Recent technological developments have led to a significant increase in energy consumption in daily life. The search for alternative means of energy production has become an important task for applied sciences and modern technology. Hydrogen technology has great potential as a source of clean energy. The production of green hydrogen is a desirable and beneficial way to contribute to the decarbonization of the energy sector. In response to the demand for environmentally friendly and economically feasible approaches, biohydrogen production from waste materials has recently attracted interest. Waste materials from industrial or municipal production can be used as low-cost substrates for biohydrogen production through microbial degradation. Green energy needs could be met through a form of sustainable development that moves hand in hand with the harnessing of the microbial potential of waste biomass. Reuse of waste materials leads to pollution reductions and energy recycling. The aim of th... [more]

In this paper, the latest research in the field of anaerobic co-digestion related to the advantages of using different mixtures of substrates on the performance of the process and increasing its efficiency is reviewed. The main aspects presented in this review refer to the study of the most commonly used types of substrates, highlighting their characteristics, the diversity of microbial communities involved in the production of biogas, the applied pretreatments, and the possibility of obtaining an improved digestate as a secondary product. The main types of substrates used in anaerobic co-digestion are food waste, sewage sludge, animal manure, lignocellulosic biomass, algae, fats, oils, and greases. The data from the studied works demonstrated that the anaerobic co-digestion process improves the carbon/nitrogen ratio and nutrient balance, increases the process stability, and diminishes the concentration of toxic inhibitors. At the same time, the use of appropriate mixtures of substrate... [more]

Hydrocarbon-containing wastes and wastewaters are produced worldwide by the activities of the oil and gas industry. Anaerobic digestion has the potential to treat these waste streams, while recovering part of its energy potential as biogas. However, hydrocarbons are toxic compounds that may inhibit the microbial processes, and particularly the methanogens. In this work, the toxicity of hexadecane (0−30 mM) towards pure cultures of hydrogenotrophic methanogens (Methanobacterium formicicum and Methanospirillum hungatei) was assessed. Significantly lower (p < 0.05) methane production rates were only verified in the incubations with more than 15 mM hexadecane and represented up to 52% and 27% inhibition for M. formicicum and M. hungatei, respectively. The results obtained point out that 50% inhibition of the methanogenic activity would likely occur at hexadecane concentrations between 5−15 mM and >30 mM for M. formicicum and M. hungatei, respectively, suggesting that toxic effects from ali... [more]

The drivers underpinning the emergence of SARS-CoV-2 and climate change attest to the fact that we are now living in the Anthropocene Epoch, with human activities significantly impacting and altering the global ecosystem. Here, we explore the historical context of zoonoses, the effect of anthropogenic climate change and interrelated drivers on the emergence of, and response to emerging infectious diseases. We call attention to an urgent need for inculcating a One Health research agenda that acknowledges the primary interconnection between animals, humans, pathogens, and their collective milieus to foster long term resilience across all systems within our shared planetary environment.

Water reuse is now becoming a global necessity. However, one of the drawbacks in releasing wastewater into the environment is some persistent pollutants that are not completely removed in wastewater treatment plant. Residual bacteria and antibiotics in the inflowing wastewater can contribute to the antibiotic resistance spread in the aquatic environment. This study determined the effectiveness of activated sludge process for fecal coliform bacteria elimination, and also the Escherichia coli resistance to antimicrobial agents as erythromycin, azithromycin, clarithromycin, ofloxacin, ciprofloxacin, trimethoprim, and metronidazole in treated wastewater. The research was carried out using the membrane filtration technique, and the susceptibility of isolates to antimicrobial agents was tested by the disc diffusion method. The concentrations of fecal coliform bacteria and Escherichia coli differed significantly depending on the seasonal period in which it was carried out. Despite up to 99% r... [more]

