Temporal changes in Leaching of Heavy Metals from ...

Inte rnational Journal of Engineering Technology, Manage ment and Applied Sciences

www.ijetmas.com September 2015, Volume 3, Special Issue, ISSN 2349-4476

Temporal changes in Leaching of Heavy Metals from Clay Bricks and Fly ash Bricks Nidhi Gupta1 , Vidyadhar V. Gedam1 , Chandrashekhar Moghe 2 , Pawan Labhasetwar2 National Environmental Engineering Research Institute (NEERI), Nagpur Abstract Fly ash,“Pollut ing Industrial Waste”contains many heavy metals and are being disposed off in ash ponds and open area of land since ages. This not only occupies large area of land near thermal power plants but also results in significant environmental problems e.g. heavy metals leaching fro m the fly ash. This leaching of heavy metals cause contamination of aquatic environment mainly when it co mes in contact with water. So proper d isposal of fly ash is a cause of concern. If fly ash is managed well, it can be used in many application like manufacturing of bricks, cement, blocks etc. These bricks also contain heavy metals of fly ash. So,leaching study was done to study the heavy metals leached fro m bricks by conducting the column leaching test. Leach study shows the concentrat ion of heavy metals leached in long term in natural environ ment conditions. Leach ate was collected fro m the bottom of the colu mn and concentration of 18 heavy metals Al, As, B, Ba, Ca, Cd, CO, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Se, Zn in leach ate was me asured using ICP-OES. A comprehensive Effect of p H and time studied on leaching of heavy metals Key Words :Column Leaching, heavy metals, Bricks, Ground Water, Soil.

Introduction Burnt clay bricks are important accommodating masonry unit of building material, made up of clay which is plastic in nature and suitable for proper drying, moulding and burning of bricks but this type of clay available only in river basin, water ponds and coastal area. In most of the central and south India clay suitable for bric ks manufacturing is not available. As clay, which is less plastic or expansive, gritty or sandy is not fit for brick making. To cater to demand of manufacturing results in higher cost and low quality of bricks due to transportation from long distances and use of sub-standard clay. In order to reduce the expenses, a substitute of burnt clay bricks is essential( Kumar, 2000). Use of rubber (Turgut and Yesilata, 2008), processed waste tea (Demir,2005), polystyrene (Veiseh and Yousefi2003)and sludge limestone dust and wood sawdust (Turgut and Algin, 2006), fly ash (Kayali, 2005;Lin,2006; Basegio and Berutti,2002) are option for replacement of clay in bricks. Fly ash bricks act as one of the best substitute for burnt clay bricks just because fly ash is solid waste generated from thermal power plants and has not been utilized effectively. In India fly ash production is around 50 million tons per year(Vermaet al., 1988], which occupies lots of land in wet state and pollutes the environment. So proper utilization of fly ash is necessary. But it is very difficult to use in cement and concrete production because of its low quality and high water content. Not only in wet form fly ash can be used in fired bricks manufacturing replacing clay but it also saved the firing energy due to carbon contained of fly ash.(Guler et al., 1995; Kalwa and Grylicki, 1983; Mukherji and Machhoya,1993). Fly ash, alumino-silicate glass consists of the oxides of Al, Fe, Si, and Ca, with minor amounts of Mg, K, Zn, Na, and S, plus various trace elements,which either adsorbed on the particle surface or incorporated into its matrix (Natuschet al. 1974). Broad array of trace elements present in fly ash in concentrations >50 mg/kg, many of which are of environmental concern. Mineralogy and particle size distribution of the raw material being burnt and the combustion temperature is responsible for the extent of the heavy metals present in fly ash (Baba et al., 2008).These heavy metals will be leached in surrounding environment when this fly ash and bricks manufactured from this fly ash will come in contact with water etc. So study on leaching behavior of these heavy metals was necessary. Leaching is fluid extraction of element or compound from solid. Leaching behavior of heavy metals from fly ash was influenced by many factors physical (particle size, particle homogeneity and porosity, temperature

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Nidhi Gupta 1 , Vidyadhar V. Gedam1 , Chandrashekhar Moghe 2 , Pawan Labhasetwar2


