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20620130101003

  1. 1. Journal of Civil Engineering and Technology (JCIET), ISSN 2347 –4203 (Print), ISSN 2347 –4211 (Online) Volume 1, Issue 1, July-December (2013), © IAEME 26 A COMPARATIVE STUDY OF NATURAL COAGULANTS IN FLOCCULATION OF LOCAL CLAY SUSPENSIONS OF VARIED TURBIDITIES Madhukar V. Jadhava * Yogesh S. Mahajanb a Civil Engineering Department, Sanjivani Rural Education Society’s College of Engineering, Kopargaon 423603, Maharashtra, India b Chemical Engineering Department, Dr. Babasaheb Ambedkar Technological University, Lonere 402123, Tal-Mangaon, Raigad, Maharashtra, India ABSTRACT In the present study, experiments were carried out in the laboratory to investigate the flocculation behavior of plant origin coagulants Nirmali seeds, Okara gum and the mucilage isolated from the fruits of Coccinia indica (Kundru) as flocculent for the treatment of synthetic turbid water. A series of experiments were performed on high (314.4 NTU), medium (146.8 NTU) and low (34.2 NTU) turbid water with varying dosage of coagulants. Effect of pH on flocculation efficiency of three coagulants has also been investigated. The result showed that C. indica, Okara gum and Nirmali seeds have significant flocculation properties. Flocculation was very rapid in pH range of 6.5 to 8.0. The performance of Coccinia indica was found to better than other two, with turbidity removal efficiency of 99.3%. The coagulation activity has enhanced with concept of coagulation aid. All three coagulants have performed better for high turbid water. There was minor change in pH of treated water with these plant derived natural coagulants. Quality of sludge produced with natural coagulants was observed to be thick and settles at more rapidly than sludge of conventional coagulants. Keywords: Coccinia indica, okara, nirmali seed, mucilage, coagulation, flocculation, dosage, turbidity 1. INTRODUCTION Water is considered as a national resource of the utmost importance. Water is vital to ensure the population’s well- being and quality of life and to preserve the productivity of the JOURNAL OF CIVIL ENGINEERING AND TECHNOLOGY (JCIET) ISSN 2347 –4203 (Print) ISSN 2347 –4211 (Online) Volume 1, Issue 1, July-December (2013), pp. 26-39 © IAEME: www.iaeme.com/jciet.asp JCIET © IAEME
  2. 2. Journal of Civil Engineering and Technology (JCIET), ISSN 2347 –4203 (Print), ISSN 2347 –4211 (Online) Volume 1, Issue 1, July-December (2013), © IAEME 27 agricultural sector. The increase in water demand for domestic uses, caused by population growth and by the rising standard of living, together with progressive environmental pollution problems have led to over-utilization of renewable drinking water sources and the diminution of water quality. Many countries and, especially large cities facing with a water scarcity problem. In order to meet the increasing water requirements for urban areas and for the adjustment industries, water supply reservoirs have usually been constructed especially for large cities. The quality of river or reservoir water is commonly characterized by the content of suspended solids (SS), colloidal particles, natural organic matter (NOM) and other soluble, mostly inorganic compounds, present in different concentrations. Therefore, when the river or reservoir water is intended for human consumption, an appropriate treatment process is usually considered as necessary to meet the respective drinking water standards. One of the most important steps during the conventional treatment process is coagulation/flocculation, which serves mainly for the removal of SS (including colloidal micro particles) and NOM (Huang C and Pan J, 2002). Nearly all the colloidal impurities in natural waters are negatively charged and, hence, these systems may be stable as a result of mutual electrical repulsions (Duan J and Gregory J, 2003). According to the coagulation and flocculation theory, colloidal destabilization can be achieved by adding cations that interact specifically with the negative colloids and reduce (or neutralize) their charge (Peavey Rowe). Alum is the most widely used coagulant in water treatment because of its proven performance and cost effectiveness. The use of alum as a coagulant in the treatment of water increases the aluminium concentration in treated water (Miller, 