(IN320433) 1. Silver nanoparticle based antibacterial media comprising stable polymeric nanocomposite of silver-chitosan nano-composite particles. 2. Silver nanoparticle based antibacterial media as claimed in claim 1 for water based bacteria comprising colloidal silver-chitosan nanocomposite particles impregnated and/ or coated on various substrates/ media. 3. Silver nanoparticle based antibacterial media as claimed in claim 2 wherein said substrates/ media includes water filtration media including sponge and/or activated carbon to favour a filtration media for the removal of microbes from contaminated water. 4. Silver nanoparticle based antibacterial media as claimed in claims 1 to 3 selected from colloids powders wherein about 100 µl of nanoparticles possesses antomicrobial activity in inhibition growth of bacterial suspension of E. coli of 106 CFU/ml in the well until a diameter of about 2.1 cm surrounding the well. 5. Silver nanoparticle based antibacterial media as claimed in claims 1 to 4 wherein the silver nanoparticles are nanosized ranging from 4-23 nm and are stable for 10-12 days in colloid form at room temperature. 6. Silver nanoparticle based antibacterial media as claimed in claims 1 to 4 comprising a substrate/ media including selected from sponge, activated carbon material impregnated and/ or coated with polymeric silver-chitosan nanocomposite particles of particle size ranging from 4-23 nm. 7. Silver nanoparticle based antibacterial media as claimed in claim 6 wherein the sponge coated substrate/ media possesses anti-bacterial activity in inhibiting growth of bacterial suspension of E. coli. of 106 CFU/ml in the well till a diameter of about 2.2 cm surrounding the well and wherein said zone of bacterial growth inhibition persists even after washing the sponge with water for a period of atleast 30-35 days, and wherein the activated carbon coated substrate/ media possesses anti-microbial activity in inhibiting growth of bacterial suspension of E. coli. of 106 CFU/ml in the well till a diameter of about 2.3 cm surrounding the well. 8. Silver nanoparticle based antibacterial media as claimed in claims 5-7 having silver content such that washing effluents from said substrate/ media maintains permissible silver concentration of 60-70 ppb. 9. Silver nanoparticle based antibacterial media as claimed in claims 5 to 8 having capacity of removal of E. coli. from water of about 1 minute contact time with contaminated water at a flow rate of 1 L/hr for complete removal of E. coli. 10. A process for the preparation of silver nanoparticle based antibacterial media as claimed in claims 1-9 comprising the steps of a) Providing chitosan solution and adding AgNO3 to the solution under vigorous stirring; b) Attaining a pH of 4 and appearance of brown colour by the addition of alkali and acid to thereby obtain said silver nanoparticle based antibacterial media therefrom. 11. A process as claimed in claim 10 wherein said step (b) involved addition of 0.1 (N) NaOH dropwise under continuous stirring to provide a brownish yellow coloured solution at the pH of 10-10.5 followed by addition of 1% acetic acid to obtain a dark brown colored stable polymeric silver-chitosan nanocomposite colloids. 12. A process as claimed in claims 10-11 comprising the steps of a) Immersing said substrate/ media with or without cutting into pieces depending on the substrate/ media into colloidal silver-chitosan nanocomposite particles at room temperature for 24 hours, b) Separating and washing said substrate/ media with distilled water followed by air and oven drying at about 1000°C for about one hour to obtain therefrom substrate/ media impregnated and/ or coated with silver-chitosan nanocomposite particles. 13. A process for purifying contaminated water comprising microbes involving the steps of a) Providing said silver nanoparticle based antibacterial media impregnated and/ or as a coated substrate as claimed in claims 1-9 in a column like housing; b) Eluting contaminated water through said housing at a desired flow rate; c) Obtaining therefrom said purified water free of microbes that is potable for drinking purposes. 14. A process as claimed in claim 13 wherein said step (b) comprises eluting contaminated water through said housing preferably at a flow rate of 1.0 L/hr to obtain clean potable water free from microbes for 30 consecutive days of operation of the housing by passing 20 L of contaminated water per day.
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