Title of Invention	A NOVEL CATALYST USEFUL FOR THE REMOVAL OF PATHOGENS FROM WASTEWATER
Abstract	The present invention relates a novel catalyst useful for the removal of enteric and other pathogens from wastewater. The process relates to the treatment of enteric and other pathogen contaminated water with metal ion impregnated activated carbon, whereby the enteric and pathogenic species are completely destroyed during the treatment resulting in no reoccurrence or regrowth of the organism. The process also ensures that no metal is leached out in the treated water. Thus the purified water can be reused.

Title of Invention

A NOVEL CATALYST USEFUL FOR THE REMOVAL OF PATHOGENS FROM WASTEWATER

Abstract

The present invention relates a novel catalyst useful for the removal of enteric and other pathogens from wastewater. The process relates to the treatment of enteric and other pathogen contaminated water with metal ion impregnated activated carbon, whereby the enteric and pathogenic species are completely destroyed during the treatment resulting in no reoccurrence or regrowth of the organism. The process also ensures that no metal is leached out in the treated water. Thus the purified water can be reused.

Full Text	Field of invention The present invention relates a novel catalyst useful for the removal of pathogens from wastewater. More particularly, the present invention provides a process for the removal of enteric pathogens, namely Escherichia coli, Shigella species, Salmonella species from domestic, public and industrial waste water by metal ion impregnated activated carbon, to ensure that the water, purified thereby can be reused. This process has enormous potential applications for supplementing the inventory towards recreational water, bath water, industrial cooling water, industrial processing water and agricultural water by sewage duly freed from enteric pathogens namely Escherichia coli, Shigella species, Salmonella species, thereby ensuring reuse of water leading to substantial reduction in fresh water requirement. Background of the Invention The enormous amount of water released by domestic, public or industrial sources pose a major environmental concern because of the presence of enteric pathogenic species namely Escherichia coli, Shigella species, Salmonella species, etc. Domestic sewage is mainly composed of soluble and insoluble human excreta and household wastes. When the sewage water mixes with industrial wastewaters (effluents), the treatment of the resulting water is difficult due to the presence of chemical as well biological pollutants in the form of pathogenic organisms. The conventional sewage disposal system has been to discharge the wastewater into river or sea. Occasionally, the sewage stream is let into land for agricultural purposes. •However, this method of discharging leads to promotion of water borne infectious diseases. Sack (Annual Review of Microbiology 29:333-353, 1975) and Smkith (Journal of Pathology & Bacteriology 93:499-529, 1967) studied the infections due to Escherichia coli. Gyles, et al. (Journal of Infectious Disease, 130: 212-218, 1974), Skerman et al (Infection and Immunology, 5: 622-624, 1972), Harris et al (Infection and Immunology. 37: 1295-1298. 1982) and Wells et al. (Journal of Clinical Microbiology 18:512-520.1983) reported that the plasmids of the Escherichia coli strains contain the traits for causing enterotoxigenic, enteroinvasive, enterohemorrohagic and enteropathogenic diseases. Generally, diarrheal out breaks and infant death in underdeveloped countries are mainly due to enterotoxigenic effect of Escherichia coli. The increasing concern of water borne diseases has promoted the implementation of more stringent standards on microbiological pollution of wastewater discharge, for public and environment safety. The persistence of the pathogens in ground water has been detected in zones of discharging treated/untreated wastewater. With regard to the removal of pathogens, the widely accepted methods are chlorination, UV (Ultraviolet) exposure and ozonation. The chlorination process employs chlorine dioxide, hypochlorite or bleaching powder. These compounds inhibit the growth of the pathogenic species exhibiting reduction in population upon immediate exposure. However, certain coliforms especially Escherichia coli develop resistance during chlorination thereby decreasing the desired effects of disinfection as evidenced by Murray et al (Applied and Environmental Microbiology, 48(1), 73-77, 1984). In addition to the development of resistance by the pathogenic species towards these compounds, the release of products such as trihalomethane, haloacetic acids and other dissolved organic halogen compounds having toxic nature was observed by Urano et al. (Water Research 17: 1797-1802,1983). With regard to UV irradiation, the disinfection effect is due to its high absorption by the bacterial DNA at 254 nm resulting in the formation of pyrimidine dimers, which inhibits the reproduction function of bacteria. However, if the bacterial load is too high, UV source does not become lethal tathe bacterial cells leading to reduced efficiency in comparison to the destruction of bacteria, as reported by Acher et al. (Water Research 31:1398-1404,1997). Another chemical disinfection method for the removal of pathogens in domestic/industrial wastewater is ozonation. The biocidal activity of ozone is due to its high oxidation potential and its ability to diffuse through biological membrane. However, studies have not been completed to probe into the species of ozone responsible for the inactivation of microorganisms, as reported by Hunt and Benito (Water Research 31: 1355-1362, 1997). Similar to other disinfectants, the quality of the treated wastewater is highly influenced by the efficiency of ozonation and it has been observed that disinfection using ozone is not cost effective. Moreover the use of ozone leads to occupational health hazard because of the release of enzymes and amino acids as a result of cell death, which alters the purity of the treated water thereby limiting the scope for its reuse. The other possible method adopted for the removal or destruction of pathogens is membrane filtration. The tests performed by membranes on different effluents showed complete removal of coliforms and other enteric pathogens from tertiary effluents. However, the removal performances highly depend on the membrane fouling status and changes of membrane cleaning periodicity etc as indicated by Langlais et al (Water Science and Technology, 25(12), 135-143,1993). The major limitation of all the aforesaid methods is that these methods remove pathogens to a maximum level of 60% Another limitation associated with these methods is that they are inefficient in restricting the reoccurrence or regrowth of the organisms in the treated water These have prompted the researchers to explore biological methods, including clarification, filtration, secondary settling, addition of flocculating agents, anaerobic digestion, activated sludge process etc for purifying pathogen contaminated wastewater Though about 90% of the microbial population decreases with the said treatment methods yet their presence at detectable levels pose health threat [Joan Rose et al (Water Science and Technology 30 (11), 2785- 2797,1996)] Attempts have also been made to explore possibilities of combining chemical and biological treatment systems Dutton et al (Applied Environmental Microbiology 46(6), 1263-7, 1983) employed biological treatment followed by chlonnation, where coliforms including Escherichia coli were again observed in the treated effluents Attempts have further been made to use heavy metal catalysts for the disinfection of pathogens Matthew et al (Applied and Environmenal Microbiolgy, 48, 289 - 293, 1984) reported the removal of Escherichia coli in drinking water by dissolving salts of copper in the contaminated water The threshold concentration of copper for the removal of Escherichia coli was in the range 0 007 to 0 54 mg/l References may also be made to Nobuo Hoshino et al (Free Radical Biology & Medicine, 2-7, 1245 - 1250, 1999) who used combinations of epigallo catechin (EGC) and epicatechin (EC) with Cu(ll) as bactericides against Escherichia coli Similarly, destruction of Escherichia coli have also been possible by the complexes such as carbono and thiocarbonohydrazone ligands with Cu(ll), Fe(ll) and Zn(ll) as reported by Alessia Bacchi et al (Journal of Inorganic Biochemistry, 75, 123 - 133, 1999) The major limitation associated with the use of the metal-based system for removal of pathogens is that the leached metal in the treated water poses health hazard This has prompted the researchers to explore methods for the viable treatment of pathogens using metal impregnated systems Sekaran et al (WAPDEC, International Conference on Water and Wastewater Perspectives of Developing Countries, December 11-13, 2002, New Delhi) studied the use of activated carbon for the removal of both chemical as well as biological pollutants and reported that the removal of pathogens by the activated carbon is merely due to the adsorption of bacterial species by the lipopolysachandes in their cell wall It has further been inferred that upon continuous exposure to the contaminated water, the adsorption efficiency of the activated carbon decreases due to the saturation at the surface of the activated carbon. This leads to the reoccurrence or regrowth of the organisms in the wastewater after treatment with activated carbon. Antibacterial activated carbon fiber with mesopores was attempted by Oya et al. (Carbon 34, 53 - 57, 1996) using phenolic resin containing cobalt as an activation catalyst and silver as an antibacterial agent against Escherichia coli and Staphylococcus aureus. In this process the silver content of the activated carbon fiber has been found to be reduced from 0.22 wt% to 0.0006 wt% upon treatment. Thus the major limitation associated with this process is that the metallic component of silver and cobalt gradually decreases in the activated carbon, thereby reducing the efficiency of the process gradually. t In addition to metals, metal oxides have also been found to play an important role in the removal of pathogenic species. Osamu Yamamoto et al, (Carbon 39,1643 - 1651, 2001) have reported inhibition of Escherichia coli on carbon materials containing zinc oxides at extremely acidic and alkaline condition. However, the reoccurrence and regrowth of the organism in the treated water limit the usage of the metal oxides for the removal of pathogens. Owing to the partial effect on removal of pollutants by activated carbon and metal oxides in free state, impregnation of metals onto activated carbon came to the lime light of research due to its immense use in various physical, chemical and environmental applications. Our co-pending Indian patent application (320 DEL 2004) provides a process for the synthesis of transition metal complexes impregnated activated carbon. The preparation of materials involves the use of metal complexes in the form of acetyl acetonates, pyridine, picoline, hexaflouroacetyl acetone, oxime of Cu, Co, Ni, and in situ impregnation of the same on activated carbon having surface area in the range of 392- 430 m2/g; Average pore diameter 35.28 - 37.20A0; Bulk density 0.56 - 0.62 g/cc and a composition of Carbon 37.96 - 39.36 %; Hydrogen 2.46 - 3.41%; Nitrogen 0.50 - 0.71% followed by curing at optimized temperatures. Hisashi Tamani et al. (Carbon 39, 1963 - 1969, 2001) studied the removal of pathogenic species using acetylacetonate complexes of nickel, cobalt, aluminum, impregnated in activated carbon. The process of impregnation of metal complexes involves mere adsorption of the metal on the surface of the activated carbon, resulting in a very weak binding between the metal complex and the activated carbon surface. Hence, the resulting material removes pathogens only at the initial stage of the treatment and on further exposure, leaching of metal complexes in the treated water occurs, which leads to the reoccurrence and regrowth of the organism in the treated water. In view of the foregoing, the hitherto known processes for the removal of pathogens are essentially associated with the following limitations: 1. Metal complexes are impregnated only in the complex form and not in the form of free metal ions 2. Only temporary inhibition to the growth of the organism occurs 3. Reoccurrence and regrowth of the organism take place after treatment 4. Addition of metal salts act as stimulant, which further increases the growth of the organism. 