Anaerobic Digestion Of Cattle Manure Research Articles

Elucidating Key Microbial Drivers for Methane Production during Cold Adaptation and Psychrophilic Anaerobic Digestion of Cattle Manure and Food Waste

At psychrophilic temperatures (<20 °C), anaerobic digestion produces less methane (CH4). For psychrophilic anaerobic digestion (PAD) to be successful, investigation of cold-adapted microbial consortia involved in methane production is critical. This study aimed to investigate the microbial community driving enhanced methane production from the cold-adaptation process and bioaugmentation of PAD with cold-adapted inoculum (BI). Microbial consortia in cattle manure (CM) and food waste (FW) were adapted and applied during batch PAD of CM and FW to bioaugment methane production at 15 °C. Cold adaptation and PAD with BI resulted in cumulative specific methane yields of 0.874 ± 0.231 and 0.552 ± 0.089 L CH4 g−1 volatile solids, respectively, after 14 weeks, while the absence of BI (control) led to acidification and no methane production during PAD. Following 16S rRNA V4–V5 amplicon sequencing and metagenomic analyses, Methanosarcina was revealed as a key driver of methanogenesis during cold adaptation and PAD bioaugmentation. Furthermore, based on the predictive functional and metabolic analysis of the communities, possible synergies were proposed in terms of substrate production and utilization by the dominant microbial groups. For instance, during methane production, Bacteroides and Methanobrevibacter were possibly involved in a syntrophic relationship, which promoted methanogenesis by Methanosarcina. These findings provide insight into the prospective microbial synergies that can be harnessed and/or regulated in cold-adapted inoculum for the improvement of methane production during PAD.

Influence of inoculum on process parameters and microbial communities during anaerobic digestion of cattle manure: Insights from metabarcoding analysis

Linking the variety of microbial ecology attributes to system functioning is critical to improve operational strategies and to support microbial pathways, in order to conceive efficient and reliable anaerobic digestion process. In the present study, we conducted a direct comparison between two digesters regarding the process parameters and microbial community dynamics between two digesters: one containing only the substrate (cattle manure) (Digester S), and the other (Digester F) enriched with an inoculum. This study aimed to investigate taxonomic and functional changes in the digester microbiome using a 16S rRNA sequencing approach. Results exhibit that the bacterial richness, diversity, and regularity were higher in Digester F. This later showed also a higher biogas yields (BY) and the process performance indicators compared to Digester S. The BY obtained in digester F was 2.17 times higher than that obtained in digester S. Furthermore, significant correlations were obtained between biogas yields (BY) and microbial communities with Firmicutes/Bacillota (Clostridium, Enterococcus, Streptococcus, Ruminococcaceae, Mogibacterium, and Turicibacter), Actinobacteria (Corynebacterium), and Bacteroidetes (Bacteroides, Paludibacter) in the AD systems. Conversely, in Digester S, biogas yield (BY) was highly significant and positively correlated with the abundance of Actinobacteria (Rhodococcus) and Proteobacteria (Moraxella, Oxalobacter). Moreover, the inoculum in digester F resulted in the enrichment of main bacterial functions involved in biogas production. This study provides results that justify the changes in the structure of the microbial community and the functional strategy used by the most representative micro-organisms in the consortia that carried out this process.

Modification of Anaerobic Digestion Model No. 1 for modeling anaerobic digestion of cattle manure with changing solids retention time

In this study, Anaerobic Digestion Model No.1 (ADM1) was modified to incorporate changes in biochemical parameters due to solids retention time (SRT) variations. Cattle manure (CM) and thermally hydrolyzed CM were selected for testing. Continuous anaerobic digestion reactors were operated under different SRT conditions ranging from 6.6 to 36.0 days for both samples. The biochemical parameters (kch, kli, kpr, um,ac, um,bu, um,pro, um,va, Kac, Kbu, Kpro, and Kva) for each SRT condition were determined. To modify ADM1, the equations obtained through linear regression were substituted into biochemical parameters as a function of SRT. The modified ADM1 demonstrated superior accuracy compared with conventional ADM1. This study implies the feasibility of optimizing biochemical parameters for modeling in response to changes in environmental variables.

