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1-1_1.arsov ywp12

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1-1_1.arsov ywp12

  1. 1. First IWA-Bulgarian Young Water Professionals ConferenceWASTEWATER TREATMENT TECHNOLOGIES – STATE OF ART Prof. D.Sc. Eng. Roumen Arsov University of Architecture, Civil Engineering and Geodesy Bulgarian Water Association Sofia, 17 May 2012 1
  2. 2. Wastewater Treatment technologies – State of Art The term “Best Available Technologies” – BAT is in use more than 20 years, but it was legally introduced by the Water Framework Directive 2000/60/ЕС, Article 10, 2(a). Definitions Technologies, insuring achievement of the standards requirements and being proved their technical, economical and social efficiency. “Best Available Technique is the most efficient and most progressed stage in development of the applied technology of wastewater treatment which was developed in such a scale enabling the employment of the technology under economically, socially and technically acceptable conditions and it is at the same time the most effective technique for water protection” (according to the Czech Republic governmental Decree No 227/2007). 2
  3. 3. Wastewater Treatment technologies – State of Art Principles of contemporary wastewater treatment technologies are known for about a century and the term “contemporary” nowadays concerns plenty of technological arrangements (layouts) and constructive modifications of the relevant technological units, stimulated by developments in ecological and technical standards, materials, equipment and construction technologies Biological Wastewater Treatment Technologies are in the core of the contemporary Best Available Technologies (BAT), applicable to municipal wastewater treatment The following two main divisions of municipal wastewater biological treatment are in use nowadays: Intensive Biotechnologies  With suspended biomass  With attached biomass Extensive Biotechnologies  Constructed wetlands  Biological lakes and lagoons  Send bed trickling filters  Hybrid biological systems 3
  4. 4. Intensive Biotechnologies with Suspended Biomass Principal layout of activated sludge system 4
  5. 5. Intensive Biotechnologies with Suspended Biomass Recirculation of NO3- Aerobic Anaerobic Anoxyc Secondar bioreactor y bioreaktor bioreactor Clarifier Recirculation of activated sludge Principal layout of nitrogen and phosphorus biological removal 5
  6. 6. Intensive Biotechnologies with Suspended Biomass Recirculation of NO3- Al2(SO4)3 Anoxic Aerobic bioreactor Secondary bioreactor calrifier Recirculation of activated sludge Principal layout of nitrogen biological removal and phosphorus chemical precipitation 6
  7. 7. Intensive Biotechnologies with Suspended BiomassGeneral view of aerated tank - construction type “Carousel” 7
  8. 8. Intensive Biotechnologies with Suspended BiomassGeneral view of aerated tanks – construction type “Plug flow” 8
  9. 9. Intensive Biotechnologies with Suspended BiomassScheme of Sequencing Batch Reactor - SBR 9
  10. 10. Intensive Biotechnologies with Suspended BiomassGeneral view of aerated tanks – technological type SBR (Hisarya WWTP, Bulgaria) 10
  11. 11. Intensive Biotechnologies with Suspended BiomassScheme of membrane biological reactor - MBR 11
  12. 12. Intensive Biotechnologies with Suspended BiomassMembrane Biological Reactor (MBR) construction 12
  13. 13. Intensive Biotechnologies with Suspended BiomassScheme (left) and general view (right) of Upflow Sludge Blanket Reactor – USBR 13
  14. 14. Intensive Biotechnologies with Suspended BiomassScheme of granule biomass – bioreactor type USBR 14
  15. 15. Intensive Biotechnologies with Suspended BiomassRecommended most efficient area of application of aerobic and anaerobic biotechnologies 15
  16. 16. Intensive Biotechnologies with Attached BiomassTechnological layout of trickling filter 16
  17. 17. Intensive Biotechnologies with Attached BiomassGeneral view of trickling filter with plastic carrier 17
  18. 18. Intensive Biotechnologies with Attached BiomassGeneral view of trickling filter with reactive distribution system 18
  19. 19. Intensive Biotechnologies with Attached BiomassScheme of rotating biological contactors – RBC 19
  20. 20. Intensive Biotechnologies with Attached BiomassGeneral view of Rotating Biological Contactors (RBC) 20
  21. 21. Intensive Biotechnologies with Attached BiomassMoving Bed Biological Reactor (MBBR) construction 21
  22. 22. Extensive Biotechnologies EU COMPENDIUM for Design and construction of extensive wastewater treatment technologies for small settlements (500 - 5000 PE) 22
  23. 23. Extensive Biotechnologies with Suspended Biomass Schemes of facultative lagoon (left) and biological lakes cascade (right) 23
  24. 24. Extensive Biotechnologies with Suspended Biomass General view of aerobic and anaerobic biological lakes and lagoons 24
  25. 25. Extensive Biotechnologies with Attached Biomass Scheme of send bed trickling filter 25
  26. 26. Extensive Biotechnologies with Attached Biomass Technological schemes of constructed wetlands  with vertical flow (top)  with horizontal flow (down) 26
  27. 27. Extensive Biotechnologies with Attached Biomass Scheme (left) and general view (right) of constructed wetlands 27
