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Membrane separation techniques and their domain of application

Membrane separation techniques and their domain of application. pressurized membrane filtration: operation with prevention of fouling. Hollow fibers. ultrafiltration unit, Vigneux 55000 m 3 /day. water disinfection by UV irradiation. European Water Framework Directive 2000/60.

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Membrane separation techniques and their domain of application

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  1. Membrane separation techniques and their domain of application

  2. pressurized membrane filtration: operation with prevention of fouling

  3. Hollow fibers

  4. ultrafiltration unit, Vigneux 55000 m3/day

  5. water disinfection by UV irradiation

  6. European Water Framework Directive 2000/60 • requires that all inland and coastal waters within defined river basin districts must reach at least good (ecological) status by 2015 • transboundary if necessary • defines how this should be achieved through the establishment of environmental objectives and ecological targets for surface waters • action plan to be published end 2009 by all Member States

  7. Phosphate removal • BNR plants • Discard phosphate anaerobically • Luxury aerobic uptake of P in aerobic stage • Process adaptations for N and P removal EBPR plants Air Wastewater Anaerobic Anoxic Aerobic

  8. Enhanced biological phosphate removal (EBPR) the principle Dry solids of conventional activated sludge have a total phosphorus contents of 1 - 1.5 %, while those of enhanced biological P removal plants (based on a luxury-uptake process) can achieve up to > 4 % TP. (Melasniemi 2000) Under anaerobic conditions phosphate-accumulating organisms (PAOs) are not able to grow but can accumulate and store organic substrate by converting small organic acids into poly-hydroxy-butyrate (PHB) and similar energy rich organic compounds. For this process the PAO bacteria need energy which they gain under anaerobic conditions from the conversion of stored energy-rich polyphosphate (polyP) to dissolved phosphate which is released to the water under these conditions. When oxic conditions are met again, PAOs reconstitute their internal polyphosphate ‘batteries’ resources. This process is called luxury uptake (because the P uptake is then far higher than what would occur in usual biotreatment conditions).

  9. Pressurized air Degassing Anaerobic This process will be illustrated by the technical visit of the biological wastewater treatment plant in Waterloo (compulsory visit for all, including EIB students).

  10. To reach good nitrification rates, it is necessary to work at a low F/M ratio. The biomass concentration thus needs to be higher than in the conventional process. These requirements have consequences regarding the subsequent sludge manipulation options and disposal routes.

  11. struvite precipitation more sustainable, because it involves nutrient recovery

  12. 1 - Agitator 2 - Flocculator 3 - Settler 4 - Raw water in 5 - Settled water out 6 - Purge

  13. Nitrogen removal • Nitrification (Nitrosomonas and Nitrobacter) • NH3 + O2  NO2-  NO3- • Denitrification • NO3- + organics  CO2 + N2 • Process adaptations Air Anoxic Aerobic

  14. Ammonia stripping • Two-step physical-chemical method • Step 1: Raise pH to 10.5-11.5 • convert ammonium ions to ammonia gas • Step 2: Air-strip • cascade wastewater countercurrent to air flow • ammonia gas escapes to atmosphere • Pro: less costly, no sludge or Cl by-products • Cons: acids/bases, scale, freezing problems

  15. electron acceptor exothermic

  16. Electron acceptors

  17. polystyren foam low-density microbeads 3 to 4 mm diameter Biostyr process (OTV)

  18. Anammox process In the 1990s, researchers discovered that there could be other biological processes other than nitrification/denitrification that are able to remove nitrogen from wastewater. The phenomenon of anaerobic ammonia oxidation was observed and the scientists at TU Delft identified the organisms responsible for the process to be from the Planctomycetes family. With this information, TUD Prof Van Loosdrecht designed an innovative process – Anammox (ANaerobic AMMonium OXidation) process which converts ammonium to harmless nitrogen gas This process only requires the conversion of half of the ammonium to nitrite resulting in the reduced need for aeration, thus saving energy. The bacteria involved in the Anammox process will then convert ammonium and nitrite together into nitrogen gas without the need for any additional organic carbon compounds. Anammox is able to reduce carbon dioxide emissions by up to 90% compared to conventional nitrification / denitrification processes. It occupies up to 50% less space and reduces aeration energy by up to 60%. NH4+ + NO2- N2 + 2H2O

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