Synchronous effects of biochar on heavy metals stress, microbial activity and nodulation process in the soil are rarely addressed. This work studied the effects, under greenhouse conditions, of selected heavy metals Cd2+, Pb2+ and Ni2+ on soybean plants grown in two different soils amended with biochar, and studied their effect on the microbial and enzymatic activity. As a result of the interference between heavy metals and biochar, biochar overcame heavy metal problems and maintained a microbial population of major groups (bacteria−fungi). There was an increase in the degree of resistance (RS) of the major microbial groups to heavy metals when biochar was added to the soil under study. Numbers of bacterial nodules significantly increased, particularly by using the higher rate of biochar compared to the control, either by adding biochar alone or by mixing it with the selected heavy metals. The arginase activity was increased by 25.5% and 37.1% in clay and sandy soil, respectively, comp... [more]

Blood from livestock slaughtering imposes a high organic pollution load and risks. If it is discharged untreated to sewer systems, it increases the organic pollution load on wastewater treatment plants by 35−50%. This paper reviews blood anaerobic digestion. It analyzes the quantities, composition, methane potential reported, microbiology, biochemical pathways of blood protein degradation, environmental and health issues, and strategies suggested to manage them during livestock blood anaerobic digestion. Although challenging, anaerobic digestion of blood as a mono-substrate is possible if the culture-reactor system is controlled based on a complete characterization and understanding of the microbial community and its metabolic activities. Co-digestion of blood and other feedstock proceeds well if the mixtures are well designed. Generally, the specific methane yield from digesting blood alone ranges between zero and 0.45 m3 kg−1 protein, whereas for co-digesting blood and other substrat... [more]

Sustainable methods of practice within the fashion and textile industry (FTI) often strive to employ a circular economy that aims to eliminate waste through the continual use of resources. Complex problems such as waste, consumption, and overproduction are heavily intertwined; the main aim of this paper is to report on research focused on re-examining the potential of food waste streams as a commercially viable and circular source of raw materials for the FTI. Herein, regenerated protein fibres (RPFs) from food production waste streams rich in protein have been chosen as the main topic of focus. RPFs have a rich and relevant history from a local manufacturing perspective during wartime and post-war clothing rationing (1941−1949) in the UK. RPFs were used to meet civilian needs for wool-based textiles as part of a wider series of ‘make do and mend’ strategies designed to manage the consumption of new textile products. However, RPFs demonstrated inferior quality in terms of durability wh... [more]

The power-to-methane technology is promising for long-term, high-capacity energy storage. Currently, there are two different industrial-scale methanation methods: the chemical one (based on the Sabatier reaction) and the biological one (using microorganisms for the conversion). The second method can be used not only to methanize the mixture of pure hydrogen and carbon dioxide but also to methanize the hydrogen and carbon dioxide content of low-quality gases, such as biogas or deponia gas, enriching them to natural gas quality; therefore, the applicability of biomethanation is very wide. In this paper, we present an overview of the existing and planned industrial-scale biomethanation facilities in Europe, as well as review the facilities closed in recent years after successful operation in the light of the scientific and socioeconomic context. To outline key directions for further developments, this paper interconnects biomethanation projects with the competitiveness of the energy secto... [more]

This paper reviews the chemical hydrolysis processes of dairy manure fiber to make its sugar accessible to microorganisms during anaerobic digestion and identifies obstacles and opportunities. Researchers, so far, investigated acid, alkali, sulfite, and advanced oxidation processes (such as hydrogen peroxide assisted by microwave/ultrasound irradiation, conventional boiling, and wet oxidation), or their combinations. Generally, dilute acid (3−10%) is less effective than concentrated acid (12.5−75%), which decrystallizes the cellulose. Excessive alkaline may produce difficult-to-degrade oxycellulose. Therefore, multi-step acid hydrolysis (without alkaline) is preferred. Such processes yielded 84% and 80% manure-to-glucose and -xylose conversion, respectively. Acid pretreatment increases lignin concentration in the treated manure and hinders subsequent enzymatic processes but is compatible with fungal cellulolytic enzymes which favor low pH. Manure high alkalinity affects dilute acid pre... [more]

