volume of Sample = 100 ml Initial Fluoride Concentration = 15mg/l Adsorbent dose = 1 gm/l pH = 6.5

80.00 60.00 40.00

A TF

20.00

390

360

330

300

270

240

210

180

150

120

90

60

30

0.00 15

% Removal of Fluoride

100.00

Contact time, min Figure 2 : Effect of contact time on the Removal of Fluoride

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80.00 60.00 Volume of Sample = 100 ml Initial Fluoride Concentration = 15mg/l Agitation time = 330 min. pH = 6.5

40.00 20.00

ATF 80 0 10 00 20 00 40 00 80 00 10 00 0 20 00 0 30 00 0

0.00 20 0 40 0

% Removal of Fluoride

100.00

Adsorbent dose Figure 3 : Effect of Adsorbent dose on the Removal of Fluoride

% Removal of Fluoride

100.00 80.00 60.00 Volume of Sample = 100 ml Adsorbent Dose = 20000 mg/l Agitation time = 330 min pH = 6.5

40.00 20.00

A TF

0.00 2

4

6

8

10

12

15

20

25

30

Initial Fluoride Concentration mg/l Figure 4 : Effect of Initial Fluoride Concentration on the Sorption

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100.00

% Removal of Fluoride

80.00 60.00 Volume of Sample = 100 ml Initial Fluoride Concentration = 10mg/l Adsorbent dose = 20000 mg/l pH = 6.5, Agitation time = 330 min.

40.00 20.00

ATF 0.00 0.45

0.3

0.15

0.075

< 0.075

Particle Size, mm Figure 5 : Effect of Adsorbent Particle Size on the Removal of Fluoride

Log Ce

0.00 -0.500.00

0.20

0.40

0.60

0.80

1.00

Log (X/m)

-1.00 -1.50 -2.00 -2.50 -3.00 -3.50

ATF y = 3.6322x - 4.3613 2 R = 0.9479

-4.00 Figure 6 : Freundlich Isotherm for the Removal of Fluoride

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To, Dr. Vimal Kumar Organizing Secretary and Director, Fly Ash Utilization Programme, Government of India, New Delhi. Subject : Submission of Full Length Paper Entitled “Removal of Fluoride in Water Using Alum Treated Flyash” Respected Sir, I am submitting the full length research paper on removal of fluoride ion in the water using alum treated flyash based on laboratory experiment work. Thanking you in anticipation. Yours Sincerely,

Date : 10.10.2005 Encl.: 1. Two copies of manuscript with CD. 2. D.D. of Rs. 4000 /D.D. No. ……………………. Dt. 10/10/05

Prof. S.B. Thakare.

Address for Correspondence : Prof. Sunil B. Thakare Behind Deshonnati Press, Ajay Colony, Gourakshan Road, Akola – 444 001 (Maharashtra). E-mail : [email protected]

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DESCRIPTION TITLE OF PRESENTATION : REMOVAL OF FLUORIDE IN WATER USING ALUM TREATED FLYASH PRIMARY AUTHOR

: Prof. Sunil Bhimarao Thakare

Organization

: Department of Civil Engineering, College of Engineering and Technology, Akola On N.H. No.6, At. Po. Babhulgaon (Jh.), Tq. Dist. Akola Pin – 444 001 (Maharashtra) Phone : 09422863496 E-mail : [email protected]

Additional Authors

: 1. Dr. Arun V. Parvate, Principal, A.V.C. Engineering college, Mayiladuthurai Dist. Nagai, (Tamilnadu) 2. Dr. M. Rao, Principal, P.R. Engineering College, At. Po. Vallam, Dist. Thanjavur (Tamilnadu) 3. Dr. S.M. Bhoyar, Asst. Professor, Department of Agricultural Chemistry and Soil Science, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola –444 001(Maharashtra).

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AUTORISATION FORM

I Sunil B. Thakare (First Author) for and on behalf of all other co-authors signing this authorisation form that the work presented in the paper " Removal of Fluoride in water using alum treated fly ash" is an original work based on laboratory findings.

Date : 10/10/05 Sunil B. Thakare ( First Author )

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