ANAEROBIC EXPERIMENTATION TO DETERMINE KEY PARAMETERS FOR OPTIMAL PERFORMANCE OF A PILOT SCALE BIO-DIGESTER FOR EMULATING LANDFILL CONDITIONS AND GAS RECOVERY

International Journal of Advanced Scientific and Technical Research ISSN 2249-9954 Available online on http://www.rspublication.com/ijst/index.html volume 15, No. 5, 2025 DOI: 10.5281/zenodo.17285090 Original Article ©2025 RS Publication, [email protected] 257 ANAEROBIC EXPERIMENTATION TO DETERMINE KEY PARAMETERS FOR OPTIMAL PERFORMANCE OF A PILOT SCALE BIO-DIGESTER FOR EMULATING LANDFILL CONDITIONS AND GAS RECOVERY *Enefiok O. Usungurua 1 , Akanimo U. Usungurua 2 , Whyte A. Akpan 3 , Aniekan E. Ikpe 4 and Uchechi E. Iroekwe 5 1, 3 Department of Mechanical Engineering, Federal University of Technology, Ikot Abasi, Nigeria 2 Department of Electrical/Electronic Engineering, Federal University of Technology, Ikot Abasi, Nigeria 4 Department of Mechanical Engineering, Akwa Ibom State Polytechnic, Ikot Osurua, Ikot Ekpene, Nigeria 5 Department of Mechanical and Aerospace Engineering, University of Uyo, Nigeria *Corresponding author: [email protected]; [email protected] ARTICLE INFO ABSTRACT Paper ID: IJASTR68D31DC8D57A8 Received: 2025-09-05 Published: 2025-10-05 DOI: https://dx.doi.org /10.5281/zenodo.17 285090 Page No: 257-272 The increasing population and economic activities in Nigeria have encouraged high generation of wastes as well as high energy crisis, resulting in the continued use of fossil fuels and increment in greenhouse gases. Therefore, the necessity to tackle these setbacks via biomass landfill biogas production, a renewable energy system from wastes cannot be overemphasized. This study examined the optimal anaerobic digestion processes of a pilot-scale bio-digesters for emulating landfill conditions. Organic feedstock from variety of food waste, cow dung and distilled water were collected from cafeterias, restaurants, hotels, and households in Ikot Abasi metropolis and cattle range in Uyo, South South Nigeria. Segregation, characterization, homogenization, parametric tests, monitoring and extraction were carried out. These samples were digested using a bio-digester with parametric testing equipment. Different masses of feedstock ranging from 10 – 25 kg with two mix ratios of 1:1 and 2:1 each were employed. From the results, the hydraulic retention time (HRT) showed linearity with approximately 0.73 days per kg, a pH of 6.9 – 7.1 (predigestion), 6.7 – 6.8 (post-digestion) and mesophilic temperature of 22–33°C. Feedstock of 1:1 ratio had gas yield of 12 ml per kg whereas 1:2 ratio had 11.4 ml per kg. System pressure was respectively 0.16 Pa per day, 0.053 Pa per kg feedstock and 0.174 Pa per day, roughly 0.058 Pa per kg feedstock. It can be concluded that a positive correlation exists between feedstock mass and biogas yield with 1:1 ratio having a consistent advantage of 21-27% gas yield over the 2:1 ratio. The pilot-scale experiments also bridged the gap between laboratory-scale research and full-scale landfill applications, reducing greenhouse gas emissions and harnessing renewable energy. Keywords: Wastes, Energy crises, Biomass, Landfill, Feedstock, Pilot-scale International Journal of Advanced Scientific and Technical Research Available online on http://www.rspublication.com/ijst/index.html ISSN 2249-9954 Cite This Paper : Enefiok O. Usungurua, Akanimo U. Usungurua, Whyte A. Akpan, Aniekan E. Ikpe and Uchechi E. Iroekwe (2025). "ANAEROBIC EXPERIMENTATION TO DETERMINE KEY PARAMETERS FOR OPTIMAL PERFORMANCE OF A PILOT SCALE BIO-DIGESTER FOR EMULATING LANDFILL CONDITIONS AND GAS RECOVERY". INTERNATIONAL JOURNAL OF ADVANCED SCIENTIFIC AND TECHNICAL RESEARCH (IJASTR), vol. 15, no. 5, 2025, pp. 257-272. DOI: https://dx.doi.org/10.5281/zenodo.17285090 International Journal of Advanced Scientific and Technical Research ISSN 2249-9954 Available online on http://www.rspublication.com/ijst/index.html volume 15, No. 5, 2025 DOI: 10.5281/zenodo.17285090 Original Article ©2025 RS Publication, [email protected] 258 1. Introduction Anaerobic digestion is a complex biological process that has gained significant attention in recent years due to its potential for sustainable waste management and renewable energy production. This process, which occurs in the absence of oxygen, involves the breakdown of organic