Anaerobic digestion (AD) plays a crucial role in sustainable waste management, converting biowaste into biogas while generating digestate as a nutrient-rich by-product. This review explores innovative digestate valorization strategies based on the principles of green chemistry, focusing on resource efficiency and waste minimization through reutilization routes involving environmentally benign processes. The study examines the physicochemical characteristics of digestate and highlights its applications in sustainable agriculture, bioprocessing for enzyme production, algal biorefineries and hydroponic systems. Advanced valorization pathways, including bio-based polymer synthesis, biochar production and recovery of high-value chemicals such as volatile fatty acids, lactic acid and humic substances for commercial viability are critically analyzed through technoeconomic feasibility and life cycle assessment insights. Inorganic nutrient recovery techniques, including ammonia stripping, struvite precipitation and membrane separation, were also explored for their potential to enhance resource utilization. Thus, by integrating digestate valorization within a circular bioeconomy framework and industrial symbiosis, this study underscores its role in reducing the environmental impact, improving the carbon footprint and contributing to net-zero emissions. Our discussion further highlights the challenges in digestate processing, regulatory considerations and future research directions to optimize sustainable valorization strategies by integrating green chemistry principles

Energy and water are two basic resources that are intricately connected, and hence, they become a vital component to the functioning of regional, national, and international economies. Water is a finite resource, and many regions around the world are already experiencing water scarcity. About a quarter of the world’s population are living in water-scarce countries. If the same trend continues, by 2040 the world would not be able to meet the demands of ensuring safe drinking water for all people and generating energy for the growing population at the same time. Hence, an innovative is to be devised and implemented in the energy sector so that the water and energy demands can be met to ensure water and energy availability to the global citizens. This chapter focuses on the innovative approach of water footprint throughout the various energy production sectors critically focusing on the renewable energy sector. Moreover, to overcome the excess water consumption, few strategies to overcome the excessive water usage and comparative analysis on water consumption between bioenergy and other renewable energy sectors are also discussed.

The prevailing global crisis revolves around waste management and the depletion of nonrenewable energy, posing significant challenges for humanity. Fossil fuel refineries, the primary energy and material producers, face scrutiny due to their reliance on nonrenewable sources. The agro- and food industries, which generate vast amounts of biodegradable by-products often labeled as waste, contribute to this environmental dilemma. The diminishing viability of oil extraction stems from escalating fossil fuel prices, their erratic availability, and environmental apprehensions, underscoring the urgency of exploring alternative sustainable solutions to mitigate climate change and reduce fossil fuel dependence. A pivotal area of recent interest is the valorization of food waste (FW) through modern biorefineries and innovative systems capable of converting various biomass sources into biofuels and value-added products. However, implementing a sustainable strategy for biorefineries presents formidable challenges in terms of technical efficiency and economic feasibility. Organic materials such as food waste, grass, and manure can be transformed into high-value volatile fatty acids, carboxylic acids, bioenergy, and bioplastics, offering a promising avenue for waste reduction. Circular bioeconomy has emerged as a viable approach to address global waste and energy challenges. By integrating waste into bioprocesses for the production of valuable goods and metabolites, a sustainable circular bioeconomy can replace petroleum as feedstock, fostering a low-carbon and cleaner environment. This study provides a comprehensive review of organic waste valorization from the agro- and food industries, emphasizing the biorefinery approach to convert waste into bioenergy and value-added products, with a specific focus on bioethanol production and integrated biorefinery applications.

Bioremediation is an effective and sustainable method for removing xenobiotic pollutants from the environment, utilizing microorganisms and plants to metabolize harmful chemicals into harmless compounds like CO2 and water. Among various bioremediation strategies, mycoremediation stands out due to the unique enzymatic capabilities and metabolic diversity of fungi, enabling them to degrade persistent and toxic pollutants under harsh environmental conditions. This review specifically addresses the application of mycoremediation to emerging contaminants pharmaceuticals and personal care products (PPCPs) which pose significant environmental challenges due to their persistence, bioaccumulation potential, and ecotoxicity. This article provides a comprehensive overview of fungal-based strategies for PPCP remediation, documenting the fate, distribution, and impacts of these contaminants in soil. It highlights the enzymatic mechanisms and fungal species involved in PPCP degradation, with an emphasis on their ecological resilience and pollutant-specific adaptability. Additionally, the review explores under-discussed factors influencing fungal efficacy, such as pH, temperature, and contaminant concentration, alongside innovative advancements like myco-nanotechnology and enzyme engineering that enhance remediation efficiency. By integrating these aspects with policy perspectives and sustainable development goals, this review contributes novel insights into the potential of mycoremediation as a cutting-edge approach for mitigating PPCP contamination. It underscores the role of fungi in advancing circular economy principles and offers a foundation for future research and practical applications in environmental management. © 2025 The Authors

