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ANAEROBID DIGESTION IN FULL EVOLUTION W. VERSTRAETE Lab. Microbial Ecology and Technology (LabMET) Faculty of Bioscience Engineering, Ghent University.

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Presentation on theme: "ANAEROBID DIGESTION IN FULL EVOLUTION W. VERSTRAETE Lab. Microbial Ecology and Technology (LabMET) Faculty of Bioscience Engineering, Ghent University."— Presentation transcript:

1 ANAEROBID DIGESTION IN FULL EVOLUTION W. VERSTRAETE Lab. Microbial Ecology and Technology (LabMET) Faculty of Bioscience Engineering, Ghent University Coupure L 653, B-9000 Gent, Belgium

2 From Less waste Less sludge production Lower carbon footprint To More energy recuperation Digestion is now all about kWh 1. THE DRIVERS

3 Table 1: Examples of subsidies in different European countries for green electricity production by anaerobic digestion of agricultural waste. These values differ based on the size of the plant, and additional bonuses (Bundesministeriums für Umwelt, Naturschutz und Reaktorsicherheit - BMU, 2011). CountryType€/MWh el Guaranteed years BelgiumQuota (Green certificates)12010 NetherlandsPrice regulation (bonus)7912 SpainPrice regulation108 – FrancePrice regulation75 – 90 * 15 GermanyFixed compensation AustriaPrice regulation124 – ItalyQuota (Certificati verdi)220 – * + additional bonuses (20 – 50 €/MWh) : Take home: €/tonCOD;150 Euro /ton DS

4 2. THE EVOLVING BIOCATALYTIC PROCESS Carbohydrates Fats Proteïns Sugars Fatty Acids Amino Acids Hydrolysis Carbonic Acids and Alcohols Hydrogen Carbon Dioxide Ammonia Hydrogen Acetate Methane Carbon dioxide 30% 70% AcidogenesisAcetogenesisMethanogenesis HM = Hydrogenotrophic Methanogenesis AM = Acetoclastic Methanogenesis BacteriaArchaea

5 Normal waste treatment reactor systems / The old route 2. THE EVOLVING BIOCATALYTIC PROCESS 70%

6 2. THE EVOLVING BIOCATALYTIC PROCESS Proposed robust methanogenesis system, based on syntrophic acetate oxidizing (SAO) bacteria and robust HM for intensive energy production reactor systems. The new route !!!

7 2. THE EVOLVING BIOCATALYTIC PROCESS: RATE LIMITING STEPS 1. Higher VFA Acetate + H ₂ Syntrophic acetogenic bacteria (SAB) Exp:Syntrophobacter Syntrophomonas …  Weak bacteria  t d = weeks Molecular monitoring: - Generic: not available -Specific: 16SrRNA probes This ‘go between ‘ group is very weak pH ₂ < atm

8 2. THE EVOLVING BIOCATALYTIC PROCESS: RATE LIMITING STEPS 2. Acetate CO ₂ + CH ₄ Acetoclastic methanogens (AM) Exp: Methanosaeta Methanosarcina  Weak archaea  t d = weeks  Robust archaea  t d = days Molecular monitoring: - Generic: All methanogenic archaea have methyl coenzym-M reductans -Specific: 16SrRNA probes There are now molecular methods to monitor these bugs ! ‘mcr / mrt’ gene

9 2. THE EVOLVING BIOCATALYTIC PROCESS: RATE LIMITING STEPS 3. H 2 + CO 2 CH 4 Exp: - Methanomicrobiales Methanomicrobium Methanoculleus - Methanobacteriales Methanobacterium Methanobrevibacter  Moderate archaea  t d = weeks  Robust archaea  t d = days Molecular monitoring: - Generic: All methanogenic Archeae have ‘mcr’ gene - Specific: 16SrRNA probes We must try to work with these robust guys

