Increase In Biogas Production Research Articles

Improvement of COD removal and biogas production from landfill leachate using bio-synthesized iron nanoparticles, sludge and FeCl3

Leftover sludge from landfill treatment is typically rich in ferrous chemical compounds, whose recovery can often be used to enhance the performance of anaerobic bioreactors. This investigation examines the biosynthesis of iron nanoparticles (Fe-NPs) from the sludge residue derived from landfill leachate treatment, and then assesses their performance as micronutrient supplements for fermentation, alone and in combination with other additives, specifically FeCl3 with sludge. The preparation of Fe-containing sludge through landfill leachate treatment involved reaching optimal recovery of Fe and its biosynthesis via black tea waste extract. The bio-synthesized Fe-NPs were then fully characterized using a vast range of analytical techniques such as ultraviolet-visible (UV–vis) spectroscopy, X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), and energy dispersive X-ray (EDX) analysis. The bio-synthesized NPs presented a chain and spherical structure with a diameter of 13–150 nm, and the alignment and adjustment of the biosynthesis process were close to those resulting from our predictive model. The anaerobic digestion trials led to COD removal of 73.64 % and increased biogas production by 69.85 % compared to the control bioreactor, under the optimal conditions of Fe-NPs, sludge, and fresh FeCl3 at the concentrations of 17.06, 0.28 and 1.46 mg/L, respectively. In conclusion, the addition of trace elements not only reduced the anaerobic digestion’s lag phase, but it also minimized the time to reach the peak of biogas production. Using a combined physicochemical-biological process is a cost-effective and eco-friendly technique for sludge disposal and energy production from treated leachate.

Enhancing anaerobic digestion efficiency in dairy waste water treatment: a comprehensive review of enzyme-based pre-treatment by microorganisms in South Africa

ABSTRACT The escalating global demand for dairy products due to population growth has led to increased production in the dairy industry, resulting in a significant rise in wastewater generation. This wastewater, laden with contaminants such as fats, oils, and greases (FOGs), biological oxygen demand (BOD), chemical oxygen demand (COD), nitrogen, and phosphorus, poses a threat to freshwater sources. Anaerobic digestion (AD) is considered the optimal treatment method for dairy wastewater, but the high-fat content poses challenges like reactor clogging. To overcome this, various authors propose and implement an enzymatic pre-treatment strategy that improves FOG and organic content removal, increases biogas production, and addresses economic and environmental concerns. Despite the proven efficacy of enzymatic pre-treatment, a significant drawback is the associated cost. However, it remains a promising strategy for enhancing the biodegradability of complex organic compounds in dairy effluents. This review delves into the crucial role of enzyme-producing microorganisms in enhancing AD efficiency for dairy wastewater treatment, emphasizing their potential benefits and addressing the economic and environmental considerations associated with this approach.

A novel additive for enhancing biomass energy production from agro-industrial wastes: synthesis of hydrophobic nanoporous silica aerogel and its effect on methane production

AbstractAnaerobic digestion (AD) is one of the most preferred processes for the treatment of organic waste. However, additional processes such as co-digestion, pretreatment, and additive addition continue to be explored to remove the limits on the applicability of AD. This study investigated the effects of hydrophobic nanoporous silica aerogel (NpSA) synthesized from waste rice husks on the anaerobic co-digestion (AnCD) of the mixture consisting of sewage sludge and fruit processing industry wastes. All bioreactors containing NpSA-free, 0.1 g, 0.2 g, 0.5 g, and 1 g NpSA (0.03–0.3 gNpSA/gVSadded) were operated in a mesophilic-batch process. Biogas and methane yields increased from 346 mL/gVS (NpSA-free) to 387 mL/gVS and from 231 mL/gVS (NpSA-free) to 288 mL/gVS, respectively, with 0.1 g NpSA addition. NpSA additive increased biogas production in all bioreactors compared to the blank. However, biogas production rate and methane content increased faster at lower doses of NpSA. Maximum soluble chemical oxygen demand (sCOD), protein, carbohydrate, and volatile solid (VS) reductions were between 45–71%, 35–54%, 44–65%, and 34–91% for NpSA added mixtures, respectively. The hydrophobic NpSA additive was effective in improving the AnCD performance and biogas/methane production. Experimental results fit the kinetic models frequently preferred in such AD processes. In addition, the possible energy and financial potential of the produced methane were also discussed, and it was determined that the direct sale of methane gas produced by the addition of NpSA in the global market could provide 1.4 $/Lmixture more financial gain than the mixture NpSA-free. Graphical Abstract

Coupling of biogas residue biochar and low-magnitude electric fields promotes anaerobic co-digestion of sewage sludge and food waste.

