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16 pages, 1208 KiB

Open AccessArticle

Effect of Endogenous Methane Production: A Step Forward in the Validation of Biochemical Methane Potential (BMP) Tests

by João V. Oliveira, José C. Costa, Ana J. Cavaleiro, Maria Alcina Pereira and Maria Madalena Alves

Energies 2022, 15(13), 4696; https://0-doi-org.brum.beds.ac.uk/10.3390/en15134696 - 27 Jun 2022

Cited by 4 | Viewed by 1519

This work evaluates the influence of the inoculum type, the pre-consumption of the residual substrate and the ratio of blanks’ headspace volume to working volume (Hv Wv⁻¹, 0.6 to 10) on Biochemical Methane Potential (BMP) measurements when methane is monitored by [...] Read more.

This work evaluates the influence of the inoculum type, the pre-consumption of the residual substrate and the ratio of blanks’ headspace volume to working volume (Hv Wv⁻¹, 0.6 to 10) on Biochemical Methane Potential (BMP) measurements when methane is monitored by gas chromatography. Different inocula were tested: digested sewage sludge—DSS, granular sludge—GS and fresh dairy manure—DM. Microcrystalline cellulose was used as the substrate. BMP surpassed the maximum theoretical value (BMP_max = 414 L kg⁻¹) when methane produced in the blanks was not discounted, showing that degassing cannot stand alone as an alternative to the procedure of discounting the inoculum’s background production. Still, when the residual substrate concentration is high (e.g., in DM), degassing is mandatory because methane produced from its digestion will conceal the methane produced from the substrate in the BMP determination. For inocula with a low residual substrate (e.g., GS), short degassing periods are recommended in order to avoid detrimental effects on methanogenic activity. For moderate residual substrate concentrations (e.g., DSS), BMP values closer to BMP_max (90–97%) were achieved after degassing and discounting the blanks with lower Hv Wv⁻¹. For higher Hv ∙ Wv⁻¹, less accurate quantification occurred, likely due to error propagation. Proper inoculum pre-incubation time and discounting the methane production from blanks with low Hv Wv⁻¹ (adjusted according to the estimated background methane) are essential for accurate BMP determinations. Full article

(This article belongs to the Special Issue Anaerobic Digestion of Organic Waste: State of the Art and Future Perspectives and Challenges)

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15 pages, 2917 KiB

Open AccessArticle

Dairy Manure Digestate Age Increases Ultrasound Disintegration Efficiency at Low Specific Energies

by Matthijs H. Somers, Samet Azman, Ruud Vanhecke and Lise Appels

Energies 2021, 14(6), 1640; https://0-doi-org.brum.beds.ac.uk/10.3390/en14061640 - 15 Mar 2021

Cited by 3 | Viewed by 1344

Abstract

Substantial insight into the effect of ultrasound disintegration on the changes in biochemical parameters of manure digestate and digestate age is needed to understand the potential of digestate treatment. To address this knowledge gap, in this study, the effect of digestate age on [...] Read more.

Substantial insight into the effect of ultrasound disintegration on the changes in biochemical parameters of manure digestate and digestate age is needed to understand the potential of digestate treatment. To address this knowledge gap, in this study, the effect of digestate age on the efficiency of ultrasound (US) disintegration was investigated. In this scope, dairy manure digestate samples were incubated in an oven at 37 °C for a predetermined amount of time to obtain simulated digestate ages of 15, 22, 29, 36 and 43 days. The results showed that US disintegration efficiency significantly affected the initial biochemical characteristics of digestate and that the digestate age had a significant effect on the US disintegration efficiency. This effect diminished when the applied specific energy (SE) was higher than 3000 kJ/kg total solids (TS). A numerical partial least squares (PLS) model was constructed to investigate the relative influences of the initial biochemical parameters on the soluble chemical oxygen demand (sCOD) and soluble carbohydrates (sCARB) solubilization. The results of the high-quality (R² = 0.8) model indicated that the most influential parameters for the efficiency of US disintegration were the SE, the initial sCARB₀, the TS, the initial sCOD₀ and the volatile solids (VS). Full article

