Advances in Anaerobic Digestion of Agricultural and Industrial Organic Waste

A special issue of Fermentation (ISSN 2311-5637). This special issue belongs to the section "Industrial Fermentation".

Deadline for manuscript submissions: closed (30 April 2023) | Viewed by 18046

Special Issue Editor

Special Issue Information

Dear Colleagues,

Anaerobic digestion (AD) represents a suitable technology for the transformation of organic waste to valuable renewable energy. However, the feeding of complex organic matrices in conventional digesters could lead to low conversion performances. Therefore, adequate methodologies are necessary to overcome the difficulty in the digestion of some agricultural and industrial wastes. In this regard, scientific research in recent years has taken different directions. The main approaches for the enhancement of anaerobic digestion processes can be summarized as: optimization of the process parameters, co-digestion, feedstock pretreatment, additive supplementation, optimization of bioreactor configurations, and application of genetic technologies. The first strategy aims to identify the optimal values of parameters that mainly affect the AD process to increase biogas production (pH, temperature, COD/N/P ratio, organic loading rate, etc.). In co-digestion processes, two or more different wastes are fed into the digesters in proper amounts to obtain a balanced mixture in terms of chemical–physical characteristics. On the other hand, the use of pretreatments exploits physical and chemical processes to improve the characteristics of waste before feeding into digesters. The supplementation of additives (activated carbon, zero-valent metals, zeolites, etc.) aims to enhance AD mechanisms including direct interspecies electron transfer (DIET). Bioreactor optimization focuses on changing digesters’ geometry from single-stage to two-stage and multi-stage to improve the digestion of complex organic waste. Genetic strategies exploit the manipulations of enzymes, methanogens and microbial strains to enhance biological activity.

This Special Issue welcomes papers focused on the latest knowledge and innovations in processes aimed at biogas production from agricultural and industrial organic wastes. The papers must show originality and give a significant contribution to the scope of the Special Issue.

Thank you for your contributions.

Dr. Alessio Siciliano
Guest Editor

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Keywords

  • anaerobic digestion
  • anaerobic bioreactors
  • biogas
  • biomethane
  • co-digestion
  • fermentation
  • methanization
  • organic waste
  • organic waste pretreatment

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Published Papers (10 papers)