Biochar-assisted anaerobic digestion (AD) remains constrained due to the inefficient decomposition of complex organics, even with the direct interspecies electron transfer (DIET) pathway. The coupling of electrochemistry with the anaerobic biological treatment could shorten lengthy retention time in co-digestion by improving electron transfer rates and inducing functional microbial acclimation. Thus, this work investigated the potential of improving the performance of AD by coupling low-magnitude electric fields with biochar derived from the anaerobically digested biogas residue. Different voltages (0.3, 0.6, and 0.9 V) were applied at various stages to assess the impact on biochar-assisted AD. The results indicate that an external voltage of 0.3 V, coupled with 5 g/L of biochar, elevates CH4 yield by 45.5% compared to biogas residue biochar alone, and the coupled approach increased biogas production by up to 143% within 10 days. This finding may be partly explained by the enhanced utilization of substrates and the increased amounts of specific methanogens such as Methanobacterium and Methanosarcina. The abundance of the former increased from 4.0 to 11.3%, which enhances the DIET between microorganisms. Furthermore, the coupling method shows better potential for enhancing AD compared to preparing iron-based biochar, and these results present potential avenues for its broader applications.

Cavitation assisted intensification of biogas production: A review

AbstractIntensified cavitation‐assisted biogas production from sustainable feedstock has been discussed describing the working principles and governing mechanisms for intensification. Various methods of biogas production discussed in the work include activated sludge processes, membrane bioreactor (MBR), and processes involving methanogenic and sulfate‐reducing microorganisms. Design aspects of cavitational reactors (sonochemical and hydrodynamic cavitation) have been presented with detailed understanding into effect of several operational parameters, such as the biomass‐to‐water ratio, operating pressure, treatment duration, operating temperature, power dissipation, and so on. Selection of optimum parameters is crucial to improve the performance and observed intensification from such processes. The possible benefits in terms of applicability to various types of biomass, efficiency, higher yields, and energy‐saving as compared to the conventional production processes have been demonstrated. Overall, cavitation‐assisted techniques are very effective in increasing biogas production and have significant potential for commercial applications, which would result in significant cost savings.

Peningkatan Kapasitas Digester Untuk Kecukupan Produksi Biogas Sebagai Bahan Bakar Generator Listrik

The development of dairy farming in Nagari Lasi District Canduang, Agam Regency, West Sumatra Province, has provided the materials a massive source of biogas production. The number of cattle in Nagari Lasi has reached around 1000 heads, plus other livestock such as Buffaloes and Goats. The manufacture of digesters in the previous year's Community service activities was a success. It produces biogas and is used for cheese production and household supply. However, the amount of biogas produced is still tiny. To realize "Community-Independent Energy," power generator installation is necessary. The biogas supply must be in large quantities and available continuously for the generator to operate. Biogas currently produced by the digester is insufficient to produce the biogas required by the generator. Therefore, biogas production capacity needs to be improved by expanding the volume of the digester that will be processing cow dung into biogas. Increasing digester capacity has significantly increased biogas production, reaching 12 m3 per day. This amount is enough to be used as fuel for an electric generator continuously.

Towards a sustainable energy future: Evaluating Arundo donax L. in continuous anaerobic digestion for biogas production

AbstractIn response to the EU's REPowerEU initiative (COM (2022) 108) which encourages an increase in biogas production by 20% in member states by 2030 to boost energy independence, it has become essential to identify sustainable alternatives to traditional feedstocks for biogas production, especially in the EU Member states where there is still high dependence on corn silage as the main raw material in biogas plants. While corn silage, predominantly used in the European biogas plants today, serves primarily for the livestock sector, alternative sources need to be explored. Therefore, this study aimed to evaluate the potential of Arundo donax, a perennial energy crop, as an alternative feedstock in a continuous anaerobic process. The biogas yield and its quality, characterized by CH4, CO2, H2S and O2 content, were determined during a continuous process with A. donax, compared with two mixed feedstocks of A. donax and corn silage over a 5‐month period in a continuous anaerobic digestion process. The results revealed that A. donax exhibits a biogas yield and methane content comparable to corn silage, indicating its potential as a viable and sustainable alternative feedstock for biogas production.

