Design of gas concentration measurement and monitoring system for biogas power plant

Biogas is a gas obtained from the breakdown of organic matter (such as animal waste, human waste, and plants) by methanogenic bacteria in an oxygen-free (anaerobic) state. The biogas produced mainly consists of 50-70% methane, 30-40% carbon dioxide, and other gases in small amounts. The gas produced has a different composition depending on the type of animal that produces it. It is challenging to obtain biogas concentration data because the monitoring equipment is currently minimal. Therefore, this research discusses how to make a monitoring system for biogas reactors. Sensors are installed in the digester tank and storage tank. The installed sensors are the MQ-4 sensor to detect methane gas (CH₄), MG-811 sensor to detect carbon dioxide (CO₂) gas, MQ-136 sensor to detect sulfide acid gas (H₂S), and Thermocouple Type-K to detect temperature. The sensor will send a signal to the control unit in Arduino Mega 2560, then processed and displayed on the liquid crystal display (LCD). The sensor calculation results' accuracy is not much different from the reference based on the sensor readings. The sensor deviation standard is below 5.0, indicating that the sensor is in precision. The sensor's linearity of MQ-4 is 0.7%, the MG-811 is 0.17%, the MQ-136 is 0.29%, and the Type-K Thermocouple is 1.19%. The installed sensor can be used to monitor gas concentration and temperature in a biogas reactor.

Dependence of energy consumptions on the type of mechanical mixer used in the biogas reactor

Purpose. Investigation of the dependence of the energy consumption of mechanical mixers and determination of an energy-efficient type of mixing device to increase the energy efficiency of the biogas formation process and the profitability of further processing into thermal and electrical energy. Methodology. Determination and analysis of energy costs for mechanical mixers, comparison and determination of their energy consumption in the process of biogas formation, generalization of the results. Findings. Biogas technologies play an important role in the formation of a modern energy system. The profitability of which directly depends on the energy efficiency of the processes of intensification of anaerobic fermentation. The process of anaerobic fermentation of waste is long, so one of the main methods of intensification of biogas production is the mixing of waste during anaerobic fermentation. Despite the large number of different types of mixing devices and systems, the main task of mixing is to create a homogeneous substance with the same temperature, acidity and other physicochemical components at any point in the volume of the substance. There is a need to increase the energy efficiency of the processes of intensification of anaerobic fermentation and the profitability of further processing of biogas into heat and electricity. Ways to improve energy efficiency are in certain dependences of the energy consumption of mechanical mixers, the choice of an energy-efficient type of mixer, certain criteria that significantly affect the consumption of electrical energy for mixing, the study of the vectors of propagation of flows created by the mixer. The implementation of these actions will allow you to establish the optimal geometric dimensions of the mixer and significantly increase the energy efficiency of biogas plants and further processing of the resulting biogas into thermal and electrical energy. Originality. The analysis of the reasons for different values of the Euler criterion for mechanical mixers is carried out with the same mode of the substance motion, its level and volume in the tank and other equal parameters. A comparative analysis of energy costs for the most common types of mechanical mixers in biogas reactors is carried out. It has been established that the use of a two-tier paddle mixer, which has two blades per tier, requires the least amount of energy to mix waste in a biogas reactor with a volume . Practical value. The data presented in this paper can be used in the design, construction and modernization of biogas plants. The direction of necessary further scientific researches is determined, the realization of which will increase the energy efficiency of biogas production and the profitability of further processing of biogas into thermal and electric energy.

Metagenomics workflow for hybrid assembly, differential coverage binning, metatranscriptomics and pathway analysis (MUFFIN)

Metagenomics has redefined many areas of microbiology. However, metagenome-assembled genomes (MAGs) are often fragmented, primarily when sequencing was performed with short reads. Recent long-read sequencing technologies promise to improve genome reconstruction. However, the integration of two different sequencing modalities makes downstream analyses complex. We, therefore, developed MUFFIN, a complete metagenomic workflow that uses short and long reads to produce high-quality bins and their annotations. The workflow is written by using Nextflow, a workflow orchestration software, to achieve high reproducibility and fast and straightforward use. This workflow also produces the taxonomic classification and KEGG pathways of the bins and can be further used for quantification and annotation by providing RNA-Seq data (optionally). We tested the workflow using twenty biogas reactor samples and assessed the capacity of MUFFIN to process and output relevant files needed to analyze the microbial community and their function. MUFFIN produces functional pathway predictions and, if provided de novo metatranscript annotations across the metagenomic sample and for each bin. MUFFIN is available on github under GNUv3 licence: https://github.com/RVanDamme/MUFFIN.

