1. NEPTUNE WP-2: Novel treatment technology for wastewater and sludge Ghent University - Laboratory of Microbial Ecology & Technology Kick-Off meeting NEPTUNE November 2th 2006, Rome

2. Introduction and objectives Wastewater as wasteWastewater as a resource

3. Introduction and objectives Wastewater as a resource Established technologies improved and complemented with novel technologies. Microbial fuel cells  Energy recovery and nutrient removal Ferrate oxidation Manganese oxide based oxidation  Removal of micropollutants High temperature pyrolysis Polymer production from sewage sludge  Valorisation of sludge waste

4. Established technologies Conventional aerobic treatment: + Simple process and high treatment efficiency - Aeration cost: 0,5 kWh m -3 = 30 kWh.IE -1.yr -1 -Sludge disposal cost: up to € 500 ton -1 DM Anaerobic digestion: +Biogas production = Energy recovery 1 kg COD converted = 1kWh - Water temperature >28 °C - Not applicable for low strength wastewaters Can microbial fuel cells be an alternative?

5. Microbial fuel cells: the challenger MFC technology + The chemical energy of various types of reducing compounds can be recovered as kWh +Works at low temperatures + Produces low amounts of excess sludge - Bacteria need to “like” it

6. Batteries and fuel cells Anode: oxidation occurs, electrons go to an electrical circuit Cathode: reduction occurs, electrons arrive from an electrical circuit

7. Microbial fuel cells Anode: oxidation of substrate by a biocatalyst Cathode: reduction of oxygen

8. MFC Biofilm ecology

9. Electricity generation from discrete substrates TAKE HOME: Power densities and substrate to current conversions are increasing

10. Electricity generation from discrete substrates TAKE HOME: Power densities and subtrate to current conversion are lower for O 2 compared to K 3 Fe(CN) 6 systems => a good functioning sustainable cathode is needed!

11. Electricity generation from wastewater TAKE HOME: Substrate to current conversions are lower compared to discrete substrates: biodegradability!

12. Reactor design: anode MFC in Neptune - Open air cathode - Tubular configuration - Continuous system

13. Can stacked MFCs provide power at enhanced voltage and current? By connecting several batteries or power sources in series and parallel, voltages and currents can be increased. Series connection:= addition of voltages Parallel connection = addition of currents Does the series and parallel connection influences the anodic biocatalytic performance of a MFC?

14. Stacked MFC design 6 individual MFC units Anode: granular graphite matrix synthetic influent Cathode: granular graphite and ferrocyanide Membrane: Ultrex Rubber sheet: separation between the individual MFCs No bipolar plates The void volume of the anode was 60 mL

15. Stacked MFCs provide power at enhanced voltage and current Maximum voltage and current generation without power generation: Open circuit voltage = 4,2V (Series) Short circuit current = 425 mA (Parallel) Voltage and current at maximum power densities (P v max) during series, parallel and individual stack operation: TAKE HOME: High power densities can be maintained during series and parallel connection

16. Reactor design: anode Select a performing electricity producing microbial consortium suited for the mix of soluble COD present in sludge digestate Maximize energy recovery and COD removal by optimizing the anode potential Investigate the influence of the operational parameters on the removal of humic acids and xenobiotics Build a technical scale MFC for energy recovery and treatment of the digestate

17. Reactor design: cathode Jurg or Korneel, could you provide a specific slide explaining your work part?

18. Reactor design: cathode Optimize the cathode compartment of an MFC Develop a cathodic denitrification process

19. Microbial fuel cells applications Stand alone MFC technology: Several MFCs in series or parallel to deliver electricity at the desired current and voltage Wastewater MFC kWh

20. Combined micro-pollutant removal Recalcitrant waste water: First: ferrate, manganese oxide, pyrolysis technology Second: MFC Wastewater MFC kWh Ferrate MnO 4 Pyrolysis

21. Ferrate technology (EAWAG) Develop kinetic database for the oxidation of phenol-, amine-, and sulphur- containing micropollutants Study and model the micropollutant oxidation by ferrate(VI) Compare phosphate removal with ferrate(VI) vs. conventional with Fe(III) Ferrate(VI): simultaneous oxidation of micropollutants and phosphate removal

22. Manganese oxide upflow bioreactor technology (LabMET) MnO 2 as solid phase oxidative agent provides catalytic surface Partly oxidizes recalcitrant compounds (humic acids, atrazine...) MnO 2 Mn 2+ Bacteria re-oxidize Mn 2+ to MnO 2 Bacteria utilize low molecular organics MnO 2 precipitate acts as catalytic surface again In situ regeneration of oxidant by Mn oxidizing bacteria

23. Mn-oxide UBR (LabMET) Pretreatment of recalcitrant wastewater 2 L upflow bioreactor filled with 750 mL MnO 2 HRT: 1 h Monitoring of effluent for recalcitrant compounds of interest: analytical methodology / biological assays UBR as stand-alone or in combination with MFC technology

24. High temperature pyrolysis Valorisation of sludge as soil amendment High temperature pyrolysis: Guarantee microbiologically and chemically safe sludge Removal of heavy metals Recovery of phosphorus

25. Polymer production from sewage sludge PHA: biodegradable copolymers of PHB and PHV (polyhydroxybutyrate and -valerate) Why biodegradable polymers ? Synthetic plastics: 25 Mton/yr in EU + US < 20% recycled or incinerated > 80% in landfills and marine environments

26. Production of PHAs Pure microbial culture: high costs ! Mixed microbial cultures: Phosphorus accumulating organisms (PAO) Glycogen accum. org. (GAO) Activated sludge- aerobic dynamic feeding (ADF) Valorize waste streams by digesting it and produce VFA (volatile fatty acids) as starting substrate for PHA production

27. PHA low-cost production Large scale production will be required to meet realistic demands in polymer supply Abundant and concentrated organic waste needed Primary and secondary sludge (biosolids) Ferment to VFA using Cambi process as pretreatment (high pressure thermal hydrolysis) Biosolids solubilization and complete pathogen destruction Optimize process for VFA and subsequent PHA production: Cambi-process, microbial inoculum, reactor feeding regime, proper C/N ratios...

28. Milestones & expected results Novel MFC design for efficient COD removal and energy recovery from domestic wastewater with demonstrated low sludge production. MFC-based treatment system to achieve nitrogen and phosphorus removal from domestic wastewater. Tailored oxidation technologies for adequate micropollutant removal Valorisation strategies for sludge with warranted microbiological and chemical safety