matter by microorganisms, resulting in the production of biogas, primarily composed of methane (CH 4 ) and carbon dioxide (CO 2 ) (Bewani et al., 2025; Ikpe et al., 2025). In the context of landfill management and gas recovery, achieving optimal anaerobic digestion processes are crucial for developing efficient and environmentally friendly waste treatment solutions. The increasing global concern over greenhouse gas emissions, coupled with the growing need for alternative energy sources, has led to a renewed interest in harnessing the potential of landfill gas (LFG) as a valuable resource. Landfills, which are essentially largescale anaerobic systems, produce significant amounts of CH 4 that can be captured and utilized as a renewable energy source (Ebunilo et al, 2018; Ikpe et al., 2020). However, the complex and heterogeneous nature of landfills presents challenges in optimizing gas production and recovery. To address the challenges associated with anaerobic digestion processes in landfill environments, researchers in this field have turned to pilot-scale bio-digesters. These experimental setups allow for controlled studies of key parameters that influence the performance of anaerobic digestion systems, providing adequate knowledge that can be applied to full-scale landfill operations (Eronmosele et al., 2020; Horchani & Koubaa, 2025). The use of pilot-scale bio-digesters for emulating landfill conditions offers several advantages. Firstly, it allows for the manipulation and monitoring of various operational parameters in a controlled environment, which is not feasible in actual landfills. Secondly, it provides a cost-effective means of testing different waste compositions, environmental conditions, and treatment strategies without the risks associated with full-scale implementation. Lastly, pilot-scale experiments can generate data that bridges the gap between laboratory-scale studies and realworld applications, enhancing the reliability and scalability of research findings (Ikpe et al., 2024; El-Sheikh et al., 2025). Key parameters that influence the performance of anaerobic digestion systems in landfill-like conditions include substrate composition and characteristics, pH and alkalinity, temperature, moisture content, organic loading rate, hydraulic retention time (HRT), nutrient balance, presence of inhibitory substances and microbial community structure and dynamics (Gabanki et al., 2025; Griggs et al., 2025; Grobelak et al., 2025). Understanding the interplay between these parameters is crucial for optimizing biogas production and recovery in landfill environments. For instance, the composition of the waste substrate can significantly affect the rate and extent of anaerobic degradation, as well as the quality of the produced biogas (Ikpe et al., 2019; Kabeyi et al., 2025; Kamboj et al., 2025). Similarly, maintaining appropriate pH levels and temperature ranges is essential for supporting the growth and activity of diverse microbial communities responsible for the different stages of anaerobic digestion (Kim et al., 2025; Makondo et al., 2025). Furthermore, the moisture content of the waste mass plays a critical role in facilitating the transport of nutrients and microorganisms, as well as the removal of inhibitory substances. Optimizing the organic loading rate and hydraulic retention time can help maximize biogas production while preventing system overload and instability (Latinwo International Journal of Advanced Scientific and Technical Research ISSN 2249-9954 Available online on http://www.rspublication.com/ijst/index.html volume 15, No. 5, 2025 DOI: 10.5281/zenodo.17285090 Original Article ©2025 RS Publication, [email protected] 259 et al., 2015, Perera et al., 2025). In recent years, advances in molecular biology techniques have enabled researchers to gain deeper insights into the complex microbial ecology of anaerobic digestion systems. Determining the structure and dynamics of microbial communities in these environments is crucial for developing strategies to enhance biogas production and process stability (Wang et al., 2019; Kasinath et al., 2021; Angelidaki et al., 2023). This study sets the stage for an in-depth exploration of anaerobic experimentation using pilot-scale bio-digesters to determine key parameters for optimal performance in emulating landfill conditions and gas recovery, through practical investigation of these parameters and their interactions. From the findings obtained, researchers can develop more efficient and sustainable strategies for landfill management and biogas utilization, contributing to the broader goals of waste reduction, renewable energy production, and environmental protection. 