scholarly journals Temperature Effects on Methanogenesis and Sulfidogenesis during Anaerobic Digestion of Sulfur-Rich Macroalgal Biomass in Sequencing Batch Reactors

2019 ◽  
Vol 7 (12) ◽  
pp. 682 ◽  
Author(s):  
Jung ◽  
Kim ◽  
Lee
Keyword(s):  
Anaerobic Digestion ◽  
Biogas Production ◽  
Suppressive Effect ◽  
Microbial Reduction ◽  
Organic Loading Rate ◽  
Batch Reactors ◽  
Sulfate Reducing ◽  
Macroalgal Biomass ◽  
Thermophilic Conditions ◽  
Mesophilic Conditions

Methanogenesis and sulfidogenesis, the major microbial reduction reactions occurring in the anaerobic digestion (AD) process, compete for common substrates. Therefore, the balance between methanogenic and sulfidogenic activities is important for efficient biogas production. In this study, changes in methanogenic and sulfidogenic performances in response to changes in organic loading rate (OLR) were examined in two digesters treating sulfur-rich macroalgal waste under mesophilic and thermophilic conditions, respectively. Both methanogenesis and sulfidogenesis were largely suppressed under thermophilic relative to mesophilic conditions, regardless of OLR. However, the suppressive effect was even more significant for sulfidogenesis, which may suggest an option for H2S control. The reactor microbial communities developed totally differently according to reactor temperature, with the abundance of both methanogens and sulfate-reducing bacteria being significantly higher under mesophilic conditions. In both reactors, sulfidogenic activity increased with increasing OLR. The findings of this study help to understand how temperature affects sulfidogenesis and methanogenesis during AD.

scholarly journals Mesophilic and Thermophilic Anaerobic Digestion of Organic Fraction Separated during Mechanical Heat Treatment of Municipal Waste

2020 ◽  
Vol 10 (7) ◽  
pp. 2412
Author(s):  
Slawomir Kasinski
Keyword(s):  
Anaerobic Digestion ◽  
Fermentation Process ◽  
Biogas Production ◽  
Municipal Waste ◽  
Organic Fraction ◽  
Thermophilic Anaerobic Digestion ◽  
Volatile Solids ◽  
Thermophilic Conditions ◽  
Potential Impact ◽  
Mesophilic Conditions

The objective of this study was to investigate the effect of process temperature on semi-continuous anaerobic digestion of the organic fraction separated during autoclaving of municipal waste. Tests were carried out in reactors with full mixing. Biogas production was higher in thermophilic conditions than in mesophilic conditions (0.92 L/g volatile solids at 55 °C vs. 0.42 L/g volatile solids at 37 °C, respectively). The resulting methane yields were 0.25-0.32 L CH4/g VS and 0.56–0.70 L CH4/g VS in mesophilic and thermophilic conditions, respectively. In both variants, the methane share was over 70% v/v. This work also discusses the potential impact of Maillard compounds on the efficiency of the fermentation process, which were probably produced during the process of autoclaving of municipal waste. These results indicate that, after autoclaving, the organic fraction of municipal waste can be an effective substrate for anaerobic digestion in thermophilic conditions.

Relative kinetics of anaerobic digestion under thermophilic and mesophilic conditions

2011 ◽  
Vol 64 (4) ◽  
pp. 848-853 ◽  
Author(s):  
H. Ge ◽  
P. D. Jensen ◽  
D. J. Batstone
Keyword(s):  
Anaerobic Digestion ◽  
Biogas Production ◽  
Hydrolysis Rate ◽  
Fermentation Products ◽  
Promising Alternative ◽  
Sludge Digestion ◽  
Increase Glucose Uptake ◽  
Thermophilic Conditions ◽  
Kinetics Of ◽  
Mesophilic Conditions