(This article belongs to the Special Issue Anaerobic Digestion of Organic Waste: State of the Art and Future Perspectives and Challenges)

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24 pages, 2532 KiB

Open AccessArticle

Correlations between the Composition of Liquid Fraction of Full-Scale Digestates and Process Conditions

by Afifi Akhiar, Felipe Guilayn, Michel Torrijos, Audrey Battimelli, Abd Halim Shamsuddin and Hélène Carrère

Energies 2021, 14(4), 971; https://0-doi-org.brum.beds.ac.uk/10.3390/en14040971 - 12 Feb 2021

Cited by 21 | Viewed by 3618

Abstract

Fast development of centralized agricultural biogas plants leads to high amounts of digestate production. The treatment and disposal of liquid fractions after on-site digestate solid–liquid separation remains problematic due to their high organic, nutrient and aromatic contents. This work aims to study the [...] Read more.

Fast development of centralized agricultural biogas plants leads to high amounts of digestate production. The treatment and disposal of liquid fractions after on-site digestate solid–liquid separation remains problematic due to their high organic, nutrient and aromatic contents. This work aims to study the variability of the remaining compounds in the digestate liquid fractions in relation to substrate origin, process parameters and solid–liquid separation techniques. Twenty-nine digestates from full-scale codigestion biogas plants and one waste activated sludge (WAS) digestate were collected and characterized. This study highlighted the combined effect of the solid–liquid separation process and the anaerobic digestion feedstock on the characteristics of liquid fractions of digestates. Two major clusters were found: (1) liquid fractions from high efficiency separation process equipment (e.g., centrifuge and others with addition of coagulant, flocculent or polymer) and (2) liquid fractions from low efficiency separation processes (e.g., screw press, vibrating screen and rotary drum), in this latter case, the concentration of chemical oxygen demand (COD) was associated with the proportion of cow manure and energy crops at biogas plant input. Finally, SUVA₂₅₄, an indicator for aromatic molecule content and the stabilization of organic matter, was associated with the hydraulic retention time (HRT). Full article

(This article belongs to the Special Issue Anaerobic Digestion of Organic Waste: State of the Art and Future Perspectives and Challenges)

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16 pages, 801 KiB

Open AccessArticle

Improving the Anaerobic Digestion of Swine Manure through an Optimized Ammonia Treatment: Process Performance, Digestate and Techno-Economic Aspects

by Anna Lymperatou, Niels B. Rasmussen, Hariklia N. Gavala and Ioannis V. Skiadas

Energies 2021, 14(3), 787; https://0-doi-org.brum.beds.ac.uk/10.3390/en14030787 - 02 Feb 2021

Cited by 12 | Viewed by 2888

Abstract

Swine manure mono-digestion results in relatively low methane productivity due to the low degradation rate of its solid fraction (manure fibers), and due to the high ammonia and water content. The aqueous ammonia soaking (AAS) pretreatment of manure fibers has been proposed for [...] Read more.

Swine manure mono-digestion results in relatively low methane productivity due to the low degradation rate of its solid fraction (manure fibers), and due to the high ammonia and water content. The aqueous ammonia soaking (AAS) pretreatment of manure fibers has been proposed for overcoming these limitations. In this study, continuous anaerobic digestion (AD) of manure mixed with optimally AAS-treated manure fibers was compared to the AD of manure mixed with untreated manure fibers. Due to lab-scale pumping restrictions, the ratio of AAS-optimally treated manure fibers to manure was only 1/3 on a total solids (TS) basis. However, the biogas productivity and methane yield were improved by 17% and 38%, respectively, also confirming the predictions from a simplified 1st order hydrolysis model based on batch experiments. Furthermore, an improved reduction efficiency of major organic components was observed for the digester processing AAS-treated manure fibers compared to the non-treated one (e.g., 42% increased reduction for cellulose fraction). A preliminary techno-economic analysis of the proposed process showed that mixing raw manure with AAS manure fibers in large-scale digesters could result in a 72% increase of revenue compared to the AD of manure mixed with untreated fibers and 135% increase compared to that of solely manure. Full article

