Methane Production Research Articles

Rumen fermentation profile and methane mitigation potential of mango and avocado byproducts as feed ingredients and supplements

Fruit byproducts represent a sustainable alternative to conventional feed for ruminants, addressing food-feed competition and environmental concerns, particularly through their potential to reduce enteric methane emissions via bioactive compounds. This study explored the use of mango and avocado byproducts as feed ingredients and supplements. In experiment 1, mango peel (MP), mango seed kernel (MSK), mango seed coat (MSC), avocado peel (AP), and avocado seed (AS) were independently tested to determine their chemical composition, in vitro digestibility, and rumen fermentation parameters, including gas production and methane emissions. In experiment 2, rumen fermentation parameters were evaluated across five treatment groups: The control group received 200 mg of alfalfa hay alone, without any supplementation. The remaining four groups each received 200 mg of alfalfa hay as the basal diet, supplemented with 15 mg of one of the following microencapsulated extracts: mango peel extract (MPE), avocado peel extract (APE), mango seed kernel extract (MSKE), or avocado seed extract (ASE). Both experiments were conducted over three runs, with each run including three replicates per treatment group, resulting in a total of nine replicates per group. Data were analyzed using linear mixed models with Bonferroni-adjusted pairwise comparisons (p < 0.05). MSK had the highest crude protein content, whereas AP had the highest ether content. MSC and AP presented the highest fiber fractions. AP and MP showed higher total phenolic content and antioxidant capacity. In experiment 1, AS, MP and MSK resulted in greater in vitro dry matter digestibility, and cumulative gas production compared to MSC and AP. Acetate to propionate ratios were higher in AS, MSC, and MSK. Methane production (ml/g dry matter incubated) was highest in MSK (43.7), while AP (19.8) and MSC (18.7) produced the lowest, representing almost 55% reduction compared to MSK (P < 0.001). MP (40.9) and AS (42.2) had intermediate methane values. Ammonia nitrogen was highest in AP and lowest in MSC. In experiment 2, MSKE, ASE and the control had the highest cumulative gas production, whereas APE reduced methane production by 16% compared to the control and lowered the acetate-to-propionate ratio. Compared with the control, all the encapsulated extracts lowered the ammonia nitrogen concentration. Overall, MP, MSK, and AS have emerged as the most promising ingredients because of their relatively high digestibility, and fermentation efficiency, whereas APE and MPE have potential as feed supplements for reducing in vitro methane production.

Effects of Chenopodium album L. Substitution Levels and Harvest Time on In Vitro Rumen Fermentation and Methane Production in Early-Fattening Hanwoo Steers

This study investigated the feasibility of incorporating Chenopodium album L. (CAL) into ruminant feed ingredients through evaluating the effects of harvest time and substitution levels on in vitro rumen fermentation. In the first phase, a sole-substrate experiment was conducted using CAL harvested from June to August, analyzing its chemical composition and total saponin content. The impact of harvest time on fermentation parameters was assessed with CAL as the sole substrate. The second phase involved a mixed-substrate experiment using an early-fattening Hanwoo diet (30% rice straw and 70% concentrate), where increasing proportions of CAL (control: 0%, T1: 5%, T2: 10%, T3: 15%, and T4: 20%) replaced rice straw. Seasonal variations in CAL composition influenced the fermentation characteristics. CAL harvested in July exhibited higher fermentability, with total volatile fatty acids (TVFAs) reaching 103.87 mM at 72 h. In contrast, CAL harvested in August showed lower fermentability and digestibility. However, August-harvested CAL was selected for the subsequent experiment, as it provided a more practical balance of sufficient biomass yield and a higher saponin concentration, aligned with the study’s methane mitigation objectives, while also exhibiting a fiber composition comparable to that of rice straw. We hypothesized that the saponins in CAL contribute to methane reductions. Supplementation with 15% of CAL significantly reduced methane production per gram of digested substrate (p &lt; 0.05), likely due to differences in crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and saponin content. However, despite having the lowest fiber content, T4 (20% CAL) exhibited the lowest in vitro dry matter digestibility (IVDMD), suggesting that factors such as saponins, CAL’s chemical composition, or microbial shifts may have hindered digestibility. Ammonia–nitrogen production increased from 0 to 3 h, but it continuously decreased between 3 and 9 h due to microbial growth and nitrogen assimilation, as microbes incorporate ammonia into their biomass (p &lt; 0.05). Fermentation characteristics further revealed that the acetate-to-propionate (A/P) ratio decreased with increasing CAL levels, with T4 showing the lowest ratio (1.55 at 72 h), confirming a shift toward propionate-based fermentation. Notably, T2 (10% CAL) showed an optimized fermentation efficiency, producing the highest TVFA concentration at 24 h (98.28 mM). These findings highlight the potential for using CAL as a functional feed ingredient, with moderate substitution levels (10–15%) enhancing fermentation efficiency while reducing methane production.