Nanobubble water promotes anaerobic digestion of high-solids cattle manure under mesophilic and thermophilic conditions

The gradual increase in cattle farming has led to a huge production of cattle manure (CM), but the conventional treatment methods are less efficient. In this study, the treatment method of anaerobic digestion (AD) of high-solids CM by combining nanobubble water (NBW) with different gases was proposed to present a new idea for the reduction, harmlessness, and resourcefulness of CM. It was found that the performance of the digester with added NBW was better than the control. Among them, the cumulative methane yield T-Air: 227.09 mL g−1 VSadded and T-CO2: 226.12 mL g−1 VSadded increased by 17.72 % and 17.22 %, respectively, compared with the control T: 192.90 mL g−1 VSadded under thermophilic conditions. Under mesophilic conditions, M-Air: 162.39 mL g−1 VSadded increased by 9.68 % compared with control M: 148.05 mL g−1 VSadded. Microbial communities analyzed at the genus level revealed that the relative abundance of bacteria favorable to hydrolysis and acid-producing processes, such as Defluviitalea, Haloplasma, and Bacillus, increased to varying degrees. Moreover, the relative abundance of archaea favorable for methanogenesis, such as Methanoculleus, Methanobrevibacter, and Methanosarcina, also increased to varying degrees. Therefore, the addition of NBW promoted the hydrolysis of high-solids CM, enhanced the stability of the reaction, improved the methanogenic performance, and increased the RA of favorable genera, which ultimately led to a better performance of the AD of high-solids CM.

Copper in different forms and tetracycline affect behavior and risk of antibiotic resistome in thermophilic anaerobic digestion of cattle manure.

The metagenomics-based behavior and risk of antibiotic resistance genes (ARGs) were investigated during cattle manure thermophilic anaerobic digestion with tetracycline and copper, namely, bulk-copper oxide, nano-copper oxide, and copper sulfate, which are common feed additives. Although bulk-copper oxide reduced ARGs' diversity, it enriched high-risk ARGs the most than the other two copper species, while copper sulfate could strongly mitigate the ARG risk by decreasing their abundances. Compared to corresponding individual effects, copper and tetracycline combinations may decrease ARGs' co-occurrence potential by 22.0%, and particularly, tetracycline combined separately with copper sulfate and nano-copper oxide reduces the ARGs' risk in abundance (by 7.2%) and human health (by 4.0%). These were mainly driven by bioavailable copper, volatile fatty acids, and pH, as well as the main potential hosts in phyla Firmicutes, Coprothermobacterota, and Euryarchaeota. Notably, the twin risks of pathogenicity and ARGs should be emphasized due to the ARGs' positive correlation with human pathogens of Clostridioides difficile and Arcobacter peruensis. These findings are important for understanding the potential ARGs' risk in treatments of livestock wastes containing feed additives of different sizes and speciation.

Feasibility of thermal hydrolysis pretreatment to reduce hydraulic retention time of anaerobic digestion of cattle manure

In this study, we investigated the potential of thermal hydrolysis pretreatment (THP) to reduce the hydraulic retention times (HRTs) in the anaerobic digestion (AD) of cattle manure (CM). The AD with THP (THP AD) outperformed the control AD by over 1.4 times in terms of methane yield and volatile solid removal, even under the same HRT conditions. Remarkably, even when the THP AD was operated with an HRT of 13.2 d, it performed better than the control AD operated with an HRT of 36.0 d. In THP AD, there was a shift in the dominant archaeal genus responsible for methane generation from Methanogranum (at HRT of 36.0 – 13.2 d) to Methanosaeta (at HRT of 8.0 d). However, decreasing HRT, and applying THP resulted in reduced stability, accompanied by increased inhibitory compounds, and changes in the microbial community. Further confirmation is required to assess the long-term stability of THP AD.

Effects of alkaline thermal hydrolysis on the formation of refractory compounds and energy balance of anaerobic digestion of cattle manure

Anaerobic digestion (AD) coupled with thermal hydrolysis pretreatment (THP) is appealing because it enhances the energy conversion rate of organic wastes. Here, cattle manure, the most abundant organic waste, was thermally hydrolyzed as a pretreatment of AD. In order to increase the process efficiency, a NaOH solution was introduced. Increasing the amount of NaOH addition during the THP enhances lignin removal and solubilization of cattle manure. The thermally hydrolyzed cattle manure (at 160 °C with 2 % (dry wt.) NaOH addition) showed a significantly higher biochemical methane potential of 227.0 ± 11.0 mL-CH4/g-volatile solid compared to that of intact cattle manure (182.2 ± 2.5 mL-CH4/g-volatile solid). Refractory compounds (humic acid-like substances and furfural) were identified at THP temperatures above 180 °C without NaOH addition, and it was enhanced by increasing NaOH addition. Energy balance analysis showed that additional 161.4 ± 39.3 MJ of energy can be gained per ton of cattle manure by applying THP (at 160 °C without NaOH addition). This study provides insights into the changes in the physicochemical and biochemical properties of cattle manure caused by alkaline THP.

