Putting the Misconceptions to Rest:

Transcription

1 Putting the Misconceptions to Rest: 2010 HWEA Conference Honolulu, HI Brandy Nussbaum I. Kruger, Inc

2 Clarification/Separation OPTIONS Following MBBR Treatment

3 Discussion Topics What is MBBR Conventional Clarification High Rate Ballasted Clarification Dissolved Air Flotation Discfiltration Granular Media Filtration Membranes Summary

4 The Principle of the Moving Bed Biofilm Reactor (MBBR) Technology Aerobic reactor Anoxic reactor

5 The Moving Bed Biofilm Reactor (MBBR) in Practice

6 Components to the MBBR Aerobic System AnoxKaldnes Media Media Retention Sieves 304L Stainless Steel Cylindrical Wedge Wire Perforated Plate foam control sieves AnoxKaldnes Aeration Grid 304L Stainless Steel Medium Bubble Maintenance Free No replacement parts

7 Components to the Anoxic MBBR System AnoxKaldnes Media Media Retention Sieves 304L Stainless Steel Flat Panel Wedge Wire Slow-Speed Mixers Submersible or Top entry Can be speed controlled

8 MBBR Solutions Highly Flexible MBBR stand-alone MBBR as pre-treatment (roughing, BAS TM ) MBBR as tertiary treatment (polishing, LagoonGuard TM ) MBBR in activated sludge (HYBAS TM /IFAS)

9 MBBR Biomass Separation Alternatives MBBR - settling MBBR Actiflo (ballasted flocculation) MBBR - Flotation MBBR Media Filtration MBBR Disc Filter MBBR Membrane Filtration

10 Development of PSD s at various MBBR loadings (HRT s) (Åhl et al, 2006) diff volume% diff number% inlet HRT = 1h HRT = 2h HRT = 3h HRT = 4h 0,01 0, particle diameter µm inlet HRT = 1h HRT = 2h HRT = 3h HRT = 4h 0,01 0, particle dimeter [µm] 1. There is a shift towards a higher volume of larger particles with increasing HRT 2. There is at the same time, however, a relative increase in the number concentration of submicron particles with increasing HRT Hypothesis : Flocculation is taking place Erosion of single bacteria or remains of dead cells happens Both are f(loading/hrt)

11 Relative amounts of COD in the different size fractions (Melin at al, 2005) Amount of COD (%) >1 µm µm 30 kd-0.1 µm <30 kd Size fraction a) Majority of COD in particles > 1 µm Increase in the suspended COD with increasing HRT Decrease in colloidal particles (0,1 1 µm) when HRT increase HRT = 0.75 h HRT = 1 h HRT = 3 h HRT = 4 h

12 Conventional Settling after MBBR Without coagulation Coagulant With coagulation Metal salt (Al, Fe) Cationic polymer Low Al/Fe + cat. polymer High Al/Fe + anionic polymer

13 Cheyenne Crow Creek WWTP

14 THE CROW CREEK WATER RECLAMATION FACILITY New Treatment Process Primary Clarifier 1 Screening & Degritting Primary Clarifier 2 Flow Split Anoxic Basins (Pre-Denite) New MBBR Reactors Future Nitrate Recycle Discharge Reuse Filters Alum/Polymer Sludge UV Disinfection Secondary Clarifier 2 Secondary Clarifier 1

15 PERFORMANCE DATA Cheyenne BOPU Crow Creek WRF TSS Removal - 30 Day Avgerage Influent Effluent Influent Effluent

16 Actiflo Microsand Ballasted Clarification Sludge Hydrocyclon M Microsand M M M Outlet Coagulant Inlet Injection Flocculation Coagulation Lamella- - Polymer sedimentation Coagulant Microsand Polymer Water Primary particles Flocs

17 South Adams WWTP MBBR-ACTIFLO Pilot Influent characteristics Coagulants and dose Effluent characteristics Process Rise rate 3 mg SS/l Turb FeCl 3 or Al s (SO 4 ) 3 + anionic polymer 1 mg SS/l Turb. mg P/l MBBR m/h 12.4 mg Fe/l + 0,8 mg/l 3 < 2 ACTIFLO most tests at m/h mg Al/l + 0,6 mg/l 6.2 mg Fe/l + 0,6 mg/l < 5 5 < mg Fe/l + 0,45 mg/l 10 MBBR + Settling m/h 13.2 mg Fe/l + 0,5 mg/l 1.4 <0,1 ACTIFLO 100 m/h 3,5 4, mg Al/l + 0,6 mg/l < 2 >0.3 MBBR + Settling + 90 m/h 13.2 mg Fe/l + 0,5 mg/l < 1 <0.1 ACTIFLO Turbo 115 m/h 3,5 4, mg Fe/l + 0,5 mg/l 1.2 < m/h 9.1 mg Al/l + 0,6 mg/l Anionic polymer M155 2 Lowest value achieved - at high Al dose (14.4 mg Al/l) 3 Rise rate, hydraulic surface load (m 3 /m 2. h) calculated on the settler foot-print area

18 Summary of Pilot Results, Quebec, Can (John Meunier, VWS, Can) Actiflo following MBBR MBBR load : Actiflo rise rate: FeCl 3 -dose : Polymer dose : 4 25 g BOD 5 /m 2 d m/h µl/l mg/l Parameter units Influent Effluent % removal Total P (mg/l) Turbidity NTU TSS (mg/l) COD (mg/l) BOD (mg/l) ph