The need for a green and sustainable nanomaterial sourced from biomass in the form of nanochitin has raised interest in paving the way towards incorporating biological resources for the production of functional materials. Nanochitin as nanofibers and nanocrystals/whiskers have attractive features like their ability to self-assemble into multidimensional biomaterials while retaining their intrinsic characteristics. Herein, the review discusses chitin's molecular association and hierarchical assemblies and gives an overview of the extraction methods adopted to produce nanochitin. Recent progress in the development of advanced functional nanochitin-based materials/composites and their current application in agriculture and environmental remediation are reviewed to gain a better understanding of their applicability for forthcoming research and improvement. Furthermore, the environmental impact assessment of chitin has been discussed, followed by the techno-economic analysis, thus providing scope for improvement in manufacturing and perspectives on the potential of nanochitin in the context of sustainable material and their role in circular bioeconomy. © 2025 Elsevier B.V.

Landfill mining is the prominent solution for the recovery of resources from legacy waste. The bio-earth recovered from landfill mining is being utilized for a variety of applications like application as fertilizer. The presence of microplastic in the recovered bio-earth disrupts its usefulness. This study investigated the composition and microplastic pollution in bio-earth derived from landfill mining at the Bhandewadi landfill, Nagpur, India. Results provided insights into its characterization and presence of microplastic. The average moisture content of the bio-earth was 25.2 ± 1.1% with total organic carbon of 14.3 ± 0.6%. The bio-earth exhibited a C:N ratio of 16.9 ± 5.0, volatile solid content of 24.6 ± 1.0%, and ash content of 75.4 ± 1.0%. Bulk density was 434.3 ± 37.2 kg/m3, pH value 6.91 ± 0.28, and electrical conductivity 4.6 ± 0.7 dS/m. Total nitrogen content was 0.9 ± 0.3%, available phosphorus 2.1 ± 0.3 g/kg, and potassium and sodium contents of 12.7 ± 0.4 g/kg and 3.9 ± 0.3 g/kg, respectively. Heavy metals detected included Fe, Zn, Mn, Cu, Pb, Ni, Cr, and Cd. Microplastics in the bio-earth samples were assessed using attenuated total reflectance–Fourier-transform infrared spectroscopy (ATR-FTIR). The amount of microplastics averaged 100,150 ± 29,286 items per kg (dry basis). Additionally, five specific polymer types were prominent as microplastics. Further research and mitigation strategies are necessary to ensure the safe and sustainable use of bio-earth in agriculture and horticulture. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.

Bioremediation can help reduce and remove the pollution we produce, to provide clean air, water, and healthy soils for future generations. Pollution damages our health and the environment, affecting wildlife and the sustainability of our planet, as summarised in our policy briefing on food security. Under controlled conditions, bioremediation is the process of biologically degrading organic wastes, typically to a state of innocuousness or to concentration levels that remain within particular concentration limits set forth by the controlling authority. In bioremediation, it is possible to do it either ex situ or in situ, depending on a number of factors, such as the type and concentration of pollutants, cost, and/or site characteristics. As a result, ex situ is generally more expensive than in situ, since excavation results in additional expenses. Biological processes are the most effective and economical way to remediate a polluted site. Though bioremediation is not a new technique, our understanding of the mechanisms behind it is growing, enabling us to use it more effectively. Frequently, bioremediation uses fewer resources and less energy than conventional technologies and doesn't produce waste products that can be hazardous bioremediation has both technical and cost advantages, though it can sometimes take longer to complete than traditional methods. © 2024 selection and editorial matter, Pratibha Gautam, Vineet Kumar and Sunil Kumar; individual chapters, the contributors.

Water pollution stands as a critical worldwide concern, bearing extensive repercussions that extend to human health and the natural ecosystem. The sources of water pollution can be diverse, arising from natural processes and human activities and the pollutants may range from chemical and biological agents to physical and radiological contaminants. The contamination of water disrupts the natural functioning of the system, leading to both immediate and prolonged health problems. Various technologies and procedures, ranging from conventional to advanced, have been developed to eliminate water impurities, with the choice depending on the type and level of contamination. Assessing risks is a crucial element in guaranteeing the safety of drinking water. Till now, research is continuing the removal of contaminates for the sake of supplying safe drinking water. The study examined physical, inorganic, organic, biological and radiological contaminants in drinking water. It looked at where these contaminants come from, their characteristics, the impact they have and successful methods used in real-world situations to clean the contaminated water. Risk assessment methodologies associated with the use of unsafe drinking water as future directives are also taken into consideration in the present study for the benefit of public concern. The manuscript introduces a comprehensive study on water pollution, focusing on assessing and mitigating risks associated with physical, inorganic, organic, biological and radiological contaminants in drinking water, with a novel emphasis on future directives and sustainable solutions for public safety. © 2024, The Author(s), under exclusive licence to Springer Nature Switzerland AG.