Dark Fermentation and Anaerobic Digestion for H2 and CH4 Production, from Food Waste Leachates

The present study investigates a two-stage process aimed at producing biogas from food waste leachates (FWL) through an experimental approach. The first stage involves biohydrogen production via dark fermentation (DF), while the second focuses on biomethane production through anaerobic digestion (AD). The substrate consists of leachates derived from fruit and vegetable waste, which are introduced into two continuous stirred-tank reactors (CSTR1) with two different inoculum-to-substrate ratios (ISR). Dark fermentation occurs in these reactors. The effluent from the CSTRs is then fed into two additional reactors for methanogenesis. All reactors operated under mesophilic conditions. During the DF stage, hydrogen yields were relatively low, with a maximum of 8.2 NmL H2/g VS added (ISR = 0.3) and 6.1 NmL H2/g VS added (ISR = 0.5). These results were attributed to limited biodegradation of volatile solids (VS), which reached only 21.9% and 23.6% in each respective assay. Similarly, the removal of organic matter was modest. In contrast, the AD stage demonstrated more robust methane production, achieving yields of 275.2 NmL CH4/g VS added (ISR = 0.3) and 277.5 NmL CH4/g VS added (ISR = 0.5). The system exhibited significant organic matter degradation, with VS biodegradability reaching 66%, and COD removal efficiencies of 50.8% (ISR = 0.3) and 60.1% (ISR = 0.5). The primary focus of the study was to monitor and quantify the production of the two biofuels, biohydrogen and biomethane. In conclusion, this study provides an assessment of the two biochemical conversion pathways, detailing the generation of two valuable and utilizable gaseous products. This research examines the process-specific operational conditions governing gas production, with a focus on optimizing process parameters to enhance yield and overall efficiency.

Highly active and stable Ru‐promoted Ni/CeO2 catalysts for CO2 methanation reaction

AbstractBiogas is not only a promising renewable source of energy that can be integrated into existing infrastructures, but biogas could also be a CO2 source for green methane synthesis by hydrogenation with renewable energy‐derived hydrogen. Since biogas is a mixture of CO2 and CH4, we targeted to accomplish direct methanation of CO2 in CH4‐rich gases that are supposed to be a simulated biogas without any processes for CH4 and CO2 separation in biogas. This direct CO2 methanation in biogas can be a more sustainable and environmentally friendly approach. Methane production from biogas‐derived CO2 by conventional methods has some difficulties, including (1) the vast energy cost for separation process of CO2 and CH4 and (2) the slow rate of the reaction in biochemical CO2 methanation. In this paper, we developed active and durable catalysts in direct methanation of CO2 contained in biogas. The focus was on the effect of coexisting CH4 and steam in biogas on CO2 methanation activity and durability of CeO2 supported Ni catalysts. Among all prepared catalysts, a 1 wt.% Ru‐10 wt.% Ni/CeO2 catalyst exhibited 90% CO2 conversion and 100% CH4 selectivity at 275°C reaction temperature. Adding steam to the standard reaction gas mixture (CO2/H2/N2 = 1/4/5) did not impact CO2 conversion in the temperature range investigated, whereas adding CH4 to the standard reaction gas mixture had only a minute decrease (i.e., 86.9% CO2 conversion and 100% CH4 selectivity at 275°C temperature). Furthermore, the 1 wt.% Ru‐10 wt.% Ni/CeO2 catalyst demonstrated remarkable stability in the CO2 methanation reaction.