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Research

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16 pages, 2767 KiB  
Article
Kinetic Study of Anaerobic Digestion of Compost Leachate from Organic Fraction of Municipal Solid Waste
by Carlo Limonti, Giulia Maria Curcio, Alessio Siciliano, Adolfo Le Pera and Goksel N. Demirer
Fermentation 2023, 9(3), 297; https://doi.org/10.3390/fermentation9030297 - 18 Mar 2023
Cited by 1 | Viewed by 1583
Abstract
The anaerobic digestion (AD) of compost leachate has been scarcely investigated and, to the best of our knowledge, no previous work has analyzed the kinetics of the process in completely stirred tank reactors (CSTR). To overcome this lack of knowledge, the present work [...] Read more.
The anaerobic digestion (AD) of compost leachate has been scarcely investigated and, to the best of our knowledge, no previous work has analyzed the kinetics of the process in completely stirred tank reactors (CSTR). To overcome this lack of knowledge, the present work aimed to deepen the study of the AD of compost leachate in CSTR and to identify the kinetics that can represent the process evolution under different operating conditions. In this regard, an experimental investigation was carried out on a laboratory anaerobic pilot plant that worked in semi-continuous mode under mesophilic conditions. After the start-up phase, the digester was fed with organic loading rates (OLR) between 4 and 30 gCOD/Ld. The chemical oxygen demand (COD) removal ranged between 80 and 85% for OLR values up to 20 gCOD/Ld and, then, it was observed as 54% at 30 gCOD/Ld. The deterioration of process performance was caused by an excessive generation of volatile fatty acids leading to a decrease of methane production yield from 0.32–0.36 LCH4/gCODremoved at 20 gCOD/Ld, to 0.23–0.26 LCH4/gCODremoved at 30 gCOD/Ld. Using kinetic analysis, the Monod model was shown to be quite accurate in modelling the trends of COD degradation rates for OLR values up to 20 gCOD/Ld. On the other hand, a better fit was achieved with the Haldane model at 30 gCOD/Ld. The conducted modelling allowed to identify the kinetic parameters for each model. The detected results could help in the management and design of the digesters for the treatment of compost leachate. Full article
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24 pages, 3573 KiB  
Article
Biomethane Potential in Anaerobic Biodegradation of Commercial Bioplastic Materials
by Zsuzsanna Üveges, Mariem Damak, Szandra Klátyik, Muhammad Wajahat Ramay, György Fekete, Zsolt Varga, Csaba Gyuricza, András Székács and László Aleksza
Fermentation 2023, 9(3), 261; https://doi.org/10.3390/fermentation9030261 - 06 Mar 2023
Cited by 4 | Viewed by 2389
Abstract
Bioplastics have emerged as a promising alternative to conventional plastics, marketed as environmentally friendly and sustainable materials. They provide a variety of methods for efficient waste management contributing to the goals of the circular economy. At their end-of-life stage, bioplastics can generate added [...] Read more.
Bioplastics have emerged as a promising alternative to conventional plastics, marketed as environmentally friendly and sustainable materials. They provide a variety of methods for efficient waste management contributing to the goals of the circular economy. At their end-of-life stage, bioplastics can generate added value through aerobic and anaerobic biological treatments (composting or anaerobic digestion). In this study, biomethane potential (BMP) tests were carried out under mesophilic conditions on eight different catering biodegradable plastics available in the market and certified as being biodegradable under industrial composting conditions. Chemical analysis of the biodegradable plastics included elemental analysis, Fourier-transform infrared spectroscopy, and inductively coupled plasma–optical emission spectrometry. Key differences were observed in total solids (TS) and volatile solids (VS) contents between the studied biopolymer products. TS values ranged between 85.00 ± 0.26% (Product 8) and 99.16 ± 0.23% (Product 4), whereas VS content ranged between 64.57 ± 0.25 %wm (Product 6) and 99.14 ± 0.17 %wm (Product 4). Elemental analysis (elements C, H, N, S, and O) was used to estimate the theoretical methane production (ThBMP) of each product. The highest ThBMP (538.6 ± 8.7 NmL/gVS) was observed in Product 4 correlated with the highest C and H contents, while the lowest ThBMP (431.8 ± 6.1 NmL/gVS) was observed in Product 2. Significant differences were recorded between BMP values according to the chemical composition of the polymers. The average of BMP values ranged between 50.4 ± 2.1 NmL/gVS and 437.5 ± 1.0 NmL/gVS. Despite being characterized by the same composition (cellulose/cellulose derivatives and calcium carbonate), Products 2, 3, and 6 revealed significant differences in terms of TS, VS, ThBMP, and BMP. Furthermore, a significant statistical relationship (p < 0.001) was found between time (days) and BMP values of the eight products (R2 = 0.899–0.964) during the initial phase. The study confirmed that cellulose-based materials can convert efficiently under mesophilic conditions into methane, at a relatively short retention time; hence, they can be regarded as a promising material for co-digestion with feedstock in industrial anaerobic biogas plants. In contrast, biodegradation of polylactic acids (PLA) does not occur under mesophilic conditions, and hence, pre-treatment of the polymers is recommended. Moreover, PLA-containing products are highly affected by the presence of other components (e.g., polybutylene adipate terephthalate and cellulose/cellulose derivatives). Full article