BIOGAS PRODUCTION POTENTIAL FROM ANAEROBIC CO-DIGESTION OF FOOD WASTE AND ANIMAL MANURE

The potential of biogas production by the anaerobic codigestion (AcoD) of canteen food waste and animal manure was investigated using the biochemical methane potential assay (BMP). The BMP assay was conducted under thermophilic temperature of 35 °C in a batch process at digestion time of 40 d. Waste substrate mixture was digested at a fixed proportion of 1:1 with different animal manure as co-substrate. Maximum cumulative biogas production (418 ml g-1 VS) was achieved during codigestion of food waste with pig manure > chicken manure (408 ml g-1 VS) > goat manure (319 ml g-1 VS). Generally, all manure codigested reactors produced 1.01 to 1.34 times more biogas than food waste alone indicating the synergistic effect of codigestion on overall biogas productivity. With analogous increase in biogas production, manure amendment produced significant (p<0.05) substrate biodegradation in terms of total and volatile solids loss. The microbial load profile prior and post-AD revealed significant reduction (p<0.05)in microbial species suggestion that anaerobic digestion can be adopted as a method of waste treatment and hygienization.

Temperature drives microbial communities in anaerobic digestion during biogas production from food waste.

Resource depletion and climate changes due to human activities and excessive burning of fossil fuels are the driving forces to explore alternatives clean energy resources. The objective of this study was to investigate the potential of potato peel waste (PPW) at various temperatures T15 (15°C), T25 (25°C), and T35 (35°C) in anaerobic digestion (AD) for biogas generation. The highest biogas and CH4 production (117mL VS-g and 74mL VS-g) was observed by applying 35°C (T35) as compared with T25 (65mL VS-g and 22mL VS-g) on day 6. Changes in microbial diversity associated with different temperatures were also explored. The Shannon index of bacterial community was not significantly affected, while there was a positive correlation of archaeal community with the applied temperatures. The bacterial phyla Firmicutes were strongly affected by T35 (39%), whereas Lactobacillus was the dominant genera at T15 (27%). Methanobacterium and Methanosarcina, as archaeal genera, dominated in T35 temperature reactors. In brief, at T35, Proteiniphilum and Methanosarcina were positively correlated with volatile fatty acids (VFAs) concentration. Spearman correlation revealed dynamic interspecies interactions among bacterial and archaeal genera; facilitating the AD system. This study revealed that temperature variations can enhance the microbial community of the AD system, leading to increased biogas production. It is recommended for optimizing the AD of food wastes.

INFLUENCE OF SUBCRITICAL WATER PRETREATMENT TEMPERATURE ON PINEAPPLE WASTE BIOGAS EFFICIENCY: EXPERIMENTAL AND KINETIC STUDY

Anaerobic digestion of pineapple waste appears to be an effective method for non-renewable energy substitution through biogas production. The potential power generation from the exploitation of pineapple waste as fuel is estimated to be roughly 20.8 MW. Nevertheless, the intricate composition of pineapple waste, characterized by the complex arrangement of its structure, poses a significant challenge in attaining a substantial amount of biogas production. This study pretreated pineapple waste with subcritical water to increase biogas production. Two temperature settings (120⁰C and 200⁰C) were used for pretreatment. Combined pre-treatment at low temperatures and short time (120⁰C, 5 minutes, 10 water to solid ratio) resulted in 31.6% higher biogas production than untreated. However, pretreatment at high temperatures and longer reaction time (200⁰C,25 min) reduced the biogas production by 9% as compared to untreated. Using the Modified Gompertz kinetic model, pretreatment improved the lag phase and increased biogas production to 14.41 mL/day. The lignocellulosic composition of pre-treated pineapple waste decreased, while process parameters such as total ammonia nitrogen removal and pH improved after the pretreatment. Subcritical water pretreatment, particularly when conducted at high temperatures, did not yield any enhancements in the anaerobic digestion of pineapple waste. As a result, it is not advisable to employ this method for these purposes.

