ATHOS WET AIR OXIDATION PROCESS.

Transcription

1 European Workshop 15, 16 september Brussels Thermal Treatment of Sewage Sludge for CHP Applications ATHOS WET AIR OXIDATION PROCESS. Case study : N-Brussels N WWTP M. BELKHODJA OTV SA VEOLIA WATER SYSTEMS

2 SEWAGE SLUDGE : THE BIG ISSUE 8.0 M Dry tons /year produced in the E.U. land application : 40% landfill : 40% incineration : 10% other : 10% Page 2

3 VEOLIA WATER SYSTEMS Sludge Thermal Processes Sludge concentration Process Treatment Description needed PYROFLUID (OTV) Incineration 25-30% PYROFLUID S (OTV) Incineration for Small capacities 18-22% PYROMIX (OTV) Co-Incineration with MSW 18 25% ATHOS (OTV) Wet Air Oxidation 4-8% THELYS (OTV) Thermal Hydrolysis 12-18% BIOTHELYS (OTV) Sludge production reduction 4% BIOCON (KRUGER) J-VAP (US-FILTER) Drying Dewatering-drying device 15-30% - Page 3

4 WET AIR OXIDATION Principle Thermal oxidation in liquid phase using molecular oxygen T 330 Conditions HP Application 260 MP 200 BP P Biological WAO Incineration 20 g/l 200 g/l Page 4

5 Sludge Volume reduction Liquid 4% Final mineral 50% MS 100 m 3 2,0 m 3 Page 5

6 Page 6 Sludge Weight Reduction

7 WAO Incineration Comparison Incineration Thickning Dewatering Incinération WET AIR OXIDATION Thickning WAO Page 7

8 ATHOS HISTORY 1992 First tests on tubular plug flow reactor 1993 Autoclave tests 1995 Continous pilot plant (25 L/h PE) 1998 Start up of ATHOS Toulouse (3 m3/h PE) Page 8

9 Anjou Recherche R&D WAO Reactors Page 9 Autoclave reactor 25 l/h pilot unit

10 ATHOS REFERENCES Toulouse Trucazzanno N-Brussells Epernay (France) (Italy)) (Belgium)) (France) WWTP capacity: PE PE PE PE ATHOS capacity : TDS/y TDS/y TDS/y TDS/y ATHOS capacity : kg DS/d kg DS/d kg DS/d kg DS/d Flowrate : 3 m 3 /h 8 m 3 /h 24 m 3 /h 4 m3/h Devices : Sludge quality : mixed digested TH + digested digested Sludge conc. : 4.5% 8.0% 7.7% 7.6% Volatile fraction : 80% 53% 53% 56% Operating hours: h/y h/y h/y h/y Start-Up : Page 10

11 Page 11 ATHOS TOULOUSE INDUSTRIAL UNIT

12 Page 12 ATHOS TOULOUSE INDUSTRIAL UNIT

13 N-Brussels WTTP Sludge Treatment Water Treatment Clarification Dewatering Thermal Hydrolysis Digestion Incineration forbidden Wet Air Oxidation Dewatering/drying Landfill Page 13

14 Sludge Train Comparison Thickning Dewatering WAO THP+WAO Design volume 96 m3/h 24 m3 /h Thermal Hydrolysis Oxygen need kg/h kg/h Digestion Wet Air Oxidation Electricity MWh/y MWh/y Wet Air Oxidation Dewatering Dewatering Landfill Landfill Page 14

15 N-Brussels Case Study : Sludge Treatment Water Treatment Clarification Dewatering Thermal Hydrolysis Digestion Wet Air Oxidation Dewatering/drying Landfill Municipal sludge TDS/y 16% DS, 73% VM Hydrolysed sludge TDS/y 16%DS, 12%SS, 73%VM Digested sludge TDS/y 12%DS, 7.7%SS, 53%VM Mineral sludge DS/y 10% DS - <5% VM Mineral sludge DS/y 95% DS - <5% VM Page 15

16 ATHOS Process Operating conditions 250 C, 50 bar, pure O2 perfectly mixed reactor Copper sulphates as catalyst Mineralization Process in liquid phase & low temperature Typical performance : - COD removal : > 85% - Volume Reduction > 98% Liquid effluent Highly biodegradable (mainly acétic acid) Residual Solid -Mineral, COT <5% -No leaching - 55% DS min dewatering with no additives Off-Gas -No dioxins, furannes, NOx, HCl, and dust - Thermal Treatment operation needed : CO, VOC Page 16

17 ATHOS PROCESS gas Oxygene Thick Sludge WWTP Page 17 Dewatering

18 ATHOS MINERAL SOLIDS Mineral solids caracterization Typical analysis (% de DS) SiO 2 CaO Al 2 O 3 CO 3 SO 4 P 2 O Particules : medium 2.7 µm (1 ~10) COT < 5 % Leaching tests : all metals fixed, Construction Solids Re-use Page 18

19 Thermal Hydrolysis and Digestion Principle : Thermal hydrolysis under moderate pressure (8 bars) and temperature (165 C) of dewatered sludges - Thermal Hydrolysis Process (THP) Batch Process Solubilization process -steam C < 10 bar < 1 hour -Digestion Page g/l - 14 à 18 days retention time VM Total removal: 55 to 62% 60 to 85% more biogas production No need of recirculation heating loop Easy dewatering : up to 35% DS

20 Sludge Thermal Hydrolysis Thermal Hydrolysis 15-16% DS sludge % SS sludge 15-16% DS sludge 10-12% SS sludge Page 20

21 Thermal Hydrolysis & Digestion Thermal Hydrolysis Flash Steam Biogaz Thick sludge T=165 C P= 8 bars T=110 C P= 3 bars T=40 C Digested sludge Centrifugation 12-16% 16% DS T=85 C Fresh Steam Fresh Steam T=190 C P=12 bars T=190 C P=12 bars TH Reactor Hot Water Turbo digestion Page 21

22 N-Brussels WWTP : Heat Recovery Water Treatment Clarification 2 x 1500 kw Flash steam Dewatering Thermal Hydrolysis Steam Electricity Water Boiler Buildings Heating kw kw kw Self- sustaining Digestion Wet Air Oxidation Biogaz Steam Steam Generator kw Hot Water kw Dewatering/drying kw Landfill Page 22

23 Dewatering/Drying Process Blow down air Feed Slurry Filter press Hot water storage tank Pre-condenser Vacuum source Filtrate Dry cake discharge Page 23

24 Conclusion: The innovative N-Brussels sludge train is cost effective for high plant capacity using THP & WAO Process Better public acceptance for WAO than Incineration Page 24