The novel technique of biochar production from food waste (FW) through pyrolysis is a proactive step towards materialising the circular economy. This review provide a detail insights on the successful utilisation of FW for biochar production and its subsequent environmental applications, along with efficiencies and mechanisms in the removal of various pollutants from wastewater. The chemical transformation during FW pyrolysis assists the resultant biochar with unique physiochemical characteristics, including structure formation, porosity, alkalinity, functional groups, polarity, cation exchange capacity and carbon structure that contribute to the efficient removal of pollutants. Based on the organic-rich nature, detailed discussions have been made on how FW could be an ideal feedstock for pyrolysis as compared to other bio-waste. Moreover, the impacts of pyrolysis temperatures on the characteristics, variations in the removal efficiencies and interactions of biochar with pollutants have been discussed. The suitability of FW biochar for environmental applications is its stability for subsequent usage without losing activity and production of secondary pollutants or by-products, as compared to other technologies. However, despite the promising benefits, FW to biochar technology is still in infancy and prone to several challenges, including scalability due to intrinsic heterogeneity, high moisture that sometimes requires an additional step of drying and grinding and variations in the physicochemical characteristics that impact the economic feasibility, scalability and end-use marketability. Hence, detailed studies on techno-economic analysis in integration with advances in FW to biochar production, applications as adsorbent, stability, and reusability after treatment to fully explore the comparison with other available similar materials.
Biochar, a carbon-rich product resulting from the thermochemical transformation of organic biomass under limited oxygen condition, is currently drawing much worldwide attention due to its multiple applications in carbon sequestration, soil improvement, environmental remediation, and biomass waste management. Initially, the focus of research was primarily on the technical possibilities of biochar production, its economic aspects, and its contribution to climate change mitigation through carbon sequestration and the promotion of sustainable agriculture. Nevertheless, recent research indicates the high complexity and dynamics of biochar interactions with the environment, driven by a combination of factors like feedstock type, process conditions, biochar properties, and other factors. While biochar exhibits multiple beneficial effects, including improving soil structure, enhancing nutrient retention, promoting microbial activities, and remediating contaminants, several environmental risks associated with biochar application have also been identified, namely the formation of polycyclic aromatic hydrocarbons (PAHs), heavy metal contamination, creation of persistent free radicals, changes in soil chemistry, and modification of soil microbial community structure. Such risks are greatly related to production process parameters, treatment methods, and biochar application practices. Moreover, differences in feedstock choice, pyrolysis temperature, reactor design, biochar application rate, and analytical methods used make comparative analysis of results difficult.
O. E. Ojewumi, Gang Chen, M. Ojewumi· Green· 0 citations
Biochar is a carbonaceous material produced from the thermochemical treatment of biomass in the absence or with a limited supply of oxygen. Despite the use of carbonized biomass to improve agricultural soils over centuries, the application and interest in biochar have grown dramatically owing to its diverse applications in the environment, energy, industry, etc. This review focuses on key technologies of biochar production, comparing their advantages, disadvantages, and their effect on biochar properties. Emphasis has been placed on the physical-chemical properties of biochar (pore structure, surface chemistry, element composition, specific surface area, etc.) as well as the production parameters that control them. Approaches for modifying and activating biochar to improve performance in targeted applications are also discussed. The review further examines the growing role of biochar in pollutant removal, renewable energy systems, and catalytic transformations. In addition, recent advances in nanobiochar are highlighted, emphasizing how reducing particle dimensions to the nanoscale alters surface reactivity, adsorption behavior, and functional performance. Nanomaterials, generally defined as materials with dimensions below 100 nm, possess exceptionally high surface-to-volume ratios that can result in unique physicochemical properties not observed in their bulk counterparts. Finally, current challenges, emerging opportunities, and future pathways for the development and application of biochar-based materials are critically evaluated.
