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12 pages, 1529 KiB

Open AccessArticle

Characteristics of Changes in Particle Size and Zeta Potential of the Digestate Fraction from the Municipal Waste Biogas Plant Treated with the Use of Chemical Coagulation/Precipitation Processes

by Agnieszka Urbanowska, Izabela Polowczyk, Małgorzata Kabsch-Korbutowicz and Przemysław Seruga

Energies 2020, 13(22), 5861; https://doi.org/10.3390/en13225861 - 10 Nov 2020

Cited by 8 | Viewed by 2571

Abstract

The organic fraction of waste is increasingly used for biogas production. However, the fermentation process used for this purpose also produces waste in the form of digestate in addition to biogas. Its liquid fraction can, among other things, be a source of water, [...] Read more.

The organic fraction of waste is increasingly used for biogas production. However, the fermentation process used for this purpose also produces waste in the form of digestate in addition to biogas. Its liquid fraction can, among other things, be a source of water, but its recovery requires many advanced technological processes. Among the first in the treatment train is usually coagulation/chemical precipitation. Its application changes properties, including the size and zeta potential (ζ) of the fractions that have to be removed in subsequent processes. Changes in particle size distribution and ζ potential occurring in the liquid fraction of municipal waste biogas plant digestate and solutions after coagulation/chemical precipitation with FeCl₃·6H₂O, PIX 112 and CaO were analyzed. The particle size distribution of the raw digestate was wide (0.4–300 µm; up to 900 µm without ultrasound). The median particle diameter was about 12 µm. The ζ potential ranged from −25 to −35 mV in the pH range 5–12, and the isoelectric point (IEP) was at pH 2. The best treatment results obtained with the use of. 10 g FeCl₃∙6H₂O/dm³ shifted particle size distribution towards finer particles (median diameter: 8 and 6 µm, respectively, before and after ultrasound). The ζ potential decreased by about 5–10 mV in the pH range 2.5–12 without changing IEP. An amount of 20 g/dm³ of FeCl₃∙6H₂O caused the disappearance of the finest and largest fraction. d₅₀ was about 21.5 µm (17.3 µm after ultrasound). An amount of 20 g/dm³ of FeCl₃∙6H₂O generated a positive high electrokinetic potential in the range of pH 1.8–5. The IEP appeared at pH 8, and after reaching about −5 mV it again became positive at pH about 11. Full article

(This article belongs to the Special Issue Bioenergy from Organic Waste)

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15 pages, 954 KiB

Open AccessArticle

Evaluating the Struvite Recovered from Anaerobic Digestate in a Farm Bio-Refinery as a Slow-Release Fertiliser

by Magdalena Szymańska, Tomasz Sosulski, Adriana Bożętka, Urszula Dawidowicz, Adam Wąs, Ewa Szara, Agata Malak-Rawlikowska, Piotr Sulewski, Gijs W. P. van Pruissen and René L. Cornelissen

Energies 2020, 13(20), 5342; https://doi.org/10.3390/en13205342 - 14 Oct 2020

Cited by 18 | Viewed by 4055

Abstract

Biogas production in agricultural biogas plants generates digestate—liquid waste containing organic matter and mineral nutrients. Utilisation of the digestate on farm fields adjacent to the biogas plants is limited. Therefore, bio-refineries implement advanced forms of digestate processing, including precipitation of struvite (MgNH₄ [...] Read more.

