Enhanced Methane Production from Sludge Anaerobic Digestion with the Addition of Potassium Permanganate
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ABSTRACT:
SUBMITTER: Tang Y
PROVIDER: S-EPMC9648141 | biostudies-literature | 2022 Oct
REPOSITORIES: biostudies-literature
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Project description:Direct interspecies electron transfer (DIET) between Geobacter species and Methanosaeta species is an alternative to interspecies hydrogen transfer (IHT) in anaerobic digester, which however has not been established in anaerobic sludge digestion as well as in bioelectrochemical systems yet. In this study, it was found that over 50% of methane production of an electric-anaerobic sludge digester was resulted from unknown pathway. Pyrosequencing analysis revealed that Geobacter species were significantly enriched with electrodes. Fluorescence in situ hybridization (FISH) further confirmed that the dominant Geobacter species enriched belonged to Geobacter metallireducens. Together with Methanosaeta species prevailing in the microbial communities, the direct electron exchange between Geobacter species and Methanosaeta species might be an important reason for the "unknown" increase of methane production. Conductivity of the sludge in this electric-anaerobic digester was about 30% higher than that of the sludge in a control digester without electrodes. This study not only revealed for the first time that DIET might be the important mechanism on the methanogenesis of bioelectrochemical system, but also provided a new method to enhance DIET by means of bioelectric enrichment of Geobacter species.
| S-EPMC4650609 | biostudies-literature
Project description:BackgroundRecently, it has been indicated that anaerobic co-digestion of waste activated sludge with other waste streams at wastewater treatment plants is a promising strategy for enhancing methane production and materials recovery. The enhanced methane production can be used as a renewable source of energy in wastewater treatment plants. It can also reduce the amount of greenhouse gas emission in landfilling of the waste streams.ResultsAccording to the results obtained in this study, anaerobic co-digestion of waste activated sludge with mixed fruit waste and cheese whey improves methane production and the quality of digested sludge in comparison to the anaerobic digestion of waste activated sludge individually. It was indicated that carbon/nitrogen ratio (C/N) in the mixture of waste activated sludge, fruit waste and cheese whey improved considerably, leading to better anaerobic organisms' activity during digestion. With assessing the activity of protease and cellulase, as the main enzymes hydrolyzing organic matter in anaerobic digestion, it was indicated that co-digestion of waste activated sludge with mixed fruit waste and cheese whey enhances the activity of these enzymes by 22 and 9% respectively. At the end of digestion, the amount of cumulative methane production significantly increased by 31% in the reactor with 85% waste activated sludge and 15% mixed fruit waste and cheese whey, compared to the reactor with 100% waste activated sludge. In addition, chemical oxygen demand (COD) and volatile solid (VS) in digested sludge was improved respectively by 9 and 7% when mixed fruit waste and cheese whey was used.ConclusionsThis study revealed that mixed fruit waste and cheese whey is potentially applicable to anaerobic digestion of waste activated sludge, as fruit waste and cheese whey have high C/N ratio that enhance low C/N in waste activated sludge and provide a better diet for anaerobic organisms. This is of significant importance because not only could higher amount of renewable energy be generated from the enhanced methane production in wastewater treatment plants, but also capital costs of the companies whose waste streams are being transported to wastewater treatments plants could be reduced considerably.
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Project description:The potential of periodate (PI) in sludge anaerobic digestion is not tapped, although it has recently attracted great research interest in organic contaminants removal and pathogens inactivation in wastewater treatment. This is the first work to demonstrate significant improvement in methane generation from waste activated sludge (WAS) with PI pretreatment and to provide underlying mechanisms. Biochemical methane potential tests indicated that methane yield enhanced from 100.2 to 146.3 L per kg VS (VS, volatile solids) with PI dosages from 0 to 100 mg per g TS (TS, total solids). Electron spin resonance showed PI could be activated without extra activator addition, which might be attributed to the native transition metals (e.g., Fe2+) in WAS, thereby generating hydroxyl radical (•OH), superoxide radicals (•O2 -), and singlet oxygen (1O2). Further scavenging tests demonstrated all of them synergistically promoted WAS disintegration, and their contributions were in the order of •O2 - > •OH > 1O2, leading to the release of substantial biodegradable substances (i.e., proteins and polysaccharides) into the liquid phase for subsequent biotransformation. Moreover, fluorescence and ultraviolet spectroscopy analyses indicated the recalcitrant organics (especially lignocellulose and humus) could be degraded by reducing their aromaticity under oxidative stress of PI, thus readily for methanogenesis. Microbial community analysis revealed some microorganisms participating in hydrolysis, acidogenesis, and acetoclastic methanogenesis were enriched after PI pretreatment. The improved key enzyme activities and up-regulated metabolic pathways further provided direct evidence for enhanced methane production. This research was expected to broaden the application scope of PI and provide more diverse pretreatment choices for energy recovery through anaerobic digestion.