Insights into anaerobic digestion of microalgal biomass for enhanced energy recovery

This review paper delves into the intricate challenge of transforming microalgal biomass into biofuel through anaerobic digestion, elucidating its significance for sustainable energy production and waste management. Despite the promise anaerobic digestion holds, obstacles like inhibitory substances, process stability issues, and residue management complexities persist. Microalgal biomass, characterized by high biogas yields and carbon sequestration potential, emerges as a viable solution to enhance anaerobic digestion efficiency. Employing a comprehensive literature selection process, the review synthesizes recent studies to shed light on breakthroughs and pinpoint areas for future investigation. Key findings underscore advancements in microalgal biomass utilization, with strategic strain selection and innovative pretreatment methods resulting up to 25% increase in biogas production. Additionally, the assimilation of co-digestion techniques yields enhanced overall process efficiency. Microalgal biomass demonstrates remarkable carbon sequestration capabilities, sequestering up to 60% of CO2 during the anaerobic digestion process. Furthermore, the analysis reveals that despite inhibitory substances posing challenges, innovative approaches have reduced inhibition by 15%, promoting more stable and efficient digestion. Implications of the review findings stress the need to scale laboratory successes to industrial applications while maintaining environmental sustainability. Identified gaps include challenges in inhibitory substance management and process stability, with future research directions advocating for multidisciplinary approaches to unlock the full potential of microalgal biomass in anaerobic digestion. In conclusion, the review contributes significantly to understanding the intricate relationship between microalgal biomass and anaerobic digestion, highlighting the importance of continued research and development to address existing challenges and advance towards a more regenerative bioeconomy.

ACIDIC-ENZYMATIC CO-TREATMENT OF FOOD WASTE FOR HIGH SUGAR RECOVERY AND BIOGAS PRODUCTION

Food-waste (FW) has a high content of fermentable sugar which can be exploited to generate an alternative source of fuel that could replace fossil fuels. Anaerobic digestion (AD) is an approach to convert organic-waste into high-value products like biomethane and hydrogen. However, hydrolysis is deemed to be a rate-limiting process in the AD process, limiting biogas production. This study seeks to improve the hydrolysis process through pre-treating FW with chemical and biological treatments. We show that the enzymatic treatment substantially improved the hydrolyzation and solubilization of food waste, resulting in a three folds increase in biogas production compared to untreated food waste. A co-treatment of biological and enzymatic treatments significantly improved the hydrolysis process, solids reduction, and solubilization of the substrate. The soluble chemical oxygen demand (SCOD) and reducing sugar were increased by 50% and 25% respectively, compared to enzymatically treated only. However, the inhibitory effect of accumulated salts from the treatment has limited the application of anaerobic digestion. Our results reveal that using enzymatic and acidic pre-treatment can significantly enhance hydrolysis of FW to increase biogas production, highlighting the potential of AD.

Optimisation and economic analysis of industrial-scale anaerobic co-digestion (ACoD) of palm oil mill effluent (POME) and decanter cake (DC) using machine learning models: A comparative study of Gradient Boosting Machines (GBM), K-nearest neighbours (KNN), and random forest (RF)

The anaerobic co-digestion (ACoD) of palm oil mill effluent (POME) with decanter cake (DC), has been proposed as a solution to enhance biogas production in industrial-scale anaerobic covered lagoon systems. Despite the potential of ACoD, there is a limited exploration of machine learning techniques, such as Gradient Boosting Machines (GBM), K-nearest neighbours (KNN), and Random Forest (RF), specifically in the context of industrial-scale facilities and anaerobic co-digestion. In this study, these machine learning techniques were employed to develop prediction models for biogas production and BOD removal using three months of operational data from a local biogas plant, with GBM yielding the highest prediction accuracy (R2 = 0.9940, MAE = 0.0101, RMSE = 0.1438). Subsequently, GBM was used in the optimisation process to determine the optimal conditions for temperature, pH, and dilution ratio of DC in the anaerobic digester. The optimal conditions were found to be 40 °C, 7.1, and 0.11, respectively, representing a 21.58 % and 26.03 % increase in biogas production and BOD removal. This integrated approach provides a sustainable solution for maintaining year-round biogas production even when the supply of POME is limited, thereby contributing to renewable energy generation and waste management in the palm oil industry.