(This article belongs to the Special Issue Anaerobic Digestion of Organic Waste: State of the Art and Future Perspectives and Challenges)

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12 pages, 1098 KiB

Open AccessArticle

Biogas Upgrading and Ammonia Recovery from Livestock Manure Digestates in a Combined Electromethanogenic Biocathode—Hydrophobic Membrane System

by Miriam Cerrillo, Laura Burgos and August Bonmatí

Energies 2021, 14(2), 503; https://0-doi-org.brum.beds.ac.uk/10.3390/en14020503 - 19 Jan 2021

Cited by 14 | Viewed by 3252

Abstract

Anaerobic digestion process can be improved in combination with bioelectrochemical systems in order to recover energy and resources from digestates. An electromethanogenic microbial electrolysis cell (MEC) coupled to an ammonia recovery system based on hydrophobic membranes (ARS-HM) has been developed in order to [...] Read more.

Anaerobic digestion process can be improved in combination with bioelectrochemical systems in order to recover energy and resources from digestates. An electromethanogenic microbial electrolysis cell (MEC) coupled to an ammonia recovery system based on hydrophobic membranes (ARS-HM) has been developed in order to recover ammonia, reduce organic matter content and upgrade biogas from digested pig slurry. A lab-scale dual-chamber MEC was equipped with a cation exchange membrane (CEM) and ARS with a hydrophobic membrane in the catholyte recirculation loop, to promote ammonia migration and absorption in an acidic solution. On the other hand, an electromethanogenic biofilm was developed in the biocathode to promote the transformation of CO₂ into methane. The average nitrogen transference through the CEM was of 0.36 g_N m⁻² h⁻¹ with a removal efficiency of 31%, with the ARS-HM in the catholyte recirculation loop. The removal of ammonia from the cathode compartment helped to maintain a lower pH value for the electromethanogenic biomass (7.69 with the ARS-HM, against 8.88 without ARS-HM) and boosted methane production from 50 L m⁻³ d⁻¹ to 73 L m⁻³ d⁻¹. Results have shown that the integration of an electromethanogenic MEC with an ARS-HM allows for the concomitant recovery of energy and ammonia from high strength wastewater digestates. Full article

(This article belongs to the Special Issue Anaerobic Digestion of Organic Waste: State of the Art and Future Perspectives and Challenges)

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14 pages, 2351 KiB

Open AccessArticle

Taxonomic Binning Approaches and Functional Characteristics of the Microbial Community during the Anaerobic Digestion of Hydrolyzed Corncob

by Luz Breton-Deval, Ilse Salinas-Peralta, Jaime Santiago Alarcón Aguirre, Belkis Sulbarán-Rangel and Kelly Joel Gurubel Tun

Energies 2021, 14(1), 66; https://0-doi-org.brum.beds.ac.uk/10.3390/en14010066 - 24 Dec 2020

Cited by 3 | Viewed by 2610

Abstract

Maize forms the basis of Mexican food. As a result, approximately six million tons of corncob are produced each year, which represents an environmental issue, as well as a potential feedstock for biogas production. This research aimed to analyze the taxonomic and functional [...] Read more.

Maize forms the basis of Mexican food. As a result, approximately six million tons of corncob are produced each year, which represents an environmental issue, as well as a potential feedstock for biogas production. This research aimed to analyze the taxonomic and functional shift in the microbiome of the fermenters using a whole metagenome shotgun approach. Two strategies were used to understand the microbial community at the beginning and the end of anaerobic digestion: (i) phylogenetic analysis to infer the presence and coverage of clade-specific markers to assign taxonomy and (ii) the recovery of the individual genomes from the samples using the binning of the assembled scaffolds. The results showed that anaerobic digestion brought some noticeable changes and the main microbial community was composed of Corynebacterium variable, Desulfovibrio desulfuricans, Vibrio furnissii, Shewanella spp., Actinoplanes spp., Pseudoxanthomonas spp., Saccharomonospora azurea, Agromyces spp., Serinicoccus spp., Cellulomonas spp., Pseudonocardia spp., Rhodococcus rhodochrous, Sphingobacterium spp. Methanosarcina mazei, Methanoculleus hydrogenitrophicus, Methanosphaerula spp., Methanoregula spp., Methanosaeta spp. and Methanospirillum spp. This study provides evidence of the drastic change in the microbial community structure in a short time and the functional strategy that the most representative microorganisms of the consortia used to carry out the process. Full article