| S-EPMC9640319 | biostudies-literature
Project description:The utilisation of water hyacinth for production of biogas is considered to be a solution to both its control and the global renewable energy challenge. In this instance, an investigation was conducted to evaluate the potential of water hyacinth inoculum to enhance methane production during anaerobic digestion (AD). Chopped whole water hyacinth (10% (w/v)) was digested to prepare an inoculum consisting mainly of water hyacinth indigenous microbes. The inoculum was incorporated in the AD of freshly chopped whole water hyacinth to set up different ratios of water hyacinth inoculum and water hyacinth mixture with appropriate controls. The results of batch tests with water hyacinth inoculum showed a maximal cumulative volume of 211.67 ml of methane after 29 days of AD as opposed to 88.6 ml of methane generated from the control treatment without inoculum. In addition to improving methane production, inclusion of water hyacinth inoculum reduced the electrical conductivity (EC) values of the resultant digestate, and, amplification of nifH and phoD genes in the digestate accentuates it as a potential soil ameliorant. This study provides an insight into the potential of water hyacinth inoculum to enhance methane production and contribute to the feasibility of the digestate as a soil fertility enhancer.
| S-EPMC10083160 | biostudies-literature
Project description:Having been generated with a tremendous amount annually, paper waste (PW) represents a large proportion in municipal solid waste (MSW) and also a potential source of renewable energy production through the application of anaerobic digestion (AD). However, the recalcitrant lignocellulosic structure poses obstacles to efficient utilization in this way. Recently, anaerobic and microaerobic pretreatment have attracted attention as approaches to overcome the obstacles of biogas production. This study was set out to present a systematic comparison and assessment of anaerobic and microaerobic pretreatment of PW with different oxygen loadings by five microbial agents: composting inoculum (CI), straw-decomposing inoculum (SI), cow manure (CM), sheep manure (SM), and digestate effluent (DE). The hints of microbial community evolution during the pretreatment and AD were tracked by 16S rRNA high-throughput sequencing. The results demonstrated that PW pretreated by DE with an oxygen loading of 15 ml/gVS showed the highest cumulative methane yield (CMY) of 343.2 ml/gVS, with a BD of 79.3%. In addition to DE, SI and SM were also regarded as outstanding microbial agents for pretreatment because of the acceleration of methane production at the early stage of AD. The microbial community analysis showed that Clostridium sensu stricto 1 and Clostridium sensu stricto 10 possessed high relative abundance after anaerobic pretreatment by SI, while Bacteroides and Macellibacteroides were enriched after microaerobic pretreatment by SM, which were all contributable to the cellulose degradation. Besides, aerobic Bacillus in SI and Acinetobacter in SM and DE probably promoted lignin degradation only under microaerobic conditions. During AD, VadinBC27, Ruminococcaceae Incertae Sedis, Clostridium sensu stricto 1, Fastidiosipila, and Caldicoprobacter were the crucial bacteria that facilitated the biodegradation of PW. By comparing the groups with same microbial agent, it could be found that changing the oxygen loading might result in the alternation between hydrogenotrophic and acetoclastic methanogens, which possibly affected the methanogenesis stage. This study not only devised a promising tactic for making full use of PW but also provided a greater understanding of the evolution of microbial community in the pretreatment and AD processes, targeting the efficient utilization of lignocellulosic biomass in full-scale applications.
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Project description: Not available
| S-EPMC11016704 | biostudies-literature
Project description:Anaerobic digestion was one of the first bioenergy strategies developed, yet the interactions of the microbial community that is responsible for the production of methane are still poorly understood. For example, it has only recently been recognized that the bacteria that oxidize organic waste components can forge electrical connections with methane-producing microbes through biologically produced, protein-based, conductive circuits. This direct interspecies electron transfer (DIET) is faster than interspecies electron exchange via diffusive electron carriers, such as H2. DIET is also more resilient to perturbations such as increases in organic load inputs or toxic compounds. However, with current digester practices DIET rarely predominates. Improvements in anaerobic digestion associated with the addition of electrically conductive materials have been attributed to increased DIET, but experimental verification has been lacking. This deficiency may soon be overcome with improved understanding of the diversity of microbes capable of DIET, which is leading to molecular tools for determining the extent of DIET. Here we review the microbiology of DIET, suggest molecular strategies for monitoring DIET in anaerobic digesters, and propose approaches for re-engineering digester design and practices to encourage DIET.