Keratin wastes are generated more than 8 million tonnes annually, which largely end up in landfills or incineration. This represents an environmental burden and a significantly underexploited resource with high nitrogen (N) (15–18%) and sulphur (S) (2–5%) that distinguishes itself from the conventional lignocellulosic biomass. The present review consolidates the current understanding of keratin-based biochar across its full value chain. It aims to provide a comprehensive analysis of the chemical composition of the major feedstock, including the processing of wastes using the hydro-pyrolysis and carbon thermolysis methods and examines the kinetics of biochar production. The keratin-based biochar exhibits variability in the yield and quality when subjected to slow and fast-pyrolysis and differs with the technique employed namely thermal pyrolysis, hydrothermal carbonization, catalytic and engineered modification. The multifunctional keratin biochar possesses the capacity to improve soil fertility, pollutant adsorption and removal, and renewable energy retention. The diverse applications are subsequently surveyed, spanning soil-fertility enhancement, pollutant adsorption in water and gas streams, carbon sequestration and renewable-energy storage, while addressing the key challenges in standardization and contamination. Collectively, this review positions keratin waste valorisation as a technically and economically potential route for advancing circular-bioeconomy integration and clean energy transition.
S. A. MarathakaRani, R. J. Nija, M. Kamaraj et al.· Discover Environment· 0 citations
The composition of biomass feedstock and pyrolysis parameters, such as temperature, heating rate, and residence time, are key factors that affect the distribution and properties of pyrolysis products and are among the most extensively studied. However, the pyrolysis atmosphere also plays a crucial role in determining process efficiency and product quality. This review examines the effects of various pyrolysis atmospheres on biochar yields and properties, and also considers impacts on pyrolysis gases and liquids. While nitrogen is commonly used in research, the demand for biochar with specific properties like increased porosity and functionality has led to exploring alternative atmospheres such as steam, oxidative, pyrolysis gas, carbon dioxide, methane and ammonia. These alternatives can produce biochar with the desired characteristics in a single step, bypassing the need for multiple modifications. This review provides an overview of these pyrolysis atmosphere options, their applications, advantages, and potential challenges. Future research directions are also identified and highlighted, offering a roadmap for advancing biochar production technology. Reactive gases (CO2, H2O, O2, NH3) enable one‐step control of biochar yields, porosity and surface chemistry. CO2 and steam raise surface area, microporosity, and pyrolysis gas/bio‐oil yields (CO2 limits tars; steam adds oxygen functionalities). NH3 (< 400 °C) nitrogenates char to improve cation exchange capacity and catalytic performance. Reactive gases (CO2, H2O, O2, NH3) enable one‐step control of biochar yields, porosity and surface chemistry. CO2 and steam raise surface area, microporosity, and pyrolysis gas/bio‐oil yields (CO2 limits tars; steam adds oxygen functionalities). NH3 (< 400 °C) nitrogenates char to improve cation exchange capacity and catalytic performance.
Ondřej Mašek, Wolfram Buss, Liang Wang et al.· Biochar· 0 citations
Anaerobic digestion (AD) is widely used for organic waste stabilization and bio-energy recovery, but its performance is often constrained by process instability, slow syntrophic metabolism, and sensitivity to acidification, ammonia, organic overloading, and inhibitory contaminants. Biochar has emerged as a promising strategy to enhance AD, with benefits extending beyond increased methane yield. This review examines how biochar properties, including pore structure, surface functional groups, alkalinity, and electrical conductivity, regulate different AD stages and improve process stability. Biochar provides microbial habitats, buffers pH, adsorbs inhibitors, accelerates volatile fatty acid conversion, and facilitates interspecies electron transfer. The effects of biochar dosage, feedstock type, reactor configuration, and operational conditions on digestion performance and resource recovery are critically evaluated. Broader contributions to organic waste valorization are also discussed. Future research should prioritize tailored biochar design, standardized characterization, long-term validation in continuous reactors, techno-economic analysis, and life-cycle assessment. These efforts are essential for translating laboratory findings into reliable and sustainable applications for organic solid waste treatment and resource recovery.