5. Mere surface adsorption of the pathogenic species on to activated carbon leads to reoccurrence of the pathogenic species in the treated water 6. No complete destruction or lysis of the organism takes place. 7. Requires treatment period of more than 24 hours 8. Leaching of metals takes place in the treated water, thereby rendering the water unusable. No prior art is available on the use of impregnated metal ions in the activated carbon for complete destruction of potent pathogenic species including Escherichia coli, Shigella species, Salmonella species, etc from contaminated water without leaching of metals in the treated water. Objects of the Invention The main objective of the present invention is therefore, to provide a process for the purification of enteric pathogen contaminated water for reusable options, which obviates the limitations as stated above. Another objective of the present invention is to use transition metal ions impregnated activated carbon for the treatment of wastewater. Yet another objective of the present invention is to use activated carbon having the following characteristics surface area of 392 - 430 m2/g; Average pore diameter of 35.28 - 37.20 °A; Bulk density 0.56 - 0.62 g/cc Composition : Carbon 37.96 - 39.36%; Hydrogen 2.46 - 3.41 %; Nitrogen 0.50 - 0.71%. Still another objective of the present invention is to impregnate the metal ions as metal complexes on activated carbon. Another objective of the present invention is to ensure that no metal is leached out in the treated water. Yet another objective of the present invention is to remove the pathogenic species such as Escherichia coli, Shigella species, Salmonella species to the extent of more than 99%. Still another objective of the present invention is to completely destruct or lyse the organisms present in the wastewater. It is still another objective of the present invention is to provide a process that removes pathogens from the pathogen contaminated water in less than 300 seconds. Accordingly, the present invention provides a novel catalyst useful for the removal of enteric pathogens from wastewater comprising of activated carbon characterized in that it is impregnated with a transition metal ion based compound. The invention further provides a process for the purification of pathogens particularly enteric pathogens contaminated water, which comprises: [a] adjusting the pH of the said water in the range of 2-10; [b] treating the water of step [a] with 0.1 - 20% (w/v) of the catalyst as claimed in claim 1, for a period in the range of 10-300 seconds [c] separating the treated water of step [b] employing conventional techniques to obtain water free from enteric and other pathogenic organisms. In an embodiment of the present invention the enteric pathogens are such as but not restricted to Escherichia coli, Shigella dysenteriae, Shigella flexneri, Shigella boydii, Shigella sonnei, Salmonella typhi, Salmonella enteritidis Klebsiella pneumoniae, Enterobacter aerogenes, enterobacter agg/omerans, serraf/a marcescens, Serratia liquefaciens, Proteus vulgaris, Proteus mirabilis and Yersinia enterocolitica obtained from sources such as but not -limited to domestic, public or industrial discharges, adjusted to a pH in the range of 2-10, with 0.1- 20% (w/v) of transition metal ion based compound impregnated activated carbon, the activated carb'on having characteristics as herein described, for a period in the range of 30-300 seconds followed by separating the treated water to obtain water free from enteric pathogenic and other pathogenic organisms for reusable options. In an embodiment of the present invention, the transition metal ion based compound may be selected from copper acetyl acetonate, cobalt acetyl acetonate, nickel acetyl acetonate, copper hexafluro acetyl acetonates, cobalt hexa fluro acetyl acetonates, nickel hexa fluro acetyl acetonates. In another embodiment of the present invention, the process of separation of treated water may be such as decantation, filtration, centrifugation. Detailed description of the Invention Water contaminated with enteric pathogens is adjusted to a pH in the range of 5-10 by known method and is then treated with 10-20 % (w/v) of transition metal ion based compound impregnated activated carbon, whereby the activated carbon exhibits the following characteristics surface area of 392 - 430 m2/g; Average pore diameter of 35.28 - 37.20 °A; Bulk density 0. 56 - 0.62 g/cc Composition : Carbon 37.96 - 39.36%; Hydrogen 2.46 - 3.41 %; Nitrogen 0.50 - 0.71%. The relative percentage of the metal impregnated in the matrix is in the range 0.150 - 2.5% "w/w, to that of the total carbon matrix. After a period of 30-300 seconds, the resulting water is subjected to separation by known methods to obtain water free from pathogen for reusable options. The treated water is highly stable and no regrowth of organism has been observed up to a period of 10 days. However, no regrowth of organism is envisaged to be observed even in the distant future. The impact of metal impregnated activated carbon on enteric bacterial mortality was studied. The treated wastewater collected from the metal impregnated reactor was subjected to detail analysis for the lysis of the E.coli and the analysis was carried at different time intervals up to 10 days. The study showed starting from the first day upto the tenth day there was no regrowth or reactivation of E.coli. This was well evidenced from the Transmission Electron Microscope image (TEM). The image well depicted that the E.coli cell wall was totally ruptured and confirmed that there cannot be reactivation of E.coli further more. The SDS-PAGE studies also revealed the damage of outer membrane proteins (OMP) in E.coli on all of our studies with treatment in Cu impregnated activated carbon reactor. Isovaleric acid was used for extraction of OMP from E.coli. The apparent molecular mass in control E.coli determined by SDS-PAGE mobility was 38 and 36 Kilo Daltons. The OMP of E.coli tested after treating with metal impregnated activated carbon showed complete loss of 38 Kilo Dalton. This proves that the strong hydrogen bonding, electrostatic, and hydrophobic interactions of OMP .are disrupted by metal impregnated activated carbon causing non-recoverable damage in E.coli. The shelf life/stability of the metal impregnated activated carbon was evaluated after storing it at 28 - 35 °C for 90 days. It was observed from the study that the amount of metals impregnated on the carbon matrix was the same and possessed same activity during the period of 90 days. There were no altered features observed on the matrix. Regarding the stability of the material, no transformation or modification on the structure was observed. Even after several runs, the material used for treating the E.coli containing wastewater inherited good stability at all the operating conditions. Comparing the metal impregnated activated carbon developed, Cu/C possessed a good stability for more than 100 cycles than the other materials Ni/C and Co/C less than 100 cycles. As the material Cu/C inherited appreciable stability Cu/C was reused for rrtore than 100 cycles than the other metal impregnated carbons. The results also suggest that that the Cu/C can be reused for many number of treatment cycles for Ecoli. the inventive step in the present invention lies in the treatment of pathogen contaminated water with metal ion complex impregnated activated carbon, which completely destroys the pathogenic species both by inhibiting the growth as well as restricting the DNA synthesis. When the pathogenic organisms are exposed to the metal ion impregnated activated carbon, the interaction between the metal ion and the sulfhydryl groups of bacterial cellular membrane reduces the metal ion to monovalent oxidation state, which subsequently gets bound with DNA synthesis resulting in complete lysis of organisms. The following examples are given by way of illustrations only and therefore should not be construed to limit the scope of the present invention. Example 1 1.2 g of copper acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 10°C. To this solution 18 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the copper acetylacetonate solution and was dried in an oven at 150°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Escherichia coli, Shigella dysenteriae and Salmonella typhi species of the collected water was measured and was found to be 10 x 108, 5 x 107 and 6 x 107 CFU/ml respectively. pH of the water was found to be 2.0 One gm of 0.5 % copper acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration. Salmonella and Shigella which were found to be nil while E.coli papulation was found to be 1 x 101 in the filtered water. The copper concentration in the treated water was estimated to be nil. Example 2 1.47 g of copper hexafluoro acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 12°C. To this solution 20g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the copper hexafluoro acetylacetonate solution and was dried in an oven at 130°C for 12 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a •glass beaker. Pathogenic bacterial population including Escherichia coli, Shigella flexneri and Salmonella enteritidis of the collected water was measured and was found to be 10 x 108, 3 x 106 and 5 x 107 CFU/ml respectively. pH of the water was found to be 2.0 One gm of 1.0 % copper hexafluoro acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Salmonella and Shigella, which were found to be nil while Escherichia population was found to be 1 x 101 in the filtered water. The copper concentration in the treated water was estimated to be nil. Example 3 1.6 g of copper acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 15°C. To this solution 25g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the copper acetylacetonate solution and was dried in an oven at 140°C for 15 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Shigella dysenteriae Shigella flexneri and Shigella boydii of the collected water was measured and was found to be 5 x 107, 3 x 106 and 3 x 106 CFU/ml respectively. pH of the water was found to be 2.0 One gm of 1.5 % copper acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration all Shigella species were found to be nil. The copper concentration in the treated water was estimated to be nil. Example 4 1.6 g of copper acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at t-0°C. To this solution 30 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the copper acetylacetonate solution and was dried in an oven at 150°C for 15 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Shigella sonnei, Salmonella typhi and Salmonella enteritidis species of the collected water was measured and was found to be 4 x 106, 6 x 107 and 5 x 107 CFU/ml respectively. pH of the water was found to be 2.0 Three grams of 1.5 % copper acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration. Salmonella and Shigella species were found to be nil. The copper concentration in the treated water was estimated to be nil. Example 5 1.8 g of copper hexafluoro acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 20°C. To this solution 32 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the copper hexafluoro acetylacetonate solution and was dried in an oven at 120°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Klebsiella pneumoniae, Enterobacter aerbgenes and Enterobacter agglomerans of the collected water was measured and was found to be 5 x 105, 4 x 105 and 3 x 104 CFU/ml respectively. pH of the water was found to be 2.0 Five grams of 1.5 % copper hexafluoro acetylacetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Klebsiella and Enterobacter species were found to be nil. The copper concentration in the treated water was estimated to be nil. Example 6 1.8 g of copper acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 10°C. To this solution 32 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the copper acetylacetonate solution and was dried in an oven at 150°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Serratia marcescens, Enterobacter aerogenes and Enterobacter agglomerans of the collected water was measured and was found to be 5 x 105, 4 x 105 and 3 x 104 CFU/ml respectively. pH of the water was found to be 5.0 Four grams of 1.5 % copper acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Serratia and Enterobacter species were found to be nil. The copper concentration in the treated water was estimated to be nil. Example 7 1.4 g of copper acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 20°C. To this solution 28g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the copper acetylacetonate solution and was dried in an oven at 120°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Serratia marcescens, Serratia liquefaciens and Proteus vulgaris of the collected water was measured and was found to be 4 x 104, 2 x 103 and 5 x 106 CFU/ml respectively. pH of the water was found to be 7.0 One gm of 1.5 % copper acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Serratia and Proteus species were found to be nil. The copper concentration in the treated water was estimated to be nil. Example 8 1.6g of copper hexafluoro acetylacetonate was dissolved in 4500 mi of acetone by continuous stirring at 10°C. To this solution 30 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the copper hexafluoro acetylacetonate solution and was dried in an oven at 140°C for 15 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Yersinia enterocolitica, Proteus mirabilis and Proteus vulgaris of the collected water was measured and was found to be 2 x 103, 6 x 106 and 5 x 106 CFU/ml respectively. pH of the water was found to be 12.0 One gm of 1.5 % copper hexafluoro acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Serratia and Proteus species were found to be nil. The copper concentration in the treated water was estimated to be nil Example 9 1.2 g of nickel acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 10°C. To this solution 18 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the nickel acetylacetonate solution and was dried in an oven at 150°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Escherichia coli, Shigella dysenteriae and Salmonella typhi species of the collected water was measured and was found to be 10 x 108, 5 x 107 and 6 x 107 CFU/ml respectively. pH of the water was found to be 2.0. 1g of 1.5 % nickel impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration. Salmonella and Shigella which were found to be nil while E.coli population was found to be 1 x 101 in the filtered water. The nickel concentration in the treated water was estimated to be nil. Example 10 1.47 g of nickel hexafluoro acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 12°C. To this solution 20g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the nickel hexafluoro acetylacetonate solution and was dried in an oven at 130°C for 12 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Escherichia coli, Shigella flexneri and Salmonella enteritidis of the collected water was measured and was found to be 10 x 108. 3 x 106 and 5 x 107 CFU/ml respectively. pH of the water was found to be 2.0 Two gram of 2.0 % nickel hexafluoro acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Salmonella and Shigella, which were found to be nil while Escherichia population was found to be 1 x 101 in the filtered water. The nickel concentration in the treated water was estimated to be nil. Example 11 1.6 g of nickel acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 15°C. To this solution 25g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the nickel acetylacetonate solution and was dried in an oven at 140°C for 15 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Shigella dysenteriae, Shigella flexneri and Shigella boydii of the collected water was measured and was found to be 5 x 107, 3 x 106 and 3 x 106 CFU/ml respectively. pH of the water was found to be 2.0 One gm of 2.46 % nickel acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration all Shigella species were found to be nil. The nickel concentration in the treated water was estimated to be nil. Example 12 1.6 g of nickel hexafluoro acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 10°C. To this solution 30 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the nickel hexafluoro acetylacetonate solution and was dried in an oven at 150°C for 15 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Shigella sonnei, Salmonella typhi and Salmonella enteritidis species of the collected water was measured and was found to be 4 x 106, 6 x 107 and 5 x 107 CFU/ml respectively. pH of the water was found to be 2.0 Five grams of 2.46 % nickel hexafluoro acetyl acetonate impregnated activated carbon was added to the beaker. After 30 sec the water was separated by filtration. Salmonella and Shigella species were found to be nil. The nickel concentration in the treated water was estimated to be nil. Example 13 1.8 g of nickel acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 20CC. To this solution 32 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the nickel acetylacetonate solution and was dried in an oven at 120°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Klebsiella pneumoniae, Enterobacter aerogenes and Enterobacter agglomerans of the collected water was measured and was found to be 5 x 105, 4 x 105 and 3 x 104 CFU/ml respectively. pH of the water was found to be 2.0 One gm of 2.46 % nickel acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Klebsiella and Enterobacter species were found to be nil. The copper concentration in the treated water was estimated to be nil. Example 14 1.8 g of nickel acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at .104C. To this solution 32 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the nickel acetylacetonate solution and was dried in an oven at 150°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Serratia marcescens, Enterobacter aerogenes and Enterobacter agglomerans of the collected water was measured and was found to be 5 x 10°, 4 x 105 and 3 x 104 CFU/ml respectively. pH of the water was found to be 5.0 Five grams of 2.46 % nickel acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Serratia and Enterobacter species were found to be nil. The nickel concentration in the treated water was estimated to be nil. Example 15 1.4 g of nickel hexafluoro acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 20°C. To this solution 28g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the nickel hexafluoro acetylacetonate solution and was dried in an oven at 120°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Serratia marcescens, Serratia liquefaciens and Proteus vulgaris of the collected water was measured and was found to be 4 x 10\ 2 x 103 and 5 x 106 CFU/ml respectively. pH of the water was found to be 7.0 One gm of 2.46 % nickel hexafluoro acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Serratia and Proteus species were found to be nil. The nickel concentration in the treated water was estimated to be nil. . Example 16 1.6 g of nickel acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 10°C. To this solution 30 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the nickel acetylacetonate solution and was dried in an oven at 140°C for 15 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Yersinia enterocolitica, Proteus mirabilis and Proteus vulgaris of the collected water was measured and was found to be 2 x 103, 6 x 106 and 5 x 106 CFU/ml respectively. pH of the water was found to be 12.0 One gm of 2.46 % nickel acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Serratia and Proteus species were found to be nil. The nickel concentration in the treated water was estimated to be nil Example 17 1.2. g of cobalt acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 10°C. To this solution 18 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the cobalt acetylacetonate solution and was dried in an oven at 150°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Escherichia coli, Shigella dysenteriae and Salmonella typhi species of the collected water was measured and was found to be 10 x 108, 5 x 107 and 6 x 107 CFU/ml respectively. pH of the water was found to be 2.0 One gm of 0.1 % cobalt acetyl .acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration. Salmonella and Shigella which were found to be nil while E.coli population was found to be 1 x 101 in the filtered water. The cobalt concentration in the treated water was estimated to be nil. Example 18 1.47 g of cobalt hexafluoro acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 12°C. To this solution 20g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the cobalt hexafluoro acetylacetonate solution and was dried in an oven at 130°C for 12 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Escherichia coli, Shigella flexneri and .Salmonella enteritidis of the collected water was measured and was found to be 10 x 108, 3 x 106 and 5 x 107 CFU/ml respectively. pH of the water was found to be 2.0 Three grams of 1.0 % copper hexafluoro acetylacetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Salmonella and Shigella, which were found to be nil while Escherichia population was found to be 1 x 101 in the filtered water. The nickel concentration in the treated water was estimated to be nil. Example 19 1.6 g of cobalt acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 15°C. To this solution 25g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the cobalt acetylacetonate solution and was dried in an oven at 140°C for 15 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Shigella dysenteriae Shigella flexneh and Shigella boydii of the collected water was measured and was found to be 5 x 107, 3 x 106 and 3 x 104 CFU/ml respectively. pH of the water was found to be 2.0 One gm of 0.19 % cobalt acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration all Shigella species were found to be nil. The cobalt concentration in the treated water was estimated to be nil. Example 20 1.6 g of cobalt hexafluoro acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 10°C. To this solution 30 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the cobalt hexafluoro acetylacetonate solution and was dried in an oven at 150°C for 15 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Shigella sonnei, Salmonella typhi and Salmonella enteritidis species of the collected water was measured and was found to be 4 x 106, 6 x 107 and 5 x 107 CFU/ml respectively. pH of the water was found to be 2.0. Five grams of 0.19 % cobalt hexafluoro acetyl acetonate impregnated activated carbon was added to the beaker. After 30 sec the water was separated by filtration. Salmonella and Shigella species were found to be nil. The cobalt concentration in the treated water was estimated to be nil. Example 21 1.8 g of cobalt acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 20°C. To this solution 32 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the cobalt acetylacetonate solution and was dried in an oven at 120°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Klebsiella pneumoniae, Enterobacter aerogenes and Enterobacter agglomerans of the collected water was measured and was found to be 5 x 10;. 