1984, Schintu M, 2000 & Gauthier, 2000).A high concentration of aluminium is also of concern because of its adverse effects on health. Aluminium intake into the body has been linked with several neuropath logical diseases including percentile dementia and Alzheimer’s disease (Craper D R, 1973, Pitchai, 1992 and Jadhav, 2011). A polyelectrolyte in concurrence with a metal coagulant improves coagulation by accelerating the process of coagulation. The coagulant aid reduces the necessity of alum and improves the physical characteristics of flocs. Most of the naturally occurring polyelectrolytes are of plant origin and the coagulants are derived from the seeds, leaves, pieces of bark or sap, roots and fruit extracts of trees and plants. Many of the researchers from the world have done their studies on various natural plant derived coagulants and flocculants.(Bhole,1990 & 1995, Megat M.,2002, Diaz A.1999, Yarahmadi M. 2009 , Zhang J. 2006, Mishra A. 2004 & 2005, Konstantinos A. 2009, Babu R. 2005, Patale Varsha 2010).The natural macromolecular compounds derived from cactus species and low cost anionic polysaccharide and the polyelectrolyte derived from Strychnos potatorum are capable of reducing turbidity of water through flocculation process (Singh 2003).Natural coagulants of plant origin have been used for water purification for many centuries. Strychnos potatorum (Nirmali seeds) was used as a clarifier between the 14th and 15th centuries BC. Shultz and Okun together with Sanghi et al., reported that seeds of the Nirmali tree were used to clarify turbid river water about 4000 years ago in India. Studies on the performance of natural coagulants derived from plants such as nirmali seeds, tamarind tree, guar plant, red sorella plant, fenugreek and lentils have been conducted using raw water with turbidity ranged from 50 to 7500 NTU. The optimum dosage for the nirmali extract was 50 mg/l, which produced a 76% reduction in turbidity. The effective dose for the other plant coagulants extracts ranged from 2 mg/ l to 20 mg/l at pH levels from 4 to 9, and proved to be more economical for turbidity values greater than 300 NTU (Shultz and Okun, 1984).
  3. 3. Journal of Civil Engineering and Technology (JCIET), ISSN 2347 –4203 (Print), ISSN 2347 –4211 (Online) Volume 1, Issue 1, July-December (2013), © IAEME 28 Moringa oleifera powder has been reported to have the capability of reducing low and high turbidity values in surface water(Madsen et al., 1987; 1995; Muyibi and Okuofu, 1995, Muyibi and Meget 2002, Muyabi and Abbs 2003, Muyabi & Alfugara 2003, Bhatia 2006 & Chaudari 2009). Moringa oleifera was used as a natural coagulant in a full-scale treatment trial at the water treatment works in Malawi. Turbidity values as high as 270–380 NTU were reduced to around four NTU, which are within the WHO (2006) guideline value with the addition of the powder (Sutherland et al., 1994). Gholamreza Nabi Bidhendi et al., showed that Plantago ovata extract is less efficient in high turbidities when used as a coagulant aid. Plantago ovata, as a coagulant aid, showed positive influence on turbidity removal from water. In addition, optimized pH showed important role in reducing turbidity. Agarwal M. et al. used okra gum for treatment of tannery effluent , they found that okra gum acts as a very effective flocculent, capable of removing more than 95 percent suspended solid and 69 percent dissolved solid from the effluent. Rajani Srinivasan et al., have done research on okra (Hibiscus esculentus) and fenugreek (Trigonella foenum graceum )mucilage for flocculation of textile effluent. Results showed that polysaccharides (mucilage) obtained from okra and fenugreek was capable of removing 90%−94% of suspended solids, 30%−44% of total dissolved solids. Mishra et al. carried out their work on Plantago psyllium mucilage for sewage and tannery effluent treatment. The maximum solid removal (94.69 %) was seen only after 1 h with the suitable pH range. Study by Zhang J. Y. et al. on the performance of cactus as a coagulant in water treatment indicates that the coagulation performance of cactus was very much effective for turbidity removal; residual turbidity of less than 5NTU could be obtained with initial turbidities from 20 to 200 NTU. Natural coagulants have been reported to have several other advantages compared