Biogas production in agricultural biogas plants generates digestate—liquid waste containing organic matter and mineral nutrients. Utilisation of the digestate on farm fields adjacent to the biogas plants is limited. Therefore, bio-refineries implement advanced forms of digestate processing, including precipitation of struvite (MgNH₄PO₄^.6H₂O). Struvite can be transported over long distances and dosed precisely to meet the nutritional needs of the plants. Divergent opinions on the fertilising value of struvite and its function over time call for further research on its effects on crop yields in the first and subsequent years after application. This study investigates the effects of struvite (STR), struvite with ammonium sulphate (STR + N), and commercial ammonium phosphate (AP) on the yields, nutrient concentration in the crops, nutrient uptake by the crops, and soil N, P, and Mg content in the second growing period after the application of fertilisers to silty loam (SL) and loamy sand (LS) soils under grass cultivation. Struvite was recovered from the liquid fraction of digestate obtained from a bio-refinery on the De Marke farm (Netherlands). The soils investigated in the pot experiment originated from Obory (SL) and Skierniewice (LS) (Central Poland). The results obtained over the first growing period following fertilisation were published earlier. In our prior work, we showed that the majority of the struvite phosphorus remains in the soil. We hypothesised that, in the second year, the yield potential of the struvite might be higher than that of commercial P fertiliser. Currently, we have demonstrated that, in the second growing period following the application, struvite causes an increase in grass yield, nutrient uptake by the crops, and P and Mg content in the soil. On SL and LS soils, the yields of the four grass harvests from the STR and STR + N treatments were higher than those from AP by approximately 8% and 16.5%, respectively. Our results confirm that struvite is more effective as a fertiliser compared to commercial ammonium phosphate. Struvite can be, therefore, recommended for fertilising grasslands at higher doses once every two years. Full article

(This article belongs to the Special Issue Bioenergy from Organic Waste)

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14 pages, 695 KiB

Open AccessArticle

Duckweed from a Biorefinery System: Nutrient Recovery Efficiency and Forage Value

by Marcin Sońta, Andrzej Łozicki, Magdalena Szymańska, Tomasz Sosulski, Ewa Szara, Adam Wąs, Gijs W. P. van Pruissen and René L. Cornelissen

Energies 2020, 13(20), 5261; https://doi.org/10.3390/en13205261 - 10 Oct 2020

Cited by 15 | Viewed by 4252

Abstract

This paper presents the results of an interdisciplinary study aimed at assessing the possibility of using duckweed to purify and recover nutrients from the effluent remaining after struvite precipitation and ammonia stripping from a liquid fraction of anaerobic digestate in a biorefinery located [...] Read more.

This paper presents the results of an interdisciplinary study aimed at assessing the possibility of using duckweed to purify and recover nutrients from the effluent remaining after struvite precipitation and ammonia stripping from a liquid fraction of anaerobic digestate in a biorefinery located at a Dutch dairy cattle production farm. The nutritional value of duckweed obtained in a biorefinery was assessed as well. Duckweed (Lemna minuta) was cultured on a growth medium with various concentrations of effluent from a biorefinery (EFL) and digested slurry (DS) not subjected to the nutrient recovery process. The study’s results showed that duckweed culture on the media with high contents of DS or EFL was impossible because they both inhibited its growth. After 15 days of culture, the highest duckweed yield was obtained from the ponds with DS or EFL contents in the medium reaching 0.39% (37.8 g fresh matter (FM) and 16.8 g FM per 8500 mL of the growth medium, respectively). The recovery of N by duckweed was approximately 75% and 81%, whereas that of P was approximately 45% and 55% of the growth media with EFL_0.39% and DS_0.39%, respectively. Duckweed obtained from the biorefinery proved to be a valuable high-protein feedstuff with high contents of α-tocopherol and carotenoids. With a protein content in duckweed approximating 35.4–36.1%, it is possible to obtain 2–4 t of protein per 1 ha from EFL_0.39% and DS_0.39% ponds, respectively. Full article

(This article belongs to the Special Issue Bioenergy from Organic Waste)

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12 pages, 1840 KiB

Open AccessArticle

Anaerobic Co-Digestion Effluent as Substrate for Chlorella vulgaris and Scenedesmus obliquus Cultivation

by Paolina Scarponi, Alessandro Bonetto, David Bolzonella, Sergi Astals and Cristina Cavinato

Energies 2020, 13(18), 4880; https://doi.org/10.3390/en13184880 - 17 Sep 2020

Cited by 3 | Viewed by 3000

Abstract

Anaerobic digestate supernatant can be used as a nutrient source for microalgae cultivation, thus integrating phytoremediation processes with high value products storage in microalgae biomass. Microalgae are able to use nitrogen and phosphorous from digestate, but high nutrient concentration can cause growth inhibition. [...] Read more.