With several advantages over the conventional mesophilic anaerobic digestion, such as better sludge quality and higher biogas production, thermophilic anaerobic digestion is regarded as a promising alternative for sludge digestion. Primary and activated sludges are complex materials, and historically, analysis of kinetics has been largely on whole sludge, without analysis of individual components. This paper analyses relative digestion kinetics of pure substrates designed to target main stages of sludge digestion under thermophilic and mesophilic conditions. Hydrolysis rate of cellulose was significantly influenced by temperature with hydrolysis coefficients of – at 55 °C (0.7 ± 0.1 day−1), 60 °C (0.8 ± 0.2 day−1), 65 °C (1.1 ± 0.2 day−1) and 70 °C (1.2 ± 0.2 day−1) over 38 °C (0.4 ± 0.1 day−1). This strongly follows the Arrhenius relationship, with an activation energy (EA) of 31 ± 4 kJ mol−1, corresponding to an increase of 1.5x for each 10 °C of temperature increase. Glucose uptake was rapid with a wide variety of fermentation products detected under mesophilic conditions, while uptake was slower under thermophilic conditions with acetate and propionate being dominant products. Propionate acetogenesis and acetate-utilizing methanogenesis kinetics were not influenced by temperatures. Hydrolysis is widely regarded as a rate-limiting step in sludge digestion, thus improvements in hydrolysis rates as measured during this study have the potential for significant improvements in overall apparent sludge digestion rates.

scholarly journals Evaluation of Anaerobic Digestion of Dairy Wastewater in an Innovative Multi-Section Horizontal Flow Reactor

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2392 ◽  
Author(s):  
Marcin Dębowski ◽  
Marcin Zieliński ◽  
Marta Kisielewska ◽  
Joanna Kazimierowicz
Keyword(s):  
Wastewater Treatment ◽  
Anaerobic Digestion ◽  
Flow Reactor ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Methane Content ◽  
Dairy Wastewater ◽  
Horizontal Flow ◽  
Organic Loading Rate ◽  
Biogas Yield

The aim of this study was the performance evaluation of anaerobic digestion of dairy wastewater in a multi-section horizontal flow reactor (HFAR) equipped with microwave and ultrasonic generators to stimulate biochemical processes. The effects of increasing organic loading rate (OLR) ranging from 1.0 g chemical oxygen demand (COD)/L·d to 4.0 g COD/L·d on treatment performance, biogas production, and percentage of methane yield were determined. The highest organic compounds removals (about 85% as COD and total organic carbon—TOC) were obtained at OLR of 1.0–2.0 g COD/L·d. The highest biogas yield of 0.33 ± 0.03 L/g COD removed and methane content in biogas of 68.1 ± 5.8% were recorded at OLR of 1.0 g COD/L·d, while at OLR of 2.0 g COD/L·d it was 0.31 ± 0.02 L/COD removed and 66.3 ± 5.7%, respectively. Increasing of the OLR led to a reduction in biogas productivity as well as a decrease in methane content in biogas. The best technological effects were recorded in series with an operating mode of ultrasonic generators of 2 min work/28 min break. More intensive sonication reduced the efficiency of anaerobic digestion of dairy wastewater as well as biogas production. A low nutrient removal efficiency was observed in all tested series of the experiment, which ranged from 2.04 ± 0.38 to 4.59 ± 0.68% for phosphorus and from 9.67 ± 3.36 to 20.36 ± 0.32% for nitrogen. The effects obtained in the study (referring to the efficiency of wastewater treatment, biogas production, as well as to the results of economic analysis) proved that the HFAR can be competitive to existing industrial technologies for food wastewater treatment.

scholarly journals Opportunity of Biogas Production from Solid Organic Wastes through Anaerobic Digestion

