Bioaugm entation of am m onia tolerant enriched m ethanogenic - PowerPoint PPT Presentation

Bioaugm entation of am m onia tolerant enriched m ethanogenic cultures: A m icrobiological process to efficiently digest am m onia-rich biom asses I oannis A. Fotidis Han W ang I rini Angelidaki

Am m onia in Anaerobic Digestion Ammonia-rich biomasses are potentially excellent anaerobic digestion co- substrates CH 4 CH 4 + NH 4 NH 3 Many full-scale AD reactors are operating in am m onia induced “inhibited steady-state” with up to 3 5 % losses of the biogas production 4 th International Conference on Sustainable Solid Waste Management 2 29/ 06/ 2016 DTU Environm ent, Technical University of Denm ark 23 nd - 25 th June 2016, Limassol, Cyprus

Am m onia in Anaerobic Digestion 4 th International Conference on Sustainable Solid Waste Management 3 29/ 06/ 2016 DTU Environm ent, Technical University of Denm ark 23 nd - 25 th June 2016, Limassol, Cyprus

Am m onia in Anaerobic Digestion + ) + Free am m onia ( NH 3 ) Ammonia = Ammonium ion (NH 4 Proton imbalance Increase maintenance energy requirements Potassium deficiency Suppress specific enzyme reactions 4 th International Conference on Sustainable Solid Waste Management 4 29/ 06/ 2016 DTU Environm ent, Technical University of Denm ark 23 nd - 25 th June 2016, Limassol, Cyprus

Conventional Methods Methods used today to alleviate ammonia toxicity: Lower the operating temperature Dilute reactor content with water These methods can alleviate ammonia toxicity only to a limited range, are cost- expensive and do not provide a long-term solution Biogas plant operators minimise or totally exclude the ammonia-rich substrates from their feedstocks There are not any know n procedures to counteract the am m onia toxicity effect and digest efficiently am m onia-rich w astes in anaerobic reactors 4 th International Conference on Sustainable Solid Waste Management 5 29/ 06/ 2016 DTU Environm ent, Technical University of Denm ark 23 nd - 25 th June 2016, Limassol, Cyprus

The Hypothesis and Aim Am m onia tolerant m ethanogenic consortia can alleviate the am m onia toxicity in anaerobic reactors Bioaugm entation Use an am m onia tolerant m ethanogenic culture as bioaugm entation inoculum in a CSTR reactor operating under ammonia induced “inhibited steady-state” 4 th International Conference on Sustainable Solid Waste Management 6 DTU Environm ent, Technical University of Denm ark 29/ 06/ 2016 23 nd - 25 th June 2016, Limassol, Cyprus

Bioaugm entation I nocula Standard definition : Bioaugmentation is a process where specific microorganisms are added to a biological system in order to improve/ recover specific functions (e.g. Enriched or Pure organic overload, decrease the lag phase) Bioaugm entation I nocula Pure strains : Specialized growth medium, sterile conditions ? Enriched cultures : general growth medium, no sterile conditions 4 th International Conference on Sustainable Solid Waste Management 7 29/ 06/ 2016 DTU Environm ent, Technical University of Denm ark 23 nd - 25 th June 2016, Limassol, Cyprus

Bioaugm entation I noculum Acclim ation to high am m onia levels 9 1 2 3 5 7 g/ L g/ L g/ L g/ L g/ L g/ L I noculum Biogas plant Stepwise Ammonia Increase Methanogenic Enriched Culture-MEC culture Methanogen (> 98% ): Methanoculleus spp. Bacteria (> 82% ): Tepidimicrobium spp. Aminobacterium spp. Petrimonas spp. Defluviitoga spp. 4 th International Conference on Sustainable Solid Waste Management 8 29/ 06/ 2016 DTU Environm ent, Technical University of Denm ark 23 nd - 25 th June 2016, Limassol, Cyprus

Reactors’ Setup 2 Continuous-flow stirred tank reactors ( CSTR) Operational Param eters Tem perature : 37 ˚ C (mesophilic) Total volum e : 2.3 L W orking volum e : 1.8 L OLR : 1.74 g VS/ L/ d HRT : 24 days + -N/ L Final am m onia : 5 g NH 4 Substrate : Cattle manure I noculum : Hashøj Biogas plant 4 th International Conference on Sustainable Solid Waste Management 9 29/ 06/ 2016 DTU Environm ent, Technical University of Denm ark 23 nd - 25 th June 2016, Limassol, Cyprus