Gas Endeavour: An Innovative Equipment for Estimating Methane Kinetics During In Vitro Rumen Fermentation.

The growing need to reduce methane emissions from ruminants while enhancing feed utilization has driven the development of innovative in vitro measurement techniques. This review examines the Gas Endeavour (GES), an automated volumetric apparatus that quantifies both total gas and methane production in real time during rumen fermentation. Utilizing the principles of liquid displacement and buoyancy, the GES integrates a thermostatically controlled water bath, specialized gas flow cells, and an alkaline CO2 absorption unit to deliver precise kinetic data on fermentation. Compared to conventional methods-which often rely on manual measurements and post-incubation gas chromatography-the GES provides continuous monitoring and immediate data acquisition, reducing labour and potential errors. This review discusses the system's design, operational challenges such as controlling headspace pressure and ensuring consistent inoculum preparation, and its applications in both animal nutrition and biomethane potential assessments. The findings suggest that, with further standardization and protocol refinement, the GES could significantly advance research aimed at optimizing feed digestibility and mitigating methane emissions in ruminant production systems.

Inclusion of fly ash effects in ADM1: calibration and validation of a simple function using real wastewater.

Including a source of trace elements such as fly ash (FA) in the ADM1 has yet to be addressed, including calibration and validation. The present work aimed to propose, calibrate, and validate a simple function for including the FA effect in the ADM1 using real wastewater from the winery industry. The new function and the ADM1 were calibrated with data of daily methane production coming from a biochemical methane potential (BMP) test of winery wastewater without FA and validated for BMPs using five FA concentrations (25, 50, 75, 100, and 150mg/L). The ADM1 calibration showed that the model fits well with the experimental data, although the parameter values are lower than the range reported in the literature. The calibration of the proposed function fits well with the experimental data under all conditions, including the inhibition and stimulating zones. Lastly, the modified ADM1 could accurately represent the accumulated methane at different FA concentrations, with NRMSE between 0.0635 and 0.1342. Furthermore, the sensitivity analysis shows that the proposed function only requires calibrating one parameter (ki). Thus, the proposed model is robust and valid for all the tested conditions.

Effect of high-quality pellet feed level on voluntary feed intake, nutrient digestibility and rumen fermentation in beef cattle

The aim of this study was to evaluate the effect of high-quality pellet feed on voluntary feed intake, nutrient digestibility and rumen fermentation in beef cattle. Four beef cattle aged approximately 2–3 years were randomly assigned according to a 4 × 4 Latin square design to compare the replacement of pelleted diets in concentrated diets at 4 levels: 0% of diets (T1), 20% of diets (T2), 40% of diets (T3) and 60% of diets (T4). The results of this study revealed that body weight change rate/day total edible amount, or the amount of feed that can be eaten out of concentrated feed, was not significantly different (P > 0.05) among the beef cattle fed all 4 treatments. The digestibility of dry matter, organic matter, crude protein, NDF and ADF was highest in pelleted-fed beef cattle, at 60%. However, the combination of a pelleted diet and a concentrated diet resulted in a statistically significant reduction in protozoa populations when the pelleted diet level was increased. The level of pelleted feed had no effect on the pH or rumen temperature of the beef cattle. With respect to ammonia nitrogen, the propionic acid, butyric acid and total volatile fatty acid levels increased when the beef cattle were fed more pelleted feed. especially at 60%, but the acetic acid and methane production decreased when the beef cattle were fed higher levels of pelleted feed. Purine derivative release was not significantly different. In addition to purine derivative absorption and microbial nitrogen supply, the efficiency of microbial protein synthesis was greater when beef cattle were fed high-quality pelleted feed than when they were not fed high-quality pelleted feed. The present study concluded that pellet feeding in conjunction with concentrated feed at 60% resulted in decreased methane production, protozoa population and nutrient digestibility, microbial protein synthesis, total volatile fatty acids and propionic acid.