Ionic liquids (ILs) are next generation solvents which are synthesized by organic salts, possess negligible vapour pressure and have low flammability. They possess high thermal and electrochemical stability, can be reused for multiple cycles, and its properties can be tuned according to the components used in its synthesis. Hence, ILs are considered to be potential alternatives for the conventional organic solvents for numerous applications such as environmental remediation, nanoparticles synthesis, as catalysts in various chemical reactions, as solvents for the extraction of biomolecules from recalcitrant lignocellulosic biomass, etc. In this review article, the holistic approach of ILs starting from various techniques adopted for its synthesis along with its critical review has been discussed followed by detailed discussion on the mechanism involved for the remediation of environmental pollutants using ILs. Further, in depth documentation of various environmental pollutants remediated till date using ILs has been done. One of the major drawbacks of solvents application is the reusability factor, and hence in this review article, techniques adopted to recycle/reuse of ILs has been discussed. Further, the adverse effect of using ILs for environmental remediation has been comprehensively discussed to present a holistic view. Future studies should focus on synthesis of environment friendly ILs and their field-scale applications for environmental remediation. © 2023 Elsevier B.V.

Search for alternatives to synthetic plastics led to the development of eco-friendly degradable polymers of natural origin termed ‘bioplastic’ which is a sustainable option to reduce the reliance on fossil fuel resources and address the needs of pressing environmental problems. Food packaging has become an important aspect of supply chain management that not only governs the food from spoilage but also contributes to a sensible biocompatible material, safe for human consumption as there is a recent concern on microplastic leaching. Polyhydroxyalkanoates (PHAs), derived from microorganisms, are extensively used as a polymeric base for packaging applications in food industries as they offer advantages such as biodegradability, non-toxicity, hydrophobicity, thermoplasticity, and superior barrier properties, thereby making them a promising alternative to conventional synthetic plastics. However, challenges related to material properties, performance, and cost of the product must be addressed for PHA to make it an economical and feasible packaging material. Recent developments in PHA formulations in terms of technology, additives, and production factors have led to improvement in the polymer properties and beaconed the advent of active packaging. PHA-based packaging systems can redefine food industry packaging, turning it from a passive physical entity into an active solution that sustainably ensures food quality and safety. This review examines the sustainable microbial production of PHA from waste resources, recent advancements in PHA formulations, and their impact on material properties. It highlights emerging trends in active food packaging with PHA, such as controlled-release, antimicrobial and antioxidant properties, advanced barrier properties and spoilage indicators. © 2024 Elsevier Ltd

The use of algae for value-added product and biorefining applications is enchanting attention among researchers in recent years due to its remarkable photosynthetic ability, adaptability, and capacity to accumulate lipids and carbohydrates. Algae biomass, based on its low manufacturing costs, is relatively renewable, sustainable, environmentally friendly and economical in comparison with other species. High production rate of algae provides a unique opportunity for its conversion to biochar with excellent physicochemical properties, viz. high surface area and pore volume, high adsorption capacity, abundant functional groups over surface, etc. Despite several potential algal-biochar, a detailed study on its application for removal of emerging contaminants from wastewater is limited. Therefore, this technical review is being carried out to evaluate the specific elimination of inorganic and organic pollutants from wastewater, with a view to assessing adsorption performances of biochar obtained from various algae species. Species-specific adsorption of emerging pollutants from wastewater have been discussed in the present review. The promising methods like pyrolysis, gasification, dry and wet torrefaction for the production of algae biochar are highlighted. The strategies include chemical and structural modifications of algae biochar for the removal of toxic contaminants have also been considered in the current work. The overall aim of this review is to confer about the synthesis, technological advancements, delineation and application of algae biochar for the treatment of wastewater. © 2024 Elsevier Inc.

With an increase in the world's economy and the human population, there's a growing need for drinking water suitable for consumption. Water management might inevitably become the top priority on a global scale. The rapidly evolving bioremediation landscape is a major driver for the development of sustainable solutions that can provide value beyond just environmental remediation. Phycoremediation or algae-mediated remediation is attracting the most attention because of its captivating sustainability characteristics, its ability to eliminate odors, fouling, and toxins, its ability to eliminate many common as well as emerging contaminants from the gaseous and aqueous environment, and its ability to produce biomass for a variety of value-added products. Algae-based wastewater treatment plants like bioreactors are gaining more attention than traditional membrane reactors as they are environmentally friendly and sustainable. Due to the non-function of traditional municipal wastewater treatment plants, emerging pollutants such as personal care products, pharmaceuticals, antibiotics, and mono- and polyaromatic hydrocarbons are discharged into the waterbody regularly causing harmful effects to aquatic lives. Algae-based membrane bioreactors (AMBRs), are the most advanced technology used to remove emerging contaminants (ECs) found in wastewater. Furthermore, mixed algae-MBRs become more popular than unialgal MBRs due to mutualistic synergism. Advancements in cylindrical and rectangular-shaped AMBRs were also found better for the bioremediation of ECs. In conclusion, various ECs and their remediation mechanisms by different algal strains and sustainable technologies are discussed in the present communication. Most importantly, modifications of AMBRs with microfiltration membrane or osmotic membrane or integrated with activated sludge have been considered in this research. © 2024 Elsevier B.V.