10 2. THE EVOLVING BIOCATALYTIC PROCESS: RATE LIMITING STEPS 4. Acetate CO ₂ + H ₂  Weak bacteria  t d = weeks  Robust bacteria  t d = days Meso Synergistic group 4 Clostridium ultenense Syntrophaceticus schinkii Tepidanaerobacter acetatoxydens Thermoacetogenium phaeum Thermotoga lettingae Thermo Molecular monitoring: All [homoacetogens] have the Formyl Terta Hydro Folate Synthetase (FTHFS) gene For these group op SAO : one works best Thermo [Reversibacter of SAO] pH ₂ ≤ atm

11 Characteristics of Methanosaeta and Methanosarcina Parameter Methanosaeta Methanosarcina μ max (d -1 ) K s (mg acetate/L) NH4 + (mg/L) < < Na + (mg/L) < < pH-range pH-shock < Temperature range (°C) Acetate concentration (mg/L) < < (De Vrieze et al.2012 ; Biores Technol 112:1-9,LabMET ) The Methanosarcina can stand high conc of ammonia and salt 2. THE EVOLVING BIOCATALYTIC PROCESS

12 Food wastes  Lactic acid - At low B v and high HRT (=20d) mainly Methanoculleus as Hydrogenotrophic Methanogens (HM) YET: - At high B v ≈ 36 g COD/L.d HRT = 4 d No conventional HM, archaea are mainly Methanosarcina (Shin et al., 2010; Wat. Res. 44: ) At high Bv : one needs to have the Sarcina -‘elephant’ 2. THE EVOLVING BIOCATALYTIC PROCESS CSTR 35°C

13 2.THE EVOLVING BIOCATALYTIC PROCESS Tentative overview of integrative tools for monitoring of methanogenic bioreactors ConventionalUnitBenchmark Gas per unit load Fatty acids over bicarbonate __________________ Conductivity (L biogas.L-¹ d-¹)/ gCOD.L-¹ d-¹ Equiv. acetate/ Equiv.HCO ̅₃ mS/cm ≥ 0.5 ≤ 0.5 ≤ 30 (De Vrieze et al.2012; Biores.Tech. 112:1-9,LabMET ) The conventional monitoring parameters are ‘weak’

14 AdvancedUnitBenchmark Total SAO FTHFS genes Total bacteria 16SrRNA genes Total Methanogens mcrA genes Total Bacteria 16SrRNA genes Methanosaeta 16SrRNA genes Methanosarcina 16SrRNA genes %%% ≥ 10 Normal ≥ 10* Heavy duty ≥ 1* *Need to be further developed FTHFS = Formyl Tetra Hydro Folate Synthese MCR = Methyl Coenzyme Reductose 2.THE EVOLVING BIOCATALYTIC PROCESS Tentative overview of integrative tools for monitoring of methanogenic bioreactors (cont.) (De Vrieze et al. 2O12; Biores.Tech. 112: 1-9; LabMET ) We can monitor the ‘ microbial machinery‘ we deal with!

15 2.THE EVOLVING BIOCATALYTIC PROCESS The moral: -AD depends on a ‘microbiome’ = a team of microbes which evolved together to cooperate ; the AD microbiome operates in ‘small steps ’ Always very critical: SAB! Impose a long SRT Critical in high rate reactors: SAO bacteria Thermo is best - How to stimulate / retain these SAB & SAO? e.g. Support matrices which enrich [SAB/SAO - HM] (Chauhan & Ogram 2005; BBRC 327: 884 – 893) Carrier materials can be of help -We need an Early Warning Indicator (EWI) for these groups! Recently a new find : Ratio VVZ /Ca is very helpful in case of oily feed (Wurdemann et al ; in press )

16 3. THE EXPANDED POTENTIAL Methanogenic degradation of PAH is possible Naphtalene Phananthrene 25 °C CH 4 Anthracene + 27 – 35 kJ/mol Pyrene for the MPB Chrysene (Dolfing et al., 2010; Microb. Biot. 2: ) Take home: AD is a “omnivalent” gasification process Geobacter in syntrophy with - Methanosaeta - Methanosarcina Fatty acids & Aromatics present in non-productive coal (Jones et al., 2010; AEM 76: ) Biogas

