Anaerobic Co-digestion Research Articles

Pre-digestion of corn straw with kitchen waste improves synergistic methanogenic profiles at different carbon-to-nitrogen ratios

Anaerobic digestion (AD) has been widely applied for treating organic solid wastes. Particularly, the anaerobic co-digestion (AcoD) of representative lignocellulosic material and kitchen waste (KW), which exhibit distinct biodegradation behaviors, has garnered increasing attention. This study characterized the methanogenic performance of the AcoD of corn straw (CS) and KW, revealing initial-stage acidification with carbon-to-nitrogen ratios ranging from 20:1 to 30:1. The prolonged lag phase observed in this study poses a challenge for practical application. Nonetheless, composting both feedstocks prior to AD notably ameliorated acidification. Composting CS with KW played a crucial role in methane production, with the highest methane yield of 334.5mL/g VS achieved at a carbon-to-nitrogen ratio of 30:1, marking a 266.9% increase compared to the untreated group. The degradation of KW and microorganisms in composting proved beneficial for AcoD. Throughout the composting process, there was a substantial increase in the abundance of Firmicutes, Lentilactobacillus, and Limosilactobacillus. Furthermore, in the CS-pretreated samples, the archaeal community was dominated by acetoclastic methanogens, indicating increased resistance to acidification. Thus, this study offers novel insights into biomethane production through the AcoD of CS and KW.

Anaerobic Co-digestion of Palm Oil Sludge, Cassava Peels, Cow Dung and Ground Eggshells: Process Optimization and Biogas Generation

Indiscriminate disposal of crop and animal wastes has grown in acceptance across the globe as an environmentally hazardous practice. This study used a 225L polyethylene digester that was specially made to produce biogas from anaerobic co-digestion of palm oil sludge, cassava peels, and cow dung using ground eggshells for pH stabilization and a greenhouse for temperature control. Cassava peels, palm oil sludge, cow dung, and water were combined in a ratio of 1:1:2:5.3, respectively, and 1.3 kilograms of crushed eggshells were added. The bio-digestion system generated 650.60 L of cumulative biogas throughout the 30-day sludge retention period. The pH averaged 6.0, and the slurry temperature averaged 34.76oC during digestion, which is favorable for the production of biogas since microbial populations thrive under hospitable conditions. The biogas produced after a hydraulic retention time (HRT) of over 20 days had the highest methane concentration of 60%, while days under 10 HRT had the lowest methane content of 45.5%. On the 13th day of anaerobic digestion, biogas output peaked at 34.90L, and pH and temperature were maintained at 6.5 and 35.0°C, respectively, the ideal ranges for a healthy process. An efficient technique for producing energy in the form of biogas was shown by optimized anaerobic co-digestion of animal and crop waste utilizing ground eggshells and a greenhouse for pH and temperature control. Future research should focus on developing more efficient, cheaper microbial agents, such as enzymes for biological pre-treatment of palm oil sludge to reduce lignin, which negatively impacts biogas generation.

Anaerobic co-digestion of swine manure and enzymatically hydrolyzed carcasses at two different biodigesters

Anaerobic co-digestion of swine manure and enzymatically hydrolyzed carcasses at two different biodigesters

Anaerobic co-digestion of Cow Manure and Food Waste: An investigation of biogas yield from feedstock percentage variation

Anaerobic co-digestion of Cow Manure and Food Waste: An investigation of biogas yield from feedstock percentage variation

Comparative Measurement of Biogas Generation of Ziziphusspina - Christi (L.) Wild Leaves and Cow Dung

To increase the production of biogas from an appropriate substrate, anaerobic co-digestion techniques are required. Methane generation and process stability can be enhanced by co-digesting animal dung and suitable biomass with a low carbon content. The objective of the study is to determine the proximate parameters and compare the biogas generation from a sample of plants sown with cow manure and leaves of Ziziphusspina. Over the course of 42 days, the experiment was conducted using a homemade anaerobic digester in the lab. Even yet, the amount of biogas produced by the plant sample was not as high as that produced by the plant sample that was fertilized with cow manure.For additional advantageous uses, such as the creation of biofertilizers, the physico-chemistry of fresh samples and spent slurries in the biodigesters might be investigated. This work has potential applications in underdeveloped nations, particularly in rural areas with abundant biological waste and limited access to energy.