Membrane Technology for Valuable Resource Recovery from Palm Oil Mill Effluent (POME): A Review

Palm oil mill effluent (POME), a byproduct of palm oil processing, has substantial resource recovery potential. Its rich biodegradable content supports methane (CH4) production via anaerobic digestion, enabling renewable energy generation. Additionally, the significant water content of POME can be reclaimed for use in boiler feed, irrigation, and drinking water. However, selecting appropriate technologies to recover valuable resources from POME is challenging, particularly for the purification and upgrading of biogas. Membrane technologies offer an effective approach for transforming POME treatment from an energy-intensive process into a resource recovery system, supporting the decarbonization of palm oil production and advancing global sustainability objectives. This technique is cost-effective and ecofriendly for biogas purification and water reclamation. For biogas purification and upgrading, membrane systems offer the lowest capital and operational costs at 5.654 USD/m3, compared to other technologies, such as 6.249 USD/m3 for water scrubbers and 6.999 USD/m3 for chemical absorbers. This review primarily explores the potential of membranes for gas purification from POME and examines their integration with other processes to develop advanced systems, such as ultrasonicated membrane anaerobic systems and membrane anaerobic systems, to enhance biogas production. In addition, water reclamation from POME is discussed, with ultrafiltration membranes emerging as the most promising candidates. Proton exchange membranes, such as Nafion, are used extensively in microbial fuel cells to improve electricity generation, and this is also summarized. Finally, challenges and future perspectives are highlighted, emphasizing the broader potential of membrane technology in POME wastewater resource recovery.

An integrated strategy for sequential nitrite removal and methane recovery: Sludge fermentation driven by nitrite reduction.

An integrated strategy for sequential nitrite removal and methane recovery: Sludge fermentation driven by nitrite reduction.

Combined inhibition of anaerobic digestion by sulfate, salinity, and ammonium: potential inhibitory factors in forward osmosis-concentrated municipal wastewater.

Combined inhibition of anaerobic digestion by sulfate, salinity, and ammonium: potential inhibitory factors in forward osmosis-concentrated municipal wastewater.

Effects of Different Levels of Thiamine Diphosphate on In Vitro Methane Reduction and Fermentation Characteristics of Korean Native Cow (Hanwoo)

This study investigated the effects of different doses of thiamine diphosphate (ThDP) on methane reduction and fermentation characteristics of Korean native cow (Hanwoo). In vitro trials used ThDP powder at 240, 360, 480, 600, and 720 ppm of substrate, with each sample incubated at 39 °C for 24 and 48 h. After incubation, each sample was analyzed for total gas, methane production, dry matter digestibility, and rumen fermentation characteristics. Mean comparisons were performed using Tukey’s test, with significant differences declared at p &lt; 0.05. Total gas production, methane ratio, and methane production per digested dry matter had a quadratic pattern (p &lt; 0.001), and the 480 ppm treatment had the lowest (p &lt; 0.05) at 24 and 48 h of incubation. Total volatile fatty acid concentration showed no significant difference at 24 h but differed significantly at 48 h (p &gt; 0.05). The concentration of propionate had a quadratic pattern (p &lt; 0.001), and the 480 ppm treatment showed the highest levels compared to the other treatments (p &lt; 0.05) after 24 and 48 h of incubation. In conclusion, ThDP supplementation had a methane inhibition effect. In particular, the methane inhibition effect was most pronounced when ThDP was supplemented at 480 ppm.

Partial replacement of high-fibre forages with corn silage across the lactation cycle: effects on methane emission, rumen fermentation and efficiency in dairy cows.