to synthetic coagulants such as alum and ferric chloride, in that, they produce much lower sludge volume and are safe to humans. Ghebremichael (2004) investigated that the sludge produced from Moringa oleifera coagulated turbid water is only 20–30% that of alum. Litherland, Katayon et al., and Sanghi et al., showed that the residue of alum in water may be carcinogenic. Natural coagulants are biodegradable and cost effective for developing countries since they can be locally grown and have a wider effective dosage range for flocculation of various colloidal suspensions (Sanghi et al., 2006). The objective of the present study is to investigate the coagulation-flocculation potential of coagulants derived from plants, such as nirmali seeds, okara mucilage and Coccinia indica mucilage, to remove the turbidity from synthetic turbid water prepared from local clays and to determine the optimal dosages. 2. MATERIALS AND METHODS The materials used in this study are seeds of S. potatorum (Nirmali seeds), Cactus opuntia pads and fruits of Coccinia indica. The seeds of S. potatorum were purchased from an ayurvedic medical shop of Nashik city, the Cactus opuntia pads were collected from a nursery at Bhagur, Nashik and Coccinia indica fruits were purchased from vegetable market Nashik. The preparation of coagulant powders and turbid water is elucidated below. 2.1 Preparation of turbid water Locally available natural clay was used to prepare synthetic turbid water by soaking the clay for 24 hours in tap water and then blending it for 10 min. The suspension was
  4. 4. Journal of Civil Engineering and Technology (JCIET), ISSN 2347 –4203 (Print), ISSN 2347 –4211 (Online) Volume 1, Issue 1, July-December (2013), © IAEME 29 washed through a 75- micron sieve. This was kept as a stock suspension for preparation of different turbidities such as low, medium and high. A portion of the stock suspension was diluted with tap water and after 30min of settling in a container, the supernatant was carefully decanted and desired turbidities of 34.2 NTU (low), 146.8 NTU (medium) and 314.4 NTU (high) were obtained by diluting it (Pramod Kumar Raghuwanshi , 2002). Sedimentation analysis of the suspension was done. Particle size distribution results are as: 73% of particles were finer than 8.6 µm, 26% of particles were finer than 1.4 µm, 19% of particles were finer than 1.25 µm, 13 % of particles were finer than 0.72 µm, and 9% of particles were finer than 0.62 µm. Chemical characteristics of the tap water used to prepare the synthetic turbid water are shown in Table 1. Table 1. Composition of the tap water used to make synthetic turbid water _______________________________________ Parameter Concentration _______________________________________ pH 7.0-7.5 Turbidity 0.2 NTU Alkalinity (as CaCO3) 247 mg/l Total hardness (as CaCO3) 188 mg/l Potassium (K+ ) 5 mg/l Sodium (Na+) 23 mg/l Chlorides (Cl-) 103 mg/l Calcium (Ca++) 34.6 mg/l Sulphates (SO4 --) 8.7 mg/l _______________________________________ 2.2 Preparation of nirmali seed powder Nirmali seeds were powdered and sieved through 150µm sieve, and a 2% suspension was prepared with distilled water. These seeds due to their hard structure, could not be powdered in a grinder. In such a case the seeds were kept immersed in 50 ml water containing 2ml conc. HCl. After a week, the mixture was mashed to a soup-like solution, and was washed through a nylon cloth and the material retained on the cloth was oven dried for 24 hours at 103°C to 105°C and weighed. By calculating the weight of the seeds dissolved, the strength of the stock solution was determined (Bhole 1990, 1995). 2.3 Preparation of Okara mucilage The raw material, seedpods of Okara was bought from local market. It was initially washed thoroughly with water to remove any impurities, dried at 100oC for 6- 8 hours. The okra gum was obtained by aqueous extraction of the seedpods of okra plant followed by precipitation with alcohol. It is a white amorphous polysaccharide consisting largely of d- galactose, l-rhamnose and lgalacturonic acid. The precipitated polysaccharide was then washed with acetone 2 to 3 times to remove impurities and finally dried (Rajani Srinivasan,2008 and Agarwal M.,2001). 2.4 Preparation of Coccinia indica powder Coccinia indica ripped fruits purchased from the market are thoroughly washed with water, cut into small pieces and soaked in distilled water overnight. The mucilaginous extract