2. Materials and Methods 2.1. Materials The various materials used in the course of the experimental procedure in this study are stated as follows: a. Samples: Organic feedstocks such as food waste, waterleaf, Cow dung and distilled water. Variety of food waste were used during the experiment. These included the following: Soya beans, Rice, Cocoyam, Cooked Plantain, Semovita, Cooked Banana and Fufu. Samples of Cow dung co-digested during the experimental process of this study was collected from a Cattle range in Uyo, Akwa Ibom State. The food wastes were sourced from different Cafeterias, Restaurants, Hotels, households in Ikot Abasi metropolis and its environs. b. Apparatus: A pH meter, stainless bowel, rubber hose, gas cylinder, ball valves, pressure gauge, thermometer, weighing scale and 100 liters Bio-digester designed with mild steel 2.2. Methods Figure 1 shows the experimental setup for anaerobic digestion to optimize a pilot-scale biodigester emulating landfill conditions for gas recovery features including a Bio-digester as the central unit where organic feedstock undergoes anaerobic decomposition. A Temperature Gauge and Pressure Gauge monitor internal conditions to ensure optimal microbial activity and gas production. The Inlet Valve allows feedstock introduction, while a Gas Hose connected to a Filter extracts biogas, removing impurities. A Hand Compressor with a Crank aids in mixing or pressure regulation, and a Gas Cylinder stores the collected biogas. This setup supports key parameter testing (e.g., temperature, pressure, retention time) to enhance gas yield and emulate landfill processes. A pH meter was used for measuring the pH of feedstock before, during and after digestion of organic feedstock. International Journal of Advanced Scientific and Technical Research ISSN 2249-9954 Available online on http://www.rspublication.com/ijst/index.html volume 15, No. 5, 2025 DOI: 10.5281/zenodo.17285090 Original Article ©2025 RS Publication, [email protected] 260 Figure 1: Experimental setup for anaerobic digestion The experimental procedure is illustrated in Figure 2. The flow chart outlines the experimental process for anaerobic digestion to optimize a pilot-scale bio-digester emulating landfill conditions for gas recovery. It begins with the Collection of Feedstock, followed by Segregation of Feedstock to separate components, and Characterization of Organic Feedstock to assess properties. Next, Preliminary Testing (pH, Mix Ratio, etc.) determines initial conditions, leading to Homogenization/Mixing of Organic Feedstock for uniformity. Further Mixing, Pouring into Bio-digesters, and Proper Sealing prepares the setup, while Observing Initial Bio-Digester Temperature and Pressure monitors early conditions. Concurrently, Monitoring Process Condition for Biogas Yield tracks performance, and Observation and Extraction of Biogas concludes with gas collection. This systematic approach identifies key parameters like pH, mix ratio, and retention time for optimal bio-digester efficiency. Figure 2: Flow chart showing experimental procedures for anaerobic digestion International Journal of Advanced Scientific and Technical Research ISSN 2249-9954 Available online on http://www.rspublication.com/ijst/index.html volume 15, No. 5, 2025 DOI: 10.5281/zenodo.17285090 Original Article ©2025 RS Publication, [email protected] 261 3. Results and Discussions In this study, the results obtained from the anaerobic experimentation to determine key parameters for optimal performance of a pilot scale bio-digester for emulating landfill conditions and gas recovery are presented in Table 1-4. Table 1: Biogas yield from 25 kg of organic waste Mix Ratio 1:1 Mix Ratio 2:1 HRT Biogas Yield (ml ) Pressure (Pa) pH before Digestion Biogas Yield (ml) Pressure (Pa) pH after Digestion Temperature ( o C) 14 10 0.2 7.1 30 0.4 6.7 22 15 20 0.3 25 0.36 23 16 25 0.34 25 0.35 24 17 30 0.4 2 5 0.45 29 18 30 0.4 23 0.32 29 19 30 