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Marelize Botes 15 March 2010. Contaminated drinking water - main cause of diseases in development countries. 1.1 billion people do not have access to.

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Presentation on theme: "Marelize Botes 15 March 2010. Contaminated drinking water - main cause of diseases in development countries. 1.1 billion people do not have access to."— Presentation transcript:

1 Marelize Botes 15 March 2010

2 Contaminated drinking water - main cause of diseases in development countries. 1.1 billion people do not have access to safe water (WHO, 2004). The importance of water disinfection and microbial control cannot be overstated.

3 Water quality problems Urban/Industrial effluent Acidic atmospheric deposits Groundwater contamination Agricultural chemicals Excessive sediment Metals (mining) Radioactivity Salinity

4 Chemical disinfectants and membrane- based water filtration systems control microbial pathogens. Harmful DBP’s and ↑resistant pathogens 2 significant obstacles in filtration are Biofouling and virus penetration

5 The accumulation of microorganisms such as bacteria, fungi and algae on the membrane surfaces, with the subsequent formation of harmful biofilms and operational problems. Membrane permeability and membrane lifetime are reduced and energy costs are increased. High cost involved in controlling membrane biofouling and subsequently buying new membranes.

6 Water loss and quality deterioration associated with aging distribution networks and the increasing cost to transport water. Increasing need for alternative water sources and wastewater reuse for water shortage problems. Urgent need for decentralized/point- of-use water treatment and reuse systems.

7 Potential solution = nanofibrous filter media High surface to volume Low basis weight High permeability Small pore size → Remove unwanted particles smaller than 0.3 µm Styrene dimethyl aminopropyl maleimide

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9 The first patent was published in the USA. Filters of Petryanov was kept top secret in Russia. Were used after the Second World War to protect the environment from nuclear-active aerosol release. Production gained momentum in 1980 in America and only started in the 1990s in Europe. Currently more than 20 enterprises worldwide.

10 S.N.EnterprisesCountry 1Donaldson Company Inc.USA 2Espin Technologies Inc.USA 3KX IndustriesUSA 4Ahlstrom CorporationFinland 5Hollingsworth Co. Ltd.USA 6US Global NanospaceUSA 7Finetex TechnologyS. Korea 8Helsa-automotiveGermany 9Nanotechnics Co. Ltd.S. Korea 10Teijin Fibers Ltd.Japan 11TorayJapan S.N.EnterprisesCountry 12 Japan Vilene Company Ltd. Japan 13 Nanoval GmbH & Co. KG Germany 14Hills Inc.USA 15 Nonwoven Technologies Inc. USA 16 Emergency Filtration products, Inc. USA 17Elmarco Czech Republic 18 Hohns Manville Sales GmbH Germany 19 Nanofiber Future Technologies Corp Canada 20Esfil Tehno Republic of Estonia

11 PolymerSolventConcentration Polyurethane (PU)Dimethyl formamide10 wt % Polycarboate (PC) Dichloro-methane Dimethylformamide: tetrahydrofuran (1:1) 15 wt % 20 wt % Polylactic acid (PLA)Dichloromethane5 wt % Polyethylene oxide (PEO)Isopropyle alcohol and water10 wt % PolyvinylcarbazoleDichlormethane7.5 wt % PolystyreneTetrahydrofuran15 wt % Polyamide (PA)DimethylacctamideNot available Cellulose acetate (CA)Acetone, acetic acid17 %

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15 Small pore sizes, high specific surface areas and high porosity ↓ 3 uses in water treatment Separate solid impurities from the liquid phase ↓ Filtration Selective absorption/ Adsorption ↓ Affinity membranes Neutralise or decompose impurities ↓ Reactive membranes

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18 Functionalization by spinning blends of specific polymers Coating of fibers Inclusion of functional components such as antimicrobial nanoparticles

19 nanobiocides Metal and metal oxides e.g. nAg, ZnO, CuO, TiO 2 Engineered/syn- thesized nanoparticles such as fullerenes e.g. nanomagnetite (nC 60 ) and carbon nanotubes Natural antimicrobial substances e.g. antimicrobial peptides and chitosan

20 Silver nanoparticles is considered to be the most toxic element to microorganisms: Ag >Hg >Cu >Cd >Cr >Pb >Co >Au >Zn >Fe >Mn >Mo >Sn considered an alternative to antibiotics. Antimicrobial filters, wound dressing material, water disinfection, sensors, air filtration

21 PAN fibers with 5 wt% AgNO 3 forming silver nanoparticles on fiber surface with lysed S.aureus Neat PAN fibers with in tact S.aureus

22 IVIS imaging of PAN fibers with or without 5%wt AgNO 3 Pseudomonas aeruginosa Escherichia coli Staphylococcus aureus

23 Zinc oxide (ZnO) nanoparticles have strong antimicrobial activity. Penetrate the bacterial cell envelope and disorganize the cell membrane. Applicated in pharmaceutical products and in surface coatings to prevent biofilm. Applications in water treatment is questioned as it is highly soluble in water increasing sensitivity of aquatic organisms towards ZnO. Copper oxide nanoparticles

24 Titanium dioxide kills bacteria and viruses. Produce hydroxyl free radicals and peroxide formed under UV-A irradiation via oxidative and reductive pathways, respectively. TiO 2 is stable in water and cost effective and can therefore be successfully incorporated in thin films or membrane filters for water filtration.

25 Fullerenes (C 60 ) Carbon nanotubes should be immobilized on a reactor surface or polymer matrix. Applicated in the prevention of biofilm formation in water filtration membranes. High cost involved and potential toxicity may hamper the use of carbon nanotubes in water filtration. NanoCeram ® cartridges

26 Natural antimicrobial substances – antimicrobial peptides and chitosan Chitosan nanoparticles show potential in drinking water disinfection applications such as antimicrobial agents in membranes, sponges and surface coatings

27 Two significant challenges in the long term are apparent. 1) the loss of antimicrobial or antiviral activity The cost involved and the impact on human health and environment. safety of escaped nanobiocides is not proved yet. Nanobiocides can also be turned into harmful chemicals when exposed to chlorine and UV. 2) Bacteria may become resistant towards the nanobiocides.

28 Solutions → Improve fixation techniques by concentrating the nanobiocides closer to the surface of the membrane. → Encapsulation in a polymer matrix to decrease the release rate. → Modify the polymeric surfaces

29 Nanofibers show potential in water treatment processes. Reactive membranes may be the solution for high-performance, small-scale/point-of-use systems. →Increase robustness of water supply networks and water systems not connected to a central network. →Emergency response following catastrophic events.

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