  5. 5. Journal of Civil Engineering and Technology (JCIET), ISSN 2347 –4203 (Print), ISSN 2347 –4211 (Online) Volume 1, Issue 1, July-December (2013), © IAEME 30 was filtered through muslin cloth. Alcohol was added to precipitate the extract. The precipitate was then washed with acetone 2-3 times and then dried by keeping in an oven at the temperature of 40°C for 24 hours. The filtered extract was then used in the experiment (Varsha Patale and Parikh Punita., 2010). 2.5 Preparation of alum solution Alum solution was prepared from aluminium sulphate, stock solutions were prepared according to the USEPA procedure for enhanced coagulation (USEPA, 1999), dissolving 10g aluminium sulfate (Al2 (SO4)3.18H2O) in distilled water and the solution was made to one litre. One ml of this stock solution gives concentration of 10 mg/l. 2.6 Experimental work Sedimentation Jar test were carried to determine the coagulation properties of the plant derived coagulants. One beaker was used as control and in other beakers varying dosage of coagulants was added. Jar tests were conducted on 500 ml synthetic turbid water samples. Following the addition of the coagulants dosages (Alum, Nirmali powder, Okara gum, and C. indica.), the samples were subjected to a rapid mixing at 100 rpm for 1 minute, and a slow mixing step at 30 rpm for 30 min., The stirrer was then switched off and the floc allowed to settle undisturbed (ASTM 1995) for 30 minutes. The samples for residual turbidity measurement were withdrawn using a pipette from a height of 5cm below the surface of each beaker, and residual turbidity was measured. Effect of combined dose of natural coagulants and alum on removal of turbidity that is natural coagulants as a coagulant aid also studied. The effect of pH on turbidity removal was also studied by varying pH of turbid water. pH of the suspension was adjusted to the desired value by adding either 0.1 M HCl solution or 0.1M NaOH solution. Turbidity measurement was carried out by Systronics Turbidity meter type 131, Systronics, India. pH value of the suspension was measured using a Elico digital pH meter model 121 . The chemical analyses were conducted as per Standard Methods (APHA 2005). The procedure conformed to that described in Standard Methods for the Examination of Water and Wastewater. 3.0 RESULT AND DISCUSSION 3.1 Determination of optimum dose of alum Results on optimization of alum dosage for low, medium and high turbid water were shown in figure 1. Optimum dose of alum for synthetic turbid waters of low (34.2 NTU), medium (146.4 NTU) and high (314.4NTU) initial turbidity were 20, 20 and 30 mg/l respectively. Above this dosage, the suspensions showed a tendency to restabilise. The lowest dose with maximal efficiency was found to be 30 mg/l in high turbidity. In the study, it was observed that irrespective of initial turbidity, application of 20-40 mg/l of alum leaves a residual turbidity less than 5 NTU (Fig. 1). WHO recommends that if water turbidity is more than 5 NTU, then some treatment to remove turbidity is needed before the water can be efficiently disinfected with chlorine.
  6. 6. Journal of Civil Engineering and Technology (JCIET), ISSN 2347 –4203 (Print), ISSN 2347 –4211 (Online) Volume 1, Issue 1, July-December (2013), © IAEME 31 Fig.1. Plot of Alum dose verses residual turbidity 3.2 Effect of pH on the flocculation of synthetic turbid water To study the effect of pH, tests were conducted on medium turbid water with pH varying from 4.0 to 9.0 in the present study. Dosage of nirmali seed, okara mucilage and C. indica were 2.0 mg/l, 2.0mg/l and 0.4 mg/l respectively. Figure 2 represents the details of results. Based on this figure, it was seen that all the natural coagulants produces appreciable reduction of turbidity only between pH 6.5-7.5. Results of this study are very much comparable to the results of Bina B. et al., and Yang Y. C. et al. Fig. 2. Plot of Effect of pH value on Turbidity Removal. 