Correction: Anaerobic Co-Digestion of Coffee Processing Wastewater and Microalgal Biomass After Protein Extraction

Correction: Anaerobic Co-Digestion of Coffee Processing Wastewater and Microalgal Biomass After Protein Extraction

Transforming by-products into renewable energy: Biochemical analysis of anaerobic digestion of biowastes for bioreactors optimization supporting the low-carbon agroindustry

With the expansion in agro-industrial operations there is an urgent need to solve the challenge of dealing with the products waste. Today, an overwhelming portion of this waste ends up in industrial waste disposal sites. Wherefore, anaerobic co-digestion (ACoD) emerges as an effective technique for waste treatment, being environmentally and economically viable, since a microbial community converts by-products into renewable energy in the form of biogas, with high levels of hydrogen and other gases. ACoD has proven effective in the management of organic waste from agro-industry. However, mastering the biochemistry of the process, especially when varying the mixtures of waste used, is essential for controlling biological reactors and optimizing energy production. Even though separate studies have evaluated the anaerobic digestion of rice parboiling effluent and peach processing residue, co-digestion of both are scarcely investigated. The knowledge and mastery of the process parameters using this mixture are essential to ensure effective operational control of anaerobic reactors with maximum energy generation. Therefore, this research evaluated the biogas production from ACoD of rice parboiling effluent and waste of peaches processing. The experiment followed a batch regime based on a 22-factorial arrangement. The factors used were the peach percentage in the substrate (P), which varied from 2.5 to 5%, and the substrate-inoculum ratio (S/I), which was alternated between 1.5 and 2.5 gCOD/gVSS. The average Chemical Oxygen Demand (COD) removal efficiency of the reactors was 82.1% and, after the digestion process, the pH of the reactors remained neutral, showing that anaerobic digestion is a suitable method for treating the assessed wastes. In the analyzed proportions, the higher the peach percentage in the substrate, the lower the total methane production, whereas the S/I demonstrated the opposite effect. Reactors III (S/I = 2.5 and P = 2.5%), presented the most durable and the highest production, being the best combination of the factorial studied. Finally, it can be said that for the state of Rio Grande do Sul, the largest rice and peach producer in Brazil, ACoD of the wastes assessed in this research represents a significantly relevant option, enabling the development of the circular economy, the industrial symbiosis, and the sustainable production in the State.

Bioplastic’s Valorisation by Anaerobic Co-Digestion with WWTP Mixed Sludge

Bioplastics are designed to degrade at the end of their lifecycle, but effective management of their end-of-life phase and integration into existing organic waste management systems remain significant challenges. Some bioplastics decompose under anaerobic conditions, with the anaerobic digestion (AD) process being a potential solution for their disposal. AD is a promising technology for valorising organic wastes, enabling biomethane production, reducing carbon footprints, and promoting product circularity. This study focuses on evaluating the continuous co-digestion of bioplastics with mixed sludge from an urban wastewater treatment plant (WWTP). Polyhydroxybutyrate (PHB) was the selected bioplastic, as various studies have reported its high and rapid degradation under anaerobic mesophilic conditions. PHB’s biodegradability under typical WWTP anaerobic digestion conditions (35 °C, 20-day retention time) was assessed in batch tests and the results indicate that PHB degradation ranged from 68 to 75%, depending on particle size. To further explore the potential of AD for PHB valorisation, the feasibility of anaerobic co-digestion of PHB with WWTP sludge was tested on a continuous laboratory scale using two digesters: a conventional digester (CSTR) and an anaerobic membrane bioreactor (AnMBR). The results indicated complete degradation of PHB, which led to higher biomethanisation percentages in both digesters, rising from 58% to 70% in the AnMBR and from 44% to 72% in the CSTR. The notable increase observed in the CSTR was attributed to changes in microbial populations that improved sludge biodegradability.