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16 pages, 1076 KiB  
Article
Effects of Water Potential on Anaerobic Methane Production and a Microbial Consortium
by Jin Yeo, Chang-Gyu Kim, Jun-Hyeong Lee, Eunhye Song and Young-Man Yoon
Fermentation 2023, 9(3), 244; https://doi.org/10.3390/fermentation9030244 - 03 Mar 2023
Cited by 2 | Viewed by 1029
Abstract
This study probed the effect of the water potential (Ψ) on anaerobic methane production and a microbial consortium. The Ψ level of the investigated anaerobic digester (n = 20) was in the range from −0.10 to −2.09 MPa with a mean value of [...] Read more.
This study probed the effect of the water potential (Ψ) on anaerobic methane production and a microbial consortium. The Ψ level of the investigated anaerobic digester (n = 20) was in the range from −0.10 to −2.09 MPa with a mean value of −1.23 MPa, and the Ψ level of the anaerobic digester was significantly correlated with the SCOD, TKN, NH4+-N, alkalinity, salinity (SPS), NH4+, Na+, K+, Cl, NO3, and PO43− (p < 0.001). The maximum methane production rate (Rm) of the Control (−0.40 MPa) was 8.11 mL day−1 and decreased to 1.70 mL day−1 at −3.91 MPa (K5), and the lag growth phase time (λ) was delayed to 35.96 and 25.34 days at −2.85 MPa (K4) and −3.91 MPa (K5), respectively. The ultimate methane potential (Bu) was 0.264 Nm3 kg−1-VSadded for the Control, and when Ψ was adjusted, Bu increased to 0.278 Nm3 kg−1-VSadded at −1.49 MPa (K3) but decreased to 0.203 and 0.172 Nm3 kg−1-VSadded at −2.85 MPa (K4) and −3.91 MPa (K5), respectively. Therefore, the methane yield was inhibited due to the decrease in Ψ, and the methane yield is predicted to be inhibited from about −1.65 MPa. In the genus-level taxonomic classification of the microbial community, the relative abundance of Methanosarcina decreased significantly to 36.76% at −3.91 MPa (K5) compared to 58.15% for the Control; however, the relative abundance of Methanoculleus significantly increased to 35.16% at −3.91 MPa (K5) compared to 14.85% for the Control. Full article
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17 pages, 1173 KiB  
Article
Anaerobic Co-Digestion of Agricultural Residues Produced in Southern and Northern Greece
by Vasiliki P. Aravani, Konstantina Tsigkou, Vagelis G. Papadakis, Wen Wang and Michael Kornaros
Fermentation 2023, 9(2), 131; https://doi.org/10.3390/fermentation9020131 - 29 Jan 2023
Cited by 2 | Viewed by 1245
Abstract
In Greece biomass is often being disposed of uncontrollably, resulting in significant environmental impacts. The aim of this study is the single-stage anaerobic co-digestion assessment, valorizing Northern and Southern Greece mixtures, resulting from previous literature reviews, experimental designs, and biochemical methane potential (BMP) [...] Read more.
In Greece biomass is often being disposed of uncontrollably, resulting in significant environmental impacts. The aim of this study is the single-stage anaerobic co-digestion assessment, valorizing Northern and Southern Greece mixtures, resulting from previous literature reviews, experimental designs, and biochemical methane potential (BMP) assays. Regarding the methane yield maximization, in Northern Greece, the most suitable mixture was 10% corn silage, 80% cattle manure, and 10% malt; while in Southern Greece it was 10% corn silage, 57% cattle manure, 23% orange peels, and 10% olive pomace for fall/winter season. The hydraulic retention time (HRT) was set at 20 d and an initial organic loading rate (OLR) of 2 g COD/(L·d) was applied, with a view to gradually increase it. However, volatile fatty acids accumulation was observed, which led to OLR reduction to 1.5 g COD/(L·d) for both experiments. The Northern Greece reactor operated successfully for OLR 1.5–5 g COD/(L·d), while further increase led to system failure. On the other hand, the reactor of the Southern Greece mixture operated successfully at OLR 1.5–2 g COD/(L·d), but further operation indicated inadequacy, probably due to inhibitor (such as limonene) accumulation. Mixtures consisting of corn silage, cattle manure, and malt can be successfully valorized at high OLR. However, further investigation for mixtures with orange peels is suggested due to the presence of inhibitors. Full article
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13 pages, 2385 KiB  
Article
Preliminary Investigation of Different Types of Inoculums and Substrate Preparation for Biohydrogen Production
by Bidattul Syirat Zainal, Sabrina Zaini, Ali Akbar Zinatizadeh, Nuruol Syuhadaa Mohd, Shaliza Ibrahim, Pin Jern Ker and Hassan Mohamed
Fermentation 2023, 9(2), 127; https://doi.org/10.3390/fermentation9020127 - 28 Jan 2023