Materials and Methods-Bioaugm entation + -N/ L Abiotic 1 .6 5 g NH 4 Augm entation + -N/ L At 5 g NH 4 ammonia induced “ inhibited steady- state ” Control Reactor Bioaugm entation Methanogenic Enriched Culture- MEC culture 4 th International Conference on Sustainable Solid Waste Management 1 0 29/ 06/ 2016 DTU Environm ent, Technical University of Denm ark 23 nd - 25 th June 2016, Limassol, Cyprus

Methane Production + -N L - 1 Ammonia: 1.65 g NH 4 Production: 457 mL CH 4 / L > 4 0 % CH 4 + -N L - 1 Ammonia: 5 g NH 4 Production: 452 mL CH 4 / L Bioaugm entation Methane production rate of the CSTR reactors R MEC reactor regained 9 9 % the m ethane production rate it had before the introduction of the ammonia to the feedstock 4 th International Conference on Sustainable Solid Waste Management 1 1 29/ 06/ 2016 DTU Environm ent, Technical University of Denm ark 23 nd - 25 th June 2016, Limassol, Cyprus

VFA Accum ulation ans pH Fluctuation Total VFA accumulation and pH fluctuation in CSTR reactors VFA accumulation and pH fluctuation of the bioaugmented reactor, were kept stable and within the limits for normal AD of cattle manure in CSTR reactors 4 th International Conference on Sustainable Solid Waste Management 1 2 29/ 06/ 2016 DTU Environm ent, Technical University of Denm ark 23 nd - 25 th June 2016, Limassol, Cyprus

Microbiological Analysis The relative abundance of Methanoculleus , w as increased fourfold after bioaugmentation Reduction of the ammonia- VFA synergistic effect allowed the less ammonia tolerant methanogens to produce methane more efficiently Both the hydrogenotrophic and the less stressed aceticlastic m ethanogens increased m ethane production 4 th International Conference on Sustainable Solid Waste Management 1 3 29/ 06/ 2016 DTU Environm ent, Technical University of Denm ark 23 nd - 25 th June 2016, Limassol, Cyprus

Enriched vs Pure Bioaugm entation I nocula The pure m ethanogenic strain ( M. bourgensis MS 2T ) demonstrated a ~ 9 0 % recovery of the initial uninhibited of methane production under the same conditions The enriched culture w as m ore effective The ammonia tolerant enriched inoculum recovered methane production ~ 9 9 % bioaugm entation inoculum com pared to of the initial uninhibited of methane production the pure culture 4 th International Conference on Sustainable Solid Waste Management 1 4 29/ 06/ 2016 DTU Environm ent, Technical University of Denm ark 23 nd - 25 th June 2016, Limassol, Cyprus

Conclusions Bioaugm entation of an enriched ammonia tolerant methanogenic culture in a CSTR reactor can im m ediately recover m ethane production up to 1 0 0 % Enriched bioaugm entation inocula could alleviate the ammonia toxicity effect up to 2 5 % m ore effectively compared to pure cultures Bioaugm entation is possible w ithout stopping the continuous mode of operation and w ithout changing the am m onia-rich substrate Bioaugm entation could support the development of an efficient anaerobic digestion process of am m onia-rich biom asses in full-scale reactors 4 th International Conference on Sustainable Solid Waste Management 1 5 29/ 06/ 2016 DTU Environm ent, Technical University of Denm ark 23 nd - 25 th June 2016, Limassol, Cyprus

Acknow ledgem ents This work was supported by Energinet.dk under the project framework ForskEL “MicrobStopNH 3 -Innovative bioaugmentation strategies to tackle ammonia inhibition in anaerobic digestion process” (program no. 2015-12327). Thank you for your attention! Thank you for your attention! 4 th International Conference on Sustainable Solid Waste Management 1 6 29/ 06/ 2016 DTU Environm ent, Technical University of Denm ark 23 nd - 25 th June 2016, Limassol, Cyprus