17 3. THE EXPANDED POTENTIAL Terephthalate (TA) converstion to biogas TA Acetate + H 2 + CO 2 Butyrate “Recycling” Acetate + H 2 CH 4 + CO 2 (Lykidis et al., 2011; The ISME Journal 5: 122 – 130) Take home: Methanogenesis proceeds by meandering metabolism; small ‘spenders’ seize dominance in the AD energy flow

18 4. BIOAUGMENTATION Cold methanogens : 0.2 m 3 biogas m -3 reactor d -1 at 5 – 7 °C (McFadden 2010; New Sci. 2785: 14) Hydrogen producing bacteria (HPB) E. coli, Enterobacter cloacae at 35°C Caldicellulosyruptor at 55°C (Bagi et al., 2007; AMB 73: ) LCFA degraders - Clostridium ludense : better lipid conversion (Cirne et al., 2006; J. Chem. Tech. & Biol. 81: ) - Syntrophomonas zehnderi on sepiolite for facter 2 faster conversion of oleate (Cavaleiro et al., 2010; Wat. Res. 44: 4940 – 4947)

19 4. BIOAUGMENTATION Constructed ligno-cellulosic cultures:  Mesophilic: Methanos ® : a combination of 2 Clostridia sp.; gas production from maize +20%; Bv x 2 Extra netto gain per m³ reactor per year: 50 – 100 € (personal info)  Thermophilic: Pretreatment of 12h of cassava residues with inoculum : from 130 to 260 mL biogas/g VSS treated. (Zhang et al., 2011; Biores. Tech. 102: )

20 4. BIOAUGMENTATION “Super” Methanosarcina acetivorans Plasmid with broad-specificity esterase of Pseudomonas GMO which could grow on acetate, formate, hydrogen, methanol + methanol released from - methyl-propionate - methyl-acetate (Lessner et al., 2010; mBio 1: issue 5) Gradually, effective inocula enter the market scene

21 5. MONITORING THE METHANOGENIC “COLLABOROME” DGGE-patterns 1. Who is there: 16 S DNA genes 2. Who is doing it with whom DGGE patterns + interpretations Three new tools To measure maturity Range-weighted richness: Rr Dynamics of change of the gel: Dy Pareto-Lorenz plot of the gel: Co (Marzorati et al., 2007; Appl. Environ. Microbiol. 73: ; LabMET)

22 5. MONITORING THE METHANOGENIC “COLLABOROME” R r (richness) (Carballa et al., 2011; Appl. Microbiol. Biotechnol. 89: ; LabMET) Richness /diversity of species is necessary GoodPoor performance TVA TAC

23 Dy (Dynamics of change) (*Pycke et al., Water Sci. Technol. 63: ; LabMET; **Zamalloa et al., 2012; Appl Microbiol Biotechnol 93:859–869; LabMET; ***Read et al Appl Microbiol Biotechnol 90: ; LabMET) *** (Low ( 24%) Dy na mi cs, Dy dfd fdf dfd fd (% ) Dynamics, Dy (% change per 15 days ) The microbiome must be dynamic ; the ghetto does not work

24 Co (community organization) Also here the 80/20 rule is valid ! Perfect evenness Ecological Pareto (Zamalloa et al., 2012; Appl Microbiol Biotechnol 93:859–869; LabMET)

25 Lab scale 6. PROCESS TECHNICAL AIDS Dosing electron sinks as H 2 -scavengers Examples- Essential oils - Tannins - Saponins - Flavonoids (Palra & Saxena, 2010; Phytochemistry 71: ) Such plant secondary metabolites inhibit HM in the rumen Take home: Some natural substances can be inhibitive

26 Lab scale 6. PROCESS TECHNICAL AIDS AD & BES: Bio-electochemical Systems (BES) (Logan et al., 2006; Env. Sci. & Tech. 40: ; LabMET) Take home: Thus far- MFC: 1 kg COD m -3 d -1 - MEC: 5 kg COD m -3 d -1 MEC-BEAMR: H 2 is produced at 1 / 3 of the energy input of normal electrolysis (Sleutels et al. 2009; Int. J. Hydrogen Energy 34: 9655–9661) (Liu et al. 2005; Env. Sci. Technol. 39: )

27 Lab scale 6. PROCESS TECHNICAL AIDS Bio-electrochemical systems (BES) Methanogenic aggregates are electrically conductive µs/cm o Water, alginate beads minimal o Geobacter species1.4 ± 0.3 o Aggregates6-7 ± 3 o Aluminium beads11 ± 0.1 (Malvankar et al., 2011 ; Nature Nanotechnology 6: ) Methane production depends on the transfer of electrical currents between various bacteria !!!

