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Environmental Science & Technology Dec 2023Successfully addressing the complex global sanitation problem is a massive undertaking. Anaerobic digestion (AD), coupled with post-treatment, has been identified as a... (Review)
Review
Successfully addressing the complex global sanitation problem is a massive undertaking. Anaerobic digestion (AD), coupled with post-treatment, has been identified as a promising technology to contribute to meeting this goal. It offers multiple benefits to the end users, such as the potential inactivation of pathogenic microorganisms in waste and the recovery of resources, including renewable energy and nutrients. This feature article provides an overview of the most frequently applied AD systems for decentralized communities and low- and lower-middle-income countries with an emphasis on sanitation, including technologies for which pathogen inactivation was considered during the design. Challenges to AD use are then identified, such as experience, economics, knowledge/training of personnel and users, and stakeholder analysis. Finally, accelerators for AD implementation are noted, such as the inclusion of field studies in academic journals, analysis of emerging contaminants, the use of sanitation toolboxes and life cycle assessment in design, incorporation of artificial intelligence in monitoring, and expansion of undergraduate and graduate curricula focused on Water, Sanitation, and Hygiene (WASH).
Topics: Anaerobiosis; Artificial Intelligence; Sanitation; Technology; Water; Water Supply
PubMed: 37956995
DOI: 10.1021/acs.est.3c05291 -
Bioresource Technology May 2022Anaerobic digestion (AD) is a bioprocess technology that integrates into circular economy systems, which produce renewable energy and biofertilizer whilst reducing... (Review)
Review
Anaerobic digestion (AD) is a bioprocess technology that integrates into circular economy systems, which produce renewable energy and biofertilizer whilst reducing greenhouse gas emissions. However, improvements in biogas production efficiency are needed in dealing with lignocellulosic biomass. The state-of-the-art of AD technology is discussed, with emphasis on feedstock digestibility and operational difficulty. Solutions to these challenges including for pre-treatment and bioaugmentation are reviewed. This article proposes an innovative integrated system combining alkali pre-treatment, temperature-phased AD and bioaugmentation techniques. The integrated system as modelled has a targeted potential to achieve a biodegradability index of 90% while increasing methane production by 47% compared to conventional AD. The methane productivity may also be improved by a target reduction in retention time from 30 to 20 days. This, if realized has the potential to lower energy production cost and the levelized cost of abatement to facilitate an increased resource of sustainable commercially viable biomethane.
Topics: Alkalies; Anaerobiosis; Biofuels; Biomass; Lignin; Methane
PubMed: 35257881
DOI: 10.1016/j.biortech.2022.126950 -
International Journal of Environmental... Mar 2021Manure and digestate liquid fractions are nutrient-rich effluents that can be fractionated and concentrated using membranes. However, these membranes tend to foul due to... (Review)
Review
Manure and digestate liquid fractions are nutrient-rich effluents that can be fractionated and concentrated using membranes. However, these membranes tend to foul due to organic matter, solids, colloids, and inorganic compounds including calcium, ammonium, sodium, sulfur, potassium, phosphorus, and magnesium contained in the feed. This review paper is intended as a theoretical and practical tool for the decision-making process during design of membrane-based systems aiming at processing manure liquid fractions. Firstly, this review paper gives an overview of the main physico-chemical characteristics of manure and digestates. Furthermore, solid-liquid separation technologies are described and the complexity of the physico-chemical variables affecting the separation process is discussed. The main factors influencing membrane fouling mechanisms, morphology and characteristics are described, as well as techniques covering membrane inspection and foulant analysis. Secondly, the effects of the feed characteristics, membrane operating conditions (pressure, cross-flow velocity, temperature), pH, flocculation-coagulation and membrane cleaning on fouling and membrane performance are presented. Finally, a summary of techniques for specific recovery of ammonia-nitrogen, phosphorus and removal of heavy metals for farm effluents is also presented.
Topics: Ammonia; Anaerobiosis; Manure; Nitrogen; Phosphorus
PubMed: 33803027
DOI: 10.3390/ijerph18063107 -
Microbial Genomics Nov 2023Archamoebae comprises free-living or endobiotic amoebiform protists that inhabit anaerobic or microaerophilic environments and possess mitochondrion-related organelles...