4 x 105 and 3 x 104 CFU/ml respectively. pH of the water was found to be 2.0 One gm of 0.19 % cobalt acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Klebsiella and Enterobacter species were found to be nil. The cobalt concentration in the treated water was estimated to be nil. Example 22 1.8 g of cobalt acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 10°C. To this solution 32 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the cobalt acetylacetonate solution and was dried in an oven at 150°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Serratia marcescens, Enterobacter aerogenes and 'Enterobacter agglomerans of the collected water was measured and was found to be 5 x 10°, 4 x 105 and 3 x 104 CFU/ml respectively. pH of the water was found to be 5.0 One gm of 0.199 % cobalt acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Serratia and Enterobacter species were found to be nil. The cobalt concentration in the treated water was estimated to be nil. Example 23 1.4 g of cobalt hexafluoro acetylacetonate was dissolved in 4500 ml of acetone by continuous .stirring at 20°C. To this solution 28g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the. cobalt hexafluoro acetylacetonate solution and was dried in an oven at 120°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Serratia marcescens, Serratia liquefaciens and Proteus vulgaris of the collected water was measured and was found to be 4 x 104, 2 x 103 and 5 x 106 CFU/ml respectively. pH of the water was found to be 7.0 One gm of 0.19 % cobalt hexafluoro acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Serratia and Proteus species were found to be nil. The copper concentration in the treated water was estimated to be nil. Example 24 1.6 g of cobalt acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 10°C. To this solution 30 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the cobalt acetylacetonate solution and was dried in an oven at 140°C for 15 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Yersinia enterocolitica, Proteus mirabilis and Proteus vulgaris of the collected water was measured and was found to be 2 x 103, 6 x 106 and 5x10° 'CFU/ml respectively. pH of the water was found to be 12.0. Four grams of 0.199 % cobalt acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Serratia and Proteus species were found to be nil. The cobalt concentration in the treated water was estimated to be nil. Characterization of metal impregnated activated carbon Electron Spin Resonance (ESR/EPR) Spectra The ESR signal in the parent carbon used for preparing metal impregnated carbons showed the presence of unpaired electron. The g-factor calculated is about 2.0083. Powder EPR spectra of the copper impregnated mesoporous activated carbon implied that the copper is dispersed onto activated carbon. The tensor component g^ referring to the lowest magnetic field (near 2600 G), the determined g value was 2.381. The other tensor quantity gx corresponding to the high magnetic field, the g value was found to be 2.072. These gn and g_ values indicate that the copper species belong to single Cu2+ species, bonded to the carbon. A narrow line with g value .2.0083 due the free radical present in the carbon matrix was also observed. The copper in the impregnated carbon samples are ESR-visible and are originally stabilized as isolated cations in the Cu2+ valance state. The Cu1+ species present in the carbon matrix cannot be identified by EPR, as Cu1+ species do not give EPR signal due to is diamagnetic behaviour. The EPR spectra for the Ni/C consists of two signals, a small one due to the Ni and intense one due to the free radical already present in the carbon The g value obtained from the spectra is 2 165, which corresponds to Ni2+ state. The spectra obtained for Ni2+ system for the Ni/C was incomplete In general Ni2+ system (ls = 3/2), exhibit a broad spectra in the typical microwave frequency 9 GHz called the X-band, while other signals start to appear in the typical microwave frequency 35 GHz called Q-band and the complete triplet spectrum should be detectable in the D-band of typical frequency 130 GHz As to this applicability, the EPR spectra for Ni/C sample recorded at 9 326 GHz corresponding to the X-band showed slightly a small broad signal, a partly resolved incomplete spectra with g value 2.165 indicating the presence of nickel species The spectra were limited to the X-band due to the instrumental limitations. Any conclusion regarding the species of the Co impregnated onto carbon matrix cannot be made, as there was no well-resolved fine hyperfine splitting. Only a very weak signal due to the free radical already present in the carbon matrix was observed. The lack or absence of well-resolved hyperfine splitting can be attributed to a very low concentration of cobalt present in the matrix of the carbon that was below the instrumental detection limit Optical property The carbon samples such as Cu/C, Ni/C and Co/C were characterized using reflectance spectroscopy The sample was scanned in the wavelength region 350nm to 2000 nm It was observed that all the carbon samples had a maximum reflectance at a wavelength corresponding to 800nm The optical energy gap (Eg) calculated was 1 55 eV It was also observed that there exists a slight decrease in the percentage reflectance for the metal impregnated carbon samples Cu/C, Ni/C and Co/C to that of the parent carbon The decrease in percentage reflection could be attributed to the impregnation of metals in the carbon matrix Also, the presence of very small peaks observed in the higher wavelength region for all the carbon samples which may be due to the presence of loosely held impurities present in the carbon matrix during precarbonization and chemical activation Thus, the physical property of reflectivity should be valuable in determining the fundamental differences in the carbon components and in the determining the basic molecular structure of carbon samples X-ray studies The status of the impregnated metals onto mesoporous activated carbon was confirmed through the X-ray diffraction pattern The impregnated copper in the mesoporous activated carbon could be in the form of copper oxides (Cu20 or CuO) as evidenced from the 20 values The peaks at 2 angle of 36.44, 42.33 and 61.40 corresponds to the Cu20 phase while the peaks near 2angle of 35.0, 38.73, and 64.56 corresponds to the CuO phase. Thus it is confirmed that the Cu/C consists of the mixture of two phases. The nickel impregnated carbon matrix exhibit peaks at 2 angles of 37.51, 43.22, 62.87 and 75.41 corresponds to the presence of NiO phase. The cobalt impregnated carbon matrix, did not show the peaks corresponding to the CoO phase indicating Co or CoO present in the carbon matrix was below the instrumental detectable limit. Thus from the Ni/AC and Cu/C, XRD patterns, it is concluded that the metal impregnated mesoporous activated carbon contains the metal oxide phase mixtures. The lower intensities of Cu20, CuO and NiO peaks in the XRD pattern is probably due to the lower amount of these phases on carbon and higher dispersion. Far IR spectra The intensity of binding of the metals such as copper, nickel and cobalt onto the carbon matrix was assessed from the spectra recorded in the Far-IR technique. The bands observed between 475 - 550 cm'1 in the Far IR spectra indicated that the metals are bound to the carbon matrix in all the three Cu/C, Ni/C and Co/C samples. Surface morphology The morphology of activated and metal impregnated carbon were observed using scanning electron microscope (SEM) analysis. The SEM images of the metal impregnated activated cjarbon depicted that the surface of the activated carbon is modified due to impregnation of rnetals. The metals copper and cobalt are well adsorbed on to the activated carbon pores and surfaces. Energy Dispersive X-ray analysis (EDX) Energy dispersive X-ray analysis was conducted on the mesoporous activated carbon before and after metal impregnation. EDX was mainly used to confirm the localization of the metals in the carbons. The existence of copper, nickel and cobalt in the carbons matrix was confirmed using EDX microanalysis even as the concentration of these metals were low. Due to this reason well-resolved peaks were not obtained. Although the EDX was not operated for a quantitative mode, the existence of metals in the carbon matrix was confirmed qualitatively. The relative weight percentage of metals in the carbon matrix studied through EDX is shown in the Table 1 below. Table 1 Relative percentage of components in the carbon matrix (Table Removed) Advantages Following are the main advantages of the present invention: 1. More than 99% removal of pathogens is enabled. 2. No reoccurrence or regrowth of the destructed organisms takes place. 3. No leaching of metals in the solution takes place 4. Retention time is very less in the order of 10-300 seconds 5. The treated water can be used for recreational purposes 6. The maintenance cost of this treatment technique will be 60 % less than the conventional technologies. We Claim: 1. A novel catalyst useful for the removal of enteric pathogens from wastewater comprising of activated carbon characterized in that, it is impregnated with a transition metal ion. 2. A catalyst as claimed in claim 1, wherein the relative percentage of the transition metal ion impregnated in the activated carbon is in the range of 0.15 to 2.50 % w/w to that of the total carbon matrix. 3. A catalyst as claimed in claim 1, wherein the transition metal ion is selected from transition metal ion complex of acetyl acetonate, thiosemicarbozones, pyridine, picoline, hexaflouroacetylacetone and oxime either individually or in any combination as precursor to prepare the transition metal ion impregnated activated carbon. 4. A catalyst as claimed in claim 1, wherein the transition metal ion used in transition metal ion complex is selected from copper, nickel, cobalt and iron. . 5. A process for the purification of pathogens particularly enteric pathogens contaminated water, which comprises: [a] adjusting the pH of the said water in the range of 2-10; [b] treating the water of step [a] with 0.1 - 20% (w/v) of the catalyst as claimed in claim 1, for a period in the range of 10-300 seconds [c] separating the treated water of step [b] employing conventional techniques to obtain water free from enteric and other pathogenic organisms. 6. A process as claimed in claim 5, wherein the enteric pathogens and other pathogens obtained from sources such as but not restricted to domestic, public or industrial discharges are preferably Escherichia coli, Shigella dysenteriae, Shigella flexneri, Shigella boydii, Shigella sonnei, Salmonella typhi, Salmonella enteritidis, Klebsiella pneumoniae, Enterobacter aerogenes, Enterobacter agglomerans, Serratia marcescens, Serratia liquefaciens, Proteus vulgaris, Proteus , mirabilis and Yersinia enterocolitica species. 7. A catalyst and a process for the purification of contaminated water substantially as herein described with reference to the foregoing examples.