28 MEC in AD Cathode and anode inside reactor Electrolysis in the AD reactor W installed/m³ reactor provided 25% higher biogas production Electricity consumed only 25% of extra electrical energy gained (Tartakovsky et al., 2011; Bioresource Technology 102: ) AD & BES

29 CSTREPAD Separator Membrane EPAD UASB Recycle Biogas Enhanced Propionic Acid Degradation (EPAD) system Can we combine a CSTR and a propionate-specific UASB? (Ma et al. 2009; Water Research, 43: ; LabMET) Lab scale 6. PROCESS TECHNICAL AIDS

30 Increasing the surface of the solids  Sonication, heat, …  Grinding Full scale 6. PROCESS TECHNICAL AIDS (Halalsheh et al., 2011; Biores. Technol., 02: ) Physiso/chemical treatments are thus far not worth the trouble cm²/ cm³ sludge% degradation

31 Inverted Anaerobic Sludge Blanket (IASB) Problem: LCFA cause sludge flotation  washout + dirty effluent with normal UASB Solution: Use of flotation instead of sedimentation as main biomass retention technique (Alves et al., 2010; US B2) Full scale 6. PROCESS TECHNICAL AIDS Note: Also Paques and GWE have flotation based full scale reactors

32 Temperature Phased Anaerobic Digestion (TPAD) - Good pathogen removal due to short thermophilic stage - Better VS-removal with same reactor volume (Adapted after Riau et al., 2010; Bioresource Techn. 101, ) Full scale 6. PROCESS TECHNICAL AIDS Mesophilic HRT= 15d TPAD-system HRT thermophilic = 3d HRT mesophilic = 12d

33 Anaerobic Membrane BioReactor (AnMBR) Low pressure * Fluxes 5 L/m².h * Biomass 3 – 5x more concentrated; digester volumes 3 – 5 x smaller * Capex -10%; Opex -40% * Water re-use facilitated At present : 14 Kubota AnMBR in Japan (Kanai et al., 2010; Desalination 250 : 964 – 967; Christian 2009, Full scale 6. PROCESS TECHNICAL AIDS High pressure * Veolia and ADI on dairy At present some 25 anMBRs; future of ‘pocket’digestors ?

34 6.1 Waters Number of non-lagoon industrial installations worldwide (After Totzke, Applied Technologies Inc.) Full scale 6. PROCESS TECHNICAL AIDS

35 Take home: About 3500 anaerobic reactors worldwide Top players :  Paques bv648  Biothane-Veolia 478  Global Water Engineering 195  Waterleau – Biotim 140 Geographic distribution  Europe 1174  Southeast Asia 894  North America 874  South America 303  Middle East/Africa63 Number of non-lagoon industrial installations worldwide Full scale 6. PROCESS TECHNICAL AIDS 6.1. Waters

36 Take home: Technological :  UASB 1000  EGSB 600  Anaerobic contact 370  Anaerobic upflow filter 90  Downflow filter 70 Number of non-lagoon industrial installations worldwide Full scale 6. PROCESS TECHNICAL AIDS 6.1. Waters Take home: - Mainly focussing on “cleaning-up” - In total some 3000 MWel worldwide

37 The mastodons - COMP. LIRA (CLNSA) - Nicaragua UAC Reactors 102,000 kg COD/d m³ biogas/d L fossilfuel/d 50m³ Full scale 6. PROCESS TECHNICAL AIDS