0.4 20 0.3 29 20 40 0.5 20 0.3 32 21 45 0.55 3 5 0.34 33 22 35 0.46 30 0.4 32 23 30 0.39 25 0.35 31 24 30 0.4 25 0.35 31 25 25 0.34 20 0.3 24 26 25 0.35 20 0.3 24 27 15 0.24 20 0.3 22 28 15 0.24 15 0.25 22 29 10 0.2 15 0.25 22 30 10 0.2 10 0.2 22 Total 425 5.91 383 5.52 Table 2: Biogas yield from 20 kg of organic waste Mix Ratio 1:1 Mix Ratio 2:1 HRT Biogas Yield (ml) Pressure (Pa) pH before Digestion Biogas Yield (ml) Pressure (Pa) pH after Digestion Temperature ( o C) 14 10 0.2 7.0 10 0.2 6.7 22 15 20 0.3 14 0.24 23 16 30 0.4 20 0.3 29 17 40 0.5 30 0.4 32 18 35 0.45 34 0.45 31 19 35 0.45 33 0.42 31 20 33 0.42 32 0.43 31 21 31 0.41 25 0.34 31 22 30 0.4 25 0.34 30 23 26 0.36 23 0.33 26 24 20 0.3 18 0.29 23 25 19 0.28 15 0.25 22 26 15 0.25 14 0.24 22 27 10 0.2 10 0.2 22 Total 354 4.82 303 4.43 International Journal of Advanced Scientific and Technical Research ISSN 2249-9954 Available online on http://www.rspublication.com/ijst/index.html volume 15, No. 5, 2025 DOI: 10.5281/zenodo.17285090 Original Article ©2025 RS Publication, [email protected] 262 Table 3: Biogas yield from 15 kg of organic waste Mix Ratio 1:1 Mix Ratio 2:1 HRT (Days) Biogas Yield (ml) Pressure (Pa) pH before Digestion Biogas Yield (ml) Pressure (Pa) pH after Digestion Temperature ( o C) 14 10 0.2 6.9 10 0.2 6.8 22 15 26 0.36 20 0.3 25 16 30 0.4 24 0.35 29 17 40 0.49 30 0.4 32 18 37 0.46 30 0.4 31 19 35 0.45 25 0.34 30 20 29 0.4 23 0.33 28 21 24 0.35 20 0.3 25 22 14 0.24 14 0.24 23 23 10 0.2 10 0.18 22 Total 255 3.45 204 3.04 Table 4: Biogas yield from 10 kg of organic waste Mix Ratio 1:1 Mix Ratio 2:1 HRT (Days) Biogas Yield (ml) Pressure (Pa) pH before Digestion Biogas Yield (ml) Pressure (Pa) pH after Digestion Temperature ( o C) 13 12 0.22 7.0 10 0.2 6.7 22 14 23 0.33 18 0.28 24 15 27 0.38 24 0.35 26 16 30 0.4 25 0.36 31 17 28 0.38 20 0.3 27 18 19 0.30 10 0.2 23 19 12 0.21 8 0.18 22 Sum 151 2.22 115 1.87 Figure 3 is a horizontal bar chart illustrating the relationship between different weights of organic feedstock (10 kg, 15 kg, 20 kg, and 25 kg) and their corresponding hydraulic retention times (HRT) in days (19 days, 23 days, 27 days, and 30 days) within the context of an anaerobic experimentation setup. The information on the chart was obtained from Tables 1-4, which were measured from the experimental setup. This setup was designed to determine key parameters for optimal performance in a pilot-scale bio-digester that emulates landfill conditions, with a focus on biogas (primarily methane) recovery. The y-axis labels the feedstock weights in ascending order from bottom to top (10 kg at the bottom, 25 kg at the top), while the x-axis represents HRT in days, ranging from 0 to 30 in increments of 5. Each bar, filled in blue, extends rightward to indicate the HRT value for that specific feedstock weight, showing a clear trend of increasing HRT as feedstock mass increases. Key observations from the chart in Figure 3 are highlighted as follows: i. 10 kg feedstock: The bar extends to approximately 19 days, indicating the shortest HRT among the tested masses. ii. 15 kg feedstock: The bar reaches about 23 days, showing a moderate increase. International Journal of Advanced Scientific and Technical Research ISSN 2249-9954 Available online on http://www.rspublication.com/ijst/index.html volume 15, No. 5, 2025 DOI: 10.5281/zenodo.17285090 Original Article ©2025 RS Publication, [email protected] 263 iii. 20 kg feedstock: The bar goes to roughly 27 days, further extending the retention period. iv. 25 kg feedstock: The bar hits around 30 days, the longest HRT in the dataset. a. Relationship between Feedstock Mass and HRT The relationship depicted is positive and nearly linear: as the mass of organic feedstock increases, the HRT also increases. This implies that higher feedstock loads require longer retention times to achieve optimal digestion and gas recovery in the bio-digester system emulating landfill conditions. To quantify this: i. The increment in feedstock mass is consistent at 5 kg intervals (from 10 to 15 kg, 15 to 20 kg, and 20 to 25 kg). ii. Corresponding HRT increases are 4 days (19 to 23), 4 days (23 to 27), and 3 days (27 to 30), averaging about 3.67 days per 5 kg increase (or roughly 0.73 days per kg). iii. Overall, from 10 kg to 25 kg (a 15 kg increase), HRT rises by 11 days (from 19 