www.ijetmas.com September 2015, Volume 3, Special Issue, ISSN 2349-4476 and others), chemical (pH, redox conditions, complexation phenomena, sorption processes and others) and biological ones (all factors affecting pH, redox capacity and complexation with organic matter) in both field and in the laboratory(Brunori,1999). To evaluate the potential of water and soil contamination from the mobilization of heavy metals many leaching methods are being proposed. It is important to notice that the results of these leaching studies vary according to combustion type, applied extraction procedure and coal composition.( Mohapatra and Rao, 2001). To evaluate the long term release of hazardous material from waste in ground water and soil column leaching test was designed. This Column leaching test is more representative of field condition than batch leaching experiments (Cote and Constable, 1982). Uniform distribution of the leaching solution is necessary, so that all grains of the solid matrix are equally exposed. Precipitation or absorption within the column may affect the results (Kim, 2003). Column experiments more closely simulate the leachant flow, particle size distribution and pore structure, and solute transport found in the fields (Zachara and Streile, 1990).Nevertheless, leach ability of waste is a matter of concern. This paper presents and discusses on the leachability of heavy metals from bricks and also studied the effects of pH and time on heavy metals leaching. Which shows that heavy metals leaching in clay bricks was comparatively less than clay fly ash bricks and alkalinity of clay bricks was also less compared to clay fly ash bricks. Leaching of Mg and K were found to be higher than other heavy metals. 2. Materials and Methodology 2.1 Materials Clay fly ash bricks (CFAB) samples were collected from a CFAB manufacturing facility near two power plants located in Khaperkheda and Badarpur Districts of Maharastra and Uttar pradesh States, respectively, in India as shown in Figure 1. Clay bricks (CB) samples was collected from only one location of clay brick manufacturing facility near Khaperkheda thermal power plants. Clay bricks composition may vary from location to location as constitutes of soil changes. To compare the heavy metal leaching from CFAB and CB comparative study was also done. Heavy metals in CB was considered to be fixed, collected from one location. Heavy metals from CFAB collected from two location were compared. Sample of bricks dried in oven and ground by mortar and pestle manually to fine grain size (CFAB-K>CB-K. It means in Clay bricks leaching was less as compare to Coal fly ash bricks, might be due to comparatively less alkalinity and less concentration of heavy metal in clay bricks. But level of leached heavy metals in all samples of bricks were with in permissible limit of drinking water standardBIS:10500:2002,except Cu and Se in few samples of CB-Kand CFAB-K respectively. Conclusion The results obtained from the column leaching study shows that, heavy metals leached in cla y bricks was comparatively less than clay fly ash bricks and in comparison of other fly ash bricks, clay bricks was less alkaline in nature. Leaching of Magnesium (Mg) and Potassium (K) was higher in comparison to other heavy metals. Except few heavy metals leaching of all metals were within the permissible limit of drinking water standards BIS:10500:2002. Due to different composition of bricks did not permit to have a general view of the mobility of metallic elements from the bricks. Table: 1 Variation of pH in Coal fly ash bricks-Badarpur(CFAB-B) with time No. of Samples 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

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pH -7

pH -4

8.76 8.61 8.54 8.54 8.52 8.51 8.5 8.41 8.4 8.4 7.94 7.93 7.89 7.86 7.84 7.78 7.69 7.0 6.93 6.63

10.18 10.07 9.98 9.98 9.93 9.89 9.88 9.87 9.84 9.83 9.74 9.71 9.69 9.68 9.67 9.66 9.66 9.64 9.62 9.60

Accumulate Time Hours 24 48 72 96 120 144 168 192 216 240 264 288 312 336 360 384 408 432 456 480

Accumulate Vo lu me 950 1800 3010 3800 4900 5850 7050 8100 9000 10050 11000 11950 13200 14500 15995 16900 17995 18000 19300 20100



www.ijetmas.com September 2015, Volume 3, Special Issue, ISSN 2349-4476 Table: 2Variation of pH in Coal fly ash bricks -Khapperkheda (CFAB-K) with time No. of pH -7 pH -4 Accumulate Time Accumulate Samples Volume Hours 1 10.18 10.16 24 850 2 10.07 10.15 48 1867 3 9.98 10.12 72 2456 4 9.98 10.08 96 3870 5 9.93 10.05 120 4860 6 9.89 9.99 144 5600 7 9.88 9.95 168 6800 8 9.87 9.94 192 7600 9 9.84 9.93 216 8970 10 9.83 9.92 240 9800 11 9.74 9.9 264 1080 12 9.71 9.89 288 1195 13 9.69 9.84 312 1290 14 9.68 9.8 336 1389 15 9.67 9.79 360 1489 16 9.66 9.79 384 1510 17 9.66 9.77 408 1680 18 9.64 9.76 432 1756 19 9.62 9.74 456 1890 20 9.62 9.71 480 1950 Table: 3 Variation of pH in Clay bricks -Khapperkheda (CB-K) with time No. of pH -7 pH -4 Accumulate Time Accumulate Samples Volume Hours 1 8.87 8.57 24 890 2 8.83 8.50 48 1980 3 8.84 8.48 72 2800 4 8.83 8.47 96 3580 5 8.71 8.36 120 4490 6 8.63 8.31 144 5800 7 8.5 8.26 168 6800 8 8.33 8.26 192 7900 9 8.23 8.20 216 8890 10 8.19 8.18 240 9800 11 8.19 8.13 264 1090 12 8.01 8.13 288 11960 13 7.98 8.1 312 12890

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www.ijetmas.com September 2015, Volume 3, Special Issue, ISSN 2349-4476 14 15 16 17 18 19 20

7.84 7.79 7.74 7.69 7.58 7.43 7.41

8.06 7.98 7.85 7.70 7.72 7.69 7.61

336 360 384 408 432 456 480

13900 14800 15980 16990 18050 19100 20290

Fig 2 Column Leaching Experiment Set Up

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Fig: 3 Variation of the concentration of metals with time (Column Procedure) References    

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