Feeding high-fibre forages to ruminants facilitates enteric methane emission but may also compromise milk yield. The aim of the present study was to investigate the possibility of reducing methane emission and improving feed conversion efficiency with a forage-based ration by replacing high-fibre forages with corn silage across the whole lactation cycle. Twenty-eight Holstein dairy cows were fed the same close-up diet for 21days before their second parturition. After calving, cows with a divergent breeding value for functional herd life were equally allocated to a lactation diet containing forage (66% of DM) of either low (LCS; 31.1% DM) or high corn silage (HCS; 37.7% DM) proportion. The increase in the proportion of corn silage was achieved by partial replacement of grass silage, straw, and hay with corn silage. Diets were fed during the whole lactation period for ad libitum intake, and DM intake and milk production were recorded daily. Cows were weighed and evaluated for their body condition score, milk samples were analysed for fat, protein, and lactose, and blood samples were taken for the analysis of glucose, non-esterified fatty acid, beta-hydroxybutyrate, insulin, adiponectin, and IGF-1. In the respiration chambers, methane production, energy balance, and digesta mean retention time were measured and rumen fluid samples were taken for short-chain fatty acid analysis. Cows fed the HCS diet had greater DM intake, milk and energy-corrected milk yield during the whole lactation period than counterparts fed the LCS diet. The molar percent of acetate was lower and that of propionate and butyrate was higher in the rumen fluid of HCS compared to LCS cows. Methane production was not different between groups but methane yield and intensity were lower in the HCS than in the LCS group. Plasma glucose and IGF-1 concentrations were higher and adiponectin, beta-hydroxy butyrate and non-esterified fatty acid concentrations were lower in HCS compared to LCS cows. In contrast, plasma insulin concentrations were not different between groups. In conclusion, partial replacement of high-fibre forages with corn silage in a lactation diet for dairy cows increased metabolisable energy supply via an increase in DM intake and ruminal fermentation efficiency all of which led to an increase in milk production, a better metabolic status, improved feed and energy use efficiency, and reduced methane yield and intensity.

Effect of Astragalus mollissimus on Ruminal Fermentation, Methane Production and Performance of Sheep.

Recent studies have shown the anti-methanogenic capacity of Astragalus mollissimus (AM), a plant found in semiarid environments, which is known to produce 3-nitro-1-propionic acid (3NPA) and 3-nitropropanol (3NPOH). However, little is known about the effects of direct supplementation in basal diets, given that it is also known to cause cattle poisoning by nitro toxins in rangelands. In the present study, two experiments were carried out to determine CH4 and volatile fatty acid production, animal performance and the presence of nitrocompounds in blood. In Experiment 1, four Pelibuey sheep (BW 52.8±6.05kg) were assigned to a 4×4 Latin square arrangement. In Experiment 2, 20 Dorper sheep were randomized to five treatments. In both experiments, AM was supplemented and fully homogenized into diets consisting of 67% oat hay and 33% concentrate. The supplementation with different amounts of AM reduces (p≤0.05) the total gas and methane production. Methane was reduced by 60% when 1gAMkg-1BWday-1 was supplemented. No effects (p>0.05) were observed in feed consumption and average daily gain. However, feed conversion was increased (p<0.05) with AM supplementation. Finally, no differences (p>0.05) were observed in nitrocompound concentration in plasma. These results demonstrate that 3NPA and 3NPOH from biological sources possess desirable anti-methanogenic properties to be considered supplementation alternatives.

Pretreatment of waste activated sludge by rotational generator of hydraulic shock.

Pretreatment of waste activated sludge by rotational generator of hydraulic shock.

Microscopic mechanism of organic carbon sequestration and redox properties influenced by iron (Oxyhydr)oxides.

Microscopic mechanism of organic carbon sequestration and redox properties influenced by iron (Oxyhydr)oxides.

Enhancing methane production in anaerobic digestion via improved electron transfer with dual-reaction-centers catalyst.

Enhancing methane production in anaerobic digestion via improved electron transfer with dual-reaction-centers catalyst.

Mechanistic insights into electric field-enhanced methanation of lignite via microbial metabolic pathway optimization.

Mechanistic insights into electric field-enhanced methanation of lignite via microbial metabolic pathway optimization.

Enhancing anaerobic digestion of food waste with chemically vapor-deposited biochar: Effective enrichment of Methanosarcina and hydrogenotrophic methanogens.

Enhancing anaerobic digestion of food waste with chemically vapor-deposited biochar: Effective enrichment of Methanosarcina and hydrogenotrophic methanogens.

Integrated application of nanoscale zero-valent iron for sulfide and methane control in sewers and improved wastewater treatment.

Integrated application of nanoscale zero-valent iron for sulfide and methane control in sewers and improved wastewater treatment.

Synergistic bio-adsorption and methane production using plant residues for enhanced heavy metal removal and anaerobic digestion efficiency

Synergistic bio-adsorption and methane production using plant residues for enhanced heavy metal removal and anaerobic digestion efficiency