Biogas and Biomethane Production and Usage: Technology Development, Advantages and Challenges in Europe

The refinery of the future

Fossil fuels-coal, oil and gas-supply most of the world's energy and also form the basis of many products essential for everyday life. Their use is the largest contributor to the carbon dioxide emissions that drive global climate change, prompting joint efforts to find renewable alternatives that might enable a carbon-neutral society by as early as 2050. There are clear paths for renewable electricity to replace fossil-fuel-based energy, but the transport fuels and chemicals produced in oil refineries will still be needed. We can attempt to close the carbon cycle associated with their use by electrifying refinery processes and by changing the raw materials that go into a refinery from fossils fuels to carbon dioxide for making hydrocarbon fuels and to agricultural and municipal waste for making chemicals and polymers. We argue that, with sufficient long-term commitment and support, the science and technology for such a completely fossil-free refinery, delivering the products required after 2050 (less fuels, more chemicals), could be developed. This future refinery will require substantially larger areas and greater mineral resources than is the case at present and critically depends on the capacity to generate large amounts of renewable energy for hydrogen production and carbon dioxide capture.

Low-Hydrophilic HKUST-1/Polymer Extrudates for the PSA Separation of CO2/CH4

HKUST-1 is an MOF adsorbent industrially produced in powder form and thus requires a post-shaping process for use as an adsorbent in fixed-bed separation processes. HKUST-1 is also sensitive to moisture, which degrades its crystalline structure. In this work, HKUST-1, in the form of crystalline powder, was extruded into pellets using a hydrophobic polymeric binder to improve its moisture stability. Thermoplastic polyurethane (TPU) was used for that purpose. The subsequent HKUST-1/TPU extrudate was then compared to HKUST-1/PLA extrudates synthesized with more hydrophilic polymer: polylactic acid (PLA), as the binder. The characterization of the composites was determined via XRD, TGA, SEM-EDS, and an N2 adsorption isotherm analysis. Meanwhile, the gas-separation performances of HKUST-1/TPU were investigated and compared with HKUST-1/PLA from measurements of CO2 and CH4 isotherms at three different temperatures, up to 10 bars. Lastly, the moisture stability of the composite materials was investigated via an aging analysis during storage under humid conditions. It is shown that HKUST-1's crystalline structure was preserved in the HKUST-1/TPU extrudates. The composites also exhibited good thermal stability under 523 K, whilst their textural properties were not significantly modified compared with the pristine HKUST-1. Furthermore, both extrudates exhibited larger CO2 and CH4 adsorption capacities in comparison to the pristine HKUST-1. After three months of storage under atmospheric humid conditions, CO2 adsorption capacities were reduced to only 10% for HKUST-1/TPU, whereas reductions of about 25% and 54% were observed for HKUST-1/PLA and the pristine HKUST-1, respectively. This study demonstrates the interest in shaping MOF powders by extrusion using a hydrophobic thermoplastic binder to operate adsorbents with enhanced moisture stability in gas-separation columns.

Potential of acetic acid to restore methane production in anaerobic reactors critically intoxicated by ammonia as evidenced by metabolic and microbial monitoring

BACKGROUND

Biogas and biomethane production from the on-farm anaerobic digestion (AD) of animal manure and agri-food wastes could play a key role in transforming Europe's energy system by mitigating its dependence on fossil fuels and tackling the climate crisis. Although ammonia is essential for microbial growth, it inhibits the AD process if present in high concentrations, especially under its free form, thus leading to economic losses. In this study, which includes both metabolic and microbial monitoring, we tested a strategy to restore substrate conversion to methane in AD reactors facing critical free ammonia intoxication.

RESULTS

The AD process of three mesophilic semi-continuous 100L reactors critically intoxicated by free ammonia (> 3.5 g_N L-1; inhibited hydrolysis and heterotrophic acetogenesis; interrupted methanogenesis) was restored by applying a strategy that included reducing pH using acetic acid, washing out total ammonia with water, re-inoculation with active microbial flora and progressively re-introducing sugar beet pulp as a feed substrate. After 5 weeks, two reactors restarted to hydrolyse the pulp and produced CH4 from the methylotrophic methanogenesis pathway. The acetoclastic pathway remained inhibited due to the transient dominance of a strictly methylotrophic methanogen (Candidatus Methanoplasma genus) to the detriment of Methanosarcina. Concomitantly, the third reactor, in which Methanosarcina remained dominant, produced CH4 from the acetoclastic pathway but faced hydrolysis inhibition. After 11 weeks, the hydrolysis, the acetoclastic pathway and possibly the hydrogenotrophic pathway were functional in all reactors. The methylotrophic pathway was no longer favoured. Although syntrophic propionate oxidation remained suboptimal, the final pulp to CH4 conversion ratio (0.41 ± 0.10 LN_CH4 g_VS-1) was analogous to the pulp biochemical methane potential (0.38 ± 0.03 LN_CH4 g_VS-1).