2018 ◽  
Vol 65 ◽  
pp. 05025 ◽  
Author(s):  
Sagor Kumar Pramanik ◽  
Fatihah Binti Suja ◽  
Biplob Kumar Pramanik ◽  
Shahrom Bindi Md Zain
Keyword(s):  
Anaerobic Digestion ◽  
Biogas Production ◽  
Nutrient Balance ◽  
Organic Wastes ◽  
Organic Loading Rate ◽  
Biogas Yield ◽  
Carbon And Nitrogen ◽  
Potential Risks ◽  
Nitrogen Ratio ◽  
Pre Treatment

Solid organic wastes create potential risks to environmental pollution and human health due to the uncontrolled discharge of huge quantities of hazardous wastes from numerous sources. Now-a-days, anaerobic digestion (AD) is considered as a verified and effective alternative compared to other techniques for treating solid organic waste. The paper reviewed the biological process and parameters involved in the AD along with the factors could enhance the AD process. Hydrolysis is considered as a rate-limiting phase in the complex AD process. The performance and stability of AD process is highly influenced by various operating parameters like temperature, pH, carbon and nitrogen ratio, retention time, and organic loading rate. Different pre-treatment (e.g. mechanical, chemical and biological) could enhance the AD process and the biogas yield. Co-digestion can also be used to provide suitable nutrient balance inside the digester. Challenges of the anaerobic digestion for biogas production are also discussed.

scholarly journals Adjusting Organic Load as a Strategy to Direct Single-Stage Food Waste Fermentation from Anaerobic Digestion to Chain Elongation

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1487
Author(s):  
Vicky De Groof ◽  
Marta Coma ◽  
Tom C. Arnot ◽  
David J. Leak ◽  
Ana B. Lanham
Keyword(s):  
Anaerobic Digestion ◽  
Food Waste ◽  
Loading Rate ◽  
Biogas Production ◽  
Single Stage ◽  
Stirred Tank ◽  
Chain Elongation ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
Operating Strategy

Production of medium chain carboxylic acids (MCCA) as renewable feedstock bio-chemicals, from food waste (FW), requires complicated reactor configurations and supplementation of chemicals to achieve product selectivity. This study evaluated the manipulation of organic loading rate in an un-supplemented, single stage stirred tank reactor to steer an anaerobic digestion (AD) microbiome towards acidogenic fermentation (AF), and thence to chain elongation. Increasing substrate availability by switching to a FW feedstock with a higher COD stimulated chain elongation. The MCCA species n-caproic (10.1 ± 1.7 g L−1) and n-caprylic (2.9 ± 0.8 g L−1) acid were produced at concentrations comparable to more complex reactor set-ups. As a result, of the adjusted operating strategy, a more specialised microbiome developed containing several MCCA-producing bacteria, lactic acid-producing Olsenella spp. and hydrogenotrophic methanogens. By contrast, in an AD reactor that was operated in parallel to produce biogas, the retention times had to be doubled when fed with the high-COD FW to maintain biogas production. The AD microbiome comprised a diverse mixture of hydrolytic and acidogenic bacteria, and acetoclastic methanogens. The results suggest that manipulation of organic loading rate and food-to-microorganism ratio may be used as an operating strategy to direct an AD microbiome towards AF, and to stimulate chain elongation in FW fermentation, using a simple, un-supplemented stirred tank set-up. This outcome provides the opportunity to repurpose existing AD assets operating on food waste for biogas production, to produce potentially higher value MCCA products, via simple manipulation of the feeding strategy.

Influence of mesophilic and thermophilic conditions on the anaerobic digestion of food waste: Focus on the microbial activity and removal of long chain fatty acids

2018 ◽  
Vol 36 (11) ◽  
pp. 1106-1112 ◽  
Author(s):  
Xiaohui Guo ◽  
Kang Kang ◽  
Gaoyuan Shang ◽  
Xiunan Yu ◽  
Ling Qiu ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Anaerobic Digestion ◽  
Microbial Activity ◽  
Food Waste ◽  
Biogas Production ◽  
Organic Loading Rate ◽  
Long Chain Fatty Acids ◽  
Methanogenic Activity ◽  
Long Chain ◽  
Chain Fatty Acids