Sustainable biogas production via anaerobic co-digestion of cheese whey and cattle manure

In Mexico, specifically in Chiapas, the dairy cattle industry plays a significant role in cheese and milk production. However, the large quantities of cattle manure (CM) and cheese whey (CW) generated as byproducts pose environmental challenges if not managed properly. To address this issue, anaerobic digestion (AD) technology offers a sustainable solution by treating organic waste and producing biogas. This research study focuses on assessing the potential of CW and CM, both individually and in co-digestion, in an anaerobic environment. The study also evaluates biogas yield and composition using an up-flow anaerobic sludge blanket (UASB) reactor with different CW and CM mixtures. The findings indicate that the 30CM:70CW ratio exhibited the highest methane yield, surpassing other assays in co-digestion and mono-digestion. Furthermore, the UASB reactor showed that a mixture of 90CW:10CM produced 25.73 L of biogas per gram of volatile solids daily, comprising 60 % methane and 40 % carbon dioxide. This research demonstrates the potential for efficient and environmentally friendly treatment of CM and CW through optimized co-digestion and UASB technology, highlighting the opportunity to generate biogas while reducing waste.

Correction: Chow et al. Anaerobic Co-Digestion of Wastewater Sludge: A Review of Potential Co-Substrates and Operating Factors for Improved Methane Yield. Processes 2020, 8, 39

The journal is publishing this correction to update the name of the Academic Editor listed on this published paper [...]

Effect of solid-state fermentation by a novel soft-rot fungus Cheatomium globosum IMA1 on the anaerobic co-digestion performances of waste activated sludge and municipal solid waste

Effect of solid-state fermentation by a novel soft-rot fungus Cheatomium globosum IMA1 on the anaerobic co-digestion performances of waste activated sludge and municipal solid waste

Mono e codigestão anaeróbia de resíduos de frutas e vegetais: Efeitos no rendimento de biogás e no biofertilizante

ABSTRACT The proper disposal of fruit and vegetable waste is essential to promote environmental sustainability, reduce the carbon footprint, improve soil quality, and contribute to the transition to a circular economy. This study examined the impact of incorporating dairy cattle wastewater (DCWW) into anaerobic co-digestion with fruit and vegetable residues and utilization of the resulting biofertilizer as a diluent in the anaerobic mono-digestion of fruit and vegetable residues (recycle). The specific biogas and methane production and the agronomic quality of the biofertilizer were evaluated in a semi-continuous trial. Two startup strategies were employed: initially, the reactors were entirely fed with inoculum (biofertilizer derived from DCWW), and fruit and vegetable residue feedstock was gradually introduced. Anaerobic co-digestion of fruit and vegetable residues with DCWW yielded the highest specific production of biogas and methane at 720 and 436 L kg-1 of volatile solids (VS), respectively. The addition of DCWW increases fruit and vegetable residue alkalinity by 249% and reduces the volatile acidity by 83.4%. Anaerobic mono-digestion of fruit and vegetable residues enhances macronutrient recovery in the biofertilizer through recycle. Logistically, directing fruit and vegetable residues to rural areas for anaerobic co-digestion with DCWW promotes agricultural biofertilizer use.

Investigating the effects of biochars and zeolites in anaerobic digestion and co-digestion of cassava wastewater with livestock manure

Investigating the effects of biochars and zeolites in anaerobic digestion and co-digestion of cassava wastewater with livestock manure

An Examination of Calculations: From Anaerobic Mono-digestion to Co-digestion

Anaerobic digestion is a biochemical process and form of sustainable technology. In comparison to mono-digestion, co-digestion is more effective in the utilization of diverse resources, supply of nutrient balance, and overall digestibility and stability. The co-digestion biodegradability index, co-digestion performance index, and synergistic effect index are generally used as anaerobic metrics to evaluate the co-digestion performance. Although they are numerical parameters, little information on their working procedures has been revealed. There is also a lack of supporting calculations for some published data hence their values cannot be verified. The aim of this article is to reconsider and examine the mathematical calculations from anaerobic mono-digestion to co-digestion. The method of study is a pen-and-paper analysis that processes both experimental and theoretical data from past studies. The article serves four purposes. First, it identifies processing parameters. Second, it shows step-by-step procedures of a series of calculations. Third, it identifies the core parameter in the calculation of anaerobic co-digestion. Fourth, it establishes the relationships between co-digestion biodegradability index, co-digestion performance index, and synergistic effect index. Critically, the mass fraction of volatile solid is identified as the core parameter that determines the valid calculations of co-digestion.