Anaerobic digestate supernatant can be used as a nutrient source for microalgae cultivation, thus integrating phytoremediation processes with high value products storage in microalgae biomass. Microalgae are able to use nitrogen and phosphorous from digestate, but high nutrient concentration can cause growth inhibition. In this study, two microalgae strains (C. vulgaris and S. obliquus) were cultivated on the anaerobic co-digestion supernatant (obtained from the organic fraction of municipal solid waste (OFMSW) and waste activated sludge (WAS)) in a preliminary Petri plate screening at different dilutions (1:10 and 1:5) using a synthetic medium (ISO) and tap water (TW). Direct Nile red screening was applied on colonies to preliminarily identify hydrophobic compound storage and then a batch test was performed (without air insufflation). Results show that C. vulgaris was able to grow on digestate supernatant 1:5 diluted, while Nile red screening allowed the preliminary detection of hydrophobic compound storage in colonies. The analysis carried out at the end of the test on ammonia, phosphate, nitrate and sulphate showed a removal percentage of 47.5 ± 0.8%, 65.0 ± 6.0%, 95.0 ± 3.0% and 99.5 ± 0.1%, respectively. Full article

(This article belongs to the Special Issue Bioenergy from Organic Waste)

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15 pages, 1384 KiB

Open AccessArticle

Co-Digestion of Salix and Manure for Biogas: Importance of Clone Choice, Coppicing Frequency and Reactor Setup

by Jonas A. Ohlsson, Ann-Christin Rönnberg-Wästljung, Nils-Erik Nordh and Anna Schnürer

Energies 2020, 13(15), 3804; https://doi.org/10.3390/en13153804 - 24 Jul 2020

Cited by 4 | Viewed by 2570

Abstract

Animal manure represents a major source of renewable energy that can be converted into biogas using anaerobic digestion. In order to most efficiently utilize this resource, it can be co-digested with energy dense, high biomethanation potential feedstocks such as energy crops. However, such [...] Read more.

Animal manure represents a major source of renewable energy that can be converted into biogas using anaerobic digestion. In order to most efficiently utilize this resource, it can be co-digested with energy dense, high biomethanation potential feedstocks such as energy crops. However, such feedstocks typically require pretreatments which are not feasible for small-scale facilities. We investigated the use of single-stage and the sequential co-digestion of comminuted but otherwise non-pretreated Salix with animal manure, and further investigated the effects of coppicing frequency and clone choice on biomethanation potential and the area requirements for a typical Swedish farm-scale anaerobic digester using Salix and manure as feedstock. In comparison with conventional single-stage digestion, sequential digestion increased the volumetric and specific methane production by 57% to 577 NmL L⁻¹ d⁻¹ and 192 NmL (g volatile solids (VS))⁻¹, respectively. Biomethanation potential was the highest for the two-year-old shoots, although gains in biomass productivity suggest that every-third-year coppicing may be a better strategy for supplying Salix feedstock for anaerobic digestion. The biomethane production performance of the sequential digestion of minimally pretreated Salix mirrors that of hydrothermally pretreated hardwoods and may provide an option where such pretreatments are not feasible. Full article

(This article belongs to the Special Issue Bioenergy from Organic Waste)

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14 pages, 2216 KiB

Open AccessArticle

Anaerobic Digestion Performance: Separate Collected vs. Mechanical Segregated Organic Fractions of Municipal Solid Waste as Feedstock

by Przemysław Seruga, Małgorzata Krzywonos, Anna Seruga, Łukasz Niedźwiecki, Halina Pawlak-Kruczek and Agnieszka Urbanowska

Energies 2020, 13(15), 3768; https://doi.org/10.3390/en13153768 - 22 Jul 2020

Cited by 40 | Viewed by 3823

Abstract

The replacement of fossil fuel with renewable energy sources seems as though it will be crucial in the future. On the other hand, waste generation increases year by year. Thus, waste-to-energy technologies fit in with the actual trends, such as the circular economy. [...] Read more.