(This article belongs to the Special Issue Anaerobic Digestion of Organic Waste: State of the Art and Future Perspectives and Challenges)

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18 pages, 1870 KiB

Open AccessArticle

Mild Thermal Pre-Treatment of Waste Activated Sludge to Increase Loading Capacity, Biogas Production, and Solids’ Degradation: A Pilot-Scale Study

by Adrian Gonzalez, Hongxiao Guo, Oscar Ortega-Ibáñez, Coert Petri, Jules B. van Lier, Merle de Kreuk and Alexander Hendriks

Energies 2020, 13(22), 6059; https://0-doi-org.brum.beds.ac.uk/10.3390/en13226059 - 19 Nov 2020

Cited by 5 | Viewed by 2033

Abstract

Sludge pre-treatments are emerging as part of the disposal process of solid by-products of wastewater purification. One of their benefits is the increase in methane production rate and/or yield, along with higher loading capacities of existing digesters. In this study, we report the [...] Read more.

Sludge pre-treatments are emerging as part of the disposal process of solid by-products of wastewater purification. One of their benefits is the increase in methane production rate and/or yield, along with higher loading capacities of existing digesters. In this study, we report the performance of a pilot-scale compartmentalized digester (volume of 18.6 m³) that utilized a mild thermal pre-treatment at 70 °C coupled with hydrogen peroxide dosing. Compared with a reference conventional anaerobic digester, this technique allowed an increased organic loading rate from 1.4 to 4.2 kg volatile solids (VS)/(m³d) and an increment in the solids degradation from 40 to 44%. To some extent, these improvements were promoted by the solubilization of the tightly-bound fraction of the extracellular polymeric substances to looser and more accessible fractions without the formation of refractory compounds. In sum, our results suggest that this pre-treatment method could increase the treatment capacity of existing digesters without significant retrofitting. Full article

(This article belongs to the Special Issue Anaerobic Digestion of Organic Waste: State of the Art and Future Perspectives and Challenges)

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Review

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30 pages, 4143 KiB

Open AccessReview

Biogas from Anaerobic Digestion as an Energy Vector: Current Upgrading Development

by Raquel Iglesias, Raúl Muñoz, María Polanco, Israel Díaz, Ana Susmozas, Antonio D. Moreno, María Guirado, Nely Carreras and Mercedes Ballesteros

Energies 2021, 14(10), 2742; https://0-doi-org.brum.beds.ac.uk/10.3390/en14102742 - 11 May 2021

Cited by 35 | Viewed by 5453

Abstract

The present work reviews the role of biogas as advanced biofuel in the renewable energy system, summarizing the main raw materials used for biogas production and the most common technologies for biogas upgrading and delving into emerging biological methanation processes. In addition, it [...] Read more.

The present work reviews the role of biogas as advanced biofuel in the renewable energy system, summarizing the main raw materials used for biogas production and the most common technologies for biogas upgrading and delving into emerging biological methanation processes. In addition, it provides a description of current European legislative framework and the potential biomethane business models as well as the main biogas production issues to be addressed to fully deploy these upgrading technologies. Biomethane could be competitive due to negative or zero waste feedstock prices, and competitive to fossil fuels in the transport sector and power generation if upgrading technologies become cheaper and environmentally sustainable. Full article

(This article belongs to the Special Issue Anaerobic Digestion of Organic Waste: State of the Art and Future Perspectives and Challenges)

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