Viewed by 1389
Abstract
A pre-culture stage is required to obtain robustly-dividing cells with high hydrogen (H2) production capabilities. However, a step-by-step process for biohydrogen production is scarcely reported, mainly from palm oil wastewater. Therefore, this study developed a guideline to find the best inoculum [...] Read more.
A pre-culture stage is required to obtain robustly-dividing cells with high hydrogen (H2) production capabilities. However, a step-by-step process for biohydrogen production is scarcely reported, mainly from palm oil wastewater. Therefore, this study developed a guideline to find the best inoculum heat treatment conditions and implement the selected conditions for biohydrogen production using palm oil wastewater. This study used raw palm oil mill effluent (POME) and POME sludge as substrate and inoculum, respectively. Our findings reveal that 80 °C and 30 min were the best conditions for inoculum heat treatment. When testing the conditions on POME sludge and inoculating with raw POME (28 g COD/L) at 37 °C (reaction temperature), 24 h (reaction time), and pH 5.5, 34 mL H2/d was recorded. A slight increase (1.1-fold) was observed compared to 5 g COD/L POME co-digested with 5 g/L glucose (31 mL H2/d). This discovery indicates that raw POME is a potential source for biohydrogen production under anaerobic fermentation and can be directly used as substrate up to 30 g COD/L. The proposed guideline could also be implemented for different organic wastes for biohydrogen production study. Full article
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11 pages, 1118 KiB  
Article
Robust Control Based on Modeling Error Compensation of Microalgae Anaerobic Digestion
by Mariana Rodríguez-Jara, Alejandra Velasco-Pérez, Jose Vian, Sergio E. Vigueras-Carmona and Héctor Puebla
Fermentation 2023, 9(1), 34; https://doi.org/10.3390/fermentation9010034 - 31 Dec 2022
Viewed by 1265
Abstract
Microalgae are used to produce renewable biofuels (biodiesel, bioethanol, biogas, and biohydrogen) and high-value-added products, as well as in bioremediation and CO2 sequestration tasks. In the case of anaerobic digestion of microalgae, biogas can be produced from mainly proteins and carbohydrates. Anaerobic [...] Read more.
Microalgae are used to produce renewable biofuels (biodiesel, bioethanol, biogas, and biohydrogen) and high-value-added products, as well as in bioremediation and CO2 sequestration tasks. In the case of anaerobic digestion of microalgae, biogas can be produced from mainly proteins and carbohydrates. Anaerobic digestion is a complex process that involves several stages and is susceptible to operational instability due to various factors. Robust controllers with simple structure and design are necessary for practical implementation purposes and to achieve a proper process operation despite process variabilities, uncertainties, and complex interactions. This paper presents the application of a control design based on the modeling error compensation technique for the anaerobic digestion of microalgae. The control design departs from a low-order input–output model by enhancement with uncertainty estimation. The results show that achieving desired organic pollution levels and methanogenic biomass concentrations as well as minimizing the effect of external perturbations on a benchmark case study of the anaerobic digestion of microalgae is possible with the proposed control design. Full article
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15 pages, 1673 KiB  
Article
Nipa Sap Can Be Both Carbon and Nutrient Source for Acetic Acid Production by Moorella thermoacetica (f. Clostridium thermoaceticum) and Reduced Minimal Media Supplements
by Dung Van Nguyen and Harifara Rabemanolontsoa
Fermentation 2022, 8(11), 663; https://doi.org/10.3390/fermentation8110663 - 21 Nov 2022
Viewed by 1790
Abstract
Nipa sap is an excellent microbial nutrient and carbon source since it contains essential minerals and vitamins, in addition to sugars. In this study, nipa sap was successfully fermented to acetic acid by the industrially important Moorella thermoacetica without additional trace metals, without [...] Read more.
Nipa sap is an excellent microbial nutrient and carbon source since it contains essential minerals and vitamins, in addition to sugars. In this study, nipa sap was successfully fermented to acetic acid by the industrially important Moorella thermoacetica without additional trace metals, without inorganics, or without yeast extract. Although microbial growth kinetics differed from one nutrient condition to another, acetic acid concentrations obtained without trace metals, without inorganics, and without yeast extract supplements were in the same range as that with full nutrient, confirming that nipa sap is a good nutrient source for M. thermoacetica. Fermentations in vials and fermenters showed comparable acetic acid production trends but acetic acid concentrations were higher in fermenters. Upon economic analysis, it was found that the most profitable nutrient condition was without yeast extract. It reduced the cost of culture medium from $1.7 to only $0.3/L, given that yeast extract costs $281/kg, while nipa sap can be available from $0.08/kg. Minimal medium instead of the traditional complex nutrient simplifies the process. This work also opens opportunities for profitable anaerobic co-digestion and co-fermentation of nipa sap with other biomass resources where nipa sap will serve as an inexpensive nutrient source and substrate. Full article