The mesophilic reactor (MR) exhibited advantages in biogas production and performance stability over thermophilic reactor (TR) during the long-term anaerobic digestion (AD) of food waste (FW) with stepwise organic loading rate elevating. It was interesting to explore the mechanism causing the divergences in performances between these two reactors. The microbial activity was compared on day 110 when TR began to deteriorate. The results show that MR had significantly higher specific acetoclastic methanogenic activities (SAMA) and specific propionate and butyrate oxidative activities (SPOA and SBOA) than TR. The SAMA, SPOA and SBOA in TR were only 50.3%, 18.6% and 46.4% of those values in MR, respectively. Remarkably, the specific hydrogenotrophic methanogenic activity of 15.5±2.1, 15.7±4.6 mmol CH4·L−1 original slurry·d−1 in MR and TR was comparative with insignificant difference, which indicates that the microbial activity in TR had been inhibited widely apart from the hydrogenotrophic methanogenesis. Additionally, many particles with the diameters of 1–2 mm were observed to form in MR and identified as complexes of calcium and long chain fatty acids (LCFAs). The formation of calcium crystallization might alleviate the inhibition of LCFAs during AD of FW, which further supports the better performance in MR than TR.

scholarly journals Elevated biogas production from the anaerobic co-digestion of farmhouse waste: Insight into the process performance and kinetics

2019 ◽  
Vol 37 (12) ◽  
pp. 1240-1249 ◽  
Author(s):  
Spyridon Achinas ◽  
Gerrit Jan Willem Euverink
Keyword(s):  
Anaerobic Digestion ◽  
Biogas Production ◽  
Ternary Mixtures ◽  
Batch Reactors ◽  
Process Performance ◽  
Mixing Ratios ◽  
Batch Tests ◽  
Biogas Plants ◽  
The Impact ◽  
Insight Into

The biodegradable portion of solid waste generated in farmhouses can be treated for energy recovery with small portable biogas plants. This action can be done across the Netherlands and all around the planet. This study aims to appraise the performance of anaerobic digestion of different wastes (cow manure, food waste and garden waste) obtained from a regional farmhouse. Batch reactors were established under mesophilic conditions in order to investigate the impact of ternary mixtures on the anaerobic digestion process performance. Different mixing ratios were set in the batch tests. The upshots from the experiments connoted that ternary digestion with cow manure:food waste:garden waste mixing ratio of 40:50:10 yielded higher biogas amount. The kinetics’ results showed quite good congruence with the experimental study. The results from the kinetic analysis appeared to be in line with the experimental one.

Ammonia influence in anaerobic digestion of OFMSW

2009 ◽  
Vol 59 (6) ◽  
pp. 1153-1158 ◽  
Author(s):  
T. Benabdallah El Hadj ◽  
S. Astals ◽  
A. Galí ◽  
S. Mace ◽  
J. Mata-Álvarez
Keyword(s):  
Anaerobic Digestion ◽  
Competitive Inhibition ◽  
Biogas Production ◽  
Gompertz Model ◽  
Ammonia Concentration ◽  
Ion Concentration ◽  
Ammonium Ion ◽  
Municipal Solid Wastes ◽  
Methane Generation ◽  
Thermophilic Conditions

