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Open research questions in Anaerobic Digestion and Biogas Production

441 gap statements mined from Anaerobic Digestion and Biogas Production papers in our 7.9M-paper local library, which holds 2,294 papers on the topic — drawn mostly from each paper's own stated research gap, future-work, challenge and limitation notes, and its abstract. The ones listed below are a selection still marked open; each names the study that raised it, with a DOI link where the paper has one.

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What the literature leaves open

  • There is a need to investigate the accumulation of heavy metals in plant biomass from mixed cultures. The study aims to fill this gap by assessing the use of a mixed cropping system for phytoremediation processes and methane production.

    Accumulation of Heavy Metals in Plant Biomass from the Mixed Culture of Zea Mays and Phaseolus Vulgaris, and Potential Biomass Use for Methane Production · 2026 · DOI

  • The lack of effective methods for reducing excess sludge generation and achieving resource recovery in wastewater treatment plants. The need for a deeper understanding of the impact of ultrasonic cavitation treatment on the sludge microbial community structure and the presence of bacteria carrying denitrification function genes.

    Ultrasonic Cavitation Transforms Organic Matter to Achieve Reduction of Excess Sludge and Recycling of Carbon Sources · 2025 · DOI

  • The gap in the simultaneous production of VFAs and biogas is also identified.

    Volatile Fatty Acid Production vs. Methane and Hydrogen in Anaerobic Digestion · 2025 · DOI

  • Methanogenic inhibition can cause sharp declines in gas yield and stability indicators. The study identifies the need for balanced substrate composition to ensure process resilience. Low waste management fees and electricity tariffs remain significant barriers to economic viability.

    How Does Methanogenic Inhibition Affect Large-Scale Waste-to-Energy Anaerobic Digestion Processes? Part 1—Techno-Economic Analysis · 2025 · DOI

  • Light attenuation caused by medium opacity is identified as a key technical challenge. Potential substrate inhibition is highlighted as another challenge. The need for future investigation into the potential microbial inhibition caused by the presence of d-limonene or its oxidative byproducts is mentioned.

    Photofermentative Hydrogen Production from Real Dark Fermentation Effluents: A Sequential Valorization of Orange Peel Waste · 2025 · DOI

  • The optimal biochar addition ratio and its effects on methanogen community composition need to be determined.

    Biochar Enhanced Anaerobic Digestion of Chicken Manure by Mitigating Ammonium Inhibition and Improving Methane Production · 2025 · DOI

  • The lack of effective methods for reducing heavy metal content in sewage sludge and anaerobically digested sludge. The need for improving dewaterability of anaerobically digested sludge. The limited understanding of the role of indigenous sulfur-oxidizing bacteria in bioleaching.

    Bioleaching Process of Sewage Sludge and Anaerobically Digested Sludge via Indigenous Sulfur-Oxidizing Bacteria to Improve Dewaterability and Reduce Heavy Metal Content · 2025 · DOI

  • Mass transfer is a major limitation of syngas fermentation technology. Increased flow rates can mitigate this limitation. The study aims to address this gap by evaluating the effect of feeding strategies on syngas fermentation.

    Improving Carbon Fixation and Acetate Production from Syngas Fermentation: On-Demand Versus Continuous Feeding · 2025 · DOI

  • Long-term continuous-flow experiments are necessary for evaluating the application potential of this synergistic strategy, including its stability, safety, and economy. The changes in activity and recovery efficiency of NiCo 2 O 4 NPs after multiple uses in continuous-flow reactors should be focused on.

    Dual Reinforcement of Biohydrogen Production from Food Waste Dark Fermentation by Thermal–Alkaline Pretreatment Coupled with Nickel-Based Nanoparticles · 2025 · DOI

  • Future work should focus on validating these findings under semi-continuous operation. Integrating microbial community profiling to simulate structure-function relationships during co-digestion. Exploring microbial community engineering or inoculum enrichment to enhance methane production.

    Effect of Co-Digestion Ratios and Temperature on Biomethane Production in Anaerobic Co-Digestion of Cheese Whey and Tomato Waste · 2025 · DOI

  • The study also identifies a need for further research on the microbial community and enzymatic analyses.

    Effect of Co-Digestion Ratios and Temperature on Biomethane Production in Anaerobic Co-Digestion of Cheese Whey and Tomato Waste · 2025 · DOI

  • The mono-substrate anaerobic digestion of spent coffee grounds has been thought to have a restriction in terms of its long-term stability. There is a need to evaluate the potential of spent coffee grounds as a co-substrate to improve anaerobic co-digestion performance.

    Improving Biogas Production and Organic Matter Degradation in Anaerobic Co-Digestion Using Spent Coffee Grounds: A Kinetic and Operational Study · 2025 · DOI

  • Studying the potential for plasma-based disinfection to be used in other wastewater treatment plants.