Archamoebae comprises free-living or endobiotic amoebiform protists that inhabit anaerobic or microaerophilic environments and possess mitochondrion-related organelles (MROs) adapted to function anaerobically. We compared reconstructed MRO proteomes of eight species (six genera) and found that the common ancestor of Archamoebae possessed very few typical components of the protein translocation machinery, electron transport chain and tricarboxylic acid cycle. On the other hand, it contained a sulphate activation pathway and bacterial iron-sulphur (Fe-S) assembly system of MIS-type. The metabolic capacity of the MROs, however, varies markedly within this clade. The glycine cleavage system is widely conserved among Archamoebae, except in , probably owing to its role in catabolic function or one-carbon metabolism. MRO-based pyruvate metabolism was dispensed within subgroups Entamoebidae and Rhizomastixidae, whereas sulphate activation could have been lost in isolated cases of , and sp. The MIS (Fe-S) assembly system was duplicated in the common ancestor of Mastigamoebidae and Pelomyxidae, and one of the copies took over Fe-S assembly in their MRO. In Entamoebidae and Rhizomastixidae, we hypothesize that Fe-S cluster assembly in both compartments may be facilitated by dual localization of the single system. We could not find evidence for changes in metabolic functions of the MRO in response to changes in habitat; it appears that such environmental drivers do not strongly affect MRO reduction in this group of eukaryotes.
Topics: Anaerobiosis; Mitochondria; Eukaryota; Iron; Sulfates
PubMed: 37994879
DOI: 10.1099/mgen.0.001143 -
Microbes and Environments Mar 2017Anaerobic methane oxidation in archaea is often presented to operate via a pathway of "reverse methanogenesis". However, if the cumulative reactions of a methanogen are... (Review)
Review
Anaerobic methane oxidation in archaea is often presented to operate via a pathway of "reverse methanogenesis". However, if the cumulative reactions of a methanogen are run in reverse there is no apparent way to conserve energy. Recent findings suggest that chemiosmotic coupling enzymes known from their use in methylotrophic and acetoclastic methanogens-in addition to unique terminal reductases-biochemically facilitate energy conservation during complete CH oxidation to CO. The apparent enzyme modularity of these organisms highlights how microbes can arrange their energy metabolisms to accommodate diverse chemical potentials in various ecological niches, even in the extreme case of utilizing "reverse" thermodynamic potentials.
Topics: Anaerobiosis; Archaea; Energy Metabolism; Metabolic Networks and Pathways; Methane; Oxidation-Reduction
PubMed: 28321009
DOI: 10.1264/jsme2.ME16166 -
Bioresource Technology Jan 2022Conventional sewage treatment applying activated sludge processes is energy-intensive and requires great financial input, hampering widespread implementation. The... (Review)
Review
Conventional sewage treatment applying activated sludge processes is energy-intensive and requires great financial input, hampering widespread implementation. The introduction of anaerobic membrane bioreactors (AnMBR) followed by an algal reactor growing species of commercial interest, may present an alternative, contributing to the envisaged resource recovery at sewage treatment plants. AnMBRs can be applied for organic matter removal with energy self-sufficiency, provided that effective membrane fouling management is applied. Haematococcus pluvialis, an algal species with commercial value, can be selected for ammonium and phosphate removal. Theoretical analysis showed that good pollutant removal, positive financial output, as well as a significant reduction in the amount of hazardous activated sludge can be achieved by applying the proposed process, showing interesting advantages over current sewage treatment processes. Microbial contamination to H. pluvialis is a challenge, and technologies for preventing the contamination during continuous sewage treatment need to be applied.
Topics: Anaerobiosis; Bioreactors; Sewage; Waste Disposal, Fluid; Wastewater
PubMed: 34655782
DOI: 10.1016/j.biortech.2021.126115 -
STAR Protocols Sep 2021The use of germ-free mice is integral to the understanding of host-gut microbiome relationships. Such models rely on faithful replication of the donor microbiome to...
The use of germ-free mice is integral to the understanding of host-gut microbiome relationships. Such models rely on faithful replication of the donor microbiome to establish causal effects of the gut microbiota on host pathophysiology. This protocol describes the preparation and transfer of donor microbiota, focusing on strict anaerobic processing methods and multiple instillations by gavage for optimal gut microbiota recovery. For complete details on the generation and use of this protocol, please refer to Choo and Rogers (2021).
Topics: Anaerobiosis; Animals; Bioreactors; Fecal Microbiota Transplantation; Germ-Free Life; Mice
PubMed: 34189475
DOI: 10.1016/j.xpro.2021.100610 -
Journal of Environmental Management Sep 2022Increased biogas production from increasing numbers of anaerobic digestion (AD) facilities has increased the mass of digestate applied to agricultural land close to AD...