3.3 Optimum dose of natural coagulants Results of coagulant test using varying dosage of natural coagulant such as N.S. (nirmali seed, okara mucilage and C. indica are presented in figures 3 (a, b, and c). From figure 3a, optimum dose of nirmali coagulant is 1.0, 2.0 and 2.0 mg/l with residual turbidities of 8.5, 27.6 and 27.6 NTU for low, medium and high turbid water. From figure 3b, optimum dose of okara mucilage coagulant is 1.0, 2.0 and 2.0 mg/l with residual turbidities of 7.4, 19.8 and 8.8 NTU for low, medium and high turbid water. Moreover, figure 3c represents, optimum dose of C. indica mucilage is 0.4, 0.4 and 0.6 mg/l with residual turbidities of 5.7, 8.2 and 6.9 NTU for low, medium and high turbid water. It was seen that 0 5 10 15 20 25 30 35 40 0 10 20 30 40 50 60 ResidualTurbidity,NTU Alum Dose,mg/l Low Turbidity Medium Turbidity High Turbidity 0 10 20 30 40 50 60 70 80 3 4 5 6 7 8 9 10 ResidualTurbidity,NTU pH Value Okara mucilage Nirmali Seeds Coccina Indica
  7. 7. Journal of Civil Engineering and Technology (JCIET), ISSN 2347 –4203 (Print), ISSN 2347 –4211 (Online) Volume 1, Issue 1, July-December (2013), © IAEME 32 pH of water after addition of alum dose decreased from 7.2 to 5.6, meaning that chemicals need to be added to raise the pH of water to meet the permissible limit (WHO2006). However with addition of natural coagulants there was minute change in pH of treated water, not necessity of pH correction .This trend is in agreement with the research carried by Ng et al., (2006).. a) b) c) Fig. 3. Performance of a) Nirmali seed b) Okara mucilage and c) C. indica coagulant at varying dosage 0 20 40 60 80 100 120 140 160 180 0 1 2 3 4 5 6 ResidualTurbidity,NTU Dose of N.S .Coagulant , mg/l Low turbidity Medium Turbidity High Turbidity 0 10 20 30 40 50 60 0 2 4 6 ResidualTurbidity,NTU Dose of Okara Mucilage, mg/l Low Turbidity Medium Turbidity High Turbidity 0 5 10 15 20 25 30 35 40 0 0.5 1 1.5 ResidualTurbidity,NTU Dose of C. Indica ,mg/l Low Turbidity Medium Turbidity High Turbidity
  8. 8. Journal of Civil Engineering and Technology (JCIET), ISSN 2347 –4203 (Print), ISSN 2347 –4211 (Online) Volume 1, Issue 1, July-December (2013), © IAEME 33 3.4 Optimization of natural coagulants as coagulant aid in combination with alum In order to decrease residual aluminium concentration in treated water, and possible adverse effects of aluminum in drinking water on human health, Nirmali seeds powder, okara mucilage and C. indica mucilage were used as coagulant aid in conjunction with alum. The performances of above natural coagulants in different turbidities were presented in Figure 4 (a, b and c). a) b) c) Fig. 4. Performance of a) Nirmali b) Okara mucilage and c) C. indica as a coagulant aid with alum 0 10 20 30 40 50 0 0.5 1 1.5 2 2.5 3 ResidualTurbidity,NTU Doses of N.S.+ Alum ,mg/l Low Turbidity Medium Turbidity 5 5 5 5 5 5 0 5 10 15 20 25 30 35 0 0.5 1 1.5 2 2.5 3 ResidualTurbidity,NTU Dose of Okara + Alum , mg/l Low Turbidity Medium Turbidity High Turbidity 5 5 5 5 5 5 0 5 10 15 20 25 30 35 40 0 0.1 0.2 0.3 0.4 0.5 0.6 ResidualTurbidity,NTU Dose of C. indica + Alum , mg/l Low Turbidity Medium Turbidity High Turbidity 5 5 5 5 5 5
  9. 9. Journal of Civil Engineering and Technology (JCIET), ISSN 2347 –4203 (Print), ISSN 2347 –4211 (Online) Volume 1, Issue 1, July-December (2013), © IAEME 34 Initially, the optimum doses of alum were determined for low, medium and high turbid water at pH 7. To study the effect of coagulant aid, one fourth quantities of optimum doses of alum and varying quantities of natural coagulants as a coagulant aid were used to determine the optimum doses of coagulant aids (Mahmut, 2003, Mohammad Hadi Mehdinejad, 2009). It is seen from figure 4a, optimum dose for nirmali seed as a coagulant aid is 1.0 mg/l with residual turbidities of 8.5, 27.6 and 27.6 NTU for low, medium and high turbid water. From figure 4b it has seen that, optimum dose of okara mucilage as a coagulant aid are 1.0, 1.5 and 1.5 mg/l with residual turbidities of 4.5, 8.2 and 6.9 NTU. While from figure 4c, optimum dose of C. indica mucilage are 0.2, 0.3 and 0.3 mg/l with residual turbidities of 4.0, 4.0 and 3.8 NTU for low, medium and high turbid water. 