Full Text

Field of invention
The present invention relates a novel catalyst useful for the removal of pathogens from wastewater. More particularly, the present invention provides a process for the removal of enteric pathogens, namely Escherichia coli, Shigella species, Salmonella species from domestic, public and industrial waste water by metal ion impregnated activated carbon, to ensure that the water, purified thereby can be reused. This process has enormous potential applications for supplementing the inventory towards recreational water, bath water, industrial cooling water, industrial processing water and agricultural water by sewage duly freed from enteric pathogens namely Escherichia coli, Shigella species, Salmonella species, thereby ensuring reuse of water leading to substantial reduction in fresh water requirement.
Background of the Invention
The enormous amount of water released by domestic, public or industrial sources pose a major environmental concern because of the presence of enteric pathogenic species namely Escherichia coli, Shigella species, Salmonella species, etc. Domestic sewage is mainly composed of soluble and insoluble human excreta and household wastes. When the sewage water mixes with industrial wastewaters (effluents), the treatment of the resulting water is difficult due to the presence of chemical as well biological pollutants in the form of pathogenic organisms. The conventional sewage disposal system has been to discharge the wastewater into river or sea. Occasionally, the sewage stream is let into land for agricultural purposes. •However, this method of discharging leads to promotion of water borne infectious diseases.
Sack (Annual Review of Microbiology 29:333-353, 1975) and Smkith (Journal of Pathology & Bacteriology 93:499-529, 1967) studied the infections due to Escherichia coli. Gyles, et al. (Journal of Infectious Disease, 130: 212-218, 1974), Skerman et al (Infection and Immunology, 5: 622-624, 1972), Harris et al (Infection and Immunology. 37: 1295-1298. 1982) and Wells et al. (Journal of Clinical Microbiology 18:512-520.1983) reported that the plasmids of the Escherichia coli strains contain the traits for causing enterotoxigenic, enteroinvasive, enterohemorrohagic and enteropathogenic diseases. Generally, diarrheal out breaks and infant death in underdeveloped countries are mainly due to enterotoxigenic effect of Escherichia coli. The increasing concern of water borne diseases has promoted the implementation of more stringent standards on microbiological pollution of wastewater discharge, for public and environment safety. The persistence of the pathogens in ground water has been detected in zones of discharging treated/untreated wastewater.
With regard to the removal of pathogens, the widely accepted methods are chlorination, UV (Ultraviolet) exposure and ozonation. The chlorination process employs chlorine dioxide, hypochlorite or bleaching powder. These compounds inhibit the growth of the pathogenic species exhibiting reduction in population upon immediate exposure. However, certain coliforms especially Escherichia coli develop resistance during chlorination thereby decreasing the desired effects of disinfection as evidenced by Murray et al (Applied and Environmental Microbiology, 48(1), 73-77, 1984). In addition to the development of resistance by the pathogenic species towards these compounds, the release of products such as trihalomethane, haloacetic acids and other dissolved organic halogen compounds having toxic nature was observed by Urano et al. (Water Research 17: 1797-1802,1983).
With regard to UV irradiation, the disinfection effect is due to its high absorption by the bacterial DNA at 254 nm resulting in the formation of pyrimidine dimers, which inhibits the reproduction function of bacteria. However, if the bacterial load is too high, UV source does not become lethal tathe bacterial cells leading to reduced efficiency in comparison to the destruction of bacteria, as reported by Acher et al. (Water Research 31:1398-1404,1997).
Another chemical disinfection method for the removal of pathogens in domestic/industrial wastewater is ozonation. The biocidal activity of ozone is due to its high oxidation potential and its ability to diffuse through biological membrane. However, studies have not been completed to probe into the species of ozone responsible for the inactivation of microorganisms, as reported by Hunt and Benito (Water Research 31: 1355-1362, 1997). Similar to other disinfectants, the quality of the treated wastewater is highly influenced by the efficiency of ozonation and it has been observed that disinfection using ozone is not cost effective. Moreover the use of ozone leads to occupational health hazard because of the release of enzymes and amino acids as a result of cell death, which alters the purity of the treated water thereby limiting the scope for its reuse.
The other possible method adopted for the removal or destruction of pathogens is membrane filtration. The tests performed by membranes on different effluents showed complete removal of coliforms and other enteric pathogens from tertiary effluents. However, the removal performances highly depend on the membrane fouling status and changes of membrane cleaning periodicity etc as indicated by Langlais et al (Water Science and Technology, 25(12), 135-143,1993).
The major limitation of all the aforesaid methods is that these methods remove pathogens to a maximum level of 60% Another limitation associated with these methods is that they are inefficient in restricting the reoccurrence or regrowth of the organisms in the treated water
These have prompted the researchers to explore biological methods, including clarification, filtration, secondary settling, addition of flocculating agents, anaerobic digestion, activated sludge process etc for purifying pathogen contaminated wastewater Though about 90% of the microbial population decreases with the said treatment methods yet their presence at detectable levels pose health threat [Joan Rose et al (Water Science and Technology 30 (11), 2785- 2797,1996)]
Attempts have also been made to explore possibilities of combining chemical and biological treatment systems Dutton et al (Applied Environmental Microbiology 46(6), 1263-7, 1983) employed biological treatment followed by chlonnation, where coliforms including Escherichia coli were again observed in the treated effluents
Attempts have further been made to use heavy metal catalysts for the disinfection of pathogens Matthew et al (Applied and Environmenal Microbiolgy, 48, 289 - 293, 1984) reported the removal of Escherichia coli in drinking water by dissolving salts of copper in the contaminated water The threshold concentration of copper for the removal of Escherichia coli was in the range 0 007 to 0 54 mg/l References may also be made to Nobuo Hoshino et al (Free Radical Biology & Medicine, 2-7, 1245 - 1250, 1999) who used combinations of epigallo catechin (EGC) and epicatechin (EC) with Cu(ll) as bactericides against Escherichia coli Similarly, destruction of Escherichia coli have also been possible by the complexes such as carbono and thiocarbonohydrazone ligands with Cu(ll), Fe(ll) and Zn(ll) as reported by Alessia Bacchi et al (Journal of Inorganic Biochemistry, 75, 123 - 133, 1999) The major limitation associated with the use of the metal-based system for removal of pathogens is that the leached metal in the treated water poses health hazard This has prompted the researchers to explore methods for the viable treatment of pathogens using metal impregnated systems
Sekaran et al (WAPDEC, International Conference on Water and Wastewater Perspectives of Developing Countries, December 11-13, 2002, New Delhi) studied the use of activated carbon for the removal of both chemical as well as biological pollutants and reported that the removal of pathogens by the activated carbon is merely due to the adsorption of bacterial species by the lipopolysachandes in their cell wall It has further been inferred that upon continuous exposure to the contaminated water, the adsorption efficiency of the activated carbon decreases due to
the saturation at the surface of the activated carbon. This leads to the reoccurrence or regrowth of the organisms in the wastewater after treatment with activated carbon.
Antibacterial activated carbon fiber with mesopores was attempted by Oya et al. (Carbon 34, 53 - 57, 1996) using phenolic resin containing cobalt as an activation catalyst and silver as an antibacterial agent against Escherichia coli and Staphylococcus aureus. In this process the silver content of the activated carbon fiber has been found to be reduced from 0.22 wt% to 0.0006 wt% upon treatment. Thus the major limitation associated with this process is that the metallic component of silver and cobalt gradually decreases in the activated carbon, thereby reducing the efficiency of the process gradually.
t
In addition to metals, metal oxides have also been found to play an important role in the removal of pathogenic species. Osamu Yamamoto et al, (Carbon 39,1643 - 1651, 2001) have reported inhibition of Escherichia coli on carbon materials containing zinc oxides at extremely acidic and alkaline condition. However, the reoccurrence and regrowth of the organism in the treated water limit the usage of the metal oxides for the removal of pathogens.
Owing to the partial effect on removal of pollutants by activated carbon and metal oxides in free state, impregnation of metals onto activated carbon came to the lime light of research due to its immense use in various physical, chemical and environmental applications. Our co-pending Indian patent application (320 DEL 2004) provides a process for the synthesis of transition metal complexes impregnated activated carbon. The preparation of materials involves the use of metal complexes in the form of acetyl acetonates, pyridine, picoline, hexaflouroacetyl acetone, oxime of Cu, Co, Ni, and in situ impregnation of the same on activated carbon having surface area in the range of 392- 430 m2/g; Average pore diameter 35.28 - 37.20A0; Bulk density 0.56 - 0.62 g/cc and a composition of Carbon 37.96 - 39.36 %; Hydrogen 2.46 - 3.41%; Nitrogen 0.50 - 0.71% followed by curing at optimized temperatures.
Hisashi Tamani et al. (Carbon 39, 1963 - 1969, 2001) studied the removal of pathogenic species using acetylacetonate complexes of nickel, cobalt, aluminum, impregnated in activated carbon. The process of impregnation of metal complexes involves mere adsorption of the metal on the surface of the activated carbon, resulting in a very weak binding between the metal complex and the activated carbon surface. Hence, the resulting material removes pathogens only at the initial stage of the treatment and on further exposure, leaching of metal complexes in
the treated water occurs, which leads to the reoccurrence and regrowth of the organism in the treated water.
In view of the foregoing, the hitherto known processes for the removal of pathogens are essentially associated with the following limitations:
1. Metal complexes are impregnated only in the complex form and not in the form of free metal ions
2. Only temporary inhibition to the growth of the organism occurs
3. Reoccurrence and regrowth of the organism take place after treatment
4. Addition of metal salts act as stimulant, which further increases the growth of the organism.
5. Mere surface adsorption of the pathogenic species on to activated carbon leads to reoccurrence of the pathogenic species in the treated water
6. No complete destruction or lysis of the organism takes place.
7. Requires treatment period of more than 24 hours
8. Leaching of metals takes place in the treated water, thereby rendering the water unusable.
No prior art is available on the use of impregnated metal ions in the activated carbon for complete destruction of potent pathogenic species including Escherichia coli, Shigella species, Salmonella species, etc from contaminated water without leaching of metals in the treated water.
Objects of the Invention
The main objective of the present invention is therefore, to provide a process for the purification of enteric pathogen contaminated water for reusable options, which obviates the limitations as stated above.
Another objective of the present invention is to use transition metal ions impregnated activated carbon for the treatment of wastewater.
Yet another objective of the present invention is to use activated carbon having the following characteristics
surface area of 392 - 430 m2/g;
Average pore diameter of 35.28 - 37.20 °A;
Bulk density 0.56 - 0.62 g/cc
Composition : Carbon 37.96 - 39.36%; Hydrogen 2.46 - 3.41 %; Nitrogen 0.50 - 0.71%.
Still another objective of the present invention is to impregnate the metal ions as metal complexes on activated carbon.
Another objective of the present invention is to ensure that no metal is leached out in the treated water.
Yet another objective of the present invention is to remove the pathogenic species such as Escherichia coli, Shigella species, Salmonella species to the extent of more than 99%.
Still another objective of the present invention is to completely destruct or lyse the organisms present in the wastewater.
It is still another objective of the present invention is to provide a process that removes pathogens from the pathogen contaminated water in less than 300 seconds.
Accordingly, the present invention provides a novel catalyst useful for the removal of enteric pathogens from wastewater comprising of activated carbon characterized in that it is impregnated with a transition metal ion based compound.
The invention further provides a process for the purification of pathogens particularly enteric pathogens contaminated water, which comprises:
[a] adjusting the pH of the said water in the range of 2-10;
[b] treating the water of step [a] with 0.1 - 20% (w/v) of the catalyst as claimed in claim 1, for a period in the range of 10-300 seconds
[c] separating the treated water of step [b] employing conventional techniques to obtain water free from enteric and other pathogenic organisms.
In an embodiment of the present invention the enteric pathogens are such as but not restricted to Escherichia coli, Shigella dysenteriae, Shigella flexneri, Shigella boydii, Shigella sonnei, Salmonella typhi, Salmonella enteritidis Klebsiella pneumoniae, Enterobacter aerogenes, enterobacter agg/omerans, serraf/a marcescens, Serratia liquefaciens, Proteus vulgaris,