Boosting biogas production and methane yield by using street dust as an additive on anaerobic digestion of cattle manure

Boosting biogas production and methane yield by using street dust as an additive on anaerobic digestion of cattle manure

Anaerobic Digestion of Agricultural Waste Using Microbial Inocula: Performance and Characterization of Bacterial Communities Using 16S rRNA Sequencing Approach

Anaerobic digestion is considered a beneficial treatment for biogas production (BP). To improve the performance of this bioprocess, the addition of well-selected inocula could be an interesting approach that affects the overall efficiency of the BP. In this study, the reactor performance and energy analysis of liquid-state anaerobic digestion of cattle manure (CM) at high solids concentration (TS%) (94.87%) with six different inocula—two cellulosic (C.I1, C.I2), one lipidic (Li.I), two lactic (La.I1, La.I2), and one saccharidic (Sacc.I)—were investigated. The results showed that inocula improved the biogas production and yield during anaerobic digestion of CM by 109%, 86%, and 52.4%, respectively, when the cellulosic (C.I1), lipidic (Li.I), and lactic (La.I1) inocula were added, compared with the substrate production alone at a substrate/inoculum (S/I) ratio of 5:3 (v/v). The addition of inocula in an appropriate range is useful for the performance of the anaerobic digestion process. In our study, the 16S rRNA sequencing approach was followed to investigate microbial community structure and diversity in the substrate CM and the three inocula that showed a significant improvement in biogas production (C.I1, Li.I, and La.I). The most abundant bacterial populations were found to be Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria, with different abundance percentages. Interestingly, C.I1, which resulted in the highest biogas production, showed the dominance of Cyanobacteria (53.44%) belonging mainly to the class Nostocophycidae. This study highlighted the role of inocula in improving biogas production from cattle manure (CM) thanks to their microbial diversity.

The impact of hematite on the anaerobic digestion of cattle manure

A metal-based conductive material, hematite (Fe2O3), was used as an amendment in the anaerobic digestion process to determine the effects on the performance of anaerobic digestion of cattle manure (CM) at mesophilic temperature (350C). The first set of experiments (Set 1) was designed to assess whether there is a need to supplement nutrients for the effective digestion of CM. To this purpose, basal medium (BM) composed of macro nutrients, micro nutrients, reducing agent, and buffer was added to the reactors and a biochemical methane production assay was conducted. The presence of BM showed negative impacts on the anaerobic digestion of CM and its absence caused up to 40% higher methane production yield. In Set 2 experiments, the impact of hematite addition on methane production performance was determined. Two different dosages as 20 mM Fe (Fe20) and 50 mM Fe (Fe50) were applied to the batch reactors. Hematite amendments increased methane yield; at Fe20 (131 ± 2.6 mL CH4/g VSadded) the increase was around 8% and at Fe50 (135 ± mL 0.2 CH4/g VSadded) the increase was around 12% as compared to the control. Further, up to 36% increase in the methane production rate was calculated via Modified Gompertz fitting.

Technological Process of Anaerobic Digestion of Cattle Manure in a Bioenergy Plant

Technological Process of Anaerobic Digestion of Cattle Manure in a Bioenergy Plant

Fate and seasonality of antimicrobial resistance genes during full-scale anaerobic digestion of cattle manure across seven livestock production facilities.

Anaerobic digestion has been suggested as an intervention to attenuate antibiotic resistance genes (ARGs) in livestock manure but supporting data have typically been collected at laboratory scale. Few studies have quantified ARG fate during full-scale digestion of livestock manure. We sampled untreated manure and digestate from seven full-scale mesophilic dairy manure digesters to assess ARG fate through each system. Samples were collected biweekly from December through August (i.e., winter, spring, and summer; n=235 total) and analyzed by quantitative polymerase chain reaction for intI1, erm(B), sul1, tet(A), and tet(W). Concentrations of intI1, sul1, and tet(A) decreased during anaerobic digestion, but their removal was less extensive than expected based on previous laboratory studies. Removal for intI1 during anaerobic digestion equaled 0.28 ± 0.03 log10 units (mean ± SE), equivalent to only 48% removal and notable given intI1's role in horizontal gene transfer and multiple resistance. Furthermore, tet(W) concentrations were unchanged during anaerobic digestion (p>0.05), and erm(B) concentrations increased by 0.52 ± 0.03 log10 units (3.3-fold), which is important given erythromycin's status as a critically important antibiotic for human medicine. Seasonal log10 changes in intI1, sul1, and tet(A) concentrations were ≥50% of corresponding log10 removals by anaerobic digestion, and variation in ARG and intI1 concentrations among digesters was quantitatively comparable to anaerobic digestion effects. These results suggest that mesophilic anaerobic digestion may be limited as an intervention for ARGs in livestock manure and emphasize the need for multiple farm-level interventions to attenuate antibiotic resistance.