CONCLUSIONS

Despite an extreme free ammonia intoxication, the proposed process recovery strategy allowed CH4 production to be restored in three intoxicated reactors within 8 weeks, a period during which re-inoculation appeared to be crucial to sustain the process. Introducing acetic acid allowed substantial CH4 production during the recovery period. Furthermore, the initial pH reduction promoted ammonium capture in the slurry, which could allow the field application of the effluents produced by full-scale digesters recovering from ammonia intoxication.

Microbial cellulase production and its potential application for textile industries

Purpose

The textile industry’s previous chemical use resulted in thousands of practical particulate emissions, such as machine component damage and drainage system blockage, both of which have practical implications. Enzyme-based textile processing is cost-effective, environmentally friendly, non-hazardous, and water-saving. The purpose of this review is to give evidence on the potential activity of microbial cellulase in the textile industry, which is mostly confined to the realm of research.

Methods

This review was progressive by considering peer-reviewed papers linked to microbial cellulase production, and its prospective application for textile industries was appraised and produced to develop this assessment. Articles were divided into two categories based on the results of trustworthy educational journals: methods used to produce the diversity of microorganisms through fermentation processes and such approaches used to produce the diversity of microbes through microbial fermentation. Submerged fermentation (SMF) and solid-state fermentation (SSF) techniques are currently being used to meet industrial demand for microbial cellulase production in the bio textile industry.

Results

Microbial cellulase is vital for increasing day to day due to its no side effect on the environment and human health becoming increasingly important. In conventional textile processing, the gray cloth was subjected to a series of chemical treatments that involved breaking the dye molecule’s amino group with Cl − , which started and accelerated dye(-resistant) bond cracking. A cellulase enzyme is primarily derived from a variety of microbial species found in various ecological settings as a biotextile/bio-based product technology for future needs in industrial applications.

Conclusion

Cellulase has been produced for its advantages in cellulose-based textiles, as well as for quality enhancement and fabric maintenance over traditional approaches. Cellulase’s role in the industry was microbial fermentation processes in textile processing which was chosen as an appropriate and environmentally sound solution for a long and healthy lifestyle.

Application of Magnetite-Nanoparticles and Microbial Fuel Cell on Anaerobic Digestion: Influence of External Resistance

In this paper, the application of magnetite-nanoparticles and a microbial fuel cell (MFC) was studied on the anaerobic digestion (AD) of sewage sludge. The experimental set-up included six 1 L biochemical methane potential (BMP) tests with different external resistors: (a) 100 Ω, (b) 300 Ω, (c) 500 Ω, (d) 800 Ω, (e) 1000 Ω, and (f) a control with no external resistor. The BMP tests were carried out using digesters with a working volume of 0.8 L fed with 0.5 L substrate, 0.3 L inoculum, and 0.53 g magnetite-nanoparticles. The results suggested that the ultimate biogas generation reached 692.7 mL/g VSfed in the 500 Ω digester, which was substantially greater than the 102.6 mL/g VSfed of the control. The electrochemical efficiency analysis also demonstrated higher coulombic efficiency (81.2%) and maximum power density (30.17 mW/ m2) for the 500 Ω digester. The digester also revealed a higher maximum voltage generation of 0.431 V, which was approximately 12.7 times the 0.034 V of the lowest-performing MFC (100 Ω digester). In terms of contaminants removed, the best-performing digester was the digester with 500 Ω, which reduced contaminants by more than 89% on COD, TS, VS, TSS and color. In terms of cost-benefit analysis, this digester produced the highest annual energy profit (48.22 ZAR/kWh or 3.45 USD/kWh). This infers the application of magnetite-nanoparticles and MFC on the AD of sewage sludge is very promising for biogas production. The digester with an external resistor of 500 Ω showed a high potential for use in bioelectrochemical biogas generation and contaminant removal for sewage sludge.

Design and Testing of a Multimode Capable Passive Battery Management System

A customized passive battery management system (BMS), which offers a selection of different operating configurations regarding the connection of external sources and loads, has been developed. The device supports balance, charge, de-balance, discharge and permanent storage battery processes. The control unit is run by its own written algorithm (code). Suggestions for potential hardware and software changes that can be made to expand the capabilities of the device are listed. The device is tested in five different operating configurations and the output data (battery-cell voltages and balancing currents) are plotted in characteristic diagrams. The output data is analyzed and the unique capabilities of the device are explained. The detailed PCB design, code, and output measurement data files are included within the paper.