38 Full scale 6. PROCESS TECHNICAL AIDS 6.2. MSW (municipal solid wastes ) Anaerobic digestion of MSW in Europe:  About 200 plants in 17 EU countries OWS, Tenneville, Belgium  About 6.0 million tons MSW (= 20 million IE ) treated per year; yields MWel  Some 1.0 million tons MSW extra capacity per year (De Baere & Mattheeuws 2010; Biocycle Febr. 24)

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40 6.3 Manure & biomass European Biogas Association:  7500 agricultural digesters across EU; Germany: 6000 !  Overall electrical capacity MWel with a turnover of € 2300 billion per year (Irish Farmers Journal, Refit moving forward, ) 6. PROCESS TECHNICAL AIDS

41 The mastodons - Corn Products Amardass (Starch) - Thailand ANUBIX™ - 150,000 kg COD/d  6 MW Full scale 6. PROCESS TECHNICAL AIDS

42 Biofuel Production Processes FuelUnit processesWastestreamReliability Pure Plant OilPressing, chemical extraction, extra refinery Pressed cake High BiodieselEsterification Glycerol residue High Bio-ethanolFermentation, distillation,… Distillery slops direct Evaporation condensates High Fisher-Tropsch Diesel Gasification, FT synthesis Light oils High Biogas  kWh-electric + kWh-thermal Anaerobic digestion + MFC after treatment None!!!Thus far: poor Now: OK 7. FEEDSTOCKS

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44 Biorefinery: The Ghent Project 7. FEEDSTOCKS Crucial Plant biotechnology Industrial biotechnology Environmental biotechnology Thermochemical conversion

45 Sugarcane whole crop 100% Bagasse + leaves Residues of vinasses bagasses leaves N, P, … nutrients as NSF Sugar juice Ethanol fermentation Hydrolysis AD Ethanol 60 % Biogas 25 % Carbonisation Biochar 15 % (After Weiland, Verstraete & Van Haandel, 2009; Biofuels, ; ISBN ) 7. FEEDSTOCKS Take home: Politics needed to make Biogas, Biochar and NSF more attractive Normally only 40% recovery

46 Methanolic glycerol from biodiesel Output nr 2 Acetoclastic methanogenesis 7. FEEDSTOCKS Methanol Methyl-CoM Methane Output nr 1 Glycerol Acetate H2H2 1,3 Propane Diol (1,3 DPO) (Bizukoje et al., 2010; Bioprocess Biosyst. Eng. 33: ) Take home: Metabolic cross-feeding in a binary culture of Methanosarcina mazei and Clostridium butyricum

47 Addition of co-substrates > 500gCOD/L e.g. 7. FEEDSTOCKS Glycerol residues Grease and fat from slaughterhouse waste Whole crop maize Food wastes Household biosolids (Grass clippings from roadside - Not well suited: high lignine content) (Pure blood or urine from slaughterhouse - Not well suited: high N-content) Take home: By adding concentrated co-substrates, the reactor productivity can be increased with a factor 5-10 !!

48 o Algae: Lipid rich algae are best Theorethical methane yield: LCH 4 /gVS Practical methane yield: LCH 4 /gVS (Sialve et al., 2009; Biotech. Adv. 27: ) (Chisti, 2007; Biotechnol. Adv. 25, ) (Zamalloa et al., 2011, Appl. Energy, in press; LabMET) If high productivities (>90 ton DM ha -1 year -1 )+ high conversion efficiencies (>75%) + high loading rates (>10 kgCOD m -3 day -1 )  Energy from microalgae can cost € kWh -1 (Zamalloa et al., 2009; Bioresource Tech. 102: ; LabMET) 7. FEEDSTOCKS Micro-algae can be grown on non-agricultural soils ; yet the production is too costly and the digestion too difficult

49 UF/RO NEWater UP- CONCENTRATION SCREENING A-line (Major flow) SEWAGE COARSE MINERALS ANAEROBIC DIGESTER FILTER PRESS P-RICH CAKE BIOGAS NITROGEN- RICH WATER COMBINE D HEAT AND POWER UNIT. THE CO 2 GOES TO THE ALGAL FARM NATURAL STABLE FERTILIZER (NSF) PYROLYSISBIOCHAR BRINE (Verstraete et al., 2009; Bioresource Techn. 100: ; LabMET) The “Zero-Waste” Water Technology B-line Minor flow (max 10 %) 7. FEEDSTOCKS