Enhanced biogas production from municipal solid waste via digestion with cow manure: A case study

Abstract Anaerobic digestion (AD) of feedstocks yields biogas, a potentially useful new energy source. This study looked into the anaerobic co-digestion of cow dung and organic garbage to produce biogas. An anaerobic biodigester, with a volume of 20 L, was used to digest organic waste (OW) and to trace the changes that occur during the AD process. It was equipped with tools that ensure complete control of the conditions affecting anaerobic biological reactions such as temperature, pH function, and mixing speed. Therefore, an anaerobic biodigester was designed to contain such biological transformations and to improve the biogas production process from OW. Based on the present investigation, the AD of OW was improved by integrating the substrate with sewage sludge or cow manure (CM) during the digestion process to provide the basic microorganisms to complete the digestion process. Feeding into the digester was a blend of 100 kg of cow dung (CM) and OW per day, diluted 1:1 with water. A gasbag was used to capture the methane that resulted. Biogas production began on the seventh day after the substrate was fed into the digester. A performance test was carried out on the produced biogas to determine its composition. For OW–CM, the generated biogas’s methane (CH4) concentration was determined to be 60%, but the rates of decline for TS and VS were 57 and 50.6%, respectively. Anaerobic biodegradation of OW–CM experiments was observed at 37°C, a mesophilic temperature. For OW–CM, the pH value was 6.7. After being adjusted to standard circumstances, the cumulative volume of methane produced which had been recorded as 4,914 mL became 3964.5 mL.

Anaerobic Co-Digestion of Coffee Processing Wastewater and Microalgal Biomass After Protein Extraction

Anaerobic Co-Digestion of Coffee Processing Wastewater and Microalgal Biomass After Protein Extraction

Biomethane Potential of Beef Cattle Slaughterhouse Waste and the Impact of Co-Digestion with Cattle Feces and Swine Slurry

Slaughterhouse waste (SW) poses significant environmental challenges due to its complex composition, but anaerobic digestion offers a way to recover valuable biogas from SW. This study investigated the anaerobic co-digestion of beef cattle slaughterhouse waste (BCSW) with either cattle feces (CF) or swine slurry (SS). The biomethane potential, maximum methane yield (Mmax), lag phase duration, and effective digestion time (Teff) for the individual substrates and the combinations were analyzed. BCSW alone exhibited Mmax of 578.5 Nml CH4/g VSadded with a lag phase of 11 days, while CF and SS alone exhibited Mmax of 397.2 and 289.8 Nml CH4/g VSadded, respectively. Co-digestion of BCSW and SS resulted in Mmax increase of 48–75.5%, with negligible effects on Teff compared to solitary SS digestion. Similarly, co-digestion of BCSW and CF increased Mmax by 6.2–40.4%, with no significant impact on Teff compared to solitary CF digestion. However, both co-digestions led to a reduction in Mmax (12.1–27%) when compared to BCSW digestion alone. Co-digestion with SS shortened the lag phase duration by 2.8–7.8 days and accelerated Teff by 5.8–8.3 days due to SS’s high concentrations of essential micronutrients like cobalt and nickel which aid digestion. This study concluded that co-digestion of BCSW with SS is an effective strategy for enhancing methane production and digestion efficiency, offering a viable approach for proper disposal of BCSW while improving biogas output.