19 Example Drammen WWTP Inlet Line 1 Line 2 Outlet Line 3 Upgrading a chemically enhanced primary plant to become a secondary plant by the use of MBBR and ACTIFLO 4 1: Flocculation 2: Sedimentation 3: Thickeners 4: Sludge silo Line 4 Line 5 Line 6 Inlet Kaldnes MBBR 1-1 Kaldnes MBBR 1-2 DAF 1 Outlet Inlet Kaldnes MBBR 1-1 Kaldnes MBBR 1-2 Outlet Kaldnes MBBR 2-1 Kaldnes MBBR 2-2 DAF 2 Kaldnes MBBR 2-1 Kaldnes MBBR Kaldnes MBBR 3-1 Kaldnes MBBR 3-2 DAF Kaldnes MBBR 3-1 Kaldnes MBBR 3-2 Kaldnes MBBR 4-1 Kaldnes MBBR 4-2 DAF 4 Kaldnes MBBR 4-1 Kaldnes MBBR Kaldnes MBBR 5-1 Kaldnes MBBR 6-1 Kaldnes MBBR 5-2 Kaldnes MBBR 6-2 DAF 5 DAF Actiflo 1 Actiflo 2 1: Kaldnes MBBR 2: DAF 3: Sludge silo 3% TS 4: Sludge silo 6% TS 1: Kaldnes MBBR 2: Actiflo 3: Thickeners 4: Sludge silos 6% 5: Free space (chemical handling)

20 Two MBBR ACTIFLO in Bergen Under Construction Bergen WWTP design: r BOD = 11,5 g BOD 5 /m 2 d v f = 60 m/h (rise rate in settling zone)

21 Handeland, Skreia MBBR/Actiflo Plants BOD5 results Handeland WWTP Influent concentration Effluent concentration Concentration BOD5, mg/l a. Handeland WWTP 0 BOD 5 results Skreia WWTP BOD5:Inlet BOD5:Outlet 35 Inlet concentration, g O/m Outlet concentration,g O/m b. Skreia WWTP Date

22 MBBR-Flotation (DAF) Historically a very popular option for compact MBBR separation in Scandinavia Data below from the Johnstown, CO LagoonGaurd MBBR- DAF Installation Parameter DAF influent Range Average DAF Effluent Range Average Turbidity, NTU BOD mg/l TSS mg/l

23 Typical design values for DAF following MBBR (Ødegaard et al, 2009) Tank depth Surface overflow rate (m 2 /m 3. h) At design flow, At maximum design flow, 2 3 m Q dim 5 Q maxdim 10 Dispersion pressure : kpa (4-6 bar) Air saturation: % Dispersion water flow (% of Q maxdim ) : % (depending on SS in and air saturation)

24 Average Results from three Scandinavian Plants using DAF after MBBR Parameter Nordre Follo WWTP Gardermoen WWTP Sjölunda WWTP Design values Design flow (m 3 /h) Max. flow (m 3 /h) Temp. ( o C) Plant size Tot. MBBR vol. (m 3 ) Flocculation vol. (m 3 ) Flotation area (m 2 ) Year documented Average in-out conc. and treatment efficiency In Out % In Out % In Out % SS (mg/l) BOD (mg/l) COD (mg/l) Tot N (mg/l) Tot P (mg/l)

25 MBBR - Microscreening The Hydrotech Disc Filter Directly after MBBR or for polishing Sieve openings: µm Operational head-loss: 10 Backwash during operation Disc Filter plant after post DN MBBR at Rya WWTP, Gothenburg, Sweden

26 Results from the Rya WWTP Discfilter (Mattson et al, 2009) Mesh pore size, µm Feed, mg SS/l Effluent, mg SS/l Capacity, m 3 /m 2 filter. h Average St.dev. Average St.dev. Average St.dev. Number of Samples micron 18 micron Filtration velocity (m/h) Influent SS (mg/l) Filtration rate (based on total filter mesh area) versus influent SS (Persson et al. 2006)

27 Discfilter With Chemical Dosing Effluent SS (mg/l) Gardermoen WWTP 40 micron Nordre Follo WWTP 40 micron Gardermoen WWTP 20 micron Effluent SS (mg/l) Gardermoen WWTP Nordre Follo WWTP Influent SS (mg/l) Polymer dose (mg PE/g SS) Effluent SS versus influent SS without any pre-coagulation/flocculation Effluent SS as a function of polymer dosing.

28 Sand filtration after MBBR Various uses: As polishing step Directly after nitrifying or denitrifying MBBR Ex.: Klagshamn WWTP 8,2 m/h at Q max Effluent : < 5 mg SS/l, 0,2 mg P/l Directly after high-rate (secondary treatment) MBBR- Cheyenne Crow Creek

29 Membrane filtration after MBBR Different strategies tested a. MBBR submerged hollow fiber UF membrane (i.e. Zenon ZeeWeed) b. MBBR Discfilter Contained hollow fiber UF membrane c. MBBR submerged membrane in reactor with settling zone d. MBBR DAF Contained hollow fiber UF membrane

30 Conclusions 1. Particle size distribution (PSD) of biomass leaving MBBR: a. Large mass fraction of relatively large particles ( µm), but a high number of small particles (0.1 1 µm). The easiest way to deal with the latter is by coagulation ahead of the separation reactor b. The PSD is shifted towards larger particles when the organic area load is decreasing (HRT is increasing). Hence the higher the area load, the better is the effect of pre-coagulation 2. All of the commonly used separation methods may be used. a. MBBR allows the use of a variety of separation methods providing greater flexibility that the AS processes miss b. DAF is well proven c. Microsand ballasted lamella settling (Actiflo) is of increasing interest and results in an extremely compact plant d. A very compact solution is also achieved with the use of Discfilter di tl ft th MBBR li hi t ti t

31 Final Thoughts