  28. 28. Wastewater Treatment technologies – State of Art Driving Forces for Best Available Technologies (BAT) Development Legislation  Historical trend for pollution removal: SS, BOD, N and P (up to now), pharmacy micro pollutants (under investigations), S (future) Climate change and water stress – a prerequisite for:  Change of paradigm: from “wastewater as a problem” towards “wastewater as a resource”  Stimulation of wastewater recycling and reuse technologies  Stimulation of decentralized sewer systems development  Urine separation and treatment technologies Requirements for energy efficiency 28
  29. 29. Driving Forces for Best Available Technologies (BAT) Development Is there a rational sense in wastewater reuse?  Necessary water for food production - 1000 m3/PE.year  Necessary water for drinking - 1 m3/PE.year  Municipal wastewater production – 30 - 60 m3/PE.year 29
  30. 30. Driving Forces for Best Available Technologies (BAT) DevelopmentThere is a rational sense in water resources pollution prevention, because Untreated wastewater would pollute the following natural water resources volumes (in BOD5 base):  About 11 000 – 20 000 m3/PE.year in sensitive zones  About 5 000 – 10 000 m3/PE.year in less sensitive zones Therefore, 1 PE would pollute from 90 to 750 times more natural water resoursece than these used for potable needs (100 – 180 l/cap.d) Necessity of wastewater recycling and reuse stimulates technologies development for their treatment 30
  31. 31. Driving Forces for Best Available Technologies (BAT) Development Scheme of general concept for wastewater recycling and reuse 31
  32. 32. Driving Forces for Best Available Technologies (BAT) Development General view of infiltration ponds (California) 32
  33. 33. Driving Forces for Best Available Technologies (BAT) Development Scheme of urine separation system 33
  34. 34. Driving Forces for Best Available Technologies (BAT) Development Tendency for WWTPs energy efficiency General view of co-generation devices for biogas utilization 34
  35. 35. Driving Forces for Best Available Technologies (BAT) Development What is the share of the wastewater energy potential in respect to overall energy consumption per 1 PE? (some figures by K. Svardal & H. Kroiss, WS&T, 2011) Specific power consumption on the base of focil fuel - 5-10 kW/PE Specific power in human food consumption - 0,11 kW/PE Specific power in polluted wastewater - 0,0225 kW/PE Only 5 % of wastewater heat recuperation is economically feasible Therefore wastewater can not be considered as a reliable source of energy since they content no more than 0,44 % of domestic energy consumption of 1 PE 35
  36. 36. Driving Forces for Best Available Technologies (BAT) Development What is the share of the wastewater energy potential in respect to overall energy balance of the WWTP (some figures by K. Svardal & H. Kroiss, WS&T, 2011) Specific power for aeration at the big (over 50 000 PE) WWTPs, depending of the technology applied – 1,0-1,9 W/PE (3 - 15 W/m3) Total specific power at the big (over 50 000 PE) WWTPs, depending of the technology applied – 1,7-3,1 W/PE Specific power in polluted wastewater - 22,5 W/PE Specific electric power which could be obtained by biogas utilization, depending of the technology applied – 0,9-2,1 W/PE (with 25-37% co-generators efficiency) 36
  37. 37. Стремеж към енергийна ефективност What is the share of the wastewater energy potential in respect to overall energy balance of the WWTP - continuation (some figures by K. Svardal & H. Kroiss, WS&T, 2011) Therefore at big WWTPs (over 50000 PE), utilization of the biogas for electricity production is technically possible and economically feasible, for covering of the vast of the power needs Generated electricity production could be increased by:  Increasing of organic content of the sludge, treated in the high rate digesters by stimulation of primary sedimentation  Optimization of design of the high rate digesters  Increasing of the co-generators efficiency At the middle sized and small WWTPs (under 20 000 PE) the energy balance is negative - (from -27 to -32 W/PE), which makes biogas capture and utilization economically infeasible 37
  38. 38. Wastewater Treatment technologies – State of Art BASIC FEEDBACK AND CONCLUSIONS “Best Available Technologies” (BAT) are these, which are implemented in the current practice, based on advanced technological achievements Technological processes, applied with the BAT are known for about a century and the term “new” concerns mainly the plenty of technological modifications, based on developments in legislation, materials, construction technologies and equipment The most power factors influencing BAT development is legislation Ecological and technological standards developments are the most influencing factors for stimulation of the BAT development in comparison with these of “climate change” and “wastewater as energy and fresh water resource Trends towards achievement of the WWTPs energy efficiency is a contemporary imperative The WWTP energy consumption depends mainly on the pollution load rather than on wastewater flowrate ( Briscoe, Wasser-Abwasser, 1995) 38
  39. 39. Wastewater Treatment technologies – State of Art 39

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