Effect of direct enzyme addition on the anaerobic digestion of OFMSW

The organic fraction of municipal solid waste (OFMSW) has high biodegradability and is a good feedstock for anaerobic digestion (AD). However, the solubilization of OFMSW is a limiting factor for AD. In this study, enzyme treatment was investigated to increase the conversion of complex materials of OFMSW into soluble fractions. Six different concentrations (0.15, 0.3, 0.5, 1.0, 1.5 and 3.0 mg/VSadded) of the alpha amylase enzyme (obtained from Aspergillus oryzae) were directly added as a powder and automated biochemical methane potential (BMP) tests were performed under thermophilic conditions. According to BMP tests, the methane (CH4) yield increased up to 17.5 % and the lag phase decreased to 19.3 % after enzyme addition. The highest CH4 yield and shortest lag phase were obtained when 0.5 mg of enzyme/VSadded was added to the reactor. These findings suggest that direct alpha amylase enzyme application obtained from Aspergillus oryzae can be used to increase biogas production by enhancing solubilization of OFMSW for AD.

Feeding strategy determine flexible biogas via shaping microbial abundance and interaction in anaerobic digestion

The optimization of anaerobic digestion systems for enhanced biogas production is reliant on the manipulation of feeding regimes and organic loading. However, the impact of these operations on the microbiota remains unclear. Here, the effects of three distinct feeding regimes (once daily, every 2nd day, and every 3rd day) with two different loading amounts (300 g and 500 g) were investigated in 2 continuously stirred tank reactors treating swine manure. Results indicated that the high organic loading (500 g daily feeding) resulted in increased biogas and methane production, albeit with reduced archaeal alpha diversity. Furthermore, a significant alteration in species distribution was observed with sudden feeding regime changes (300 g every 2nd day) and higher organic loading. Wherein, the core species determined the methane production regarding the different organic loading. The resultant species turnover likely drove the increased biogas production while species loss contributed to the fluctuation of biogas production in intermittent feeding regimes. Despite a decrease in positive connections with high organic loading, the connectivity of Methanosarcinaceae with bacteria increased, thus ensuring higher biogas production. In conclusion, the present study underscores the association between feeding strategies and elevated levels of organic loading with regards to the interdependence between methanogenic microorganisms and keystone bacterial populations. As a consequence, this interplay exerts a discernible influence on the biogas production process.

Environmental impact of sewage sludge co-digestion with food waste and fat-oil-grease: Integrating plant-wide modeling with life cycle assessment approach

Anaerobic co-digestion of fat-oil-grease (FOG) and food waste (FW) with sewage sludge (SS) in wastewater treatment plants is a method used to increase biogas production. In this study, digestion scenarios were compared using plant-wide modeling and life cycle assessment: Scenario-0 (mono-digestion of waste-activated sludge (WAS)), Scenario-1 (co-digestion of WAS with FOG), and Scenario-2 (co-digestion of WAS with FW). Scenario-0, with the highest energy use and landfilling of FOG/FW, has the worst environmental impact. Scenario-1 and Scenario-2 minimize the environmental load by energy recovery and avoiding landfilling of organic waste. Scenario-wise, the change in greenhouse gas (GHG) emissions from treatment was negligible. However, due to the impact of landfilling, GHG emissions in Scenario-0 were 21% and 30% higher than in Scenario-1 and 2, respectively. The environmental benefit of anaerobic co-digestion of FOG/FW with SS is not only in the contribution to energy production but also in the recycling of organic waste.

Anaerobic Co-Digestion of Cattle Manure and Brewer’s Residual Yeast: Process Stability and Methane and Hydrogen Sulfide Production

Anaerobic co-digestion (AcoD) of animal waste and agro-industrial by-products has been widely studied and employed to increase biogas production potential and enhance process stability. This study evaluated the AcoD of cattle manure (CM) and brewer’s residual yeast (RY) in semi-continuous biodigesters, focusing on energy potential (biogas and methane yields) and process stability. Four treatments were assessed, each with different proportions (% of volatile solids) of CM and RY: 100:0, 88:12, 78:22, and 68:32. Trials were conducted in 30-L tubular reactors at room temperature with a hydraulic retention time of 30 days. The inclusion of RY led to a gradual rise in biogas and methane production, with more significant reductions in solid content than mono-digestion of CM. The addition of RY resulted in daily CH4 production increases of 18.5, 32.3, and 51.9% for treatments with 12, 22, and 32% of RY, respectively, compared to the control treatment. Therefore, AcoD demonstrated a higher potential for energy recovery. However, RY introduced elevated H2S levels in the biogas. Caution is advised when adding this co-substrate to AcoD due to potential process influence and biogas application restrictions.