Strategies for recovery of imbalanced full-scale biogas reactor feeding with palm oil mill effluent

Background Full-scale biogas production from palm oil mill effluent (POME) was inhibited by low pH and highly volatile fatty acid (VFA) accumulation. Three strategies were investigated for recovering the anaerobic digestion (AD) imbalance on biogas production, namely the dilution method (tap water vs. biogas effluent), pH adjustment method (NaOH, NaHCO3, Ca(OH)2, oil palm ash), and bioaugmentation (active methane-producing sludge) method. The highly economical and feasible method was selected and validated in a full-scale application. Results The inhibited sludge from a full-scale biogas reactor could be recovered within 30–36 days by employing various strategies. Dilution of the inhibited sludge with biogas effluent at a ratio of 8:2, pH adjustment with 0.14% w/v NaOH, and 8.0% w/v oil palm ash were considered to be more economically feasible than other strategies tested (dilution with tap water, or pH adjustment with 0.50% w/v Ca(OH)2, or 1.25% NaHCO3 and bioaugmentation) with a recovery time of 30–36 days. The recovered biogas reactor exhibited a 35–83% higher methane yield than self-recovery, with a significantly increased hydrolysis constant (kH) and specific methanogenic activity (SMA). The population of Clostridium sp., Bacillus sp., and Methanosarcina sp. increased in the recovered sludge. The imbalanced full-scale hybrid cover lagoon reactor was recovered within 15 days by dilution with biogas effluent at a ratio of 8:2 and a better result than the lab-scale test (36 days). Conclusion Dilution of the inhibited sludge with biogas effluent could recover the imbalance of the full-scale POME-biogas reactor with economically feasible and high biogas production performance.

Calculation of the power of thermal energy consumed for heating the reactor of a bioenergy plant

The issues of calculating the power of thermal energy consumed for heating biomass in the reactor of a bioenergy plant are considered. Based on the Fourier heat equation, a solution for the axisymmetric cylindrical problem under boundary conditions of the first kind is obtained, and the power of additional heat sources in a cylindrical biogas reactor is calculated. The influence of the height of the bioreactor and the temperature difference of the biomass on the power consumption of an additional source of thermal energy is analyzed

The Role of Petrimonas mucosa ING2-E5AT in Mesophilic Biogas Reactor Systems as Deduced from Multiomics Analyses

Members of the genera Proteiniphilum and Petrimonas were speculated to represent indicators reflecting process instability within anaerobic digestion (AD) microbiomes. Therefore, Petrimonas mucosa ING2-E5AT was isolated from a biogas reactor sample and sequenced on the PacBio RSII and Illumina MiSeq sequencers. Phylogenetic classification positioned the strain ING2-E5AT in close proximity to Fermentimonas and Proteiniphilum species (family Dysgonomonadaceae). ING2-E5AT encodes a number of genes for glycosyl-hydrolyses (GH) which are organized in Polysaccharide Utilization Loci (PUL) comprising tandem susCD-like genes for a TonB-dependent outer-membrane transporter and a cell surface glycan-binding protein. Different GHs encoded in PUL are involved in pectin degradation, reflecting a pronounced specialization of the ING2-E5AT PUL systems regarding the decomposition of this polysaccharide. Genes encoding enzymes participating in amino acids fermentation were also identified. Fragment recruitments with the ING2-E5AT genome as a template and publicly available metagenomes of AD microbiomes revealed that Petrimonas species are present in 146 out of 257 datasets supporting their importance in AD microbiomes. Metatranscriptome analyses of AD microbiomes uncovered active sugar and amino acid fermentation pathways for Petrimonas species. Likewise, screening of metaproteome datasets demonstrated expression of the Petrimonas PUL-specific component SusC providing further evidence that PUL play a central role for the lifestyle of Petrimonas species.

Substantiation of creation of electrothermomechanical system for mixing and heating of biomass

To date, biomass fermentation in biogas plants is one of the most advanced, environmentally and economically viable solutions for energy production from waste. However, the process of anaerobic fermentation of waste is long, so one of the main ways to intensify biogas production is mixing and heating of biomass during fermentation. The article is devoted to the question of substantiation of creation of electrothermomechanical system for mixing and heating of biomass in a biogas reactor. The combination of two intensification processes in a combined system pays special attention to the energy efficiency of such a system, so the creation of the system requires in-depth study of heat fluctuations from speed and the presence of a contaminant layer on the heater surface and determine the optimal stirrer speed. The studies were performed for a cylindrical biogas reactor, assuming that the contaminant layer is evenly distributed on the surface of the blades and the shaft in which the electric heaters are installed. When determining the optimal frequency of biomass mixing, the criterion of optimality was taken to be the smallest value of the difference between the heat flux of the contaminated and uncontaminated surface of the heater. During the study it was found that at speed , the difference between the heat flux of the contaminated surface and uncontaminated is 40 %. At speed , the difference between the values is 26%. According to the selected optimality criterion, the optimal speed of the electrothermomechanical system taking into account the contaminant layer is in the range . The increase in heat flux from the stirring frequency is non-linear for both contaminated and non-contaminated heaters.