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14 pages, 288 KiB  
Article
The Effects of Two-Stage Fermented Feather Meal-Soybean Meal Product on Growth Performance, Blood Biochemistry, and Immunity of Nursery Pigs
by Hsien-Juang Huang, Bor-Chun Weng, Yueh-Sheng Lee, Cheng-Yung Lin, Yan-Der Hsuuw and Kuo-Lung Chen
Fermentation 2022, 8(11), 634; https://doi.org/10.3390/fermentation8110634 - 12 Nov 2022
Cited by 3 | Viewed by 1491
Abstract
The keratinase-producing microbes can readily change the feather waste into more bioavailable peptides and amino acids. This study aimed to improve two-stage fermented feather meal-soybean meal product (TSFP) quality with five selected Bacillus strains and Saccharomyces cerevisiae Y10, as well as investigate the [...] Read more.
The keratinase-producing microbes can readily change the feather waste into more bioavailable peptides and amino acids. This study aimed to improve two-stage fermented feather meal-soybean meal product (TSFP) quality with five selected Bacillus strains and Saccharomyces cerevisiae Y10, as well as investigate the effects of TSFP on growth performance, blood biochemistry, and immunity of nursery pigs. In trial 1, 100 hybrid piglets (Duroc x KHAPS) were randomly assigned to dietary supplementation of 5% fish meal or 5% TSFP prepared with 0, 32, 40, or 48 h in the first-stage fermentation. The results showed that the body weight (BW), average daily gain (ADG), and feed conversion ratio (FCR) of fermented groups were significantly better than the unfermented group (p < 0.05) at weeks 0 to 3 and 0 to 5. The ADG of 32-hr and 48-hr TSFP groups were better than the unfermented group (p < 0.05) at weeks 3 to 5. In trial 2, 80 hybrid piglets (Duroc × KHAPS) were randomly assigned into 5% fish meal or different supplementation levels of TSFP (32-hr first-stage fermented time) at 0, 2.5, or 5%. The 5% TSFP group had better BW, ADG, FCR, and PEF than the 0% group (p < 0.05) at weeks 0 to 5. Furthermore, the ex vivo mitogen-induced lymphoblastogenesis, the interferon-γ production, the oxidative burst activity, and the IgG production of the 5% TSFP group were higher than the fish meal group (p < 0.05). In conclusion, the first-stage fermentation time can be shortened from 48 h to 32 h using selected Bacillus strains in TSFP production when supplemented at 5% of the diet for nursery pigs shows the best growth performance and immunity. Full article
14 pages, 1800 KiB  
Article
Micro-Aerobic Pre-Treatment vs. Thermal Pre-Treatment of Waste Activated Sludge for Its Subsequent Anaerobic Digestion in Semi-Continuous Digesters: A Comparative Study
by Alejandra Castillo, Eduardo Ortega-Martínez, Jhosané Pagés-Díaz, Silvio Montalvo and Cesar Huiliñir
Fermentation 2022, 8(10), 565; https://doi.org/10.3390/fermentation8100565 - 21 Oct 2022
Cited by 3 | Viewed by 1536
Abstract
This article investigates methane production, organic matter removal, and energy by comparing micro-aerobic pre-treatment and thermal pre-treatment of waste-activated sludge (WAS). For micro-aerobic pre-treatment, WAS was pre-treated at 0.35 vvm (volume of air per volume of medium per minute) for 48 h. The [...] Read more.
This article investigates methane production, organic matter removal, and energy by comparing micro-aerobic pre-treatment and thermal pre-treatment of waste-activated sludge (WAS). For micro-aerobic pre-treatment, WAS was pre-treated at 0.35 vvm (volume of air per volume of medium per minute) for 48 h. The data showed over a 30% increase in soluble Chemical Oxygen Demand (COD) and soluble proteins when this pre-treatment was applied. Then, the micro-aerobically pre-treated sludge was mixed with primary sludge and anaerobically digested in semi-continuous digesters with Hydraulic Retention Times (HRT) of 20, 15, and 10 days at 35 °C. We used two digesters as a control: one fed with a mixture of primary sludge (PS) and raw WAS; another fed with a mixture of PS and thermally pre-treated WAS. The results showed a better performance for the digester fed with micro-aerobically pre-treated sludge than the other two at all the HRT tested. The better performance is because of the solubilization of particulate organic matter, as shown at the reactor outlet. Energy consumption analysis showed that micro-aerobic pre-treatment required 32% more energy in a year than thermal pre-treatment. However, if sludge is pre-thickened in a similar way as performed for thermal pre-treatment, then the energy demand required by micro-aerobic pre-treatment is reduced by 41% concerning the thermal pre-treatment; nevertheless, more studies should be performed to verify that methane production and solid reduction advantages are maintained. Full article
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Review