to 30), yielding a slope of approximately 0.73 days per kg if assuming a linear fit. b. Integration of Provided Parameters (pH and Temperature) The experiment's conditions of 6.9-7.1 pH before digestion, dropping to 6.7-6.8 after, and a temperature range of 22-33°C provide critical context for interpreting this relationship, as they influence microbial activity and digestion kinetics. pH Considerations i. Pre-digestion pH (6.9-7.1) is near neutral, ideal for introducing feedstock without immediate shocking the microbial community. This range supports initial hydrolysis by acid-forming bacteria. ii. Post-digestion pH (6.7-6.8) shows a slight decrease, which is typical in anaerobic systems due to VFA production during acidogenesis. However, it remains within the optimal range for methanogens (generally 6.5-7.5), indicating good buffering capacity (possibly from inherent feedstock alkalinity or amendments not specified). If HRT were too short for higher masses, VFAs could accumulate excessively, dropping pH below 6.5 and causing "sour" digester failure (inhibited methane production). The increasing HRT with mass likely prevents this by allowing more time for VFA consumption, maintaining pH stability and enabling consistent gas recovery across all loads. iii. In landfill-emulating bio-digesters, stable pH is crucial for simulating long-term waste stabilization, where uncontrolled acidification can reduce gas yields by 20-50% in poorly managed systems. Temperature Considerations i. The 22–33°C range falls within the mesophilic regime (typically 20-40°C), where mesophilic bacteria thrive at moderate rates without the energy inputs needed for thermophilic systems (50-60°C). This is energy-efficient for pilot-scale setups emulating ambient landfill temperatures, which often vary seasonally but average around 25-35°C due to exothermic decomposition. ii. At lower temperatures (e.g., 22°C), reaction rates slow, necessitating longer HRT to achieve similar degradation levels-aligning with the chart's trend of extended retention for higher masses. Conversely, at the upper end (33°C), kinetics accelerate, but higher loads International Journal of Advanced Scientific and Technical Research ISSN 2249-9954 Available online on http://www.rspublication.com/ijst/index.html volume 15, No. 5, 2025 DOI: 10.5281/zenodo.17285090 Original Article ©2025 RS Publication, [email protected] 264 still require more time to handle increased substrate volume without overwhelming the system. iii. Temperature fluctuations within this range could slightly affect the exact HRT needed; for instance, cooler conditions might amplify the need for longer retention to compensate for reduced microbial activity. Overall, this mesophilic setup promotes stable, cost-effective operation for gas recovery, with HRT adjustments ensuring optimal performance despite varying feedstock masses. c. Implications for Optimal Bio-Digester Performance Determining key parameters for a pilot-scale bio-digester emulating landfill conditions, the chart in Figure 3 highlights HRT as a scalable parameter tied to feedstock mass. For optimal gas recovery: i. Lower masses (e.g., 10 kg) allow shorter HRT (19 days), suitable for low-load scenarios with faster turnover and potentially higher daily gas output per unit mass. ii. Higher masses (e.g., 25 kg) demand longer HRT (30 days) to avoid overload, ensuring complete digestion and maximizing cumulative biogas yield (typically 0.2-0.6 m³/kg volatile solids in mesophilic systems). iii. This relationship indicates the trade-off in bio-digester design: shorter HRT improves throughput but risks instability at high loads, while longer HRT enhances reliability and gas quality (higher methane content) but reduces capacity. iv. Considering the pH stability and mesophilic temperatures, the system appears welloptimized, with no signs of inhibition. For real-world landfill emulation, these findings could inform scaling: e.g., HRT should be adjusted proportionally to waste input to sustain 50-70% methane in recovered gas, reducing greenhouse emissions compared to uncontrolled landfills. Figure 3: Relationship between masses of organic feedstock and corresponding HRT in days Figure 4 graphically illustrates a horizontal grouped bar chart depicting the cumulative biogas yield (in ml) for two