Increased biogas production from increasing numbers of anaerobic digestion (AD) facilities has increased the mass of digestate applied to agricultural land close to AD plants and has led to an oversupply in some regions. This necessitates long distance digestate transportation accompanied by economic, environmental, and social drawbacks. This work assesses the performance of three different digestate management options (MOs); land application of whole digestate (MO1), digestate separation (MO2), and digestate separation and evaporation (MO3), combined with centralised or decentralised digestate storage. All MOs required the same landbank area, whilst MO2 and MO3 reduced digestate management costs by 9% and 37% (if recovered heat is used) respectively. GHG emissions from MO2 were 41% lower than MO1 if renewable electricity was used. MO3 reduced GHG emissions by 63% compared to MO1, if renewable electricity and recovered heat were used. MO2 required the same centralised digestate storage volume as MO1 while MO3 required 44% of the centralised storage volume. Centralised digestate storage required a maximum of 79 days for digestate transportation (33 trucks/day, 20 m capacity) to land for MO1 and MO2, and 35 days for MO3. Decentralised digestate storage required 63 storage tanks and 15 trucks/day for MO1, 69 tanks and 15 trucks/day for MO2, and 68 tanks and 7 trucks/day for MO3. Tank size ranged from 500 m to 20,000 m. MO3 combined with decentralised storage could reduce the cost and GHG emissions (if recovered energy is used), vehicle movements, and the number of storage tanks required for digestate management.
Topics: Agriculture; Anaerobiosis; Biofuels
PubMed: 35751231
DOI: 10.1016/j.jenvman.2022.115312 -
Journal of Environmental Management Jan 2024Anaerobic Digestion (AD) technology emerges as a viable solution for managing municipal organic waste, offering pollution reduction and the generation of biogas and... (Review)
Review
Anaerobic Digestion (AD) technology emerges as a viable solution for managing municipal organic waste, offering pollution reduction and the generation of biogas and fertilisers. This study reviews the research works for the advancements in AD implementation to effectively impact the UN Sustainable Development Goals (SDGs). Furthermore, the study critically analyses responsible waste management that contributes to health and safety, elevating quality of life in both rural and urban areas and, finally, creates a map of AD outputs onto all 17 SDGs. Finally, the assessment employs the three sustainability pillars (i.e., economic, environmental, and social perspectives) to examine the direct and indirect links between AD and all 17 UN SDGs. The findings reveal substantial progress, such as poverty reduction through job creation, bolstering economic growth (SDGs 1, 8, 10, 12), enhancing agricultural productivity (SDG 2), advancing renewable energy usage and diminishing reliance on fossil fuels (SDG 7), fostering inclusive education and gender equality (SDGs 4, 5, 9), combating climate change (SDG 13), transforming cities into sustainable and harmonious environments (SDGs 11, 16, 17), and curbing environmental pollution (SDGs 3, 6, 12, 14, 15). Nonetheless, the study highlights the need for further efforts to achieve the SDG targets, particularly in part of liquid and solid fertilisers as the AD outputs.
Topics: Sustainable Development; Quality of Life; Anaerobiosis; Fertilizers; Cities; Goals
PubMed: 37918233
DOI: 10.1016/j.jenvman.2023.119458 -
Microbial Biotechnology Apr 2022Carbon-based materials (CBM), including activated carbon (AC), activated fibres (ACF), biochar (BC), nanotubes (CNT), carbon xenogels (CX) and graphene nanosheets (GNS),... (Review)
Review
Carbon-based materials (CBM), including activated carbon (AC), activated fibres (ACF), biochar (BC), nanotubes (CNT), carbon xenogels (CX) and graphene nanosheets (GNS), possess unique properties such as high surface area, sorption and catalytic characteristics, making them very versatile for many applications in environmental remediation. They are powerful redox mediators (RM) in anaerobic processes, accelerating the rates and extending the level of the reduction of pollutants and, consequently, affecting positively the global efficiency of their partial or total removal. The extraordinary conductive properties of CBM, and the possibility of tailoring their surface to address specific pollutants, make them promising as catalysts in the treatment of effluents containing diverse pollutants. CBM can be combined with magnetic nanoparticles (MNM) assembling catalytic and magnetic properties in a single composite (C@MNM), allowing their recovery and reuse after the treatment process. Furthermore, these composites have demonstrated extraordinary catalytic properties. Evaluation of the toxicological and environmental impact of direct and indirect exposure to nanomaterials is an important issue that must be considered when nanomaterials are applied. Though the chemical composition, size and physical characteristics may contribute to toxicological effects, the potential toxic impact of using CBM is not completely clear and is not always assessed. This review gives an overview of the current research on the application of CBM and C@MNM in bioremediation and on the possible environmental impact and toxicity.
Topics: Anaerobiosis; Biodegradation, Environmental; Catalysis; Environmental Restoration and Remediation; Nanostructures
PubMed: 34586713
DOI: 10.1111/1751-7915.13822