Optimization of biomethanization processes through trace metals supplementation

Transcription

1 Engineering Conferences International ECI Digital Archives BioEnergy IV: Innovations in Biomass Conversion for Heat, Power, Fuels and Chemicals Proceedings Spring Optimization of biomethanization processes through trace metals supplementation Christpeace Ezebuiro Hamburg University of Technology K. Techamanoon Hamburg University of Technology J. Ezinma Hamburg University of Technology I. Korner Hamburg University of Technology Follow this and additional works at: Part of the Chemical Engineering Commons Recommended Citation Christpeace Ezebuiro, K. Techamanoon, J. Ezinma, and I. Korner, "Optimization of biomethanization processes through trace metals supplementation" in "BioEnergy IV: Innovations in Biomass Conversion for Heat, Power, Fuels and Chemicals", Manuel Garcia- Perez,Washington State University, USA Dietrich Meier, Thünen Institute of Wood, Germany Raffaella Ocone, Heriot-Watt University, United Kingdom Paul de Wild, Biomass & Energy Efficiency, ECN, The Netherlands Eds, ECI Symposium Series, (2013). This Conference Proceeding is brought to you for free and open access by the Proceedings at ECI Digital Archives. It has been accepted for inclusion in BioEnergy IV: Innovations in Biomass Conversion for Heat, Power, Fuels and Chemicals by an authorized administrator of ECI Digital Archives. For more information, please contact

2 Optimization of Biomethanization Processes through Trace Metals Supplementation Ezebuiro N. C., Techamanoon K., Ezinma J., and Körner I. Hamburg University of Technology Bioconversion and Emission Control Institute for Wastewater Management and Water Protection Basiliani Resort, Otranto, Italy June 9-14, 2013

3 Outline (AD) Method Results Summary, Conclusion and Outlook 2

4 and Trace metals Method Method and enzymes Hydrolysis Acidification Acetogenesis Methanogenesis Carbo-hydrate, Protein, Fat +H 2 O Volatile Fatty Acids: CH 3 COOH CH 3 CH 2 COOH CH 3 CH 2 CH 2 - COOH, etc. + H 2 + CO 2 CH 3 COO- Biogas: CH 4 + CO 2 1. Aim: Degrade fatty acids to one-carbon intermediates- CO 2 and CH 4 2. Mechanism: Bio-catalysis (metallo-enzymes dependent); Transfer of Alkyl- (C x H y ) Carbonyl- (COO-) and Hydride (H-) ions (1). (1) Ragsdale W,

5 Method Challenges De-coupling of methanogenetic activities potential Acidification Acetogenesis Methanogenesis VFA accumulation: CH 3 COOH CH 3 CH 2 COOH CH 3 CH 2 CH 2 - COOH + H 2 + CO 2 CH 3 COO- Biogas: CH 4 + CO 2 Volatile fatty acids (VFA) accumulation leads to decoupling of methanogenesis and subsequent digester failure. Defra Project

6 Method Optimization Approaches: Enzymology C-1 metabolism H 2 + CO 2 Acetogenesis CH 3 COO- C-1 CH 3 Methanogenesis C-1 CH 3 Biogas: CH 4 + CO 2 Critical methanization processes are metallo-enzyme dependent Wood H. G., (1991); Diekert G. and Wohlfarth G. (1994). 5

7 Method Se; The metals play catalytic roles providing charged surfaces for the binding and transfer of functional groups. Nickel (Ni), Cobalt (Co), Selenium (Se and Molybdenum (Mo) are the most important trace elements (TMs) of the metallo-enzymes. Co Ni Bapteste et al.,

8 Method Loss of VFA degradation potential (functional group transfer) and low methane production in anaerobic digesters are related to insufficiency of trace elements in the digestion matrix. questions: I. Are there sufficient trace elements in AD substrates? II. Is supplementation necessary? III. What are the considerations for supplementation? 7

9 Method: Question-I Determination of trace element concentration in substrates Substrates Cow dung Horse dung Fruit residue Mixed leaves Maize silage Food waste Lawn grass cutting Digested Sewage Sludge Grease trap residues Blackwater Trace elements measured Measurement method Ni, Co, Se, Mo DIN S7 Equipment Ball mill Microwave Atomic Absorption Spectroscopy 8

10 Method: Question-II and III Ni, Co, Se Mo Supplementation matrix JMP 10.0: SAS Institute, NC. Trace metals contained in inoculum = Control conc. Total volatile fatty acid mixture = acetic-, butyric and propionic acid in molar ratio 1: 3: 5 Treatment Total VFA (mmol/l) Ni (mg/l) Co (mg/l) Se (mg/l) Mo (mg/l) Low TMs conc (mg/l) concentration ControlLow 0,09 0,03 0,00 0, Medium Conc. Ni: Co: Se: ControlMedium 0,09 0,03 0,00 0, Mo: High Conc ControlHigh 0,09 0,03 0,00 0,04

