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

DTU Environm ent, Technical University of Denm ark 29/ 06/ 2016

2

4th International Conference on Sustainable Solid Waste Management 23nd - 25th June 2016, Limassol, Cyprus

Am m onia in Anaerobic Digestion

Ammonia-rich biomasses are potentially excellent anaerobic digestion co- substrates

CH 4 NH 4

+

NH 3 CH 4

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

DTU Environm ent, Technical University of Denm ark 29/ 06/ 2016

3

4th International Conference on Sustainable Solid Waste Management 23nd - 25th June 2016, Limassol, Cyprus

Am m onia in Anaerobic Digestion

DTU Environm ent, Technical University of Denm ark 29/ 06/ 2016

4

4th International Conference on Sustainable Solid Waste Management 23nd - 25th June 2016, Limassol, Cyprus

Am m onia in Anaerobic Digestion

Ammonia = Ammonium ion (NH4

+ ) + Free am m onia ( NH 3)

Proton imbalance Increase maintenance energy requirements Potassium deficiency Suppress specific enzyme reactions

DTU Environm ent, Technical University of Denm ark 29/ 06/ 2016

5

4th International Conference on Sustainable Solid Waste Management 23nd - 25th 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

DTU Environm ent, Technical University of Denm ark 29/ 06/ 2016

6

4th International Conference on Sustainable Solid Waste Management 23nd - 25th 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”

DTU Environm ent, Technical University of Denm ark 29/ 06/ 2016

7

4th International Conference on Sustainable Solid Waste Management 23nd - 25th 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.

• rganic overload, decrease the lag phase)

Pure strains: Specialized growth medium, sterile conditions Enriched cultures: general growth medium, no sterile conditions

Enriched or Pure

Bioaugm entation I nocula

?

DTU Environm ent, Technical University of Denm ark 29/ 06/ 2016

8

4th International Conference on Sustainable Solid Waste Management 23nd - 25th June 2016, Limassol, Cyprus

1 g/ L

Bioaugm entation I noculum

7 g/ L 5 g/ L 3 g/ L 2 g/ L I noculum

Acclim ation to high am m onia levels Stepwise Ammonia Increase

9 g/ L

Methanogenic Enriched Culture-MEC culture

Methanogen (> 98% ): Methanoculleus spp. Bacteria (> 82% ): Tepidimicrobium spp. Aminobacterium spp. Petrimonas spp. Defluviitoga spp. Biogas plant

DTU Environm ent, Technical University of Denm ark 29/ 06/ 2016

9

4th International Conference on Sustainable Solid Waste Management 23nd - 25th June 2016, Limassol, Cyprus

Reactors’ Setup

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 Final am m onia: 5 g NH4

+ -N/ L

Substrate: Cattle manure I noculum : Hashøj Biogas plant 2 Continuous-flow stirred tank reactors ( CSTR)

DTU Environm ent, Technical University of Denm ark 29/ 06/ 2016

1 0

4th International Conference on Sustainable Solid Waste Management 23nd - 25th June 2016, Limassol, Cyprus

Materials and Methods-Bioaugm entation

Methanogenic Enriched Culture- MEC culture 1 .6 5 g NH 4

+ -N/ L

At 5 g NH4

+ -N/ L

ammonia induced “inhibited steady- state”

Bioaugm entation

Abiotic Augm entation Control Reactor

DTU Environm ent, Technical University of Denm ark 29/ 06/ 2016

1 1

4th International Conference on Sustainable Solid Waste Management 23nd - 25th June 2016, Limassol, Cyprus

Methane Production

> 4 0 % CH 4

RMEC reactor regained 9 9 % the m ethane production rate it had before the introduction of the ammonia to the feedstock

Bioaugm entation

Ammonia: 1.65 g NH4

+ -N L- 1

Production: 457 mL CH4/ L Ammonia: 5 g NH4

+ -N L- 1

Production: 452 mL CH4/ L

Methane production rate of the CSTR reactors

DTU Environm ent, Technical University of Denm ark 29/ 06/ 2016

1 2

4th International Conference on Sustainable Solid Waste Management 23nd - 25th 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

DTU Environm ent, Technical University of Denm ark 29/ 06/ 2016

1 3

4th International Conference on Sustainable Solid Waste Management 23nd - 25th 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

DTU Environm ent, Technical University of Denm ark 29/ 06/ 2016

1 4

4th International Conference on Sustainable Solid Waste Management 23nd - 25th June 2016, Limassol, Cyprus

Enriched vs Pure Bioaugm entation I nocula

The pure m ethanogenic strain (M. bourgensis MS2T) demonstrated a ~ 9 0 % recovery of the initial uninhibited of methane production under the same conditions The ammonia tolerant enriched inoculum recovered methane production ~ 9 9 %

• f the initial uninhibited of methane production

The enriched culture w as m ore effective bioaugm entation inoculum com pared to the pure culture

DTU Environm ent, Technical University of Denm ark 29/ 06/ 2016

1 5

4th International Conference on Sustainable Solid Waste Management 23nd - 25th 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

DTU Environm ent, Technical University of Denm ark 29/ 06/ 2016

1 6

4th International Conference on Sustainable Solid Waste Management 23nd - 25th June 2016, Limassol, Cyprus

Acknow ledgem ents

This work was supported by Energinet.dk under the project framework ForskEL “MicrobStopNH3-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!