50 The “Zero-Waste” Water Technology Up-concentration of “raw” domestic organics Chemically assisted primary sedimentation (CEPT) Bio-floculation or A/B-Boehnke concept  Low HRT (0.4 – 1 h)  High B x (> 1.5 kg BOD kgVSS -1 d -1 ) (Boehnke et al., 1998; Water-Engineering & Management 145: 31-34) AD Coagulation + floculation Influent UF Decantor AD Clean permeate 7. FEEDSTOCKS (Verstraete & Vlaeminck, 2010; 2 de Xiamen Int. Forum on Urban Env.; LabMET) In the near future, we have to retrofit all our STP ; we must put up-concentration and digestion upfront.

51 8. OUTLOOK AND CHALLENGES CH 4 -saturated effluent of AD > 11 mg CH 4 /L Up to 25% of produced methane in case of low strength waters (Cakir & Stenstrom, 2005; Water research 39: ) (Hartley and Lant, 2006; Biotech. and Bioeng. 95: ) 1. Diffuse methane emissions from storage and effluents Porous burner with alumina saddles stable down to 1.1 vol%CH 4 (Wood et al., 2009; Env. Sci. Technol. 43: )

52 8. OUTLOOK AND CHALLENGES (Van der Ha et al., 2010; Appl. Env. Microbiol. 87: ; LabMET) 1. Diffuse methane emissions from storage and effluents Effluent AD Algal culture + Methanotrophic bacteria No diffuse methane emissions Biomass with added value as: Protein Oil (PHB/ PHA) PUFA Antibiotics Algae – Methanotroph co-cultures

53 8. OUTLOOK AND CHALLENGES 2. Biogas desulphurization  Desulphurization coupled to lithotrophic denitrifcation Biogas Scrubbing with activated sludge Biogas free of H 2 S S 0 To be used as a fungicide 2–4 kg S 2- m -3 d -1 EBRT 10 min. (Basphinar et al. 2011, Process Biochemistry 46: ) !

54 8. Outlook and challenges 3. Special mixed cultures(Constructed consortia) : *Cellulose degraders and methanogens on cassava residues (Zhang et al. 2011; Biores. Techn. 102: ) * Methanosarcina + Clostridium butyricum to produce both Biogas and 1,3 Propane Diol from methanolic glycerol in the biodiesel factory (Bizukoje et al ; Bioprocess Biosyst.Eng. 33: ) 54

55 8.Outlook and challenges 4.Chain elongation of fatty acids & ethanol * Ethanol+ Acetate Become hydrophobic LCFA (n-caproic ) Bv : Several kg /m3.d *Harvest by -Acidification and flotation -In line membrane extraction *Use as :Feed additive/Green antimicrobials/Fuel *The microbiome consists of Clostridium / Bifidobacterium / Desulfitobacterium sp… ( Agler et al. 2012; EST DOI ) (Steinbusch et al.2011; En. Env.Sci 4: )

56 A. Chemical  Potato factory Colsen process Plant-derived Moerman process struvite  Sewage treatment plant about 0.5 kg crude struvite per IE per year (Wallaeys Plant, Belgium) NuReSys: high quality MAP 8. OUTLOOK AND CHALLENGES (Shu et al., 2006; Bioresource Technol. 97: ) 5. Advanced recovery of phosphate

57 B. Biological: The ureolytic bio-catalytic process + The process removes down to 2 mg PO P/L + The cost is competitive with Fe 3+ (Carballa et al., 2009; J. Chem. Technol. Biotechnol. 84: 63-68; LabMET) 8. OUTLOOK AND CHALLENGES 5. Advanced recovery of phosphate Mg NH 4 PO 4 (struvite) AD Effluent Urea MgO/MgCl 2 Agriculture must ‘certify’ the ‘Natural Stable Fertilizers.

