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Wang Z, Wang S, Hu Y, Du B, Meng J, Wu G, Liu H, Zhan X. Distinguishing responses of acetoclastic and hydrogenotrophic methanogens to ammonia stress in mesophilic mixed cultures. WATER RESEARCH 2022; 224:119029. [PMID: 36099760 DOI: 10.1016/j.watres.2022.119029] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 08/14/2022] [Accepted: 08/26/2022] [Indexed: 06/15/2023]
Abstract
A shift from the acetoclastic to the hydrogenotrophic pathway in methanogenesis under ammonia inhibition is a common observation in anaerobic digestion. However, there are still considerable knowledge gaps concerning the differential ammonia tolerance of acetoclastic and hydrogenotrophic methanogens (AMs and HMs), their responses to different ammonia species (NH4+, NH3), and their recoverability after ammonia inhibition. With the successful enrichment of mesophilic AMs and HMs cultures, this study aimed at addressing the above knowledge gaps through batch inhibition/recovery tests and kinetic modeling under varying total ammonia (TAN, 0.2-10 g N/L) and pH (7.0-8.5) conditions. The results showed that the tolerance level of HMs to free ammonia (FAN, IC50=1345 mg N/L) and NH4+ (IC50=6050 mg N/L) was nearly 11 times and 3 times those of AMs (NH3, IC50=123 mg N/L; NH4+, IC50=2133 mg N/L), respectively. Consistent with general belief, the AMs were more impacted by FAN. However, the HMs were more adversely affected by NH4+ when the pH was ≤8.0. A low TAN (1.0-4.0 g N/L) could cause irreversible inhibition of the AMs due to significant cell death, whereas the activity of HMs could be fully or even over recovered from severe ammonia stress (FAN≤ 0.9 g N/L or TAN≤10 g N/L; pH ≤8.0). The different tolerance responses of AMs and HMs might be associated with the cell morphology, multiple energy-converting systems, and Gibbs free energy from substrate-level phosphorylation.
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Affiliation(s)
- Zhongzhong Wang
- Civil Engineering, College of Science and Engineering, National University of Ireland, Galway, Ireland; Ryan Institute, National University of Ireland, Galway, Ireland; MaREI Center for Marine and Renewable Energy, National University of Ireland, Galway, Ireland
| | - Shun Wang
- Civil Engineering, College of Science and Engineering, National University of Ireland, Galway, Ireland; Ryan Institute, National University of Ireland, Galway, Ireland; MaREI Center for Marine and Renewable Energy, National University of Ireland, Galway, Ireland
| | - Yuansheng Hu
- Civil Engineering, College of Science and Engineering, National University of Ireland, Galway, Ireland; Ryan Institute, National University of Ireland, Galway, Ireland.
| | - Bang Du
- Civil Engineering, College of Science and Engineering, National University of Ireland, Galway, Ireland
| | - Jizhong Meng
- Civil Engineering, College of Science and Engineering, National University of Ireland, Galway, Ireland; Ryan Institute, National University of Ireland, Galway, Ireland
| | - Guangxue Wu
- Civil Engineering, College of Science and Engineering, National University of Ireland, Galway, Ireland
| | - He Liu
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Civil Engineering, Jiangnan University, Wuxi 214122, Jiangsu Province, PR China
| | - Xinmin Zhan
- Civil Engineering, College of Science and Engineering, National University of Ireland, Galway, Ireland; Ryan Institute, National University of Ireland, Galway, Ireland; MaREI Center for Marine and Renewable Energy, National University of Ireland, Galway, Ireland.
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Forouzanmehr F, Solon K, Maisonnave V, Daniel O, Volcke EIP, Gillot S, Buffiere P. Sulfur transformations during two-stage anaerobic digestion and intermediate thermal hydrolysis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 810:151247. [PMID: 34710429 DOI: 10.1016/j.scitotenv.2021.151247] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 10/22/2021] [Accepted: 10/22/2021] [Indexed: 06/13/2023]
Abstract
The formation of hydrogen sulfide (H2S) during anaerobic digestion (AD) imposes constraints on the valorisation of biogas. So far, inorganic sulfur compounds -mainly sulfate - have been considered as the main contributors to H2S formation, while the contribution of organic sulfur compounds is mostly neglected. This study investigates the fate of organic and inorganic sulfur compounds during two-stage anaerobic digestion with intermediate thermal hydrolysis for treatment of primary and secondary sludge in a WWTP treating domestic wastewater. The results of a seven-week monitoring campaign showed an overall decrease of organic sulfur compounds in both stages of anaerobic digestion. Further fractionation of organic sulfur revealed a high conversion of the particulate organic fraction during the first digestion stage and of the soluble organic fraction during the second digestion stage. The decrease of soluble organic sulfur during the second digestion stage was attributed to the solubilisation and hydrolysis of sulfur-containing organic compounds during thermal hydrolysis. In both digestion stages, more organic sulfur was taken up than particulate inorganic sulfur (metal sulfide) was produced, indicating the formation of other reduced sulfur forms (e.g. H2S). Further batch experiments confirmed the role of organic sulfur uptake in the formation of H2S during anaerobic digestion as sulfate reduction only partly explained the total sulfide formed (H2S in biogas and precipitated FeS). Overall, the conversion of organic sulfur was demonstrated to play a major role in H2S formation (and thus the biogas quality), especially in case of thermal hydrolysis pretreatment.