Proteus mirabilis and Yersinia enterocolitica obtained from sources such as but not -limited to domestic, public or industrial discharges, adjusted to a pH in the range of 2-10, with 0.1- 20% (w/v) of transition metal ion based compound impregnated activated carbon, the activated carb'on having characteristics as herein described, for a period in the range of 30-300 seconds followed by separating the treated water to obtain water free from enteric pathogenic and other pathogenic organisms for reusable options.
In an embodiment of the present invention, the transition metal ion based compound may be selected from copper acetyl acetonate, cobalt acetyl acetonate, nickel acetyl acetonate, copper hexafluro acetyl acetonates, cobalt hexa fluro acetyl acetonates, nickel hexa fluro acetyl acetonates.
In another embodiment of the present invention, the process of separation of treated water may be such as decantation, filtration, centrifugation.
Detailed description of the Invention
Water contaminated with enteric pathogens is adjusted to a pH in the range of 5-10 by known method and is then treated with 10-20 % (w/v) of transition metal ion based compound impregnated activated carbon, whereby the activated carbon exhibits the following characteristics
surface area of 392 - 430 m2/g;
Average pore diameter of 35.28 - 37.20 °A;
Bulk density 0. 56 - 0.62 g/cc
Composition : Carbon 37.96 - 39.36%; Hydrogen 2.46 - 3.41 %; Nitrogen 0.50 - 0.71%. The relative percentage of the metal impregnated in the matrix is in the range 0.150 - 2.5% "w/w, to that of the total carbon matrix. After a period of 30-300 seconds, the resulting water is subjected to separation by known methods to obtain water free from pathogen for reusable options.
The treated water is highly stable and no regrowth of organism has been observed up to a period of 10 days. However, no regrowth of organism is envisaged to be observed even in the distant future.
The impact of metal impregnated activated carbon on enteric bacterial mortality was studied. The treated wastewater collected from the metal impregnated reactor was subjected to detail analysis for the lysis of the E.coli and the analysis was carried at different time intervals up to 10
days. The study showed starting from the first day upto the tenth day there was no regrowth or reactivation of E.coli. This was well evidenced from the Transmission Electron Microscope image (TEM). The image well depicted that the E.coli cell wall was totally ruptured and confirmed that there cannot be reactivation of E.coli further more.
The SDS-PAGE studies also revealed the damage of outer membrane proteins (OMP) in E.coli on all of our studies with treatment in Cu impregnated activated carbon reactor. Isovaleric acid was used for extraction of OMP from E.coli. The apparent molecular mass in control E.coli determined by SDS-PAGE mobility was 38 and 36 Kilo Daltons. The OMP of E.coli tested after treating with metal impregnated activated carbon showed complete loss of 38 Kilo Dalton. This proves that the strong hydrogen bonding, electrostatic, and hydrophobic interactions of OMP .are disrupted by metal impregnated activated carbon causing non-recoverable damage in E.coli.
The shelf life/stability of the metal impregnated activated carbon was evaluated after storing it at 28 - 35 °C for 90 days. It was observed from the study that the amount of metals impregnated on the carbon matrix was the same and possessed same activity during the period of 90 days. There were no altered features observed on the matrix. Regarding the stability of the material, no transformation or modification on the structure was observed. Even after several runs, the material used for treating the E.coli containing wastewater inherited good stability at all the operating conditions. Comparing the metal impregnated activated carbon developed, Cu/C possessed a good stability for more than 100 cycles than the other materials Ni/C and Co/C less than 100 cycles. As the material Cu/C inherited appreciable stability Cu/C was reused for rrtore than 100 cycles than the other metal impregnated carbons. The results also suggest that that the Cu/C can be reused for many number of treatment cycles for Ecoli.
the inventive step in the present invention lies in the treatment of pathogen contaminated water with metal ion complex impregnated activated carbon, which completely destroys the pathogenic species both by inhibiting the growth as well as restricting the DNA synthesis. When the pathogenic organisms are exposed to the metal ion impregnated activated carbon, the interaction between the metal ion and the sulfhydryl groups of bacterial cellular membrane reduces the metal ion to monovalent oxidation state, which subsequently gets bound with DNA synthesis resulting in complete lysis of organisms.
The following examples are given by way of illustrations only and therefore should not be construed to limit the scope of the present invention.
Example 1
1.2 g of copper acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 10°C. To this solution 18 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the copper acetylacetonate solution and was dried in an oven at 150°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Escherichia coli, Shigella dysenteriae and Salmonella typhi species of the collected water was measured and was found to be 10 x 108, 5 x 107 and 6 x 107 CFU/ml respectively. pH of the water was found to be 2.0 One gm of 0.5 % copper acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration. Salmonella and Shigella which were found to be nil while E.coli papulation was found to be 1 x 101 in the filtered water. The copper concentration in the treated water was estimated to be nil.
Example 2
1.47 g of copper hexafluoro acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 12°C. To this solution 20g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the copper hexafluoro acetylacetonate solution and was dried in an oven at 130°C for 12 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a •glass beaker. Pathogenic bacterial population including Escherichia coli, Shigella flexneri and Salmonella enteritidis of the collected water was measured and was found to be 10 x 108, 3 x 106 and 5 x 107 CFU/ml respectively. pH of the water was found to be 2.0 One gm of 1.0 % copper hexafluoro acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Salmonella and Shigella, which were found to be nil while Escherichia population was found to be 1 x 101 in the filtered water. The copper concentration in the treated water was estimated to be nil. Example 3
1.6 g of copper acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 15°C. To this solution 25g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the copper acetylacetonate solution and was dried in an oven at 140°C for 15 hours. One hundred
ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Shigella dysenteriae Shigella flexneri and Shigella boydii of the collected water was measured and was found to be 5 x 107, 3 x 106 and 3 x 106 CFU/ml respectively. pH of the water was found to be 2.0 One gm of 1.5 % copper acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration all Shigella species were found to be nil. The copper concentration in the treated water was estimated to be nil.
Example 4
1.6 g of copper acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at t-0°C. To this solution 30 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the copper acetylacetonate solution and was dried in an oven at 150°C for 15 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Shigella sonnei, Salmonella typhi and Salmonella enteritidis species of the collected water was measured and was found to be 4 x 106, 6 x 107 and 5 x 107 CFU/ml respectively. pH of the water was found to be 2.0 Three grams of 1.5 % copper acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration. Salmonella and Shigella species were found to be nil. The copper concentration in the treated water was estimated to be nil.
Example 5
1.8 g of copper hexafluoro acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 20°C. To this solution 32 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the copper hexafluoro acetylacetonate solution and was dried in an oven at 120°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Klebsiella pneumoniae, Enterobacter aerbgenes and Enterobacter agglomerans of the collected water was measured and was found to be 5 x 105, 4 x 105 and 3 x 104 CFU/ml respectively. pH of the water was found to be 2.0 Five grams of 1.5 % copper hexafluoro acetylacetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Klebsiella and Enterobacter
species were found to be nil. The copper concentration in the treated water was estimated to be nil.
Example 6
1.8 g of copper acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 10°C. To this solution 32 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the copper acetylacetonate solution and was dried in an oven at 150°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Serratia marcescens, Enterobacter aerogenes and Enterobacter agglomerans of the collected water was measured and was found to be 5 x 105, 4 x 105 and 3 x 104 CFU/ml respectively. pH of the water was found to be 5.0 Four grams of 1.5 % copper acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Serratia and Enterobacter species were found to be nil. The copper concentration in the treated water was estimated to be nil.
Example 7
1.4 g of copper acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 20°C. To this solution 28g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the copper acetylacetonate solution and was dried in an oven at 120°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Serratia marcescens, Serratia liquefaciens and Proteus vulgaris of the collected water was measured and was found to be 4 x 104, 2 x 103 and 5 x 106 CFU/ml respectively. pH of the water was found to be 7.0 One gm of 1.5 % copper acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Serratia and Proteus species were found to be nil. The copper concentration in the treated water was estimated to be nil. Example 8
1.6g of copper hexafluoro acetylacetonate was dissolved in 4500 mi of acetone by continuous stirring at 10°C. To this solution 30 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the copper hexafluoro acetylacetonate solution and was dried in an oven at 140°C for 15 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a
glass beaker. Pathogenic bacterial population including Yersinia enterocolitica, Proteus mirabilis and Proteus vulgaris of the collected water was measured and was found to be 2 x 103, 6 x 106 and 5 x 106 CFU/ml respectively. pH of the water was found to be 12.0 One gm of 1.5 % copper hexafluoro acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Serratia and Proteus species were found to be nil. The copper concentration in the treated water was estimated to be nil
Example 9
1.2 g of nickel acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 10°C. To this solution 18 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the nickel acetylacetonate solution and was dried in an oven at 150°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Escherichia coli, Shigella dysenteriae and Salmonella typhi species of the collected water was measured and was found to be 10 x 108, 5 x 107 and 6 x 107 CFU/ml respectively. pH of the water was found to be 2.0. 1g of 1.5 % nickel impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration. Salmonella and Shigella which were found to be nil while E.coli population was found to be 1 x 101 in the filtered water. The nickel concentration in the treated water was estimated to be nil.
Example 10
1.47 g of nickel hexafluoro acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 12°C. To this solution 20g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the nickel hexafluoro acetylacetonate solution and was dried in an oven at 130°C for 12 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Escherichia coli, Shigella flexneri and Salmonella enteritidis of the collected water was measured and was found to be 10 x 108. 3 x 106 and 5 x 107 CFU/ml respectively. pH of the water was found to be 2.0 Two gram of 2.0 % nickel hexafluoro acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Salmonella and Shigella, which were found to be nil while Escherichia population was found to be 1 x 101 in the filtered water. The nickel concentration in the treated water was estimated to be nil.
Example 11
1.6 g of nickel acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 15°C. To this solution 25g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the nickel acetylacetonate solution and was dried in an oven at 140°C for 15 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Shigella dysenteriae, Shigella flexneri and Shigella boydii of the collected water was measured and was found to be 5 x 107, 3 x 106 and 3 x 106 CFU/ml respectively. pH of the water was found to be 2.0 One gm of 2.46 % nickel acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration all Shigella species were found to be nil. The nickel concentration in the treated water was estimated to be nil.
Example 12
1.6 g of nickel hexafluoro acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 10°C. To this solution 30 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the nickel hexafluoro acetylacetonate solution and was dried in an oven at 150°C for 15 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Shigella sonnei, Salmonella typhi and Salmonella enteritidis species of the collected water was measured and was found to be 4 x 106, 6 x 107 and 5 x 107 CFU/ml respectively. pH of the water was found to be 2.0 Five grams of 2.46 % nickel hexafluoro acetyl acetonate impregnated activated carbon was added to the beaker. After 30 sec the water was separated by filtration. Salmonella and Shigella species were found to be nil. The nickel concentration in the treated water was estimated to be nil.
Example 13
1.8 g of nickel acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 20CC. To this solution 32 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the nickel acetylacetonate solution and was dried in an oven at 120°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Klebsiella pneumoniae, Enterobacter aerogenes and
Enterobacter agglomerans of the collected water was measured and was found to be 5 x 105, 4 x 105 and 3 x 104 CFU/ml respectively. pH of the water was found to be 2.0 One gm of 2.46 % nickel acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Klebsiella and Enterobacter species were found to be nil. The copper concentration in the treated water was estimated to be nil.