The replacement of fossil fuel with renewable energy sources seems as though it will be crucial in the future. On the other hand, waste generation increases year by year. Thus, waste-to-energy technologies fit in with the actual trends, such as the circular economy. The crucial type of generated waste is municipal solid waste, which is in the research area. Regarding the organic fraction of municipal solid waste (OFMSW), anaerobic digestion (AD) allows the recovery of biogas and energy. Furthermore, if it is supported by source segregation, it should allow the recovery of material as fertilizer. The AD process performance (biogas yield and stability) comparison of source-segregated OFMSW (ss-OFMWS) and mechanically sorted OFMSW (ms-OFMSW) as feedstocks was performed in full-scale conditions. The daily biogas volume and methane content were measured to assess AD efficiency. To verify the process stability, the volatile fatty acid (VFA) content, pH value, acidity, alkalinity, and dry matter were determined. The obtained biogas yield per ton was slightly higher in the case of ss-OFMSW (111.1 m³/ton), compared to ms-OFMSW (105.3 m³/ton), together with a higher methane concentration: 58–60% and 51–53%, respectively, and followed by a higher electricity production capacity of almost 700 MWh for ss-OFMSW digestion. The obtained VFA concentrations, at levels around 1.1 g/kg, pH values (slightly above 8.0), acidity, and alkalinity indicate the possibilities of the digester feeding and no-risk exploitation of either as feedstock. Full article

(This article belongs to the Special Issue Bioenergy from Organic Waste)

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10 pages, 1614 KiB

Open AccessCommunication

Lessons Learned from an Experimental Campaign on Promoting Energy Content of Renewable Biogas by Injecting H₂ during Anaerobic Digestion

by Shiplu Sarker, Sander N. Wijnsma and Kristian M. Lien

Energies 2020, 13(14), 3542; https://doi.org/10.3390/en13143542 - 9 Jul 2020

Cited by 5 | Viewed by 2894

Abstract

Direct injection of H₂ to an anaerobic reactor enables biological fixation of CO₂ into CH₄ (biomethanation) and consequently boosts methane content in the produced biogas. However, there has been only a small amount of literature reporting results on this technique [...] Read more.

Direct injection of H₂ to an anaerobic reactor enables biological fixation of CO₂ into CH₄ (biomethanation) and consequently boosts methane content in the produced biogas. However, there has been only a small amount of literature reporting results on this technique in a continuous reactor framework to date. To fill this gap, the present study devoted an experimental work to direct H₂ addition to a fed-batch semi-continuous reactor, where the injected H₂ concentration increased gradually (~3–30 mmol), spanning a moderate operational period of about 70 days. As the results revealed, the reactor continued anaerobic operation for each level of H₂ dosing and produced an average methane content in the biogas ranging between 65% and 72%. The exhibited biogas upgrading trend appeared to be under-developed, and thereby suggests the need for further research. Full article

(This article belongs to the Special Issue Bioenergy from Organic Waste)

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19 pages, 6447 KiB

Open AccessArticle

Effects of Ammonia Stripping and Other Physico-Chemical Pretreatments on Anaerobic Digestion of Swine Wastewater

by Adele Folino, Paolo Salvatore Calabrò and Demetrio Antonio Zema

Energies 2020, 13(13), 3413; https://doi.org/10.3390/en13133413 - 2 Jul 2020

Cited by 14 | Viewed by 3066

Abstract

In order to overcome anaerobic digestion (AD) inhibition due to the large nitrogen content of swine wastewater (SW), air stripping (AS) and other chemical and physical pretreatments were applied on raw SW before AD. The efficiency of these pretreatments on both ammonia removal—recovering [...] Read more.