Biolubricants refer to eco-friendly, biodegradable, and non-toxic lubricants. Their applications are still limited compared to mineral oils; however, their sustainable credentials are making them increasingly attractive. Vegetable oils are frequently used for this purpose. However, vegetable oils have issues of low lipid productivity, dependence on climatic conditions, and need for agricultural land. Microbial oils represent a more sustainable alternative. To ensure their widespread applicability, the suitability of microbial oils from a physicochemical point of view needs to be determined first. In this study, oils obtained from various oleagenic microbes—such as microalgae, thraustochytrids, and yeasts—were characterized in terms of their fatty acid profile, viscosity, friction coefficient, wear, and thermal stability. Oleaginous microalgal strains (Auxenochlorella protothecoides and Chlorella sorokiniana), thraustochytrids strains (Aurantiochytrium limacinum SR21 and Aurantiochytriu... [more]

Even thoughdigestate, which is continually generated in anaerobic digestion process, can only be used as fertilizer during the growing season, digestate treatment is still a critical, environmental problem. That is why the present work aims to develop a method to manage digestate in agricultural biogas plant in periods when its use as fertilizer is not possible. A lab-scale system for the biological treatment of the digestate liquid fraction using the activated sludge method with a separate denitrification chamber was constructed and tested. The nitrogen load that was added tothe digestate liquid fraction accounted for 78.53% of the total nitrogen load fed into the reactor. External carbon sources, such as acetic acid, as well as flume water and molasses, i.e., wastewater and by-products from a sugar factory, were used to support the denitrification process. The best results were obtained using an acetic acid and COD (Chemical Oxygen Demand)/NO3−N (Nitrate Nitrogen) ratio of 7.5. The r... [more]

The codigestion of slaughter waste with animal manure can improve its methane yield, and digestion parameters; however, limited studies are available for the effectiveness of anaerobic codigestion using swine slaughter waste (SSW) and swine slurry (SS). Hence, this study was conducted to determine the characteristics of SSW and the effect of anaerobic codigestion with (SS) and explored the potential of CH4 production (Mmax), the lag phase period (λ), and effective digestion time (Teff). SSW contains fat and protein contents of 54% and 30% dry weight within 18.2% of solid matters, whereas SS showed only 6% and 28% within 4.1% of solid matters, respectively. During sole anaerobic digestion, SSW produced a high Mmax (711 Nml CH4/g VSadded) but had a long duration λ (~9 days); whereas SS produced a low Mmax (516 Nml CH4/g VSadded) but had a shorter duration λ (1 day). Codigestion increased the Mmax from 22−84% with no significant Teff compared to sole SS digestion. However, the low Mmax of... [more]

Fungal pretreatment of switchgrass using Phanerochaete chrysosporium (PC), Trametes versicolor 52J (TV52J), and the Trametes versicolor mutant strain (m4D) under solid-state fermentation was conducted to improve its pellet quality. For all three fungal strains, the fermentation temperature had a significant effect (p < 0.05) on pellet unit density and tensile strength. The p-values of the quadratic models for all the response variables showed highly significant regression models (p < 0.01) except for dimensional stability. In addition, 3.1-fold and 2.8-fold increase in pellet tensile strength were obtained from P. chrysosporium- and T. versicolor 52J-treated materials, respectively. Microstructural examination showed that fungal pretreatment reduced pores in the pellets and enhanced pellet particle bonding. Among the fungal strains, PC had the shortest optimum fermentation time (21 d) and most positive impact on the pellet tensile strength and hydrophobicity. Therefore, switchgra... [more]

This study investigated the impact of sonication parameters on the efficiency of the extraction of bioactive substances from hawthorn berries. The ultrasonic treatment was performed in two modes: continuous and pulse. In the pulse mode, the samples were sonicated with the following processor settings: 1 s on-2 s off. The effective ultrasonic processor times were 5, 10, and 15 min, and the total extraction times were 15 min, 30 min, and 45 min. The content of total polyphenols and total anthocyanins was determined by a spectrophotometric method. We show that the operating mode of the processor affects extraction efficiency, energy consumption and unit energy inputs. Extraction supported by a pulsating ultrasonic field allowed saving from 20% to 51% of energy with a simultaneous higher efficiency of the process. In addition, we show that the unit energy consumption in the pulsed mode was about 40% to 68% lower than the energy consumption in the case of continuous operation.