Example 14
1.8 g of nickel acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at .104C. To this solution 32 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the nickel acetylacetonate solution and was dried in an oven at 150°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Serratia marcescens, Enterobacter aerogenes and Enterobacter agglomerans of the collected water was measured and was found to be 5 x 10°, 4 x 105 and 3 x 104 CFU/ml respectively. pH of the water was found to be 5.0 Five grams of 2.46 % nickel acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Serratia and Enterobacter species were found to be nil. The nickel concentration in the treated water was estimated to be nil.
Example 15
1.4 g of nickel hexafluoro acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 20°C. To this solution 28g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the nickel hexafluoro acetylacetonate solution and was dried in an oven at 120°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Serratia marcescens, Serratia liquefaciens and Proteus vulgaris of the collected water was measured and was found to be 4 x 10\ 2 x 103 and 5 x 106 CFU/ml respectively. pH of the water was found to be 7.0 One gm of 2.46 % nickel hexafluoro acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Serratia and Proteus species were found to be nil. The nickel concentration in the treated water was estimated to be nil. .
Example 16
1.6 g of nickel acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 10°C. To this solution 30 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the nickel acetylacetonate solution and was dried in an oven at 140°C for 15 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Yersinia enterocolitica, Proteus mirabilis and Proteus vulgaris of the collected water was measured and was found to be 2 x 103, 6 x 106 and 5 x 106 CFU/ml respectively. pH of the water was found to be 12.0 One gm of 2.46 % nickel acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Serratia and Proteus species were found to be nil. The nickel concentration in the treated water was estimated to be nil
Example 17
1.2. g of cobalt acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 10°C. To this solution 18 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the cobalt acetylacetonate solution and was dried in an oven at 150°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Escherichia coli, Shigella dysenteriae and Salmonella typhi species of the collected water was measured and was found to be 10 x 108, 5 x 107 and 6 x 107 CFU/ml respectively. pH of the water was found to be 2.0 One gm of 0.1 % cobalt acetyl .acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration. Salmonella and Shigella which were found to be nil while E.coli population was found to be 1 x 101 in the filtered water. The cobalt concentration in the treated water was estimated to be nil.
Example 18
1.47 g of cobalt hexafluoro acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 12°C. To this solution 20g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the cobalt hexafluoro acetylacetonate solution and was dried in an oven at 130°C for 12 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Escherichia coli, Shigella flexneri and .Salmonella enteritidis of the collected water was measured and was found to be 10 x 108, 3 x
106 and 5 x 107 CFU/ml respectively. pH of the water was found to be 2.0 Three grams of 1.0 % copper hexafluoro acetylacetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Salmonella and Shigella, which were found to be nil while Escherichia population was found to be 1 x 101 in the filtered water. The nickel concentration in the treated water was estimated to be nil.
Example 19
1.6 g of cobalt acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 15°C. To this solution 25g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the cobalt acetylacetonate solution and was dried in an oven at 140°C for 15 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Shigella dysenteriae Shigella flexneh and Shigella boydii of the collected water was measured and was found to be 5 x 107, 3 x 106 and 3 x 104 CFU/ml respectively. pH of the water was found to be 2.0 One gm of 0.19 % cobalt acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration all Shigella species were found to be nil. The cobalt concentration in the treated water was estimated to be nil.
Example 20
1.6 g of cobalt hexafluoro acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 10°C. To this solution 30 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the cobalt hexafluoro acetylacetonate solution and was dried in an oven at 150°C for 15 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Shigella sonnei, Salmonella typhi and Salmonella enteritidis species of the collected water was measured and was found to be 4 x 106, 6 x 107 and 5 x 107 CFU/ml respectively. pH of the water was found to be 2.0. Five grams of 0.19 % cobalt hexafluoro acetyl acetonate impregnated activated carbon was added to the beaker. After 30 sec the water was separated by filtration. Salmonella and Shigella species were found to be nil. The cobalt concentration in the treated water was estimated to be nil.
Example 21
1.8 g of cobalt acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 20°C. To this solution 32 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the cobalt acetylacetonate solution and was dried in an oven at 120°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Klebsiella pneumoniae, Enterobacter aerogenes and Enterobacter agglomerans of the collected water was measured and was found to be 5 x 10;. 4 x 105 and 3 x 104 CFU/ml respectively. pH of the water was found to be 2.0 One gm of 0.19 % cobalt acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Klebsiella and Enterobacter species were found to be nil. The cobalt concentration in the treated water was estimated to be nil.
Example 22
1.8 g of cobalt acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 10°C. To this solution 32 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the cobalt acetylacetonate solution and was dried in an oven at 150°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Serratia marcescens, Enterobacter aerogenes and 'Enterobacter agglomerans of the collected water was measured and was found to be 5 x 10°, 4 x 105 and 3 x 104 CFU/ml respectively. pH of the water was found to be 5.0 One gm of 0.199 % cobalt acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Serratia and Enterobacter species were found to be nil. The cobalt concentration in the treated water was estimated to be nil.
Example 23
1.4 g of cobalt hexafluoro acetylacetonate was dissolved in 4500 ml of acetone by continuous .stirring at 20°C. To this solution 28g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the. cobalt hexafluoro acetylacetonate solution and was dried in an oven at 120°C for 10 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a
glass beaker. Pathogenic bacterial population including Serratia marcescens, Serratia liquefaciens and Proteus vulgaris of the collected water was measured and was found to be 4 x 104, 2 x 103 and 5 x 106 CFU/ml respectively. pH of the water was found to be 7.0 One gm of 0.19 % cobalt hexafluoro acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Serratia and Proteus species were found to be nil. The copper concentration in the treated water was estimated to be nil.
Example 24
1.6 g of cobalt acetylacetonate was dissolved in 4500 ml of acetone by continuous stirring at 10°C. To this solution 30 g of carbon was added and kept for agitation for five hours. After saturation, ie. after equilibrium concentration was reached, the carbon was separated from the cobalt acetylacetonate solution and was dried in an oven at 140°C for 15 hours. One hundred ml of domestic water contaminated with pathogenic species was collected in a glass beaker. Pathogenic bacterial population including Yersinia enterocolitica, Proteus mirabilis and Proteus vulgaris of the collected water was measured and was found to be 2 x 103, 6 x 106 and 5x10° 'CFU/ml respectively. pH of the water was found to be 12.0. Four grams of 0.199 % cobalt acetyl acetonate impregnated activated carbon was added to the beaker. After 30 seconds the water was separated by filtration Serratia and Proteus species were found to be nil. The cobalt concentration in the treated water was estimated to be nil.
Characterization of metal impregnated activated carbon
Electron Spin Resonance (ESR/EPR) Spectra
The ESR signal in the parent carbon used for preparing metal impregnated carbons showed the presence of unpaired electron. The g-factor calculated is about 2.0083. Powder EPR spectra of the copper impregnated mesoporous activated carbon implied that the copper is dispersed onto activated carbon. The tensor component g^ referring to the lowest magnetic field (near 2600 G), the determined g value was 2.381. The other tensor quantity gx corresponding to the high magnetic field, the g value was found to be 2.072. These gn and g_ values indicate that the copper species belong to single Cu2+ species, bonded to the carbon. A narrow line with g value .2.0083 due the free radical present in the carbon matrix was also observed. The copper in the impregnated carbon samples are ESR-visible and are originally stabilized as isolated cations in the Cu2+ valance state. The Cu1+ species present in the carbon matrix cannot be identified by EPR, as Cu1+ species do not give EPR signal due to is diamagnetic behaviour.
The EPR spectra for the Ni/C consists of two signals, a small one due to the Ni and intense one due to the free radical already present in the carbon The g value obtained from the spectra is 2 165, which corresponds to Ni2+ state. The spectra obtained for Ni2+ system for the Ni/C was incomplete In general Ni2+ system (ls = 3/2), exhibit a broad spectra in the typical microwave frequency 9 GHz called the X-band, while other signals start to appear in the typical microwave frequency 35 GHz called Q-band and the complete triplet spectrum should be detectable in the D-band of typical frequency 130 GHz As to this applicability, the EPR spectra for Ni/C sample recorded at 9 326 GHz corresponding to the X-band showed slightly a small broad signal, a partly resolved incomplete spectra with g value 2.165 indicating the presence of nickel species The spectra were limited to the X-band due to the instrumental limitations.
Any conclusion regarding the species of the Co impregnated onto carbon matrix cannot be made, as there was no well-resolved fine hyperfine splitting. Only a very weak signal due to the free radical already present in the carbon matrix was observed. The lack or absence of well-resolved hyperfine splitting can be attributed to a very low concentration of cobalt present in the matrix of the carbon that was below the instrumental detection limit Optical property
The carbon samples such as Cu/C, Ni/C and Co/C were characterized using reflectance spectroscopy The sample was scanned in the wavelength region 350nm to 2000 nm It was observed that all the carbon samples had a maximum reflectance at a wavelength corresponding to 800nm The optical energy gap (Eg) calculated was 1 55 eV It was also observed that there exists a slight decrease in the percentage reflectance for the metal impregnated carbon samples Cu/C, Ni/C and Co/C to that of the parent carbon The decrease in percentage reflection could be attributed to the impregnation of metals in the carbon matrix Also, the presence of very small peaks observed in the higher wavelength region for all the carbon samples which may be due to the presence of loosely held impurities present in the carbon matrix during precarbonization and chemical activation Thus, the physical property of reflectivity should be valuable in determining the fundamental differences in the carbon components and in the determining the basic molecular structure of carbon samples
X-ray studies
The status of the impregnated metals onto mesoporous activated carbon was confirmed through the X-ray diffraction pattern The impregnated copper in the mesoporous activated carbon could be in the form of copper oxides (Cu20 or CuO) as evidenced from the 20 values The peaks at
2 angle of 36.44, 42.33 and 61.40 corresponds to the Cu20 phase while the peaks near 2angle of 35.0, 38.73, and 64.56 corresponds to the CuO phase. Thus it is confirmed that the Cu/C consists of the mixture of two phases. The nickel impregnated carbon matrix exhibit peaks at 2 angles of 37.51, 43.22, 62.87 and 75.41 corresponds to the presence of NiO phase. The cobalt impregnated carbon matrix, did not show the peaks corresponding to the CoO phase indicating Co or CoO present in the carbon matrix was below the instrumental detectable limit. Thus from the Ni/AC and Cu/C, XRD patterns, it is concluded that the metal impregnated mesoporous activated carbon contains the metal oxide phase mixtures. The lower intensities of Cu20, CuO and NiO peaks in the XRD pattern is probably due to the lower amount of these phases on carbon and higher dispersion.
Far IR spectra
The intensity of binding of the metals such as copper, nickel and cobalt onto the carbon matrix was assessed from the spectra recorded in the Far-IR technique. The bands observed between 475 - 550 cm'1 in the Far IR spectra indicated that the metals are bound to the carbon matrix in all the three Cu/C, Ni/C and Co/C samples.
Surface morphology
The morphology of activated and metal impregnated carbon were observed using scanning electron microscope (SEM) analysis. The SEM images of the metal impregnated activated cjarbon depicted that the surface of the activated carbon is modified due to impregnation of rnetals. The metals copper and cobalt are well adsorbed on to the activated carbon pores and surfaces.
Energy Dispersive X-ray analysis (EDX)
Energy dispersive X-ray analysis was conducted on the mesoporous activated carbon before and after metal impregnation. EDX was mainly used to confirm the localization of the metals in the carbons. The existence of copper, nickel and cobalt in the carbons matrix was confirmed using EDX microanalysis even as the concentration of these metals were low. Due to this reason well-resolved peaks were not obtained. Although the EDX was not operated for a quantitative mode, the existence of metals in the carbon matrix was confirmed qualitatively. The relative weight percentage of metals in the carbon matrix studied through EDX is shown in the Table 1 below.