Potential of perennial sorghum for biogas production: Pretreatment with yeast-contained inoculants during anaerobic storage

To investigate the behind mechanism on microbial roles during anaerobic storage of forages for biogas production, inoculants with different ratios of exogenous Lactiplantibacillus plantarum and Saccharomyces cerevisiae were applied during anerobic storage of perennial sorghum. Yeast-contained inoculants increased biogas production of perennial sorghum by 3.81–11.70%. When the proportion of yeast in microbial inoculant increased, the lactic, acetic and butyric acid contents significantly increased (P < 0.01) across the anaerobic storage. Species of Levilactobacillus brevis was the dominant bacteria, while the growth of some pernicious fungi such as Candia and Hannaella were restricted in samples. An equal appliance of lactic acid bacteria and yeast reduced relative abundances of Weissella cibaria and L. plantarum and increased relative abundance of L. brevis of perennial sorghum. In conclusion, the appropriate inclusion of yeasts in the pretreatment process of perennial sorghum can effectively improve the pretreatment efficacy and thus increase the biogas production.

Determine the Optimal Parameters for Biogas Production from Common Reed (Phragmites australis)

A series of batch assays have been conducted to investigate the optimal factors that can be adopted to improve the anaerobic digestion (AD) performance of Phragmites australis and increase biogas production. The assays were carried out using 125 mL microcosm reactors with a working volume of 80 mL and incubated at mesophilic conditions (37 ± 1ºC). The effect of particle size (10, 5, 2, and < 1 mm) and alkaline pre-treatment of P. australis using various concentrations of sodium hydroxide (0.5, 1, 2, and 4%) on biogas production was examined. Furthermore, the best pre-treatment incubation time (12, 24, 48, 72, 96, and 120 h) and the optimal inoculum to substrate ratio (ISR: 4:1, 2:1, 1:1, 1:2 and 1:4) were also assessed. The results revealed that the highest biogas production from P. australis was achieved at particle size < 1 mm (27.97 ± 0.07 and 16.67 ± 0.09 mL/g VS added, for pre-treated and untreated P. australis respectively); 2% and 4% NaOH concentration for pre-treatment (70.01 ± 3.75 and 76.14 ± 2.62 mL/g VS added, respectively); pre-treatment incubation time of 72, 96, and 120 h (71.18 ± 1.79, 72.46 ± 1.08, and 73.78 ± 1.87 mL/g VS added, respectively); and ISR of 1:2 for pre-treated P. australis (78.21 ± 0.36 mL/g VS added) and ISR 1:4 for untreated P. australis (28.93 ± 1.55 mL/g VS added). Determining optimal parameters in this work would guide further development of process configurations, such as continuous AD systems.

Thermal and Electrical Analysis of N-PVT-FPC Hybrid Active Heating of Biogas Plant

Abstract In order to increase biogas production during winter months/cold climatic conditions, a self-sustained N-photovoltaic thermal and flat plate collector (PVT-FPC) hybrid active heating biogas plant has been analyzed in terms of thermal energy and electrical energy. A general analytical expression for thermal and electrical energy of the biogas plant has been derived as a function of climatic and design parameters from one order coupled differential equations. Various photovoltaic thermal and flat plate collector (N-PVT-FPC) configurations have been considered for optimizing maximum electrical and thermal energy gain for a given total number of N-PVT-FPC collectors. Based on mathematical computation for Indian cold climatic conditions, it has been found that the N-PVT-FPC combination is always better than the flat plate collector-photovoltaic thermal (N-FPC-PVT) collector for maximum electrical and thermal energy. Overall exergy analysis of hybrid active heating of biogas plants has also been carried out.