Fang Zhang
Huijie Hou
Jie Fu
Juan-Rodrigo Bastidas-Oyanedel- 1College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
- 2School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, China
- 3SDU-Department of Chemical Engineering, Biotechnology, and Environmental Technology, University of Southern Denmark, Odense, Denmark
Editorial on the Research Topic
Anaerobic digestion of waste organics: toxicity and management
As an important anaerobic environmental biotechnology, anaerobic digestion (AD) can convert biodegradable organic waste, including organic wastewaters, waste-activated sludge, and food waste, into biogas (Dai et al., 2020; Toutian et al., 2020). AD involves cascading steps of hydrolysis/acidogenesis, acetogenesis/homoacetogensis, and methanogenesis, in which the distinct different microorganisms involved include acidogenic bacteria, acetogens, homoacetogens, and hydrogenotrophic and aceticlastic methanogens (Saha et al., 2020). This method offers several advantages, including low running costs, adaptability to various feedstock or conditions, and the lack of need for sterilization. However, toxicants present in organic wastes, such as antibiotics, metal ions, nanoparticles, and microplastic fibers, may hinder the overall performance of AD (Mu and Chen, 2011; Hart et al., 2022; Tang et al., 2023).
The present Research Topic “Anaerobic digestion of waste organics: toxicity and management” aims to cover promising and novel research into biological strategies for improving AD performance, especially physicochemical analyses and multi-omics technologies. This topic comprises four original articles contributed by 23 authors. Propionic acid (HPr) is known as a frequently accumulated intermediate in anaerobic digesters due to the thermodynamical limitation. Thus, Kim et al. identify key players as metagenome-assembled genomes in HPr oxidation and organic overloading recovery in anaerobic digesters. The results showed that at least two key species of JABUEY01 sp013314815 and Methanoculleus sp002497965 are responsible for efficient propionate removal, which can be used as microbial cocktails for the stable operation of AD. The conductive materials of biochar and activated carbon were capable of improving methane production from organic waste via direct interspecific electron transfer (DIET) between acidogens and methanogens. Thus, Abid et al. investigated the impact of biochar on the anaerobic degradation of olive mill wastewater. The results demonstrated that adding biochar to olive mill wastewater increased the methane yield by 97.8%. The microbial diversity revealed that biochar supplementation significantly increased the abundance of the genera Methanothrix and Methanosarcina potentially involved in DIET. Meanwhile, Wu et al. studied the effects of activated carbon- and graphite-conductive media on methane production in WAS fermentation. Their results show that the largest biogas yield in a 100 mesh-activated carbon group was 468.2 ml/g VSS, which was 13.8% higher than the blank group. The three genera Nitrososphaeraceae, Methanobacterium, and Methanosaeta were cultured in the activated carbon and graphite groups. On the other hand, mitigating CH4 emissions may reduce the current global warming effects due to its high global warming potential. Thus, Im et al. reported that adding salt to the pig slurry storage tank can inhibit the activity of methanogens and reduce unwanted CH4 emissions. More CH4 can be obtained in the following biogas production from the stored pig slurry due to the preservation of organics.
In summary, the articles included in this Research Topic demonstrate the importance of toxicity and management in the anaerobic digestion of waste organics. Additionally, physicochemical analyses potentially augmented by omics technologies are shown to be useful tools for providing solid evidence and revealing the potential mechanism. The outcome of such studies may improve understanding of the toxicity and management of organic waste degradation and subsequently help improve the development of anaerobic fermentation.
Author contributions
FZ, HH, JF, and J-RB-O wrote the manuscript. All authors read and approved the final manuscript.
Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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References
Dai, K., Zhang, W., Zeng, R. J., and Zhang, F. (2020). Production of chemicals in thermophilic mixed culture fermentation: mechanism and strategy. Crit. Rev. Environ. Sci. Technol. 50, 1–30. doi: 10.1080/10643389.2019.1616487
Hart, S. G., Young, M. N., Parameswaran, P., Rittmann, B. E., and Torres, C. I. (2022). What is the right rate? Determining digestibility kinetics of pretreated waste activated sludge during anaerobic digestion. Environ. Eng. Sci. 39, 877–885. doi: 10.1089/ees.2021.0580
Mu, H., and Chen, Y. (2011). Long-term effect of ZnO nanoparticles on waste activated sludge anaerobic digestion. Water Res. 45, 5612–5620. doi: 10.1016/j.watres.2011.08.022
Saha, S., Basak, B., Hwang, J. H., Salama, E. S., Chatterjee, P. K., Jeon, B. H., et al. (2020). Microbial symbiosis: a network towards biomethanation. Trends Microbiol. 28, 968–984. doi: 10.1016/j.tim.2020.03.012
Tang, Y., Sun, J., Dong, B., and Dai, X. (2023). Citric acid treatment directly on anaerobic digestor sludge alleviates the inhibitory effect of in-situ generated humic acids by their deconstruction and redistribution. Water Res. 233, 119680. doi: 10.1016/j.watres.2023.119680
Keywords: anaerobic digestion, waste organics, methane, methanogens, toxicity
Citation: Zhang F, Hou H, Fu J and Bastidas-Oyanedel J-R (2023) Editorial: Anaerobic digestion of waste organics: toxicity and management. Front. Microbiol. 14:1243205. doi: 10.3389/fmicb.2023.1243205
Received: 20 June 2023; Accepted: 11 July 2023;
Published: 18 July 2023.
Edited and reviewed by: William James Hickey, University of Wisconsin-Madison, United States
Copyright © 2023 Zhang, Hou, Fu and Bastidas-Oyanedel. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Fang Zhang, zhfang@fafu.edu.cn