Biogas Formation Research Articles

The Analysis of Geospatial Factors Necessary for the Planning, Design, and Construction of Agricultural Biogas Plants in the Context of Sustainable Development

This spatial analysis focuses on the relevant elements regarding the use of renewable energy sources, in particular, biogas, taking into account sustainability. The characteristics of the processes of biogas formation are presented, including the technological and biological aspects of its production. The issues of agricultural biogas plant profitability are discussed using examples from Poland, analyzing the economic and financial aspects of investing in this type of plant. Geospatial analysis supported by geographic information systems (GISs) looked at factors affecting the relief of the land and also the analysis of local plans or zoning decisions for the selected site. In addition, distance relationships and geological aspects taking into account terrain, landslides, and forestation, as well as hydrological aspects relating to flood and flooding hazards, were examined. It analyzed the availability of utility networks and proximity to road infrastructure. It was also examined that the proposed project will not have a negative impact on environmental protection. The analyzed site meets favorable conditions for the construction of the proposed project, and the conclusion drawn from this study is to emphasize the importance of integrating renewable energy sources with information systems to achieve sustainable development.

Potensi Sampah Organik TPS 3R Menjadi Biogas dan Pupuk (Studi Kasus: TPS 3R Kasih, Kabupaten Bantul, Daerah Istimewa Yogyakarta)

The generation of organic waste at TPS 3R Kasih increased and dominated but its separation has not been carried out optimally. The purpose of this study was to determine the chemical characteristics of organic waste and analyze the potential for biogas that can be produced from organic waste anaerobically. The research method included sample collection using the purposive sampling method, surveys, and laboratory experiments using a batch or closed anaerobic reactor without any reactant movement to determine the potential for methane formation during 40 days of processing. The chemical characteristics of the slurry before and after processing were analyzed to determine its potential use after biogas formation as compost. The results showed that the slurry content before and after processing did not meet the fertilizer quality standards. Methane gas was formed starting on the 35th day in both reactors 1 and 2 with the highest concentration achieved at 1.2% of a mixture of organic waste, water, animal waste and EM4 with an optimum time of 40 days.

Low-energy advanced wastewater treatment using submerged nanofiltration

The use of submerged nanofiltration (NF) membranes in wastewater treatment is an emerging process that produces high-quality recycled water with low energy consumption. This study aimed to identify the potential of coupling anaerobic digestion with this low-energy advanced wastewater treatment using submerged NF membranes. The direct NF of primary wastewater effluent using four types of commercial NF membranes resulted in progressive membrane fouling over 4 d. However, almost all the foulants contributing to hydraulic loss were removed by one-swipe sponge cleaning. This indicated that the major foulants were generally deposited on the membrane surface during direct NF. The membrane fouling speed varied during the long-term test depending on the feed wastewater quality. Although the transmembrane pressure increased by up to 50 kPa in every filtration cycle (4–7 d), sponge cleaning removed all the membrane foulants, resulting in >30 d of operation without chemical cleaning. The NF concentrates (four times concentrated wastewater) were then used for biogas production in an anaerobic digester. The volume of biogas formed from the NF concentrates sufficiently compensated for the energy consumption of direct NF. This study realized a low-energy advanced wastewater treatment utilizing NF concentrates that can also be used for biogas formation.

Design and Study of Simple Biogas Reactor using Kitchen Waste Within the Habitat of Federal Polytechnic of Oil and Gas Bonny Island, Rivers State, Nigeria

This research work is about design and study of simple biogas reactor using Kitchen Waste within the habitat of Federal Polytechnic of Oil and Gas Bonny Island, Rivers State, Nigeria to produce gas. The objective of the work is to collect and measure the amount of waste that is been generated within the study area as well as to construct a simple laboratory scale biogas reactor and using the kitchen waste as substrate and measure the amount of gas that is been generated from biogas reactor per day. Based on the objective for this research a biogas digester was designed. Two experiments was carried out to determine the extent of production of biogas and the duration required so as to determine the rate of formation of biogas. In experiment one, dissimilar kinds of biomass like rice, potato, green leaves, sugar in different amounts were mixed with cow dung and rice husk to prepare 4 samples to determine the maximum generation of biogas through fermentation process. The gas is collected in balloons and they were measured to determine the amount of gas produced in each sample. The extent to which the blowing of balloons took place determined the quantity of gas evolved in each of the incumbent samples. In experiment two, we have used two 5lt. bottles in which the amount of cow dung used varies while same amount of kitchen waste mixture was utilized. The process and conditions for trapping and analyzing the gas is the same as in experiment one. From this experiment the rapidness of formation of biogas was observed. The experimental analysis carried out also gives us a clear idea of the indulgence of materials with respect to their combination to deferring extent of concentration to deliver optimum generation of biogas, in particular methane thereby unveiling us to develop an imminent and high performance derivative affordable biogas reactor.

Analisis Pengaruh Rasio Jerami Dan Kotoran Sapi Pada Biodigester Terapung Pada Gas Yang Dihasilkan

To address the concerning trend of increasing fossil fuel use due to population growth, it is necessaryto prioritize alternative energy sources like renewable energy.This study aims to analyze the energy parameters produced through biogas formation in a floating drum biodigester, highlighting the potential for sustainable energy solutions.This research method uses experimental research using three treatments of the ratio of straw, water, and cow dung. The parameters observed and analyzed include the amount of biogas produced, biogas pressure, flame length, combustion rate, and calorific value.The experiment results clearly demonstrate that the first treatment was significantly more effective in producing biogas, with a volume of 0.101 m3 or 101 litre, a pressure of 0.0081 atm, a combustion rate of 0.00266 m3/min, a flame length of 38 minutes, and a combustion calorific value of 210,045 joules.In contrast, the second treatment produced a total biogas volume of only 0.0775 m3 or 77.5 litre, at a pressure of 0.0131 atm, a combustion rate of 0.00209 m3/min, a flame duration of 37 minutes, and a combustion calorific value of 184,965 joules. These results provide strong evidence for the superiority of the first treatment in terms of biogas production. The third treatment produced a biogas volume of 0.0771 m3 or 77.1 litre at a pressure of 0.013 atm, with a combustion rate of 0.00214 m3/min, a flame duration of 36 minutes, and a combustion heating value of 164,587.5 joules.

Prediction of Biogas Production Volumes from Household Organic Waste Based on Machine Learning

The article proposes to use machine learning as one of the areas of artificial intelligence to forecast the volume of biogas production from household organic waste. The use of five regression algorithms (Linear Regression, Ridge Regression, Lasso Regression, Random Forest Regression, and Gradient Boosting Regression) to create an effective model for forecasting the volume of biogas production from household organic waste is considered. Based on the comparison of these algorithms by MSE and MAE indicators, the quality of training and their accuracy during forecasting are evaluated. The proposed algorithm for creating a model for forecasting biogas production volumes from household organic waste involves the implementation of 10 main and 3 auxiliary steps. Their advantage is that they aid in the performance of component data analysis, which is carried out based on the method of reducing the dimensionality of the data set, increasing interpretability, and minimizing the risk of data loss. An analysis of 2433 data is was carried out, which characterizes the formation of biogas from food (FW) and yard waste (YW) according to four features. Data preparation is performed using the Jupyter Notebook environment in Python. We select five machine learning algorithms to substantiate an effective model for forecasting volumes of biogas production from household organic waste. On the basis of the conducted research, the main advantages and disadvantages of the used algorithms for building forecasting models of biogas production volumes from household organic waste are determined. It is found that two models, “Random Forest Regressor” and “Gradient Boosting Regressor”, show the best accuracy indicators. The other three models (Linear Regression, Ridge Regression, Lasso Regression) are inferior in accuracy and were not considered further. To determine the accuracy of the “Random Forest Regressor” and “Gradient Boosting Regressor” models, we choose the MSE and MAE indicators. The Random Forest Regressor model is found to be a more accurate model compared to the Gradient Boosting Regressor. This is confirmed by the fact that the MSE of the “Random Forest Regressor” model on the training data set is 7.14 times smaller than that of the “Gradient Boosting Regressor” model. At the same time, MAE is 2.67 times smaller in the “Random Forest Regressor” model than in the “Gradient Boosting Regressor” model. The MSE and MAE of both models are worse on the test data set, which indicates overtraining tendencies. The Gradient Boosting Regressor model has worse MSE and MAE than the Random Forest Regressor model on both the training and test data sets. It is established that the model based on the “Random Forest Regressor” algorithm is the most effective for forecasting the volume of biogas production from household organic waste. It provides MAE = 0.088 on test data and the smallest absolute errors in predictions. Further systematic improvement of the “Random Forest Regressor” model for forecasting biogas production volumes from household organic waste based on new data will ensure its accuracy and maintain competitive advantages.

Method for Calculating the Engineering Design of a Mobile Bioreactor for Organic Waste Processing

The article discusses the engineering calculation methodology for developing the design of a mobile bioreactor for processing organic waste. The calculations for processing organic waste were based on SNiP, instructions and methods of leading scientists. When calculating the mobile bioreactor, we took into account: the limit of decomposition of fats, proteins, carbohydrates and the formation of biogas with the density of the mixture. A diagram of the phase process of ongoing and sequential decomposition with the maximum possibility of fermentation for an organic mixture with activated sludge over time, under aerobic and anaerobic conditions during waste disposal, is presented. The advantages and disadvantages of dry and wet waste processing methods are analyzed. From the calculations obtained, we can draw the following conclusion: in a bioreactor with a volume of 7.5 liters, in thermophilic mode, and with a volume of 15 liters, in mesophilic mode, approximately 50% of the organic mixture is fermented, and with activated sludge with a wet substrate, about 95%.

Biogas Production in a Variety of Sawdust and Cow Dung Mixtures Using the Intermittent Mixing Method

Cow dung is livestock waste that is very useful for renewable energy sources. The acceleration of the gas rate in cow dung biogas fermentation can be accelerated by the addition of secondary material, sawdust is one of the organic materials that can accelerate the rate of gas production in the formation of cow dung biogas. This study used a mixture composition: (B1) 675 g cow dung and 0 g sawdust, (B2) 472.5 g cow dung and 202.5 sawdust, (B3) 450 g cow dung and 225 g sawdust, and (B4) 427.5 g cow dung and 247.5 g of sawdust by fermentation for 20 days. In the research process, measurements of pH at the beginning and at the end of the study, gas pressure, gas volume, biodigester temperature, production rate, methane gas content, and flame test were carried out. In this study, the pH values ranged from 7-7.5 and the biodigester temperature was 27.5-31°C. The results of this study indicate that an organic mixture with a mixture of sawdust can accelerate production faster than without organic sawdust. Optimal results are found in the variation of the organic mixture of sawdust with a mixture of 450 g cow dung and 250 g sawdust having the highest production rate of 281.72 ml/day.

Biogas Production from the Potato Peel Waste: Study of the Effect of C/N Ratio, EM-4 Bacteria Addition and Initial PH

Objective: The objective of this study was to examine the effect of the C/N ratio, EM-4 addition and initial pH on the yield of biogas from potato peels. Theoretical Framework: In this topic, the concept and theory of biogas production from potato peels on a laboratory scale is presented, then the best conditions and kinetic constants are studied using the Gompertz model. Method: The variables in this study were the C/N ratio of 25 and 30, the EM-4 addition of 10%v/v, and initial pH of 6.8 and 7. This research was conducted on laboratory scale digesters under batch system. This study also discussed the kinetics of biogas production using the modified Gompertz model. Results and Discussion: The results showed that the C/N ratio of 30 produced a more biogas yield 17.6-26.1% compared to the C/N ratio of 25. The addition of EM-4 bacteria resulted in a more biogas yield 17.8-23.4% compared to the without addition case. The initial pH of 7 resulted in a more biogas yield 26-29% compared to the initial pH of 6.8. In kinetic analysis, the C/N ratio of 30, with EM-4 addition of 10% and initial pH of 7 resulted the greatest values of the maximum biogas production (A) which was 6,570.24 mL/grTS and the biogas production rate (U) which was 168.56 mL/grTS.day and resulted the lowest value of the minimal biogas formation (λ) which was 13.69 days, with R2 = 0.998. Research Implications: The practical and theoretical implications of this research are discussed, providing insight into how the results can be applied or influence practice in the field of renewable energy in the form of biogas from potato peels. Originality/Value: This research contributes to the literature by presenting the concept of biogas production using potato peel as raw material. The relevance and value of this research is proven by the C/N ratio, EM-4 bacteria and pH were proven to increase the productivity of biogas from waste potato peel.

Production of Biogas From a Mixture of Chicken Litter and Cow Manure and Its Effect on the Resulting Volume and C/N Ratio

The livestock sector's waste is a potential raw material for producing biogas because it is abundantly available. This experiment aimed to understand the potential of two types of livestock waste to produce biogas. The two sources of raw material were mixed with different variations. The results showed that the volume of fermentation gas produced from livestock waste varied depending on the type and composition of the raw material used. Mixing was done to determine the best variation in producing biogas from chicken litter and cow manure. The volume ratio of litter to cow manure used was (0%:100%), (25%:75%), (50%:50%), (75%:25%), (and 100%:0%), with a total volume of 2 liters. In addition, 10% of EM-4 (effective microorganism) was added to the mixture of livestock waste that had previously been given 2 liters of water. The waste mixture was then fermented for 30 days. The fermentation process was carried out under mesophilic conditions at room temperature and pressure. This study showed that the higher the concentration of chicken litter in the mixture, the higher the carbon-to-nitrogen (C/N) ratio value. On the other hand, if there is a higher composition of cow manure in the mixture, the substrate pH value will be higher. Furthermore, a 50%:50% composition of chicken litter and cow manure produced a high volume of biogas. Similarly, the biogas formation rate in this composition showed the best performance. These results prove that the balance of carbon and nitrogen composition, temperature, and substrate acidity significantly affect biogas production.

Simple Methods for Observing and Utilizing Biogas as a Renewable Energy Source

One combustible and burnable gas that can be created through an anaerobic fermentation process is biogas. An anaerobic process occurs when organic material, like animal dung, is processed in a digester (reactor) without the presence of oxygen. This observation's objectives are to (i) disseminate knowledge about the biogas production process and (ii) acquire a generation system for producing biogas. The observation methods are based on the use of an observation algorithm in the form of a flow chart, and it includes (a) observations related to various stages of choosing the type of installation, the requirements and processes for the formation of biogas observed and utilized from readily available organic materials, and influencing factors; and (b) observations related to the generation system for the production of biogas observed and utilized, including the physical reservoir, the amount of biogas produced, and the biogas utilized for supply to the electricity generator. The results of the observations related to the generation system, including the physical reservoir, the amount of biogas produced, and the biogas used for supplying the electricity generator, while the results of the observations related to the biogas production process, including the availability of installations, requirements and processes for biogas production, and influencing factors for the formation of biogas. Based on these findings, it can be said that the best period of time for biogas production is between 14 and 16 days, with a production volume of 6.0 m3 /day. While 0.64 m3 of biogas is needed for electric lighting, 0.30 m3 /hour of biogas at a pressure of 75 mm H2O is needed for cooking activities. While pure methane gas has an energy content of 8,900 kcal/m3 , the resulting calorific value is relatively high, ranging from 4,800 to 6,700 kcal/m3.

THE ROLE OF BACTERIAL AND ARCHAEA IN DETERMINING THE METABOLIC PATHWAY OF BIOGAS FERMENTATION AT LOW TEMPERATURES

The challenge in achieving large-scale biogas production still lies in the biogas fermentation process at low temperatures. Our goal was to delve into the metabolic pathway behind the formation of biogas at these lower temperatures, focusing on the dominant bacterial and archaeal communities. Employing a batch system with activated sludge inoculum at 10°C, we fermented cow manure at 12°C for 150 days. Through genetic sequencing and taxonomic analysis using OTUs from the 16S rDNA gene, we investigated bacterial and archaeal species. Correlation analysis between their abundance was conducted using Pearson correlation and t-tests via IBM SPSS Statistics. Our findings revealed a biogas production of around 0.74 L/day, with CH4 levels surpassing 0.45 L/g VS. Peak efficiency occurred between day 60 and 110, reaching its apex on day 90. Clostridium cellulovorans dominated, ranging from 13.9% to 27%, followed by Terrisporobacter petrolarius, around 16.2% to 23%. Specifically, the formation of biogas (CH4) predominantly occurred through the H2 pathway, led by significant hydrogenotrophic Archaea OTUs like Methanocorpusculum sinense (ranging from 4.95% to 37.10%) and Methanobrevibacter millerae (with relative abundances between 2.00% and 11.20%)

Energy Potential from Waste Activated Sludge in Domestic Wastewater Treatment Plant South Jakarta

Wasted activated sludge (WAS) a byproduct of wastewater treatment, holds significant untapped energy value. Conventional practice in DKI Jakarta involves collecting and directly disposing of WAS into landfill sites, overlooking the potential benefits of the sludge. Anaerobic digestion (AD) is a sustainable process that converts organic matter in the absence of oxygen offering a promising solution to harness this potential. The study aims to emphasize waste into energy by analyzing the volume of biogas through the Biochemical Methane Potential (BMP) value of WAS from the domestic WWTP in Setiabudi, South Jakarta. Characterization of WAS and its suitability for AD will be explored using DIN standards for 21 days. The experiment was duplicated into variants I1 and I2 and the parameters tested were pH, COD, TKN, VS, TS, concentration and volume of methane gas. In this study, the biogas yield from WAS obtained at 54,98 and 89,62 ml CH4/g VS along with the composition of biogas determined through GC readings at 61,78% CH4 and 56,08% CH4 from I1 dan I2, respectively. By optimizing AD processes, this study seeks to contribute to sustainable waste management and renewable energy production. Further research is needed regarding pre-treatment that may influence the formation of biogas.

ТЕОРЕТИЧЕСКИЕ ИССЛЕДОВАНИЯ ПРОЦЕССА ОБРАЗОВАНИЯ БИОГАЗА В МЕТАНТЕНКЕ С БИОФИЛЬТРОМ

The main essence of the theoretical research methodology is based on the construction of a mathematical model of the accumulation of active biomass (methane-forming microorganisms) on biofilter carriers, which characterizes the intensity of biogas formation in a methane tank. With existing technologies, the concentration of active biomass is removed from the methane tank with unloaded processed raw materials. Therefore, when studying the kinetics of microbiological processes of biogas formation, the main attention was paid to the theoretical study of the processing of organic biomass, depending on the effectiveness of the biofilter in the methane tank. The article presents the technological scheme and technical characteristics of a methane tank with a biofilter. The results of theoretical studies present the mathematical model of intensification of the biogas formation process obtained by us, depending on the accumulation of active biomass of methane-forming microorganisms on the carriers of a spherical biofilter and its energy characteristics.

Investigation of land surface temperature heterogeneity in municipal landfills by satellite images

With the increasing population and urbanization, the amount of municipal solid waste (MSW) is increasing day by day. As a result, problems such as odor, fire, and intense biogas formation originate from landfills. In order to detect and solve these problems, landfills should be monitored regularly. Geographic Information Systems (GIS) and Remote Sensing offer fast and practical solutions for the regular monitoring of landfills compared to field studies. In this study, Kömürcüoda landfill on the Anatolian side of Istanbul is monitored throughout 2022 with open source Landsat8/9 and Sentinel-2 satellite images. In this context, the surface temperature heterogeneity of the landfill was mapped by generating Land Surface Temperature (LST) images for the landfill from the Landsat thermal band. Points with statistically significant high - low LST values were determined with Hot Spot Analysis. The average annual LST for 2022 was calculated as 25.5 °C. It was observed that LST had the highest values during the summer season and the lowest values during the winter season. Additionally, it has been determined that there are persistent hot spots and cold spots in the landfill. This study presents a simple methodology using open source satellite data to monitor LST and detect LST abnormalities on landfills.

Evaluating the efficiency of the enhanced ultrasonic–assisted hydrogen peroxide degradation of low–rank coal biogenic gas

ABSTRACT The efficiency of biogas formation from low-rank coal was improved through ultrasonic-assisted hydrogen peroxide degradation. We investigated various aspects of this process, including the mass of the small-molecule organic matter, changes in the composition of biogas components in three systems, and alterations in the microscopic morphology of coal before and after biogas formation. Our analytical methods included UV-vis spectrophotometry, drainage gas collection method, gas chromatography, infrared spectroscopy, and scanning electron microscopy. Optimal pretreatment conditions were identified with an ultrasonic power of 400 W, a reaction time of 90 min, and a reaction temperature of 60°C. The biogenic methanogenic cycle was delineated into three stages, with the raw coal and filtrate systems exhibiting fast and slow gas production stages during the first and second stages, respectively. In contrast, the residual coal system displayed slow and fast gas production stages during these stages. Methane yields were measured at 270.72 μmol g−1 (raw coal), 303.50 μmol g−1 (residual coal), and 293.43 μmol g−1 (filtrate). Pretreated coal exhibited biomethane yields (residual coal and filtrate) approximately 120% higher than untreated raw coal. Notably, the gas-forming potential of the filtrate should not be underestimated. Ultrasonic-assisted hydrogen peroxide pretreatment disrupted the macromolecular reticulation structure within the raw coal, resulting in the opening of a portion of the aromatic ring structure. This innovative approach offers a novel strategy for augmenting biomethane production from low-rank coal and furnishes a scientific foundation for advancing industrial applications.

Fast pyrolysis of agricultural residues: Reaction mechanisms and effects of feedstock properties and microwave operating conditions on the yield and product composition

Fundamental understanding of the pyrolysis process plays an indispensable role in valorization of wastes and the development of novel sustainable technologies. This study introduces a novel approach by investigating the reaction mechanisms involve in Microwave-Assisted Fast Pyrolysis (MAFP) to unveil the thermal decomposition of agricultural residues: pecan nutshell (NS), sugarcane bagasse (SB), and orange seed (OS) biomasses. The holistic understanding of the pyrolysis process for these biomasses was analyzed based on the final chemical compositions and yields of bio-oil, biochar and biogas and correlated to the microwave processing conditions and feedstock’s chemical composition. The findings revealed that the bio-oil is enhanced at moderated microwave energy (<5 GJ/t) as result of endothermic reactions such as heterolytic fragmentation, Maccoll elimination, Friedel-Craft acylation, Piancatelli rearrangement and methoxylation. The maximum yield of bio-oil for protein-rich biomass was due to selective heating (Paal-Knorr pyrrole synthesis, Baeyer-Villiger oxidation, Maillard reaction, and ring conversion of γ-butyrolactone). The formation of biochar and biogas is attributed to the repolymerization of aromatic aldehydes, hydrocarbons, amines, and ethers, as well as dehydroxymethylation and dealkylation processes. This study provides a comprehensive understanding of the reaction mechanisms for several wastes using microwave pyrolysis, to establish the bases for effective valorization and agricultural waste management.

Model-based comparison of biological wastewater and sludge treatment combinations for nutrient removal, sludge and biogas production

One of the strategies for reducing the potential environmental and health-related risks associated with wastewater treatment sludge is to select treatment options that would minimize its production while using its beneficial products and meeting effluent discharge standards. In this regard, simulation models can aid in estimating treatment performance, sludge production, and biogas formation. This study evaluates effluent concentrations focusing on nutrients, sludge production, and biogas generation rates for various combinations of wastewater and sludge treatment alternatives for varying strengths of domestic wastewater. Overall, 105 scenarios were simulated for three different wastewater strengths for 35 treatment schemes. Bardenpho-5 (B5) was superior over A2O (A2) in removing nitrogen and phosphorous. Adding primary sedimentation to A2 and B5 models improved sludge and in turn biogas production. Effluent total phosphorus (TP) was usually higher in scenarios with anaerobic sludge digestion. However, struvite precipitation following anaerobic digestion helped reduce total nitrogen (TN) and TP effluent concentrations for all wastewater treatment technologies. Sludge production amounts ranged between 2865 kg/day to 38,709 kg/day (total solids) for an influent flow rate of 100,000 m3/day. Sludge production rates were relatively insensitive to sludge treatment alternatives for extended aeration (EA) compared to conventional activated sludge (AS), A2, A/O (AO), and B5. Generally, the impact of a sludge treatment option was significant for wastewater treatment technologies with higher waste sludge production. Thermal hydrolysis followed by anaerobic digestion provided the lowest sludge production and significantly improved the biogas production.

A comprehensive analysis on the synthesis of value-added chemicals via slow pyrolysis: Valorisation of rapeseed residue, whitewood, and seaweed (Laminaria digitata)

Pyrolysis has emerged as a crucial thermochemical conversion technology in the field of biomass processing. Maximising the valorisation of biomass is an essential area of investigation, as it plays a pivotal role in understanding the economic viability and practical application of these advanced technologies. The novelty of this research is to investigate how slow pyrolysis and process interdependencies influence the synthesis of value-added products (bio-oil and biogas formation alongside biochar) from distinctly different UK-based biomass feedstocks: rapeseed residue, whitewood, and seaweed (Laminaria digitata). This research also analysed the chemical composition of these products to provide a holistic understanding of the reaction mechanisms involved in their formation. The maximum yield of bio-oil from lignocellulose-rich whitewood was due to the higher selectivity of several endothermic reactions including conversions of 5-hydroxymethylfurfural into cyclic C5-ketones and alkoxyphenols into cresols and aliphatic hydrocarbons, minimizing the biochar formation. The improvement of bio-oil yield from protein-rich seaweed and lipid-rich rapeseed residue was enabled by the formation of N-heterocyclics (e.g., via the Maillard reaction, Dieckmann cyclization, and Buchwald–Hartwig amination) and aliphatic hydrocarbons (e.g., via deamination of fatty amides and nitriles and decarboxylation of fatty acids), respectively. Meanwhile, the dealkylation and demethoxylation of alkoxyphenols and alkylphenols were responsible for the increased content of hydrocarbons in biogas. The findings provide valuable insights into the maximum valorisation of different types of UK-based biomass resources in slow pyrolysis for the production of biochars and lighter bio-oils to make pyrolysis a key process in biorefineries.

Thermodynamic prediction of biogas production and combustion: The spontaneity and energy conversion efficiency from photosynthesis to combustion

Due to inappropriate energy consumption and subpar waste management, the growing population leads to an increase in energy demand and environmental damage. The creation of biogas enhances the management of organic waste and provides renewable energy. The production of biogas, which is a mixture of several gases, primarily methane and carbon dioxide, occurs during the four phases of aerobic digestion (AD). The four stages are hydrolysis, acidogenesis, acetogenesis, and methanogensis. Biogas comprises 50–70% Methane, 25–40% carbon dioxide and remaining traces of gases. In this paper, these biogas production processes are not thoroughly studied utilizing thermodynamic principles. Using thermodynamic criteria, this article analyses and assesses why the aerobic digesting process is spontaneous. Entropy, enthalpy, and Gibbs free energy of reactions during the various stages of the formation of biogas are examined. At Standard Temperature and Pressure Conditions (STP), the combined four phases of biogas formation are exothermic and spontaneous based on the analysis of Entropy, enthalpy, and Gibbs free energy of reactions from balanced equations at standard conditions of temperature and pressure. A unit mole of glucose is used to compare the energy released during photosynthesis with the energy released during biogas burning. Three moles of methane can be produced from decomposition of glucose. The combustion of three moles of methane yields 2406.876 kJ energy and if the same amount of moles of biogas (60% methane and 40% carbon dioxide) burns the energy yield is reduced to 1604.584 kJ. From the energy captured by photosynthesis i.e., 2808.1 kJ/mol 57.141% of the energy is recovered in the biogas combustion process. This efficiency reaches to 85.711% if pure methane is burned. As the separation of methane from biogas, mixture in actual plants is not economically feasible the combustion of methane gas the ideal limit of the efficiency.