3.5 Performance of selected natural coagulants To remove the turbidity from low turbid water (34.2NTU) prepared from local clay, C. indica produced the best results, with percentage reduction in turbidity of 81.2 %. .Okara mucilage ranked second with percentage reduction of 78.2%. , while Nirmali seed coagulant has removed 75.0% turbidity (fig.3). In terms of acceptable guideline values the World Health Organization (2006) publishes that for drinking water the turbidity should be less than 5 NTU. From Figure 3, it was observed that none of the residual turbidity has attained the guideline value of WHO (5NTU). Hence further study was performed using the concept of coagulant aid. Figure 4 represents the performance of selected natural coagulants as a coagulant aid. With ¼ of optimum dose of alum and nearly ½ of optimum dose of natural coagulants, C. indica has attained percentage reduction in turbidity of 88.4%, okara mucilage achieve reduction of 86.8% and nirmali seed coagulant removed 84.2% turbidity from low turbid water. For medium turbid water (146.8 NTU), C. indica produced reduction of 90.0%, okara mucilage achieves 86.5% reduction, while, nirmali seed coagulant removed 81.2% turbidity. Experiments with technique of coagulant aid improved the results, with increase in percentage removal from 90 to 97.3% for C. indica, 86.5 to 94.4% for okara and 81.2 to 92.8% for nirmali coagulant. Residual turbidities were 10.5, 8.2 and 4.0 NTU, only C. indica give residual turbidity within permissible limit. Therefore, further study is necessary by passing the turbid water through slow sand/rapid sand filter to achieve residual turbidity well within safe guideline. For high turbid water 314.4 NTU turbidity, C. indica produced percentage reduction of 92.8% , okara mucilage has achieved 90.2% reduction, while, nirmali seed coagulant removed 88.2% turbidity. Coagulant aid technique improved removal efficiency better for C. indica and okara mucilage. C. indica produced reduction of 99.3%, okara mucilage has attained reduction of 98.7%, while, nirmali seed coagulant removed 96.7% turbidity. Residual turbidities for C. indica and okara are well within permissible limit of WHO. Investigation on use of mallom mucilage and okara for treatment of synthetic wastewater and effluent was carried by Konstantinos et al. (2009). With dosage of 12-26 mg/l of mallon, there was 96.3- 97.7 % reduction in turbidity for synthetic waste water and 61-66 % reduction in turbidity for effluent. For okara with optimum dose of 5mg/l there was 93.0 - 97.3 % reduction in turbidity for synthetic wastewater and 70- 72 % reduction in turbidity for effluent. These results are very much comparable with the results of this study.
  10. 10. Journal of Civil Engineering and Technology (JCIET), ISSN 2347 –4203 (Print), ISSN 2347 –4211 (Online) Volume 1, Issue 1, July-December (2013), © IAEME 35 To purify water relatively of high initial turbidity (Kumponda, shallow well water in Malawi), Pritchard M. et al., (2005) utilized guar gum, J. Curcas and M. oleifera for purification. With dose of 250 mg/l of M.O. there was 96% reduction in turbidity the optimum dose of gaur Gum was 50mg/l, which reduces 95% turbidity and J. Curcas reduces 92% turbidity with optimum dose of 50mg/l, higher decline efficiency for high turbid water. Same trend of result for this study as well. Research on nirmali seed powder in coagulation-flocculation of turbid synthetic water prepared from Kaolin with varying coagulant dose and pH on removal of turbidity was investigated by Babu R. et al., (2005). For optimum dose of 1.5 mg/l of nirmali seed coagulant there was 90% reduction in turbidity. pH of treated water was unaffected by addition of coagulant dose .Results of research furnished in this paper, on natural coagulants nirmali seeds, okara and coccinia indica are in agreement with the results of other researchers. One of the important parameters that have been considered to determine the optimum condition for the performance of natural coagulants in coagulation and flocculation is dosage. Several researchers were reported that during the initial stages with the increase in the dosage, the percentage turbidity removal increases, but after the optimal dose, there is a decrease in the removal efficiency (figure 3). The behavior could be explained by the fact that the optimal dosage of flocculent in suspension causes larger amount of solids to aggregate and settle. However further increase in the dosage of coagulant would cause the aggregated particle to redisperse in the suspension and would also disturb particle settling. Table 2 compares the results obtained in this study to those obtained in other studies where natural or chemical coagulants were used. Compared