The anaerobic digestion of the organic fraction of municipal solid wastes is taking increasing importance in the recent years. The main problem of some anaerobic digestion process is the large quantity of ammonia that is released, especially when high solid digestion is implemented. A fraction of the supernatant is treated and the remaining is recirculated to maintain the reactor in the optimum solids concentration. The question arising is if this recirculation stream should also be treated to improve biogas production. However, when doing the latter the quantity of ammonia inside the reactor increases too which could lead to inhibit the reactor operation. In this paper it appears that not only free ammonia affects the methanogenic fermentation but also ammonium ion concentration. Biogas production profiles are estimated using the Gompertz model. On the other hand, inhibition constants are fitted using a non-competitive inhibition model equation Thus, 50% inhibition of biomethane production was observed at level of 215 and 468 mg NH3_N/L under mesophilic and thermophilic conditions. However, the methane generation under mesophilic and thermophilic conditions was reduced by 50% when ammonium ion reach concentrations of 3,860 and 5,600 mg NH4+_N/L respectively. Under mesophilic conditions, pH higher than 7 impacted the methanogens bacteria negatively. This threshold pH limit, is variable under thermophilic conditions, depending on the total ammonia concentration.

Anaerobic digestion of mixed microalgae cultivated in secondary effluent under mesophilic and thermophilic conditions

2015 ◽  
Vol 72 (8) ◽  
pp. 1398-1403 ◽  
Author(s):  
Glenda Cea-Barcia ◽  
Gloria Moreno ◽  
Germán Buitrón
Keyword(s):  
Anaerobic Digestion ◽  
Methane Production ◽  
Incubation Temperature ◽  
Secondary Effluent ◽  
Microalgae Culture ◽  
Batch Tests ◽  
Volatile Solids ◽  
Thermophilic Conditions ◽  
Maximum Production Rate ◽  
Mesophilic Conditions

The anaerobic digestion of mixed indigenous microalgae, grown in a secondary effluent, was evaluated in batch tests at mesophilic (35°C) and thermophilic (50°C) conditions. Under mesophilic conditions, specific methane production varied from 178 to 207 mL CH4/g volatile solids (VS) and the maximum production rate varied from 8.8 to 26.1 mL CH4/(gVS day), depending on the type of microalgae culture. Lower methane parameters were observed in those cultures where Scenedesmus represents more than 95% of the microalge. The culture with the lowest digestion performances under mesophilic conditions was studied under thermophilic conditions. The increase in the incubation temperature significantly increased the specific methane production (390 mL CH4/g VS) and rate (26.0 mL CH4/(gVS day)). However, under thermophilic conditions a lag period of 30 days was observed.

Ultrasound pre-treatment for anaerobic digestion improvement

2009 ◽  
Vol 60 (6) ◽  
pp. 1525-1532 ◽  
Author(s):  
S. Pérez-Elvira ◽  
M. Fdz-Polanco ◽  
F. I. Plaza ◽  
G. Garralón ◽  
F. Fdz-Polanco
Keyword(s):  
Anaerobic Digestion ◽  
Energy Balance ◽  
Specific Energy ◽  
Biogas Production ◽  
Pilot Scale ◽  
Laboratory Scale ◽  
Net Generation ◽  
Batch Reactors ◽  
Anaerobic Reactors ◽  
Pre Treatment

Prior research indicates that ultrasounds can be used in batch reactors as pre-treatment before anaerobic digestion, but the specific energy required at laboratory-scale is too high. This work evaluates both the continuous ultrasound device performance (efficiency and solubilisation) and the operation of anaerobic digesters continuously fed with sonicated sludge, and presents energy balance considerations. The results of sludge solubilisation after the sonication treatment indicate that, applying identical specific energy, it is better to increase the power than the residence time. Working with secondary sludge, batch biodegradability tests show that by applying 30 kWh/m3 of sludge, it is possible to increase biogas production by 42%. Data from continuous pilot-scale anaerobic reactors (V=100 L) indicate that operating with a conventional HRT = 20 d, a reactor fed with pre-treated sludge increases the volatile solids removal and the biogas production by 25 and 37% respectively. Operating with HRT = 15 d, the removal efficiency is similar to the obtained with a reactor fed with non-hydrolysed sludge at HTR = 20 d, although the specific biogas productivity per volume of reactor is higher for the pretreated sludge. Regarding the energy balance, although for laboratory-scale devices it is negative, full-scale suppliers state a net generation of 3–10 kW per kW of energy used.

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