58 8. OUTLOOK AND CHALLENGES 6. Advanced recovery of nitrogen Dry organic fertilizer Mechanical Vapor Recompression (MVR) Steamstripping + MVR

59 Anaerobic digestion and combustion – The Nitrogen case After Udert & Waechter, 2012, Wat. Res. 26: Manure at 4 kg N/ m³ Anaerobic digestion Biogas Partial nitrification NH 4 + → NH 4 NO 3 MF/IO to 20% volume 80% 20% Ion Exchange Distillation with vapor compression Water Solid residue with some 25% NH 4 NO 3 Cofuel ? Costs to remove 1 kg N 0 € 0,1 € 1,0 € 3,75 € ∑ 5,0 € Calorific value per kg N ≈ 1,0 € Netto cost ≈ 4,0 € per kg N  Netto cost in case of conventional N/DN: 4-5 €/kg N

60 8. OUTLOOK AND CHALLENGES 7..Boosters ‘all-in-one’ dosed at 5% of Bv *Steady multi e-acceptor *All round bio-available macro & micro nutrients ( Ni, Co, W !....) (Jiang et al Renewable Energy 44: ) * Cross inoculum ( new genes ) *Calcium binder for LCFA (Kleybocker et al ; Waste Management 32: ) ( Zhang et al. 2011; J.Chem.Technol. 86: ) Anaerobic Digestion can profit from clever additives (Foley et al., 2010; Env. Sci. Technol. 44:

61 8. OUTLOOK AND CHALLENGES 8. Life Cycle Analysis (LCA) Comparisment of the LCA-data for the treatment of industrial wastewaters: 1. AD 2.MFC 3.MEC (with recovery of H 2 O,…) Results: 1 ≈ 2 < 3 Yet: AD can be empowered with plenty extra recoveries ! (Foley et al., 2010; Env. Sci. Technol. 44: ) Anaerobic Digestion is top noth sustainable

62 9. AD Biogas based sustainable organic chemistry Commodity chemicals with AD as a first line “all mash” biomass convertor Biocatalytic conversions Conventional petro-chemistry Upgrading to syngas by Fisher Trops “All mash” biogas convertor All kinds of biomass Humus + Clean nutrient Flexible crop production (Datar et al., 2004; Biot. Bioeng. J. 86: ) (Yeuneshi et al., 2005; Biochem. Eng. J. 27: ) 8. OUTLOOK AND CHALLENGES

63 9. OUT OF THE BOX  GMO methanogens e.g. ● Low sensitivity to NH 3, H 2 S, salt ● Improved mixotrophic growth  Industrial production of SAO + mixotrophic Methanosarcina Production of ‘all round booster inocula’ (cfr. dried yeast)  COD Clean biogas Use on the farm the biogas to produce pre/pro biotics for animal husbandry

64 9. OUT OF THE BOX  Nano-metals to enhance H 2 -transfer H 2 e.g. BioPd (De Windt et al., 2005; Environ. Microbiol. 7, ; LabMET). Fermentative bacteria Methanogens Sugar

65 9. OUT OF THE BOX *High conductivities (≥ 30 mS cm -1 ) Electrodialysis Salts + NH 4 + Organics Better digestibility (3 € m -3 ) ! * OTHER NITROGEN REMOVAL TO IMPROVE AD 1.AIR STRIPPING 2.ION EXCHANGE/ADSORBANTS 3.REVERSE OSMOSIS 4.MFC 5…… PROGRESS IS MORE THAN WELCOME The brine can stripped and the NH3 adsorbed (Desloovere et al. 2012; LabMET )

66 10. CONCLUSIONS  AD becomes a player in MegaWatt energy supply  The AD microbiology is up for revision! Other workhorses and microbiomes are possible  Bioaugmentation comes of age ! Special ‘ booster products ’ are coming on the market  Plenty of new technical aids e.g. electro-assisted AD are under development  New feedstocks & new outputs (e.g. via designed co-cultures)  Biomethane fits in - the biorefinery - the bioeconomy  AD is fine in terms of LCA!  AD is bound to grow in overall importance


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