In order to overcome anaerobic digestion (AD) inhibition due to the large nitrogen content of swine wastewater (SW), air stripping (AS) and other chemical and physical pretreatments were applied on raw SW before AD. The efficiency of these pretreatments on both ammonia removal—recovering ammonia salts to be used as fertilizers in agriculture—and the increase of methane production were assessed in batch tests. Since the pH, temperature, and air flow rate heavily influence AS efficiency and the composition of treated SW, these parameters were set individually or in combination. In more detail, the pH was increased from the natural value of SW to 8 or 10, temperature was increased from the room value to 40 °C, and the air flow rate was increased from zero to 5 Lair L_SW⁻¹ min⁻¹. AS was generally more efficient at removing ammonia (up to 97%) from raw (non-treated) SW compared to the other treatments. However, the tested pretreatments were not as efficient as expected in increasing the biogas production, because the methane yields of all pretreated substrates were lower (by about 10–50%) to compared raw SW. The inhibitory effect on AD could have been due to the lack of nutrients and organic matter in the substrate (due to the excessive removal of the pretreatments), the concentration of toxic compounds (such as metal ions or furfural due to water evaporation), and an excess of alkali ions (used to increase the pH in AS). Overall, AS can be considered a sustainable process for the recovery of ammonium sulphate and the removal of other polluting compounds (e.g., organic matter) from SW. Conversely, the use of AS and other chemical and/or thermal processes tested in this study as pretreatments of SW before AD is not advised because these processes appear to reduce methane yields. Full article

(This article belongs to the Special Issue Bioenergy from Organic Waste)

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14 pages, 2513 KiB

Open AccessArticle

An Unstructured Model for Anaerobic Treatment of Raw Cheese Whey for Volatile Fatty Acids Production

by Claudio B-Arroyo, Antonio Lara-Musule, Ervin Alvarez-Sanchez, Gloria Trejo-Aguilar, Juan-Rodrigo Bastidas-Oyanedel and Eliseo Hernandez-Martinez

Energies 2020, 13(7), 1850; https://doi.org/10.3390/en13071850 - 10 Apr 2020

Cited by 3 | Viewed by 2807

Abstract

The whey is a byproduct of the dairy industry that, if not treated properly, can cause serious environmental pollution problems. Anaerobic treatment is an alternative for its recovery, since, in addition to reducing the organic load. it allows the generation of value-added products [...] Read more.

The whey is a byproduct of the dairy industry that, if not treated properly, can cause serious environmental pollution problems. Anaerobic treatment is an alternative for its recovery, since, in addition to reducing the organic load. it allows the generation of value-added products such as volatile fatty acids (VFA) and biogas. However, the process is very complex and requires specific operating conditions that guarantee its stability and favor the production of value-added compounds. In this work, an unstructured mathematical model is proposed to evaluate the dynamic behavior of the stages of the anaerobic degradation process of the whey (i.e., hydrolysis, acidogenesis, acetogenesis and methanogenesis). The proposed model considers the dynamic variation in pH during the experiment. To validate the model, an experimental set was carried out at pH and temperature conditions that favor the production of VFAs. Experimental results show that the anaerobic treatment of the raw cheese whey favors pH = 5.5; for T = 40 °C, the maximum VFA production is obtained (30.71 g_COD L⁻¹), and for T = 35 °C, a 45.81% COD degradation is reached. The proposed model considers the effect of pH and temperature and it is validated in the region where the experimental tests were carried out. The model parameters were estimated using the Levenberg–Marquardt method, obtaining coefficients of determination R² > 0.94. The proposed model can describe the dynamic behavior of the key variables in the anaerobic treatment of raw cheese whey at different pH and temperature conditions, finding that VFA production is favored at pH ≥ 7, while the highest COD removal results in acidic conditions Full article

(This article belongs to the Special Issue Bioenergy from Organic Waste)