Particle size effects in microbial characteristics in thermophilic anaerobic digestion of cattle manure containing copper oxide.

Roles of bulk-, micron-, and nano-copper oxide (CuO) on methane production, microbial diversity, functions during thermophilic anaerobic digestion (AD) were investigated in this study. Results showed that bulk-, micron-, and nano-CuO promoted methane production by 27.8%, 47.6%. and 83.1% compared to the control group, respectively. Microbial community analysis demonstrated that different particle sizes could cause various shifts on bacteria community, while had little effect on archaeal diversity. Thereinto, bacteria belonging to phylum Firmicutes and Coprothermobacterota dominated in enhanced hydrolysis process in groups with nano-CuO and bulk-CuO, respectively, while micron-CuO had stronger promotion on the abundances of hydrolytic and fermentative bacteria belonging to families Peptostreptococcaceae, Caloramatoraceae, Erysipelotrichaceae, and Clostridiaceae, than other two CuO sizes. Metabolic pathways revealed that energy-related metabolism and material transformation in bacteria were only boosted by micron-CuO, and nano-CuO and bulk-CuO were important to methanogenic activity, stimulating energy consumption and methane metabolism, respectively.

Metagenomic Analysis of the Long-Term Synergistic Effects of Antibiotics on the Anaerobic Digestion of Cattle Manure

The conversion of cattle manure into biogas in anaerobic digestion (AD) processes has been gaining attention in recent years. However, antibiotic consumption continues to increase worldwide, which is why antimicrobial concentrations can be expected to rise in cattle manure and in digestate. This study examined the long-term synergistic effects of antimicrobials on the anaerobic digestion of cattle manure. The prevalence of antibiotic resistance genes (ARGs) and changes in microbial biodiversity under exposure to the tested drugs was investigated using a metagenomic approach. Methane production was analyzed in lab-scale anaerobic bioreactors. Bacteroidetes, Firmicutes, and Actinobacteria were the most abundant bacteria in the samples. The domain Archaea was represented mainly by methanogenic genera Methanothrix and Methanosarcina and the order Methanomassiliicoccales. Exposure to antibiotics inhibited the growth and development of methanogenic microorganisms in the substrate. Antibiotics also influenced the abundance and prevalence of ARGs in samples. Seventeen types of ARGs were identified and classified. Genes encoding resistance to tetracyclines, macrolide–lincosamide–streptogramin antibiotics, and aminoglycosides, as well as multi-drug resistance genes, were most abundant. Antibiotics affected homoacetogenic bacteria and methanogens, and decreased the production of CH4. However, the antibiotic-induced decrease in CH4 production was minimized in the presence of highly drug-resistant microorganisms in AD bioreactors.

Effect of low levels of oxytetracycline on anaerobic digestion of cattle manure

Cattle manure is rich in organic matter and nutrients, but it may also contain harmful substances such as residual antibiotics and other toxic compounds. Oxytetracycline (OTC) is a widely used veterinary antibiotic and its presence in manure can affect the subsequent anaerobic digestion process. This study evaluated the effect of OTC concentrations viz. 0.12, 0.3, 0.6, 1.2, 3, 6 and 12 mg L−1 on batch mesophilic anaerobic digestion of cattle manure. The results showed that cumulative biogas yield decreased by 25, 29 and 55% at 3, 6 and 12 mg OTC L−1 in contrast to control. Volatile solids removal was 39% for control which reduced to 13% in 12 mg L−1 OTC spiked reactor. Effect on stability parameters was significant at OTC concentrations from 1.2 to 12 mg L−1. Two different kinetic models were used for biogas data validation and the modified Gompertz model best fitted to the experimental data.