| S-EPMC7695907 | biostudies-literature
Project description:Anaerobic digestion (AD) plays an important role in waste activated sludge (WAS) treatment; however, conventional AD (CAD) process needs substantial improvements, especially for the treatment of WAS with low solids content and poor anaerobic biodegradability. Herein, we propose a submerged anaerobic dynamic membrane bioreactor (AnDMBR) for simultaneous WAS thickening and digestion without any pretreatment. During the long-term operation, the AnDMBR exhibited an enhanced sludge reduction and improved methane production over CAD process. Moreover, the biogas generated in the AnDMBR contained higher methane content than CAD process. Stable carbon isotopic signatures elucidated the occurrence of combined methanogenic pathways in the AnDMBR process, in which hydrogenotrophic methanogenic pathway made a larger contribution to the total methane production. It was also found that organic matter degradation was enhanced in the AnDMBR, thus providing more favorable substrates for microorganisms. Pyrosequencing revealed that Proteobacteria and Bacteroidetes were abundant in bacterial communities and Methanosarcina and Methanosaeta in archaeal communities, which played an important role in the AnDMBR system. This study shed light on the enhanced digestion of WAS using AnDMBR technology.
| S-EPMC4735592 | biostudies-literature
Project description:Anaerobic digestion (AD) is a widespread microbial technology used to treat organic waste and recover energy in the form of methane ("biogas"). While most AD systems have been designed to treat a single input, mixtures of digester sludge and solid organic waste are emerging as a means to improve efficiency and methane yield. We examined laboratory anaerobic cultures of AD sludge from two sources amended with food waste, xylose, and xylan at mesophilic temperatures, and with cellulose at meso- and thermophilic temperatures, to determine whether and how the inoculum and substrate affect biogas yield and community composition. All substrate and inoculum combinations yielded methane, with food waste most productive by mass. Pyrosequencing of transcribed bacterial and archaeal 16S rRNA showed that community composition varied across substrates and inocula, with differing ratios of hydrogenotrophic/acetoclastic methanogenic archaea associated with syntrophic partners. While communities did not cluster by either inoculum or substrate, additional sequencing of the bacterial 16S rRNA gene in the source sludge revealed that the bacterial communities were influenced by their inoculum. These results suggest that complete and efficient AD systems could potentially be assembled from different microbial inocula and consist of taxonomically diverse communities that nevertheless perform similar functions.
| S-EPMC4602121 | biostudies-literature
Project description:Anaerobic digestion (AD) is commonly used to dispose of laying hen manure. However, veterinary antibiotic residues present in chicken manure may affect the AD process. Here, the effects of three types of veterinary antibiotics commonly used in laying hen breeding on AD were explored. Manures containing antibiotics at two different concentrations were continuously added during AD for 5 days: amoxicillin (HAMX: 145.06 mg/kg, LAMX: 57.88 mg/kg), doxycycline (HDOC: 183.61 mg/kg, LDOC: 98.00 mg/kg), and ciprofloxacin (HCIP: 96.34 mg/kg, LCIP: 40.43 mg/kg). Compared with a control with no veterinary antibiotics, the amoxicillin and doxycycline groups presented no significant effects on biogas production, methane production, VFA concentration, acetic acid concentration or the pH of the AD system (P > 0.05). However, compared with the control, the ciprofloxacin groups presented significantly inhibited biogas and methane production during AD (P < 0.05), and the HCIP and LCIP groups presented significantly decreased biogas (47.82% and 45.37%, respectively) and methane (58.24% and 52.55%, respectively) production (P < 0.05). Moreover, the VFA and acetic acid concentrations of the ciprofloxacin groups were significantly higher than those of control during the entire AD period (P < 0.05), and the pH value at the withdrawal stage was significantly lower than that of the control group (P < 0.01), with no significant difference between the HCIP and LCIP groups (P > 0.05). Our results suggest that ciprofloxacin causes VFA and acetic acid accumulation in AD systems, thereby reducing the pH of the systems and inhibiting methanogen growth, ultimately reducing methane production in the AD systems. These findings contribute to a deeper understanding of the impact of ciprofloxacin on methane production in AD systems and offer some considerations for the application of AD systems.
| S-EPMC11609544 | biostudies-literature