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Affiliation(s)
- F Forouzanmehr
- Univ Lyon, INSA Lyon, DEEP EA7429, 69621 Villeurbanne, France; BioCo Research Group, Department of Green Chemistry and Technology, Ghent University, Belgium; Veolia Research & Innovation (VeRI), Maisons-Laffitte, France
| | - K Solon
- BioCo Research Group, Department of Green Chemistry and Technology, Ghent University, Belgium
| | - V Maisonnave
- Veolia Research & Innovation (VeRI), Maisons-Laffitte, France
| | - O Daniel
- Veolia Research & Innovation (VeRI), Maisons-Laffitte, France
| | - E I P Volcke
- BioCo Research Group, Department of Green Chemistry and Technology, Ghent University, Belgium
| | - S Gillot
- INRAE, UR REVERSAAL, F-69625 Villeurbanne Cedex, France
| | - P Buffiere
- Univ Lyon, INSA Lyon, DEEP EA7429, 69621 Villeurbanne, France.
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Aichinger P, DeBarbadillo C, Al-Omari A, Wett B. 'Hot topic' - combined energy and process modeling in thermal hydrolysis systems. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2019; 79:84-92. [PMID: 30816865 DOI: 10.2166/wst.2019.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The thermal hydrolysis process (THP) is applied to enhance biogas production in anaerobic digestion (AD), reduce viscosity for improved mixing and dewatering and to reduce and sterilize cake solids. Large heat demands for steam production rely on dynamic effects like sludge throughput, gas availability and THP process parameters. Here, we propose a combined energy and process model suitable to describe the dynamic behaviour of THP in a full-plant context. The process model addresses interactions of THP with operational conditions covered by the AD model obeying mass continuity. Energy conservation is considered in balancing and converting various energy species dominated by thermal heat and calorific energy. The combined energy and process model was then applied on the THP at Blue Plains advanced WWTP (DC Water) to analyse the process and assess potential energy optimizations. It was found that dynamic effects like mismatched steam production and consumption, temporary gas shortages and underloaded units are responsible for energy inefficiencies with losses in electricity-production up to 29%.
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Affiliation(s)
- Peter Aichinger
- Unit of Environmental Engineering, University of Innsbruck, Technikerstrasse 13, 6020 Innsbruck, Austria E-mail: ; ARAconsult GmbH, Unterbergerstrasse 1, 6020 Innsbruck, Austria
| | | | - Ahmed Al-Omari
- DC Water, 5000 Overlook Avenue, SW Washington, DC 20032, USA
| | - Bernhard Wett
- ARAconsult GmbH, Unterbergerstrasse 1, 6020 Innsbruck, Austria; Dynamita Process Modelling, 7 Lieu-dit Eoupe, La Redoute, 26110 Nyons, France
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Wilson CA, Novak J, Takacs I, Wett B, Murthy S. The kinetics of process dependent ammonia inhibition of methanogenesis from acetic acid. WATER RESEARCH 2012; 46:6247-56. [PMID: 23062786 DOI: 10.1016/j.watres.2012.08.028] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 08/16/2012] [Accepted: 08/19/2012] [Indexed: 05/24/2023]
Abstract
Advanced anaerobic digestion processes aimed at improving the methanization of sewage sludge may be potentially impaired by the production of inhibitory compounds (e.g. free ammonia). The result of methanogenic inhibition is relatively high effluent concentrations of acetic acid and other soluble organics, as well as reduced methane yields. An extreme example of such an advanced process is the thermal hydrolytic pretreatment of sludge prior to high solids digestion (THD). Compared to a conventional mesophilic anaerobic digestion process (MAD), THD operates in a state of constant inhibition driven by high free ammonia concentrations, and elevated pH values. As such, previous investigations of the kinetics of methanogenesis from acetic acid under uninhibited conditions do not necessarily apply well to the modeling of extreme processes such as THD. By conducting batch ammonia toxicity assays using biomass from THD and MAD reactors, we compared the response of these communities over a broad range of ammonia inhibition. For both processes, increased inhibitor concentrations resulted in a reduction of biomass growth rate (r(max) = μ(max)∙X) and a resulting decrease in the substrate half saturation coefficient (K(S)). These two parameters exhibited a high degree of correlation, suggesting that for a constant transport limited system, the K(S) was mostly a linear function of the growth rate. After correcting for reactor pH and temperature, we found that the THD and MAD biomass were both able to perform methanogenesis from acetate at high free ammonia concentrations (equivalent to 3-5 g/L total ammonia nitrogen), albeit at less than 30% of their respective maximum rates. The reduction in methane production was slightly less pronounced for the THD biomass than for MAD, suggesting that the long term exposure to ammonia had selected for a methanogenic pathway less dependent on those organisms most sensitive to ammonia inhibition (i.e. aceticlastic methanogens).
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