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13 pages, 1520 KiB

Open AccessArticle

Modeling Dark Fermentation of Coffee Mucilage Wastes for Hydrogen Production: Artificial Neural Network Model vs. Fuzzy Logic Model

by Edilson León Moreno Cárdenas, Arley David Zapata-Zapata and Daehwan Kim

Energies 2020, 13(7), 1663; https://doi.org/10.3390/en13071663 - 2 Apr 2020

Cited by 28 | Viewed by 3020

Abstract

This study presents the analysis and estimation of the hydrogen production from coffee mucilage mixed with organic wastes by dark anaerobic fermentation in a co-digestion system using an artificial neural network and fuzzy logic model. Different ratios of organic wastes (vegetal and fruit [...] Read more.

This study presents the analysis and estimation of the hydrogen production from coffee mucilage mixed with organic wastes by dark anaerobic fermentation in a co-digestion system using an artificial neural network and fuzzy logic model. Different ratios of organic wastes (vegetal and fruit garbage) were added and combined with coffee mucilage, which led to an increase of the total hydrogen yield by providing proper sources of carbon, nitrogen, mineral, and other nutrients. A two-level factorial experiment was designed and conducted with independent variables of mucilage/organic wastes ratio, chemical oxygen demand (COD), acidification time, pH, and temperature in a 20-L bioreactor in order to demonstrate the predictive capability of two analytical modeling approaches. An artificial neural network configuration of three layers with 5-10-1 neurons was developed. The trapezoidal fuzzy functions and an inference system in the IF-THEN format were applied for the fuzzy logic model. The quality fit between experimental hydrogen productions and analytical predictions exhibited a predictive performance on the accumulative hydrogen yield with the correlation coefficient (R²) for the artificial neural network (> 0.7866) and fuzzy logic model (> 0.8485), respectively. Further tests of anaerobic dark fermentation with predefined factors at given experimental conditions showed that fuzzy logic model predictions had a higher quality of fit (R² > 0.9508) than those from the artificial neural network model (R² > 0.8369). The findings of this study confirm that coffee mucilage is a potential resource as the renewable energy carrier, and the fuzzy-logic-based model is able to predict hydrogen production with a satisfactory correlation coefficient, which is more sensitive than the predictive capacity of the artificial neural network model. Full article

(This article belongs to the Special Issue Bioenergy from Organic Waste)

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20 pages, 10293 KiB

Open AccessArticle

Reduction in Energy Requirement and CO₂ Emission for Microalgae Oil Production Using Wastewater

by Riaru Ishizaki, Ryozo Noguchi, Agusta Samodra Putra, Sosaku Ichikawa, Tofael Ahamed and Makoto M Watanabe

Energies 2020, 13(7), 1641; https://doi.org/10.3390/en13071641 - 2 Apr 2020

Cited by 12 | Viewed by 3591

Abstract

A comparative evaluation of energy requirement and CO₂ emission was performed for native polyculture microalgae oil production in a wastewater treatment plant (WWTP). The wastewater provided nutrients for algae growth. Datasets of microalgae oil production and their details were collected from the [...] Read more.

A comparative evaluation of energy requirement and CO₂ emission was performed for native polyculture microalgae oil production in a wastewater treatment plant (WWTP). The wastewater provided nutrients for algae growth. Datasets of microalgae oil production and their details were collected from the Minamisoma pilot plant. Environmental impact estimation from direct energy and material balance was analyzed using SimaPro^® v8.0.4. in two scenarios: existing and algal scenarios. In the existing scenario, CO₂ emission sources were from wastewater treatment, sludge treatment, and import of crude oil. In the algal scenario, CO₂ emission with microalgae production was considered using wastewater treatment, CO₂ absorption from growing algae, and hydrothermal liquefaction (HTL) for extraction, along with the exclusion of exhausted CO₂ emission for growing algae and use of discharged heat for HTL. In these two scenarios, 1 m³ of wastewater was treated, and 2.17 MJ higher heating value (HHV) output was obtained. Consequently, 2.76 kg-CO₂ eq/m³-wastewater in the existing scenario and 1.59 kg-CO₂ eq/m³-wastewater in the algal scenario were calculated. In the HTL process, 21.5 MJ/m³-wastewater of the discharged heat energy was required in the algal scenario. Hence, the efficiency of the biocrude production system will surpass those of the WWTP and imported crude oil. Full article