different mix ratios of water to organic feedstock, 2:1 (orange bars) and 0 5 10 15 20 25 30 25 Kg of feedstock 20 Kg of feedstock 15 Kg of feedstock 10 Kg of feedstock HRT (Days) Weight of Feedstock International Journal of Advanced Scientific and Technical Research ISSN 2249-9954 Available online on http://www.rspublication.com/ijst/index.html volume 15, No. 5, 2025 DOI: 10.5281/zenodo.17285090 Original Article ©2025 RS Publication, [email protected] 265 1:1 (blue bars) across varying feedstock masses (10 kg, 15 kg, 20 kg, and 25 kg). This data appears to stem from the same anaerobic experimentation context as previously discussed, aimed at optimizing parameters for a pilot-scale bio-digester that emulates landfill conditions for enhanced gas recovery. The y-axis categorizes the feedstock masses in ascending order from bottom to top (10 kg at the bottom, 25 kg at the top), while the x-axis measures cumulative biogas yield from 0 to 450 ml in increments of 50 ml. For each feedstock mass, two bars are presented side-by-side: orange for the 2:1 mix ratio (more diluted, higher water content) and blue for the 1:1 mix ratio (less diluted, higher substrate concentration). These results indicate consistent patterns: higher feedstock masses produce greater absolute biogas yields for both ratios, and the 1:1 ratio outperforms the 2:1 ratio across all masses. The bars are uniformly styled, emphasizing direct comparisons within and across categories. a. Relationship between Mix Ratios, Feedstock Mass, and Cumulative Biogas Yield Figure 4 illustrates two primary relationships: (1) a positive correlation between feedstock mass and biogas yield for each mix ratio, and (2) a consistent advantage of the 1:1 water-to-feedstock ratio over the 2:1 ratio in terms of yield, with the gap widening slightly at higher masses. These trends are analysed in this study, with respect to the context of anaerobic digestion principles, where biogas (primarily methane and carbon dioxide) is produced through microbial breakdown of organic matter in oxygen-free conditions. b. Effect of Feedstock Mass on Biogas Yield In Figure 4, as feedstock mass increases from 10 kg to 25 kg, cumulative biogas yield rises proportionally for both mix ratios. This is expected, as greater organic mass provides more substrate (volatile solids) for microbial degradation, leading to higher gas production. The relationship appears nearly linear: i. For the 2:1 ratio: Yield increases by 40 ml (10 to 15 kg), 60 ml (15 to 20 kg), and 70 ml (20 to 25 kg), averaging 57 ml per 5 kg increment (or 11.4 ml per kg). ii. For the 1:1 ratio: Yield increases by 40 ml (10 to 15 kg), 60 ml (15 to 20 kg), and 80 ml (20 to 25 kg), averaging 60 ml per 5 kg increment (or 12 ml per kg). iii. Overall slope: From 10 kg to 25 kg (15 kg increase), yields rise by 170 ml for 2:1 (110 to 280 ml) and 180 ml for 1:1 (140 to 320 ml), yielding approximate linear fits of Yield (2:1) 40 + 11.3 × mass (kg) and Yield (1:1) 70 + 12 × mass (kg). The slight acceleration at higher masses (larger increments) may indicate economies of scale, where larger loads enhance microbial synergies or heat retention in the digester, boosting efficiency. c. Implications for Bio-Digester Performance In a pilot-scale system emulating landfill conditions (slow, layered decomposition), higher masses mimic denser waste accumulation, potentially increasing gas recovery potential. However, without corresponding adjustments (e.g., to hydraulic retention time, as noted in prior analysis: 19 days for 10 kg, up to 30 days for 25 kg), overload could occur. The increasing yields suggest the experiment maintained stability, allowing full substrate utilization. Absolute yields are modest (e.g., 11-13 ml/kg for 1:1), typical for lab/pilot scales with organic waste under mesophilic conditions, but scalable to landfill scenarios where yields can reach 100-200 ml/kg volatile solids over longer periods (Ikpe et al., 2023). International Journal of Advanced Scientific and Technical Research ISSN 2249-9954 Available online on http://www.rspublication.com/ijst/index.html volume 15, No. 5, 2025 DOI: 10.5281/zenodo.17285090 Original Article ©2025 RS Publication, [email protected] 272 Griggs, A. T., Roulier, A., Granda, N. A., & Burek, J. (2025). 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