Anaerobic digestion using cigarette butts, one of most littered items, was studied not only as a waste treatment, but also as an energy production method. Methane production from cigarette butts was measured through the biochemical methane potential (BMP) test and it was evaluated whether it is possible to produce electrical energy. Intact cigarettes or individual components (filter, paper, and leaf) were supplied as the sole carbon source (substrate) for the BMP test. The tendency of methane production indicated biodegradation in the order of paper, filter, and leaves; however, the filter of cigarettes was the substrate produced the highest amount of methane per total solid. The microbial community was also analyzed in each anaerobic digestion reactor, and substrate-specific microorganisms were identified, such as Proteiniphilum strain (filter) and Methanobacterium formicicum (paper). In intact cigarettes, the related microbial community became dominant over time in the order of paper... [more]

In the present study, the protein-extracted grass residue (press cake) was processed through hydrothermal liquefaction under sub and supercritical temperatures (300, 350 and 400 °C) with and without using a potassium carbonate catalyst. The results revealed that bio-crude yield was influenced by both temperature and the catalyst. The catalyst was found to be effective at 350 °C (350 Cat) for enhancing the bio-crude yield, whereas supercritical state in both catalytic and non-catalytic conditions improved the quality of bio-crude with reasonable HHVs (33 to 36 MJ/kg). The thermal behaviour of bio-crude was analysed and higher volatile contents (more than 50% under the range of 350 °C) were found at supercritical conditions. The overall TOC values in the residual aqueous phase varied from 22 to 38 g/L. Higher carbon loss was noticed in the aqueous phase in supercritical conditions. Furthermore, GCMS analysis showed ketones, acids and ester, aromatics and hydrocarbon with negligible nitro... [more]

Microbial fuel cells (MFCs) are biochemical systems having the benefit of producing green energy through the microbial degradation of organic contaminants in wastewater. The efficiency of MFCs largely depends on the cathode oxygen reduction reaction (ORR). A preferable ORR catalyst must have good oxygen reduction kinetics, high conductivity and durability, together with cost-effectiveness. Platinum-based electrodes are considered a state-of-the-art ORR catalyst. However, the scarcity and higher cost of Pt are the main challenges for the commercialization of MFCs; therefore, in search of alternative, cost-effective catalysts, those such as doped carbons and transition-metal-based electrocatalysts have been researched for more than a decade. Recently, perovskite-oxide-based nanocomposites have emerged as a potential ORR catalyst due to their versatile elemental composition, molecular mechanism and the scope of nanoengineering for further developments. In this article, we discuss various... [more]

Carbonate sediments are susceptible to many factors, such as paleostructure, diagenesis, and strong microbial alteration; as such, their sedimentary architecture still calls for further research. In this study, the reef and shoal bodies in the XVm and XVp layers of the Middle−Upper Jurassic Karlov-Oxfordian in the S gas field were used as the object, and the architecture of the reef-shoal facies was studied. Based on the idea of “vertical grading and horizontal boundary”, the interface characteristics of the 6th to 4th levels of reef-shoal bodies in the study area were summarized, as were four ways to determine the boundaries of reef-shoal bodies. Based on the dense well network, we quantitatively described the scale of each small layer of single reef shoal body through the point-line-surface method and established a geological database of the reef shoal bodies in the study area. In addition, we established the width and thickness of the reef shoal body and the empirical formula for re... [more]