Jump to: Research

20 pages, 1517 KiB  
Review
Current Status and Prospects of Valorizing Organic Waste via Arrested Anaerobic Digestion: Production and Separation of Volatile Fatty Acids
by Anthony T. Giduthuri and Birgitte K. Ahring
Fermentation 2023, 9(1), 13; https://doi.org/10.3390/fermentation9010013 - 23 Dec 2022
Cited by 6 | Viewed by 2993
Abstract
Volatile fatty acids (VFA) are intermediary degradation products during anaerobic digestion (AD) that are subsequently converted to methanogenic substrates, such as hydrogen (H2), carbon dioxide (CO2), and acetic acid (CH3COOH). The final step of AD is the [...] Read more.
Volatile fatty acids (VFA) are intermediary degradation products during anaerobic digestion (AD) that are subsequently converted to methanogenic substrates, such as hydrogen (H2), carbon dioxide (CO2), and acetic acid (CH3COOH). The final step of AD is the conversion of these methanogenic substrates into biogas, a mixture of methane (CH4) and CO2. In arrested AD (AAD), the methanogenic step is suppressed to inhibit VFA conversion to biogas, making VFA the main product of AAD, with CO2 and H2. VFA recovered from the AAD fermentation can be further converted to sustainable biofuels and bioproducts. Although this concept is known, commercialization of the AAD concept has been hindered by low VFA titers and productivity and lack of cost-effective separation methods for recovering VFA. This article reviews the different techniques used to rewire AD to AAD and the current state of the art of VFA production with AAD, emphasizing recent developments made for increasing the production and separation of VFA from complex organic materials. Finally, this paper discusses VFA production by AAD could play a pivotal role in producing sustainable jet fuels from agricultural biomass and wet organic waste materials. Full article
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