(This article belongs to the Special Issue Bioenergy from Organic Waste)

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14 pages, 1910 KiB

Open AccessCommunication

Comparison of Variable and Constant Loading for Mesophilic Food Waste Digestion in a Long-Term Experiment

by He Song, Yue Zhang, Sigrid Kusch-Brandt and Charles J. Banks

Energies 2020, 13(5), 1279; https://doi.org/10.3390/en13051279 - 10 Mar 2020

Cited by 15 | Viewed by 4025

Abstract

Operators of commercial anaerobic digestion (AD) plants frequently note the challenge of transferring research results to an industrial setting, especially in matching well-controlled laboratory studies at a constant organic loading rate (OLR) with full-scale digesters subject to day-to-day variation in loadings. This study [...] Read more.

Operators of commercial anaerobic digestion (AD) plants frequently note the challenge of transferring research results to an industrial setting, especially in matching well-controlled laboratory studies at a constant organic loading rate (OLR) with full-scale digesters subject to day-to-day variation in loadings. This study compared the performance of food waste digesters at fluctuating and constant OLR. In a long-term experiment over nearly three years, variable daily OLR with a range as wide as 0 to 10.0 g VS L⁻¹ day⁻¹ (weekly average 5.0 g VS L⁻¹ day⁻¹) were applied to one laboratory-scale digester, while a pair of control digesters was operated at a constant daily loading of 5.0 g VS L⁻¹ day⁻¹. Different schemes of trace elements (TE) supplementation were also tested to examine how they contributed to process stability. Variable loading had no adverse impact on biogas production or operational stability when 11 TE species were dosed. When TE addition was limited to cobalt and selenium, the stability of the variable-load digester was well maintained for nearly 300 days before the experiment was terminated, while the control digesters required re-supplementation with other TE species to reverse an accumulation of volatile fatty acids. This work demonstrated that variation in daily OLR across quite a wide range of applied loadings is possible with no adverse effects on methane production or stability of food waste digestion, giving confidence in the transferability of research findings. The positive effect of variable OLR on TE requirement requires further investigation considering its practical significance for AD industry. Full article

(This article belongs to the Special Issue Bioenergy from Organic Waste)

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13 pages, 2715 KiB

Open AccessArticle

Experiments and Modeling for Flexible Biogas Production by Co-Digestion of Food Waste and Sewage Sludge

by Yiyun Liu, Tao Huang, Xiaofeng Li, Jingjing Huang, Daoping Peng, Claudia Maurer and Martin Kranert

Energies 2020, 13(4), 818; https://doi.org/10.3390/en13040818 - 13 Feb 2020

Cited by 15 | Viewed by 3727

Abstract

This paper explores the feasibility of flexible biogas production by co-digestion of food waste and sewage sludge based on experiments and mathematical modeling. First, laboratory-scale experiments were carried out in variable operating conditions in terms of organic loading rate and feeding frequency to [...] Read more.

This paper explores the feasibility of flexible biogas production by co-digestion of food waste and sewage sludge based on experiments and mathematical modeling. First, laboratory-scale experiments were carried out in variable operating conditions in terms of organic loading rate and feeding frequency to the digester. It is demonstrated that biogas production can achieve rapid responses to arbitrary feedings through co-digestion, and the stability of the anaerobic digestion process is not affected by the overloading of substrates. Compared with the conventional continuous mode, the required biogas storage capacity in flexible feeding mode can be significantly reduced. The optimum employed feeding organic loading rate (OLR) is identified, and how to adjust the feeding scheme for flexible biogas production is also discussed. Finally, a simplified prediction model for flexible biogas production is proposed and verified by experimental data, which could be conveniently used for demand-oriented control. It is expected that this research could give some theoretical basis for the enhancement of biogas utilization efficiency, thus expanding the applications of bio-energy. Full article