Peracetic acid enhanced anaerobic co-digestion of excess sludge and food waste: performance and mechanism

ABSTRACT Anaerobic co-digestion of excess sludge (ES) and food waste (FW) has been proven to be a clean and efficient strategy for the resource recovery of organic waste. However, the methane production from the anaerobic co-digestion of ES and FW is not optimal. This study reports a new strategy of using peracetic acid (PAA) pretreatment to enhance the anaerobic co-digestion of ES and FW and reveals the underlying mechanisms. The results confirm that PAA can effectively promote the production of methane from the anaerobic co-digestion of ES and FW, with the maximum methane yield reaching 416 mL/g volatile suspended solids at a PAA content of 9% (w/w). Mechanistic analysis indicates that PAA efficiently facilitates the solubilization of organic matter, promoting the release of soluble proteins and polysaccharides, and accelerating the metabolic conversion of volatile fatty acids (VFAs) to prevent excessive acidification. The maximum output of VFA in the PAA group was 1,511–1,974 mg/L, which was lower than that in the control group. Batch experimental analysis revealed that PAA promoted the hydrolysis and acidification processes, but inhibited the methanogenic process. The PAA pretreatment technique provides a theoretical basis for the efficient treatment of organic matter in urban areas.

Energy recovery from poultry manure in the process of semi-continuous anaerobic co-digestion with sewage sludge

In the face of significant legislative changes in renewable energy sources and conservation of natural resources, bio-waste must be managed efficiently. Developing wastewater treatment technologies generate a large amount of sewage sludge requiring appropriate use. A well-known and practiced process is the anaerobic digestion of sewage sludge, but due to its characteristics, the production of biogas is not sufficient enough to ensure the energy self-sufficiency of a wastewater treatment plant. Another waste whose management is a challenge is poultry manure, whose production in Poland is high due to intensive poultry farming. This study investigated the possibility of co-digestion of poultry manure and sewage sludge and its effect on increasing biogas production compared to processing sludge alone. The process was performed in two continuously stirred-tank glass reactors at mesophilic conditions, with 20 days of hydraulic retention time. In the first stage, the batch assay with sewage sludge was applied to promote the development of an anaerobic community. The second stage involved feeding the reactors on a semi-continuous regime with sewage sludge for the control sample and a mixture with the gradual addition of poultry manure from 2.5 % to 60 %. During the experiment, the most important parameters affecting the process and the quantity and quality of the obtained products in the form of biogas and digestate were monitored. The study’s results indicated an advantage of the co-digestion process of poultry manure and sewage sludge over the digestion of sludge alone in terms of process efficiency. The highest biogas production was obtained with a co-substrate ratio of 42 % manure to 58 % sewage sludge (ratio based on volatile solids). Co-digestion had no significant effect on gas quality; in both cases, the methane content was more than 60 %. Moreover, a digestate with fertilizer potential was obtained for each sample.

Biochars from waste as an additive material in anaerobic co-digestion: Characterization and application in batch and semi-continuous systems

The conversion of organic waste into energy through anaerobic digestion (AD) is a profitable and environmentally friendly strategy. Enhancing the process is crucial for optimizing and maximizing biogas and methane production. To achieve this, various strategies can be employed, such as anaerobic co-digestion (co-AD) and the use of biochar. Biochar aids in process stability, provides buffering capacity, mitigates inhibitory toxins, immobilizes microorganisms, facilitates microbial colonization, and accelerates electron transfer between microorganisms. This study aimed to produce biochar from different wastes and pyrolysis temperatures and to investigate its use as an additive material in the co-AD of fruit and vegetable waste (FVW) and laying chicken manure (LCM) in batch and semi-continuous systems. Thermogravimetric analysis (TGA) and differential scanning calorimetry were performed to determine the pyrolysis temperature for biochar production, defining temperatures of 450 and 550 °C. A biochemical methane potential (BMP) test was conducted in 120 mL reactors (working volume) with the addition of 10 g/L of biochar from FVW, LCM, and wood pruning waste (WPW). WPW450 biochar showed the highest fixed carbon content, rough surface, and deep porous structure, factors that contributed to a 28 % increase in methane production compared to the control. Semi-continuous tests were conducted in 50 L reactors (working volume) using a reduced dosage (1 g/L) of WPW450 biochar, providing process stability and better biogas quality, resulting in a 31 % increase in methane production. The reduction in biochar dosage did not negatively impact the semi-continuous system, which showed a 74 % higher methane yield compared to the batch system. The results of this study highlight the importance of biochar addition to increase methane production in the co-AD of FVW and LCM at different scales, as well as the study of different biomasses and temperatures for biochar production.