to other coagulants C. indica has performed better. The results obtained by this study exhibited that natural coagulant of plant origin can be effectively utilized in water and wastewater treatment. However, many of the studies reported, in literature carried under controlled laboratory scale models and conditions. Table 2: Comparison of coagulation efficiency of selected coagulant and chemical in a variety of water ______________________________________________________________________________ Reference Type of water or w/w Type of Coagulant Optimum dose mg/l % reduction in Turbidity _________________________________________________________________________________________ This work Synthetic turbid Nirmali seed 2.0 75.0 - 88.2 water with local clay Okara mucilage 1, 2, 3 for L, M, H 78.2 - 90.2 C. Indica 0.4 81.2 - 92.8 N.S. + alum 1+5 84.2 - 96.7 Okara+ alum 1.5 + 5 86.8 - 98.7 C. Indica + alum 0.2 + 5 88.4 - 99.3 [05] Kaolin turbid water Nirmali seed 1.5 90.0 [38] Natural clay Nirmali seed 3+ 20 alum 99.0 [46] Kaolin turbid water C. Indica 0.4 94.0 [20] w/w & synthetic Okara 5 93- 97.3 [50] Estuarine & river water Cactus op. 13 49.2-98.2 [35] Surface water MO+ Alum (60+41) % 98.99 ______________________________________________________________________________
  11. 11. Journal of Civil Engineering and Technology (JCIET), ISSN 2347 –4203 (Print), ISSN 2347 –4211 (Online) Volume 1, Issue 1, July-December (2013), © IAEME 36 4. CONCLUSIONS From a plant extract record and laboratory analysis, natural coagulants derived from plants such as, nirmali seed, okara and Coccinia indica have been identified to be suitable for treating turbid water either as a sole coagulant or in combination with alum as a coagulant aid. A large reduction in turbidity is achieved at optimal dosage conditions. All the three coagulants have performed better for high turbid water. With addition of natural coagulants dosage, there has been found minor change in pH of treated water but not necessity of pH correction. Quality of sludge with natural coagulants observed to be thick and settles at more rapidly than sludge with conventional coagulants. WHO and IS1500 guideline value for residual turbidity has achieved with a plant extract dose as a coagulant aid. With reducing optimum dose of alum to 1/4 and optimum dose of natural coagulant to 1/2, there is rise of 10 to 15 % in turbidity removal efficiency for all the three natural coagulants for turbidity levels of low, medium and high. REFERENCES 1. Agarwal M., Srinivasan R., Mishra A., (2001) ‘Study on flocculation efficiency of okra gum in sewage wastewater’, Macromol. Mater. Eng. 286: 560–563. 2. Agarwal M., Rajani S., Mishra A., Rai J.S.P., (2003) ‘Utilization of Okra gum for treatment of tannery effluent’, Int. J. Polym. Mater. 52: 1049–1057. 3. APHA, AWWA and WPCF (2005)’Standard Methods for the Examination of Water and Wastewater. 21st edn. American Public Health Association, Washington DC. 4. ASTM (1995)’Standard Practice for Coagulation-Flocculation Jar Test of Water, E1- 1994 R. D 2035- 80. Annual book of ASTM Standard 11.02 5. Babu R chaudhuri M , (2005)’Home water treatment by direct filtration with natural coagulants’ J. water health, 3:27-30. 6. Bhatia S., Othman Z., and Ahmad A. L., (2006) ‘Palm oil mill effluent pretreatment using Moringa Oleifera seeds as an environmentally friendly coagulant: laboratory and pilot plant studies’, J. Chem. Technol. Biotechnology. 81: 1852–1858. 7. Bina B, Mehdinejad M. H., Nikaeen M. and Mova-hedian H. A, (2009) ‘Effectiveness of Chitosan as Natural Coagulant Aid in Treating Turbid Waters,’ Iranian Journal of Environmental Health Science & Engineering, 6(4): 247-252. 8. Bhole A.G., (1990) ‘Performance studies of a few natural coagulants,’ J. Indian Water Works Assoc., 81-84. 9. Bhole AG, (1995) ‘Relative evaluation of a few natural coagulants,’ J. Water Supply Res. Technology -Aqua, 44: 184-190. 10. Chaudhuri, M. and Khairuldin, P. S., (2009) ‘Coagulation- Clarification of Coloured Water by Natural Coagulant (Moringa Oleifera) Seed Extract,’ Nature Environment and Pollution Technology,8(1): 137- 139. 11. Crapper D R, Krishnan S S, Dalton A J., (1973) ‘Brain aluminium in Alzheimer’s disease experiment at neurofibrillary degeneration,’ Science, 180:511-573.
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