    Plasma-Assisted Valorization of Liquid Digestate from the Ravda Wastewater Treatment Plant: Microbiological and Chemical Aspects · 2025 · DOI

  • Investigate the effects of other environmental factors on HM accumulation, - Examine the potential of mixed cropping systems for phytoremediation in different soil types, - Study the long-term effects of mixed cropping systems on soil health and HM…

    Accumulation of Heavy Metals in Plant Biomass from the Mixed Culture of Zea Mays and Phaseolus Vulgaris, and Potential Biomass Use for Methane Production · 2026 · DOI

  • Batch tests were chosen as a controlled first step, - Continuous stirred-tank reactor experiments are recommended for future scalability assessment, - The study only investigated the anaerobic digestion of Sedum alfredii…

    Anaerobic Digestion of Phytoremediation Biomass: Biogas Production and Cadmium Stabilization from Sedum alfredii · 2026 · DOI

  • Continuous stirred-tank reactor experiments under steady and dynamic Cd loadings, - Investigation of other phytoremediation biomasses, - Assessment of the long-term stability of the anaerobic digestion…

    Anaerobic Digestion of Phytoremediation Biomass: Biogas Production and Cadmium Stabilization from Sedum alfredii · 2026 · DOI

  • Investigating the long-term effects of the ultrasonic cavitation treatment on the sludge microbial community. Comparing the ultrasonic cavitation technology with other sludge reduction methods. Analyzing the economic benefits of the ultrasonic cavitation technology.

    Ultrasonic Cavitation Transforms Organic Matter to Achieve Reduction of Excess Sludge and Recycling of Carbon Sources · 2025 · DOI

  • Sensitivity analyses could be conducted to evaluate the impact of different economic and operational parameters on the viability of WtE-AD plants, - Further research could investigate the effects of different substrate compositions on methanogenic inhibition, - Studies could explore the development of new technologies or strategies to improve the resilience of WtE-AD…

    How Does Methanogenic Inhibition Affect Large-Scale Waste-to-Energy Anaerobic Digestion Processes? Part 1—Techno-Economic Analysis · 2025 · DOI

  • Investigation of the effects of other DFE concentrations on hydrogen yield. Verification of the presence of d-limonene or its oxidative byproducts and their potential impact on microbial growth. Exploration of other potential applications of the photofermentative hydrogen production process.

    Photofermentative Hydrogen Production from Real Dark Fermentation Effluents: A Sequential Valorization of Orange Peel Waste · 2025 · DOI

  • Investigate the effects of biochar on other types of feedstock, - Compare the effectiveness of biochar with other additives or technologies, - Scale up the experiment…

    Biochar Enhanced Anaerobic Digestion of Chicken Manure by Mitigating Ammonium Inhibition and Improving Methane Production · 2025 · DOI

  • The study was conducted at a specific laboratory and location, which may not be representative of all scenarios, - The experiment was limited to a specific set of inoculum proportions and substrate ratios, - The study did not investigate the long-term effects of inoculum addition on AD…

    Anaerobic Co-Digestion of Cattle Manure and Sewage Sludge Using Different Inoculum Proportions · 2025 · DOI

  • Investigating the effects of different inoculum sources and preparation methods on AD performance, - Evaluating the scalability of the optimized biogas production process, - Examining the potential for integrating AD with other waste management…

    Anaerobic Co-Digestion of Cattle Manure and Sewage Sludge Using Different Inoculum Proportions · 2025 · DOI

  • Investigating the long-term effects of bioleaching on sludge dewaterability, - Exploring the use of other microorganisms for heavy metal removal, - Studying the effects of different sulfur supply levels on bioleaching pH and heavy metal…

    Bioleaching Process of Sewage Sludge and Anaerobically Digested Sludge via Indigenous Sulfur-Oxidizing Bacteria to Improve Dewaterability and Reduce Heavy Metal Content · 2025 · DOI

  • Investigating more efficient CO2 utilization strategies, such as sequential fermentations. Testing the influence of different syngas feeding rates on the cells and the efficiency of carbon fixation and acid titters. Exploring the application of the strain in large-scale syngas fermentation.

    Improving Carbon Fixation and Acetate Production from Syngas Fermentation: On-Demand Versus Continuous Feeding · 2025 · DOI

  • Further study on the optimization of SCG concentrations for improved biogas production, - Investigation of the effects of different mixing ratios on biogas production and methane content, - Research on the application of SCGs in large-scale AcD…

    Improving Biogas Production and Organic Matter Degradation in Anaerobic Co-Digestion Using Spent Coffee Grounds: A Kinetic and Operational Study · 2025 · DOI

Most-cited papers in Anaerobic Digestion and Biogas Production

Most recent work

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Open questions raised by papers listed on this page include: (1) There is a need to investigate the accumulation of heavy metals in plant biomass from mixed cultures (“Accumulation of Heavy Metals in Plant Biomass from the Mixed Culture of Zea…”, 2026); (2) The lack of effective methods for reducing excess sludge generation and achieving resource recovery in wastewater treatment plants (“Ultrasonic Cavitation Transforms Organic Matter to Achieve Reduction of Excess…”, 2025); (3) The lack of effective methods for reducing heavy metal content in sewage sludge and anaerobically digested sludge (“Bioleaching Process of Sewage Sludge and Anaerobically Digested Sludge via…”, 2025); (4) Future work should focus on validating these findings under semi-continuous operation (“Effect of Co-Digestion Ratios and Temperature on Biomethane Production in…”, 2025); (5) There is a need to evaluate the potential of spent coffee grounds as a co-substrate to improve anaerobic co-digestion performance (“Improving Biogas Production and Organic Matter Degradation in Anaerobic…”, 2025). 441 gap statements have been mined from Anaerobic Digestion and Biogas Production papers in our 7.9M-paper local library, which holds 2,294 papers on the topic; the gaps come from whichever of those papers state one. They are mostly the research gaps the authors state and the papers' abstracts, plus future-work, limitations and challenges passages. The ones listed below are a selection still marked open; each names the study that raised it, with a DOI link where the paper has one, so you can read the original claim in context.

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