scholarly journals Use of extracellular polymer substances as additives for improving biogas yield and digestion performance

2019 ◽  
Author(s):  
Haitong Ma ◽  
Chen Yan Guo ◽  
Ming Wu ◽  
Hui Liu ◽  
Zhiwei Wang ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Anaerobic Digestion ◽  
Methane Production ◽  
Suspended Solids ◽  
Granular Sludge ◽  
Average Particle ◽  
Anaerobic Granular Sludge ◽  
Conductive Materials ◽  
Secondary Pollution ◽  
Extracellular Polymer

AbstractTo understand how extracellular polymer substances (EPS) as additives promotes methanogenesis, batch tests of methane production potential in anaerobic reactors with the addition of EPS or not were conducted. Research showed that EPS increased remarkably methane production during anaerobic digestion (36.5% increase compared with the control). EPS enriched functional microorganisms such as Firmicutes, Actinobacteria, Synergistetes, and Chloroflexi. Among them, 8.86% OTUs from the important hydrolysis and acidification phyla, which may be an important reason for the enhanced methanogenic capacity of anaerobic granular sludge. Additionally, EPS also improved the abundance of cytochrome c (c-Cyts), accelerating the direct interspecies electron transfer (DIET) between syntrophic bacteria and methanogens, thus enhancing the methane production. Interestingly, the average particle size, volatile suspended solids/total suspended solids (VSS/TSS) and EPS content of anaerobic granular sludge (AnGS) in the EPS reactor were approximately equal to that of the control reactor during the anaerobic digestion, illustrating that EPS could not affect the physicochemical properties of AnGS. Therefore, these results suggested that EPS mainly played a role in the form of conductive materials in the anaerobic digestion process. Compared with conductive materials, EPS as biomass conductive materials was not only environmentally friendly and economical but also no secondary pollution.ImportanceCompared with the reported conductive materials, EPS has the potential of biodegradation, electron transfer and no significant secondary pollution. Besides, there are few studies on the utilization of EPS resources, especially the effect of EPS as an additive on anaerobic digestion performance. To clarify whether EPS as conductive materials or carbon source promotes methanogenesis. Therefore, in this study, we investigated the influence of EPS as an additive on the methanogenic capacity, physical-chemical properties, microbial community structure and metabolic function of anaerobic granular sludge (AnGS), and preliminarily expatiate the influence mechanism of EPS as an additive on methanogenesis. At the meantime, the research is expected to provide new solutions for the improvement of anaerobic digestion performance and disposal of waste mud.

scholarly journals The treatment of solvent recovery raffinate by aerobic granular sludge in a pilot-scale sequencing batch reactor

2015 ◽  
Vol 13 (3) ◽  
pp. 746-757 ◽  
Author(s):  
Bei Long ◽  
Chang-zhu Yang ◽  
Wen-hong Pu ◽  
Jia-kuan Yang ◽  
Guo-sheng Jiang ◽  
...  
Keyword(s):  
Suspended Solids ◽  
Sequencing Batch Reactor ◽  
Batch Reactor ◽  
Granular Sludge ◽  
Pilot Scale ◽  
Volume Index ◽  
Aerobic Granular Sludge ◽  
Average Particle ◽  
Solvent Recovery ◽  
Mixed Liquor

Mature aerobic granular sludge (AGS) was inoculated for the start-up of a pilot-scale sequencing batch reactor for the treatment of high concentration solvent recovery raffinate (SRR). The proportion of simulated wastewater (SW) (w/w) in the influent gradually decreased to zero during the operation, while volume of SRR gradually increased from zero to 10.84 L. AGS was successfully domesticated after 48 days, which maintained its structure during the operation. The domesticated AGS was orange, irregular, smooth and compact. Sludge volume index (SVI), SV30/SV5, mixed liquor volatile suspended solids/mixed liquor suspended solids (MLVSS/MLSS), extracellular polymeric substances, proteins/polysaccharides, average particle size, granulation rate, specific oxygen utilization rates (SOUR)H and (SOUR)N of AGS were about 38 mL/g, 0.97, 0.52, 39.73 mg/g MLVSS, 1.17, 1.51 mm, 96.66%, 47.40 mg O2/h g volatile suspended solids (VSS) and 8.96 mg O2/h g VSS, respectively. Good removal effect was achieved by the reactor. Finally, the removal rates of chemical oxygen demand (COD), total inorganic nitrogen (TIN), NH4+-N and total phosphorus (TP) were more than 98%, 96%, 97% and 97%, respectively. The result indicated gradually increasing the proportion of real wastewater in influent was a useful domestication method, and the feasibility of AGS for treatment of high C/N ratio industrial wastewater.

scholarly journals Hydrogen and Methane Production Under Conditions of Anaerobic Digestion of Key-Lime and Cabbage Wastes

2019 ◽  
Vol 39 (3) ◽  
pp. 243 ◽  
Author(s):  
Gaweł Sołowski ◽  
Izabela Konkol ◽  
Bartosz Hrycak ◽  
Dariusz Czylkowski
Keyword(s):  
Anaerobic Digestion ◽  
Hydrogen Production ◽  
Methane Production ◽  
Substrate Concentration ◽  
Suspended Solids ◽  
Batch Process ◽  
Citrus Aurantifolia ◽  
Total Solids ◽  
Neutral Ph ◽  
Key Lime

In this article, the results of key lime fruit (Citrus aurantifolia) wastes and cabbage (Brassica L.) wastes anaerobic digestion are presented. Anaerobic digestion of the wastes was performed in batch process, neutral pH (key-lime 7.47 and cabbage 7.67) and substrate concentration of Volatile Suspended Solids (VSS) 10 gVSS/L. One of the aims of this research was to check the availability of these substrates to be the source of methane and hydrogen. Key lime wastes produced 32 times more methane than raw cabbage. However, hydrogen production from cabbage was 149 times higher than key lime. The percentage of methane production in cabbage was up to 81% and in key lime was up to 75%. This research showed from the substrates comparison that efficient hydrogen production is less dependent on low pKa, pH than on total solids of the substrates.

Identification of mesophilic and thermophilic fermentative species in anaerobic granular sludge

2006 ◽  
Vol 54 (2) ◽  
pp. 19-24 ◽  
Author(s):  
F. Hernon ◽  
C. Forbes ◽  
E. Colleran
Keyword(s):  
Growth Rate ◽  
Anaerobic Digestion ◽  
Molecular Biology ◽  
Food Waste ◽  
Granular Sludge ◽  
Anaerobic Granular Sludge ◽  
Digestion Process ◽  
Fermentative Bacteria ◽  
Landfill Sites ◽  
Rapid Growth Rate

Large quantities of biodegradable food waste in the form of fruit and vegetables are still being deposited in landfill sites in Ireland. The development of an anaerobic digestion process using fermentative species which degrade the carbohydrate-rich waste could divert the food waste from landfills. We identified fermentative species grown on glucose and sucrose at mesophilic and thermophilic temperatures using molecular biology techniques. The dominating fermentative bacteria of the mesophilic sludge were of the Bacteroidetes and Spirochaetes classes. Although both groups of bacteria are typically fermentative their substrate range appears to be limited. The dominating fermentative bacteria in the thermophilic sludge was Thermoanaerobacterium aotearoense of the Clostridia class. The indications are that Thermoanaerobacterium aotearoense may be highly suitable to biodegrade a carbohydrate-rich influent feed due to its possibly very rapid growth rate and also an extensive substrate range.

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