Enhancement of biogas production from cattle manure using glycerine phase as a co-substrate in anaerobic digestion

This study investigated the effect of glycerine phase on the anaerobic digestion of cattle manure under mesophilic conditions. The process was carried out in semi-continuous stirred tank reactors at a constant organic loading rate of 2.3 g VS/L·d and a hydraulic retention time of 30 days. It was found that the addition of 10% (as volatile solids) glycerine phase to cattle manure produced 3.1-times more biogas than cattle manure alone (237.5 L vs. 76.4 L) and a 10% higher methane content (69% vs. 59%). Biogas formation during co-digestion was strongly correlated with the concentrations of ammonium nitrogen (r = 0.89, p < 0.05) and volatile fatty acids (r = −0.71, p < 0.05), which resulted in a decrease in biogas production over time despite a stable pH value. The proposed use of glycerine phase could provide an advanced anaerobic digestion system that is technologically simple, has a positive energy balance, and produces upgraded biogas, although additional monitoring of the concentration of volatile acids and ammonium nitrogen is needed to maintain stable biogas production. These findings will be useful for reducing demand for non-renewable energy resources, and more broadly, they will assist in the shift from a traditional economy to a circular bioeconomy.

Use of bag-filter gas dust in anaerobic digestion of cattle manure for boosting the methane yield and digestate utilization

Plenty of refractory and environmentally hazardous bag-filter gas dust (BGD) is produced in the iron-making process. The effects of untreated BGD on anaerobic digestion (AD) with cattle manure were investigated. The BGD had the potential to boost the methane yield and digestate utilization considerably. The digester with 2.0 wt% BGD gained the highest methane yield (256.3 mL/g VS) and chemical oxygen demand removal rate (56.8%), 51.3% and 20.1% higher than that (169.4 mL/g VS, 47.3%) of the control group, respectively. The digestates with BGD possessed a utilization potential with the stability of 49.5–57.9% and fertility of 4.65–4.86%. Electrochemical measurements demonstrated that 2.0 wt% BGD improved the electron transport capacity of the AD system and increased the limiting current and redox peak current by 40.3% and 12.9%, respectively. A strategy for understanding the BGD reinforcing methanogenesis was proposed. This work also provides a technical support for recycling the BGD.

Analysis of enzyme activity and microbial community structure changes in the anaerobic digestion process of cattle manure at sub-mesophilic temperatures

Abstract To improve the biogas potential in anaerobic digestion of cattle manure in cold regions, we investigated, in this study, the potential of the anaerobic digestion of cattle manure through sequencing batch anaerobic digestion experiments at sub-mesophilic temperatures (15°C, 20°C, 25°C, and 37°C) for 50 days. Specifically, the changes in the biogas yield, pH, sCOD concentration, enzyme activity, and microbial community structure were examined. The maximum daily yield of biogas was 19.18 mL·gVS−1, which was recorded on day 6 at 37°C, and the final biogas accumulation yield at this temperature was 403.64 mL·gTS−1. The concentration of sCOD gradually increased as enzyme activity increased. The maximum activities of cellulase, hemicellulase, protease, and amylase were recorded in the 37°C experimental group. The decrease in temperature severely limited the activity of different types of enzymes, resulting in a decrease in the activity of microorganisms, which greatly influenced the methanogenic reaction. The dominant bacteria at the phylum level were Bacteroidetes and Proteobacteria, and the dominant methanogen at the genus level was Methanosaeta.

Steady state of semi-continuous anaerobic digestion of cattle manure under the stress of adding iron and titanium oxide nanoparticles

Steady state of semi-continuous anaerobic digestion of cattle manure under the stress of adding iron and titanium oxide nanoparticles

Metal nanoparticle mixtures to improve the biogas yield of cattle manure

Metal nanoparticle elements such as Fe, Ni, and Co are promising in improving the performance and stability of anaerobic digestion. However, the impact of nanoparticle mixtures of Fe, Ni, and Co on biogas production from anaerobic digestion of cattle manure still needs further studies. Therefore, this study investigated the effect of the most effective concentrations of nanoparticle additives on biogas and CH4 production and H2S mitigation during anaerobic digestion of cattle manure. The nanoparticle additive concentrations were selected from the findings of previous studies and were 30 mg/L Fe, 2 mg/L Ni, and 1 mg/L Co at four combinations. Biogas production increased by 14.61% upon the use of nanoparticle mixtures of 30 mg/L Fe and 2 mg/L Ni compared with control (cattle manure-only). Furthermore, the addition of nanoparticle mixtures of 30 mg/L Fe, 2 mg/L, and 1 mg/L Co increased CH4 production by 19.30% compared with control. Moreover, H2S production decreased by 35.10% in the presence of nanoparticles mixture of 30 mg/L Fe, 2 mg/L, and 1 mg/L Co in comparison with control. Modified Gompertz and logistic function models were used to determine the kinetic constant of the reaction. The modified Gompertz model has the better predicting ability for cattle manure anaerobic digestion.