, a xylose-fermenting yeast, has the potential for converting cellulosic biomass to ethanol. Thermotolerant C. tropicalis X-17, which was isolated in Laos, was subjected to repetitive long-term cultivation with a gradual increase in temperature (RLCGT) in the presence of a high concentration of glucose, which exposed cells to various stresses in addition to the high concentration of glucose and high temperatures. The resultant adapted strain demonstrated increased tolerance to ethanol, furfural and hydroxymethylfurfural at high temperatures and displayed improvement in fermentation ability at high glucose concentrations and xylose-fermenting ability. Transcriptome analysis revealed the up-regulation of a gene for a glucose transporter of the major facilitator superfamily and genes for stress response and cell wall proteins. Additionally, hydropathy analysis revealed that three genes for putative membrane proteins with multiple membrane-spanning segments were also up-regulated. From the... [more]

In order to valorize lignin wastes to produce useful aromatic compounds, the thermal degradation pyrolysis of Kraft lignin in the absence of catalysts has been investigated at 350, 450, and 550 °C. The high content of sulfur in the fresh sample led to the formation of S-containing compounds in products whose evolution in the gas phase was monitored through GC-MS analysis. Pyrolytic gas is rich in CH4, CO, CO2, and H2S with the presence of other sulfur compounds in smaller amounts (i.e., CH3SH, CH3-S-CH3, SO2, COS, and CS2). Biochar morphology and elemental composition have been investigated by means of SEM and EDX. The carbon content reaches ~90% after pyrolysis at 550 °C, while the oxygen content showed a decreasing trend with increasing temperature. From GC-MS analysis, bio-oil resulted rich in alkyl-alkoxy phenols, together with (alkyl)dihydroxy benzenes and minor amounts of hydrocarbons and sulfur compounds. NaOH/H2O and EtOH/H2O extraction were performed with the aim of extracting... [more]

Reactive transport (RT) couples bio-geo-chemical reactions and transport. RT is important to understand numerous scientific questions and solve some engineering problems. RT is highly multidisciplinary, which hinders the development of a body of knowledge shared by RT modelers and developers. The goal of this paper is to review the basic conceptual issues shared by all RT problems, so as to facilitate advancement along the current frontier: biochemical reactions. To this end, we review the basic equations to indicate that chemical systems are controlled by the set of equilibrium reactions, which are easy to model, but whose rate is controlled by mixing. Since mixing is not properly represented by the standard advection-dispersion equation (ADE), we conclude that this equation is poor for RT. This leads us to review alternative transport formulations, and the methods to solve RT problems using both the ADE and alternative equations. Since equilibrium is easy, difficulties arise for kine... [more]

Lubricants are substances of the foremost importance in the modern world, as they are essential to the proper functioning of various mechanisms. Most lubricants, however, are still made from petroleum fractions. I light of this, and due to various environmental problems, the search for feasible biolubricants has become essential. This study obtained biolubricants through the in situ transesterification of microbial biomass, containing at least 20 wt% of lipids. The following two distinct biomasses were evaluated: the marine microalgae, Dunaliella salina, and the consortium of microalgae-fungi, Scenedesmus obliquus and Mucor circinelloides. Microbial oil from both biomasses presented a fatty acid profile with high amounts of oleic acid. The oil of D. salina had a lower content of polyunsaturated fatty acids relative to the microbial consortium profile, which indicates that this is a good configuration for increasing biolubricant oxidation resistance. The catalyst used was a Keggin-struc... [more]

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. Antibiotic... [more]

The aim of this study was to evaluate the influence of simultaneous, long-term exposure to increasing concentrations of three classes of antimicrobials (β-lactams, fluoroquinolones and nitroimidazoles) on: (1) the efficiency of anaerobic digestion of sewage sludge, (2) qualitative and quantitative changes in microbial consortia that participate in methane fermentation, and (3) fate of antibiotic resistance genes (ARGs). Long-term supplementation of sewage sludge with a combination of metronidazole, amoxicillin and ciprofloxacin applied at different doses did not induce significant changes in process parameters, including the concentrations of volatile fatty acids (VFAs), or the total abundance of ARGs. Exposure to antibiotics significantly decreased methane production and modified microbial composition. The sequencing analysis revealed that the abundance of OTUs characteristic of Archaea was not correlated with the biogas production efficiency. The study also demonstrated that the hydr... [more]