(This article belongs to the Special Issue Bioenergy from Organic Waste)

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15 pages, 1643 KiB

Open AccessArticle

Preliminary Assessment of a Biogas-Based Power Plant from Organic Waste in the North Netherlands

by Spyridon Achinas, Demi Martherus, Janneke Krooneman and Gerrit Jan Willem Euverink

Energies 2019, 12(21), 4034; https://doi.org/10.3390/en12214034 - 23 Oct 2019

Cited by 15 | Viewed by 4811

Abstract

Biogas is expected to play a crucial role in achieving the energy targets set by the European Union. Biogas, which mainly comprises methane and carbon dioxide, is produced in an anaerobic reactor, which transforms biomass into biogas. A consortium of anaerobic bacteria and [...] Read more.

Biogas is expected to play a crucial role in achieving the energy targets set by the European Union. Biogas, which mainly comprises methane and carbon dioxide, is produced in an anaerobic reactor, which transforms biomass into biogas. A consortium of anaerobic bacteria and archaea produces biogas during the anaerobic digestion (AD) of various types of feedstocks, such as animal slurries, energy crops, and agricultural residues. A biogas-fed gas turbine-generator and steam generator produce heat and power. In this study, a combined heat and power installation is studied. The biogas-based power plant treating cow manure, grass straw, and sugar beet pulp was examined using the software SuperPro Designer, and the obtained economic reports are evaluated. From the results, subsidy for electricity does not change the feasibility of the plants in case that cow manure or sugar beet pulp are used as feedstocks. The net present value (NPV) of biogas plants treating cow manure and sugar beet pulp was negative and the subsidy is not sufficient to make profitable these cases. The biogas power plant treating straw showed a positive net present value even without subsidy, which means that it is more desirable to invest in a plant that produces electricity and digestate from grass straw. Full article

(This article belongs to the Special Issue Bioenergy from Organic Waste)

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Review

Jump to: Research

25 pages, 3875 KiB

Open AccessReview

The Development Strategies and Technology Roadmap of Bioenergy for a Typical Region: A Case Study in the Beijing-Tianjin-Hebei Region in China

by Xin Zhang, Yun-Ze Li, Ao-Bing Wang, Li-Jun Gao, Hui-Juan Xu and Xian-Wen Ning

Energies 2020, 13(4), 844; https://doi.org/10.3390/en13040844 - 14 Feb 2020

Cited by 7 | Viewed by 2634

Abstract

The Beijing-Tianjin-Hebei region has abundant biomass resources, which are difficult to collect and thus are underutilized. However, the potential estimation of biomass energy can result in a comprehensive understanding of bioenergy resources in order to establish a technology roadmap for the region’s bioenergy [...] Read more.

The Beijing-Tianjin-Hebei region has abundant biomass resources, which are difficult to collect and thus are underutilized. However, the potential estimation of biomass energy can result in a comprehensive understanding of bioenergy resources in order to establish a technology roadmap for the region’s bioenergy development. Therefore, it is essential to estimate the potential of Beijing-Tianjin-Hebei biomass resources and bioenergy utilization. In this paper, the amount of main biomass resources for possible energy use and bioenergy utilization are calculated based on a statistical data estimation method for crop residues; human, poultry, and livestock manure; and municipal solid wastes. On the basis of biomass resources and bioenergy utilization potential, the technology roadmap is established. The results show that the amount for available biomass energy use is unevenly distributed in the Beijing-Tianjin-Hebei region, and the largest amount of resources is crop residues (36.52 million tons or 18.26 million tons coal equivalent). The biogas from human, poultry, and livestock manure and densified solids from crop residue technology roadmap is suitable for the Beijing-Tianjin-Hebei region. Full article

(This article belongs to the Special Issue Bioenergy from Organic Waste)

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