Table 1 Relative percentage of components in the carbon matrix (Table Removed)

Advantages
Following are the main advantages of the present invention:
1. More than 99% removal of pathogens is enabled.
2. No reoccurrence or regrowth of the destructed organisms takes place.
3. No leaching of metals in the solution takes place
4. Retention time is very less in the order of 10-300 seconds
5. The treated water can be used for recreational purposes
6. The maintenance cost of this treatment technique will be 60 % less than the conventional technologies.

We Claim:
1. A novel catalyst useful for the removal of enteric pathogens from wastewater comprising of activated carbon characterized in that, it is impregnated with a transition metal ion.
2. A catalyst as claimed in claim 1, wherein the relative percentage of the transition metal ion impregnated in the activated carbon is in the range of 0.15 to 2.50 % w/w to that of the total carbon matrix.
3. A catalyst as claimed in claim 1, wherein the transition metal ion is selected from transition metal ion complex of acetyl acetonate, thiosemicarbozones, pyridine, picoline, hexaflouroacetylacetone and oxime either individually or in any combination as precursor to prepare the transition metal ion impregnated activated carbon.
4. A catalyst as claimed in claim 1, wherein the transition metal ion used in transition metal ion complex is selected from copper, nickel, cobalt and iron. .
5. A process for the purification of pathogens particularly enteric pathogens contaminated water, which comprises:

[a] adjusting the pH of the said water in the range of 2-10;
[b] treating the water of step [a] with 0.1 - 20% (w/v) of the catalyst as claimed in claim 1, for a period in the range of 10-300 seconds
[c] separating the treated water of step [b] employing conventional techniques to obtain water free from enteric and other pathogenic organisms.
6. A process as claimed in claim 5, wherein the enteric pathogens and other
pathogens
obtained from sources such as but not restricted to domestic, public or
industrial
discharges are preferably Escherichia coli, Shigella dysenteriae, Shigella
flexneri, Shigella boydii, Shigella sonnei, Salmonella typhi, Salmonella
enteritidis, Klebsiella pneumoniae, Enterobacter aerogenes, Enterobacter
agglomerans, Serratia marcescens, Serratia liquefaciens, Proteus vulgaris,
Proteus , mirabilis and Yersinia enterocolitica species.
7. A catalyst and a process for the purification of contaminated water substantially as herein described with reference to the foregoing examples.

Documents:

2497-del-2005-abstract.pdf

2497-DEL-2005-Claims-(28-03-2012).pdf

2497-del-2005-claims.pdf

2497-del-2005-Correspondence Others-(27-08-2012).pdf

2497-DEL-2005-Correspondence Others-(28-03-2012).pdf

2497-del-2005-correspondence-others.pdf

2497-del-2005-description (complete).pdf

2497-del-2005-form-1.pdf

2497-del-2005-form-18.pdf

2497-del-2005-form-2.pdf

2497-del-2005-form-3.pdf

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Patent Number

255419

Indian Patent Application Number

2497/DEL/2005

PG Journal Number

08/2013

Publication Date

22-Feb-2013

Grant Date

20-Feb-2013

Date of Filing

15-Sep-2005

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

ANUSANDHAN BHAWAN, RAFI MARG, NEW DELHI-110 001, INDIA

Inventors:

#	Inventor's Name	Inventor's Address
1	GANESAN SEKARAN	CENTRAL RESEARCH INSTITUTE ADYAR, CHENNAI-600 020, TAMIL NADU
2	ARUMUGAM GNANAMANI	CENTRAL RESEARCH INSTITUTE ADYAR, CHENNAI-600 020, TAMIL NADU
3	LOURDUSAMY JOHN KENNEDY	CENTRAL RESEARCH INSTITUTE ADYAR, CHENNAI-600 020, TAMIL NADU
4	ARUMUGAM GANESH KUMAR	CENTRAL RESEARCH INSTITUTE ADYAR, CHENNAI-600 020, TAMIL NADU

PCT International Classification Number

B01J 23/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA