Average Biogas Research Articles

Effects of slurry concentration and co-digestion on biogas yields from unseeded Phaseolus vulgaris (bean) peels chaff and unseeded Musa paradisiaca (plantain) peels chaff

This study explored converting agricultural wastes of Bean peel chaff (Bu) and Plantain peel chaff (Pu) into biogas, an eco-friendly biofuel, without cow rumen liquor. By digesting these wastes anaerobically in various combinations and slurry concentrations, the study assessed their individual and combined biogas yields. Bean and plantain peels were digested alone and in two mixtures: BP1u (bean-to-plantain ratio 0.691:1) and BP2u (1:1 ratio). Three waste-to-water slurry concentrations (1:6, 1:11, and 1:16) were used, with anaerobic digestion lasting 37 days in triplicate 1000ml mini digesters. Biogas production was measured via water displacement. The study found total solids percentages of 96.03% for Bu, 90.12% for Pu, 84.15% for BP1u, and 84.94% for BP2u. The carbon/nitrogen (C/N) ratios ranged from 9.04 to 15.3. Average biogas yields showed BP1u produced the highest (11.12 ml/day), followed by Bu (9.8 ml/day), BP2u (7.5 ml/day), and Pu (0.55 ml/day). Among slurry concentrations, 1:6 (C1) yielded the most biogas (17.45 ml/day), followed by 1:11 (C2) and 1:16 (C3). ANOVA indicated significant effects from both slurry concentration and co-digestion on biogas yield, along with a notable interaction between both factors. In conclusion, both bean and plantain peels can generate biogas effectively, especially when combined and digested in higher slurry concentrations for improved yield. This approach supports waste management and renewable energy goals by transforming agricultural residues into valuable biofuel.

Experimental Investigation of Biogas Yielding Rate from Anaerobic Co-Digestion of Multiple Organic Feedstocks Using a Bio-digester

Background: The high cost of fossil fuels has driven the exploration of renewable energy alternatives. This study investigates the anaerobic co-digestion of waterleaf, cow dung, and food waste to optimize biogas production. Methods: Four co-digestion experiments were performed using a prototype plastic bio-digester over 50 days. The combinations tested were: waterleaf with cow dung, waterleaf with food waste, food waste with cow dung, and a mix of all three feedstocks. Results: Co-digestion of waterleaf and food waste yielded an average biogas output of 25%, with a pH of 7.2 and a carbon-to-nitrogen (C/N) ratio of 28. Combining waterleaf and cow dung produced a 31% yield, a pH of 7.2, and a C/N ratio of 29. The mixture of food waste and cow dung resulted in a 34% biogas yield, with a pH of 7.1 and a C/N ratio of 30. The highest yield, 46%, was achieved by co-digesting waterleaf, cow dung, and food waste, with a pH of 7 and a C/N ratio of 32. All feedstock combinations maintained neutral pH levels, benefiting from the unique properties of each component: waterleaf provided vitamins A and C, food waste supplied carbohydrates and proteins, and cow dung contributed anaerobic microbes essential for digestion. Additionally, temperature was a significant factor influencing biogas production. Conclusion: Co-digesting waterleaf, cow dung, and food waste maximized biogas production, demonstrating the potential for enhanced renewable energy generation through optimized anaerobic digestion processes.

Performance Evaluation and Economic Sustainability of the PAU Model Batch Type Paddy Straw Biogas Plant

This study evaluates the performance and economic viability of the Punjab Agricultural University (PAU) Model Batch Type Paddy Straw Biogas Plant in rural India, addressing critical challenges in agricultural residue management and sustainable energy production. Data collected from two plants over four months showed an average daily biogas production of 1.46 to 3.13 m3 per day, with a total gas production of 284.8 m3 in a period of four months. Plant performance correlated moderately with ambient temperature. Economic analysis revealed annual savings of Rs. 47,600 through reduced LPG use and biogas slurry sales. The study concludes that the PAU Model is technically efficient and economically viable, offering a sustainable solution for paddy straw management and rural energy security. These findings have significant implications for policymakers and rural development practitioners in promoting sustainable agriculture and renewable energy adoption in developing regions.

How Scheduled Maintenance Affects Anaerobic Digester Supervision Through Modelling: A Practical Approach

Anaerobic digestion plays a crucial role in the transition toward a circular economy. Incorporating system supervision through mathematical modelling can enhance control and resilience. This study aims to assess the impact of scheduled digester maintenance on the effectiveness of modelling as a tool for monitoring and control. Data from a pilot-scale plug-flow digester were analyzed using an adapted ADM1 model. The maintenance involved halting the digester and removing sedimented solids. Model calibration indicated solid retention in the first two zones of the reactor, while the hydrolysis coefficient and biogas potential remained at 0.122 d−1 and 100.4 mL CH4/gVS, respectively. The average biogas production decreased from 156 to 109 mL/gVS pre- and post-maintenance. Simulations showed a decline in the model’s predictive accuracy after maintenance. To improve model fit, the initial conditions, solids retention, and kinetic parameters were adjusted. Optimal performance was achieved with khyd at 0.045 d−1 and B0 at 52.28 mL gVS−1, revealing an issue with the digester’s heating system. In conclusion, maintenance can significantly alter digester conditions, requiring model recalibration to maintain its effectiveness as a digital copilot for process supervision.

Influence of Molasses and Caesalpinia spinosa Meal Inoculums on Biogas Production from Cattle Manure

The management of organic waste through anaerobic digestion is an alternative to energy recovery. This research focused on evaluating the production of biogas with different inoculums. For this purpose, two types of systems were implemented—one used a heating system controlled by an STC-1000 thermostat, while the other used a solar heating system under a polycarbonate parabolic trough. The experiment was carried out at laboratory level with 3 L PET bottle biodigesters and the biogas produced was collected with the water displacement technique in 3 L bottles, calibrated every 50 mL, over 43 days. Inoculums of the following manure concentrations were used: water (1:5, 1:2, 1:3) mixed with Caesalpinia spinosa meal and molasses. The results determined that the thermostat-controlled heating system generated 69.6 mL/day of biogas while the other system produced 610.9 mL/day. On the other hand, the T1 treatment with a manure:water ratio of 1:5 and molasses and Caesalpinia spinosa meal inoculums in both systems had a higher average biogas volume. In terms of methane (CH₄), the highest value of 76.9% was obtained through the T1 treatment under the controlled heating system. This allows the production of biogas with a high concentration of methane, which in future applications can be utilized for residential or industrial purposes, promoting economic, social and environmental development. Since the main challenge in the production of biogas is to reduce the digestion time, which is influenced by the temperature of the site, two types of inoculums with a low cost and easy access were used.

Long-term performance and activity study of a two-stage anaerobic EGSB reactors system treating complex and toxic industrial wastewater.

Anaerobic treatment of industrial wastewater using upflow anaerobic reactors is an extended trend due to its high efficiency and biogas production potential, but its implementation in some sectors is limited due to the complexity and toxicity of the wastewaters. In this study, a two-stage expanded granular sludge bed (EGSB) reactors system has been investigated at both bench and pilot scale for the treatment of complex and toxic real wastewater from a petrochemical industry. The effect of different operational parameters including organic loading rate (OLR), hydraulic retention time (HRT) and influent characteristics over COD removal and biogas production and composition have been studied. Additionally, biomass specific methanogenic activity (SMA) and wastewater toxicity have been evaluated after long-term operation. Optimum total HRT of 24 h has been determined resulting in total COD and SO4 2- removal of 56.30 ± 5.25% and 31.68 ± 14.71%, respectively, at pilot scale, and average biogas production of 93.47 ± 34.92 NL/day with 67.01 ± 10.23 %CH4 content and 5210.11 ± 6802.27 ppmv of H2S. SMA and toxicity tests have confirmed inhibitory and toxic effects of wastewater over anaerobic biomass with average maximum inhibition of 65.34% in the unacclimated anaerobic inoculum while chronic toxicity produced a decrease of an order of magnitude in SMA after 600 days of operation. This study demonstrates the feasibility of applying an anaerobic treatment to this wastewater using EGSB reactors between a 0.97-1.74 gCOD/L/day OLR range. Nonetheless, periodic reinoculation would be necessary for long-term operation due to chronic toxicity of the wastewater exerted on the anaerobic biomass. PRACTITIONER POINTS: A two-stage EGSB reactors system has been operated at bench and pilot scale to treat complex and toxic petrochemical wastewater. Optimal total HRT of 24 h resulted in average COD removal ranging from 40% to 60%. SMA and toxicity tests have been performed to study long-term acclimation, detecting an activity depletion of an order of magnitude.

A matheuristic applied to clustering rural properties and allocating plants for biogas generation

Establishing partnerships among agro-industrial properties and selecting ideal locations for biogas plants are crucial challenges in large-scale biogas production and can influence both operational efficiency and waste management. In this context, this research proposes a new matheuristic that addresses the problems of defining a group of properties and an optimal number of groups and identifies the best allocation to the biogas plant. The group properties were defined by hierarchical and K-means cluster algorithms. The best location for the biogas plant was determined by the proposed multiobjective mathematical model. The best cluster number was decided by two strategies: (1) one that selected the closest non-dominated solutions to the ideal solution (M1) and (2) one that favored the most environmentally friendly solution (M2). The matheuristic was tested using three real databases, which yielded strategic clusters with an average daily biogas production of 544.93 m³/day (M1 and M2) for DataBase 1, 1635,156.00 m³/day (M1) and 403,497.50 m³/day (M2) for DataBase 2, and 318,662.50 m³/day (M1) and 20,479.58 m³/day (M2) for DataBase 3. This research provides an opportunity to add value to agro-industrial properties by achieving energy security and developing new business networks.

Anaerobic dynamic membrane bioreactor for the co-digestion of toilet blackwater and kitchen waste.

Anaerobic co-digestion using an anaerobic dynamic membrane bioreactor (AnDMBR) can separate the sludge retention time and hydraulic retention time, retaining the biomass for efficient degradation and the use of less expensive large pore-size membrane materials and more sustainable dynamic membranes (DMs). Therefore, anaerobic co-digestion of toilet blackwater (BW) and kitchen waste (KW) using an AnDMBR was hypothesized to increase the potential for co-digestion. Here, the efficiency and stability of AnDMBR in anaerobic co-digestion of toilet BW and KW were investigated. DM morphology and structural characteristics, filtration properties, and composition, as well as membrane contamination and membrane regeneration mechanisms, were investigated. Average daily biogas yields of the reactor in two membrane cycles before and after cleaning were 788.67 and 746.09 ml/g volatile solids, with average methane content of 66.64% and 67.27% and average COD removal efficiencies of 82.03% and 80.96%, respectively. The results showed that the bioreactor obtained good performance and stability. During the stabilization phase of the DM operation, the flux was maintained between 43.65 and 65.15L/m2/h. DM was mainly composed of organic and inorganic elements. Off-line cleaning facilitated DM regulation and regeneration, restoring new Anaerobic morphology and structure. PRACTITIONER POINTS: High efficiency co-digestion of BW and KW was realized in the DMBR system. Average daily biogas yields before and after membrane cleaning were 788.67 and 746.09 ml/g volatile solids. Off-line cleaning facilitated DM regulation and regeneration as well as system stability. The flux was maintained between 43.65 and 65.15L/m2/h during operation.

Evaluation of biogas production and bacterial load from co‐digestion of chicken manure with different types of household waste

AbstractBackgroundThe aim of this study was to evaluate the biogas production of chicken manure (CM) co‐digestion with different types of household waste (soft organic [SO] and food waste [FW]), as well as to evaluate the bacterial load of feeding stock and digested slurry samples before and after anaerobic digestion (AD). The experiment was carried out using lab‐based prototype digesters for co‐digestion of CM with different household wastes (5%). Three experimental groups (T1, T2, and T3) were designed using mixing ratios of SO:CM:H2O:inoculum (5:22.5:22.5:50), FW:CM:H2O:inoculum (5:22.5:22.5:50), and (SO + FW):CM:H2O:inoculum (2.5 + 2.5:22.5:22.5:50). The digesters were set at 28–34°C for 30 days for hydraulic retention time (HRT). Total viable count (TVC), Escherichia coli, and Salmonella spp. counts were determined using the spread plate technique.ResultsThe study revealed that the highest average cumulative biogas yield was achieved from T1 > T3 > T2, but the concentration of CH4 was found in T3 > T2 > T1. The biogas production between the three groups was statistically nonsignificant (p > 0.05) but the daily concentration of CH4 was found statistically significant (p < 0.05). The average concentration of CH4 and CO2 in biogas was found to be 30% and 68% for T1, 60% and 37% for T2, and 69% and 27% for T3. However, the H2S content was within the acceptable range. The bacterial load was decreased by 2–3 logs before and after AD, and this reduction was statistically significant (p < 0.05).ConclusionThe research found that the co‐digestion of CM with combined household wastes increased the methane concentration in biogas.

Photosynthetic process for removing H2S and CO2 from biogas using the microalgae Chlorella sorokiniana

Biogas is an alternative source of energy that contributes on reducing the emissions of polluting gas in comparison to fossil fuels as well as promoting the treatment of organic waste. However depending on the substrate used in its production, it may have a high concentration of carbon dioxide (CO2) and hydrogen sulfide (H2S); in these cases a treatment is necessary to make its use viable, for comply with current legislation and avoid damage to materials and health. Currently, the most widely used methods are physical-chemical, such as absorption, adsorption, membrane separation, and Pressure Swing Adsorption (PSA), among others. However, these methods are expensive and generate waste that needs to be treated. In this sense, biological methods have proved to be promising alternatives, especially photosynthetic processes using microalgae. This study aimed to evaluate the efficiency in removing CO2 and H2S from biogas through a bench-scale purifier prototype consisting of a photobioreactor and an absorption column, in a continuous biogas flow system. The experiment lasted 240 hours, during which 9 m³ of biogas were treated. In the first 24 hours, the flow rate was 1 L/min, resulting in an average removal of 60.8% of H2S and 20.2% of CO2. Between 24 hours and 240 hours of the study, the average biogas flow rate was 0.54 L/min, and an improvement in removal was observed, reaching 83.4% of H2S and 29.7% of CO2. The system showed efficiency in biogas treatment. However, possibilities for improvement were identified in terms of biogas flow and process, which could further enhance the results presented here.

Anaerobic Digestion of Maize Husk in Co-Digestion with Goat and Cow Dung for Enhanced Biogas Production

In recent investigations, Anaerobic co-digestion has been superior to traditional anaerobic digestion (AD). The advantages of employing co-substrates for improved bioenergy generation and solids reduction have drawn researchers to investigate the co-digestion technology and understand the impact of multiple substrates on digester performance. This study aimed to generate biogas by co-digestion of maize husk with cow and goat dung as substrates, isolate the bacteria involved in the process, and assess the quantity and makeup of the biogas generated by the substrates. The substrates were fed to mini-digesters fabricated in the laboratory using 1L bottles for 49 days’ retention time. It assessed the production potential of the substrates for biogas yield in mono-digestion and co-digestion. The average biogas yield (cm3) and methane content (%) in the D1, D2, D3, D4, D5, and D6 were 9135 (58%), 8660 (71%), 9820 (69%), 6545 (65%), 5915 (48%) and 1965 (21%) respectively. The highest gas yield was observed in digesters with co-digestion of the substrates (D1 and D2) than the mono-digestion of the GD and CD by 35.2% and 24.4%, respectively, with an improvement in methane content. The process was carried out in a mesophilic condition and a pH range of 6.8-8.2. The study's findings showed that the most frequently isolated and identified bacteria were Klebsiella pneumoniae and Bacillus species, indicating that these species are essential to the microbial activities involved in biogas production. The investigation additionally showed that maize husk in co-digestion with cow dung and goat dung had great potential for generating and producing large quantities of biogas within 49 days’ retention time.

Performance analysis of three pilot-scale multi-compartment anaerobic baffled reactors treating domestic wastewater at psychrophilic temperatures in Colorado.

A transition from inefficient aerobic wastewater treatment methods to sustainable approaches is needed. Anaerobic bioreactors are a viable solution as they consume less energy, reduce biosolid production, and provide a source of renewable methane-rich biogas. A barrier to widespread implementation of anaerobic technologies is the lack of design guidance, especially in colder climates. This study bridges this knowledge gap by deriving design principles from three long-running pilot-scale anaerobic baffled reactors (ABRs) operating under psychrophilic conditions. The ABRs removed an average of 56% and 80% chemical oxygen demand (COD) and suspended solids, respectively, with a methane yield of 0.21L CH4 /g CODrem . Methane production may be improved with increased influent sCOD concentrations and decreased sulfate concentrations. Results suggest that ABRs can treat a range of wastewater strengths accompanied by useable methane production. Despite sharing location, temperature, and HRT, the ABRs displayed distinct performances, highlighting the significance of influent wastewater characteristics. PRACTITIONER POINTS: ABRs achieved 56% and 80% removal efficiencies for COD and suspended solids. Average biogas was 63% methane, and methane yield was 0.21 L CH4 /g CODrem . Volumetric methane production was positively correlated with the influent sCOD/sulfate ratio and negatively correlated with influent sulfate loading.

Effect of acclimatization rate on biogas production from anaerobic digestion of biodiesel waste products

AbstractDigester acclimatization can improve the efficiency of anaerobic digestion (AD), a potentially sustainable process for generating biogas from the biological decomposition of organic byproducts from biodiesel production. This study examined the impact of acclimatization rate on biogas production and conversion efficiency in laboratory digesters using inocula from a wastewater treatment plant digester and from an agro‐industrial waste digester. The results showed that co‐digestion of crude glycerol and biodiesel wastewater at high organic loading rates, up to 6.8 g chemical oxygen demand (COD) L−1 day−1, is possible without the addition of other substrates or pretreatment. Higher organic loading rates were achieved in the digesters using inocula from the agro‐industrial waste digester than in the digesters using the wastewater treatment plant digester, indicating that an inoculum with similar physical characteristics may be most appropriate for the AD of biodiesel waste. Of the two acclimatization rates studied, the slower rate improved the cumulative biogas production for both inocula. Both inocula also exhibited higher maximum daily efficiencies with a slower rate of acclimatization, up to a maximum average daily biogas yield of 621 mL biogas g−1 COD added. This implied that the rate of acclimatization can impact the ability of the digester to adapt efficiently to a new substrate.

Biogas production from canteen waste

Abstract Day by day as the population increases, food waste keeps on growing. This waste needs to be managed in order to reduce the number of landfills and to use food waste efficiently. Among the various processes available, Anaerobic Digestion (AD) of food waste is one of the alternatives for processing food waste. The two biggest obstacles to anaerobic digestion of food waste are high biodegradability and high C/N ratio. The C/N ratio determines the ratio between substrate and nutrients; the latter is essential for microbial synthesis and for providing alkalinity through ammonia metabolism. Biogas, a product of the anaerobic digestion process, is a clean and renewable form of energy that can replace conventional energy sources that cause ecological-environmental problems and at the same time are depleted more quickly. The aim of this work was to increase the nitrogen content to enhance the production of biogas from canteen waste. During the process, two digesters of the same capacity were operated. Anaerobic digestion of canteen waste along with addition of ammonium chloride was carried out in Digester 1 while AD of only canteen waste was carried out in Digester 2. The amount of biogas produced in Digester 1 was in the range of 0.04 m3/kg–0.075 m3/kg, while in Digester 2 the volume range was 0.02 m3/kg–0.04 m3/kg. The average biogas produced in digester 1 consisting of canteen waste and nitrogen source was 0.053 m3/kg while biogas production in digester 2 with only canteen waste was 0.030 m3/kg. So, biogas produced by addition of nitrogen source was 77 % higher than that of only canteen waste. From this study we obtained a higher amount of biogas by addition of ammonium chloride as an external nitrogen source. Nitrogen demand of methanogens was fulfilled by additional supply of nitrogen resulting in increased quantity of biogas. Therefore, in anaerobic digestion addition of ammonium chloride was beneficial for food waste digestion. Hence, nitrogen content in canteen waste turned out to be the main parameter affecting anaerobic digestion of canteen waste which is justified in this research.

Biogas Production from Kitchen Wastes by Anaerobic Digestion

Abstract: This paper aimed to study the biogas production from kitchen wastes mixed with cattle dung. A vertical bench scale biogas digesters were constructed. Each three of them were replicates and their average biogas yields were recorded. The mixing ratios were 75%, 50% and 25% of kitchen wastes to the total slurry. The pH, alkalinity and temperature were measured during the experiments. It was found that digestion process was sensitive to temperature changes. Also, the pH and alkalinity were increasing over time. Moreover, it was found that the mixing ratio of 75% kitchen wastes to the total slurry enhanced the biogas production by 17.3% in comparison to the ratio of 25% kitchen wastes.

Biogas potential from agricultural waste and its CO2 emission reduction: a case study of Hubei Province, China.

Biogas produced from agricultural waste can have potential benefits, such as offer clean renewable energy, protect the ecological environment, and reduce CO2 emission. However, few studies have been conducted on the biogas potential from agricultural waste and its CO2 emission reduction at the county level. Herein, the biogas potential from agricultural waste was calculated, and its spatial distribution in Hubei Province in 2017 was determined using a geographic information system. Then, an evaluation model for the competitive advantage of the biogas potential from agricultural waste was established using entropy weight and linear weighting methods. Moreover, the space partition of the biogas potential from agricultural waste was obtained through hot spot analysis. Lastly, the standard coal equivalent of biogas, the equivalent of coal consumption of biogas, and the CO2 emission reduction based on the space partition result were estimated. Results showed that the total and average biogas potentials from agricultural waste in Hubei Province were 18,498,317,558.54 and 222,871,295.89 m3, respectively. Qianjiang City, Jianli County, Xiantao City, and Zaoyang City had a high competitive advantage in the biogas potential from agricultural waste. The CO2 emission reduction of the biogas potential from agricultural waste was mainly in classes I and II.

Giant reed from wetlands as a potential resource for biomethane production

This study aimed to evaluate the potential and the use of the natural and treatment wetland biomass for local energy production. Specifically, it was addressed by determining the giant reed (Arundo donax L.) Biochemical Methane Potential at different harvest times, since plant characteristics vary noticeably along the growing season. In the last decades, this perennial rhizomatous grass has achieved great success in the renewable energy market to produce biogas through the anaerobic digestion process, because is a non-food crop with high biomass yield (about 35 Mg dry matter per hectare) and low input required for its growth. Several studies showed that the harvest time, in relation to the stage of the plant development, significantly affect the Biochemical Methane Potential. Moreover, it is well known that giant reed presents feature comparable in terms of biomass yield and physicochemical composition both in natural and treatment wetland systems. Anaerobic digestion laboratory tests were carried out to assess biomethane production from aerial biomass samples collected from July to November 2021. The average biogas production for the five different harvest times was of 312.77 Nm3/tVS (±62.87), and the mean methane content was equal to 187.06 Nm3 CH4/tVS (±38.32). The gas quality at the end of the Biochemical Methane Potential test displayed average contents of methane of 58.88% (±5.06) and CO2 of 18.54% (±7.91) and mean sulfides content of 112.10 ppm (±103.61). The results highlighted that giant reed has a high energy returned on energy invested (EROEI) value. The research activity allowed to identify the harvest time associated with the highest Biochemical Methane Potential and biomethane production per hectare. Finally, the experimental results achieved in riverbank conditions could be applied to treatment wetland systems increasing their environmental sustainability and reducing their maintenance costs.

A Novel Method Using Two-stage Anaerobic Digestion Integrated with Greenhouse Solar Dryer for Increased Biogas Production

Solar energy is infinite and environmental-friendly energy that is widely used in many fields such as solar cells, solar roofs, solar dryers and so on. However, solar energy has never been used in anaerobic digestion processes for biogas production. The use of solar energy may accelerate the biogas reaction to achieve higher gas production rates. Hence, the purpose of this research was to study a two-stage anaerobic digestion system in combination with a greenhouse solar dryer to increase the rate of biogas production. The study consisted of two parts: the first was to study the temperature variations in greenhouse solar dryers using computational fluid dynamic techniques, and the second was to conduct two-stage anaerobic digestion integrated with the greenhouse solar dryer system for biogas production. The results showed that the average temperature and biogas production rate in the integrated two-stage anaerobic digestion system compared to a conventional system increased by 16.2% and 19.69 %, respectively

Opportunities and Potential for Energy Utilization from Agricultural and Livestock Residues in the Region of Thessaly

In recent years, due to the circular economy, the use of green energy forms, such as biofuels and biogas from anaerobic digestion of fermentable materials (e.g., agricultural and livestock residues) has entered our lives. According to the International Energy Agency it is estimated that the needs in 2040 will be 48% higher than in 2012 so all political decisions have converged on an urgent need for the use of more and more renewable and green energy. Considering the overall economic activity of these sectors in the region of Thessaly, the aim of this study is to highlight the residues from agricultural and livestock activities in the primary sector and calculate the annual biomass production, the methane and biogas potential, the electrical and thermal energy that can be produced from these wastes, as well as the solid residue that can be used to improve the soil of the region. The study was based on data referring to the years 2015 to 2020. The production of livestock and agricultural residues, averaged over the above six-year period in the study area, was estimated at approximately 4.8 × 106 t·yr.−1, with livestock residues accounting for 83% and agricultural residues for 17%. Furthermore, the total residues can produce an average biogas potential of approximately 4.7 × 106 m3·yr.−1, while the amount of electricity that can be produced ranges from 708–1091 GWh·yr.−1, and the corresponding thermal energy from 1112–1577 GWh·yr.−1. As a result of the complete anaerobic digestion process, a solid residue could also be obtained for the improvement of the region’s soil, which translates into a quantity in the range of 4.01 × 104 to 5.10 × 104 t·yr.−1.

Evaluating the Potential of Renewable Energy Sources in a Full-Scale Upflow Anaerobic Sludge Blanket Reactor Treating Municipal Wastewater in Ghana

Wastewater management remains a major challenge in developing countries due to the lack of adequate infrastructure, making the need for economically viable and efficient technologies that can be sustained by emerging economies imperative. The upflow anaerobic sludge blanket (UASB) reactor represents an efficient and low-cost technology that produces by-products from which valuable resources can be recovered. This study assessed the energy recovery potential in the form of electricity from biogas and sludge by-products produced by a full-scale UASB reactor. Biogas production rate and composition were monitored to determine the biogas energy recovery potential. Dehydrated sludge from sludge drying beds was likewise quantified and characterised for its elemental composition, immediate composition, gross calorific value and net calorific value to estimate sludge energy recovery potential. The average daily biogas production was found to be 611 ± 275 Nm3/d, with 65% methane in the biogas output. Average sludge dry matter production was determined to be 358.24 TS kg/d. The net energy recovery potential was estimated to be 534.1 MWh/yr, 36% more than the yearly energy demand (392.7 MWh/yr) of the entire plant. Conservative energy recovery at a UASB-based municipal wastewater treatment facility could serve as a self-supply energy option to support its operations.