11 Method: Question- II, III Set up of test system and measured parameters ph: ; Temperature : 37 C, 55 C; Volatile Suspended Solids (VSS) g/l inoculum: 7.40 ± 0.32 Estimation method for process efficiency: 1 Derringer, G., and Suich, R., (1980) Inoculum + basic nutrient media + VFA mixture + trace metals = treatment reactor 10

12 Results-I: Trace element content of selected substrates Trace Element Content (mg/kg DM) AD Substrate Ni Mo Co Se Cowdung 0.07± ± ±0.01 <0.25 Food Waste 0.12± ± ±0.08 <0.25 Mixed Fruit 0.69±0.10 <0.25 <0.25 <0.25 Black water 1.19± ± ±0.03 <0.25 Maize Silage composite Grease trap residues 6.09± ± ± ± ± ±0.02 <0.25 <0.25 Substrate trace elements concentrations are relatively low and may not sustain AD processes: Co, Se are most limiting. 11

13 PhD Progress Report: Ezebuiro Nwagbo Christpeace Results-II: Supplementation effects on VFA 200mmol/L Treatment Ni Co Se Mo : Control Supervisor: PD. Dr.-Ing. Habil. Ina Körner CH 4 /gvss.d Retention time Positive effects require microbial adaption to Ni, Co, Se, Mo, and a combination of Ni and Co or Se 12

14 Relative gain Outline Results-III: Ni, Co, Se and Mo supplementation - Effects on Process efficiency (37 C) Retention time 1.42 CH 4 (Nml/g VSS.d)) 1.71 Deg.rate (mmol/l) 1.60 Process Efficiency 0.70 Method: Derringer, G., and Suich, R., (1980), VFA (mmol/l) Ni (mg/l) Co (mg/l) Se (mg/l) Mo (mg/l) Process Efficiency Ni, Co, Se, Mo supplementations have substantial positive effects on mesophilic systems 13

15 Relative gain Outline Deg.rate (mmol/l) 1.60 Retention time 1.31 Results-III: Ni, Co, Se and Mo supplementation - Factors of Influence: VFA conc. (37 C)- Process Efficiency CH (Nml/g VSS.d) 1.21 Deg.rate (mmol/l) VFA (mmol/l) Ni (mg/l) Co (mg/l) Se (mg/l) Mo (mg/l) Process E Process Efficiency 0.59 Method: Derringer, G., and Suich, R., (1980), VFA (mmol/l) Ni (mg/l) Co (mg/l) Se (mg/l) Mo (mg/l) Ni, Co, Se, Mo supplementations have substantial positive effects on mesophilic systems 14

16 (Nml/g VSS.d) 1.21 Outline Results-III: Ni, Co, Se and Mo supplementation Deg.rate - (mmol/l) Factors of Influence: Temperature ( 200mmol/l) C CH Process 4 (Nml/g Efficiency VSS.d) Deg.rate (mmol/l) C Process Efficiency VFA (mmol/l) Ni (mg/l) Co (mg/l) Se (mg/l) Mo (mg/l) VFA (mmol/l) Ni (mg/l) Co (mg/l) Se (mg/l) Mo (mg/l) Co is antagonistic at thermophilic AD, but higher Se is necessary; Mo is antagonistic at mesophilic AD but higher Co is necessary. 15

17 Results- IV: Ni, Co, Se and Mo supplementation - Mechanism of influence (37 C)- Kinetics of TMs supplementation for VFAs degradation Gain in maximum degradation rate (%) - at 37 C - Maximum degradation rate (mmol/l.d) Gain in inverse affinity (%) Similar conversion potential Varying substrate affinity Treatment Groups Mesophilic optimization mechanism is by increase in catalytic rate and substrate affinity 16

18 Results Summary Conclusion and Outlook Summary: AD substrates contain insuffient amount of trace elements Ni, Co, Se, Mo with Co and Se being most limiting. Ni, Co, Se or Mo requirements depend on VFA concentration or loading rate and process temperature; supplementation based on VFAs concentration is most effective. Mesophilic systems are more succeptible to TM deficiency than thermophilic systems; and trace elements increase the cataytic potential and substrate affinity in mesophilic system but only substrate affinity in thermophilic. Outlook: Continuous system: TMs speciation and influence of Ni, Co, Se, Mo on changes in microbial population 17

19 Thank you for your attention! Hamburg University of Technology Bioconversion and Emission Control Group Institute for Wastewater Management and Water Protection Eissendorfer 42, Hamburg 18