In a globalized world, energy remains a critical driver of development. The reliance on non-renewable fossil fuels has led to pollution, health concerns, and accelerated climate change due to greenhouse gas emissions. As fossil fuel reserves diminish, biofuels derived from biomass present a promising and sustainable alternative. Biomass, being abundant and renewable, has the potential to replace fossil fuels, with advances in technology and a focus on green synthesis enabling more efficient and environmentally friendly production processes. Heterogeneous catalysts play a crucial role in biofuel production, significantly impacting the development of more sustainable energy solutions. These catalysts, which operate in a different phase from the reactants, are crucial for achieving high conversion efficiency, recyclability, and minimal environmental impact in biofuel production. Specifically designed to break down lignocellulosic biomass, these catalysts are essential for a carbon-neutral biofuel production process and for driving sustainable development. This article explores the historical development and evolving role of these catalysts in biofuel technology along with a categorization of various catalysts used in biofuel production. The discussion includes an examination of biomass sources and its structural and chemical compositions vital for conversion processes. The application of heterogeneous catalysts in producing diverse biofuels—such as bioethanol, biobutanol, biogas, biodiesel and biohydrogen are analyzed, highlighting recent advancements and improvements in efficiency. Insights and recommendations for future research underscore the indispensable role of heterogeneous catalysts in advancing sustainable energy practices and securing our energy future. © 2024 Elsevier Ltd

Carbon dioxide (CO2) emissions from a variety of sources, such as transportation, fossil fuel burning, and cement manufacturing facilities, are widely regarded to be the root cause of global warming. The rising CO2 levels call for immediate improvements in CO2 capture, extraction, and utilization technology. Methods for capturing and converting CO2 into useful products have included the use of microbial enzymes, nonporous materials, metal-organic frameworks (MOFs), chemicals, and hybrid membranes. However, these methods possess limitations that make the scale up and commercialization challenging. Scientists are concentrating on maximizing CO2 utilization by incorporating CO2-philic components into enzyme-chemical-material combinations, due to the high solubility of CO2. Here, the focus is on the chemistry of CO2-phillic materials, enzymes and biomolecules engaged in CO2 conversion, and the hybrid micro-reactors that contain material and enzymes integrating together to convert the CO2 into value-added products (organic acids, bioelectricity, carbonates, carbamates, methane, methanol, etc.). The difficulties and obstacles inherent in creating and sustaining such systems have also been highlighted. © 2023

Face masks, a prime component of personal protective equipment (PPE) items, have become an integral part of human beings to survive under the ongoing COVID-19 pandemic situation. The global population requires an estimated 130 billion face masks and 64 billion gloves/month, while the COVID-19 pandemic has led to the daily disposal of approximately 3.5 billion single-use face masks, resulting in a staggering 14,245,230.63 kg of face mask waste. The improper disposal of face mask wastes followed by its mismanagement is a challenge to the scientists as the wastes create pollution leading to environmental degradation, especially plastic pollution (macro/meso/micro/nano). Each year, an estimated 0.15–0.39 million tons of COVID-19 face mask waste, along with 173,000 microfibers released daily from discarded surgical masks, could enter the marine environment, while used masks have a significantly higher microplastic release capacity (1246.62 ± 403.50 particles/piece) compared to new masks (183.00 ± 78.42 particles/piece). Surgical face masks emit around 59 g CO2-eq greenhouse gas emissions per single use, cloth face masks emit approximately 60 g CO2-eq/single mask, and inhaling or ingesting microplastics (MPs) caused adverse health problems including chronic inflammation, granulomas or fibrosis, DNA damage, cellular damage, oxidative stress, and cytokine secretion. The present review critically addresses the role of face masks in reducing COVID-19 infections, their distribution pattern in diverse environments, the volume of waste produced, degradation in the natural environment, and adverse impacts on different environmental segments, and proposes sustainable remediation options to tackle environmental challenges posed by disposable COVID-19 face masks. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

Since the enactment of the Clean Water Act (1972), which was supplemented by increased accountability under Resource Conservation and Recovery Act (RCRA) Subtitle D (1991) and the Clean Air Act Amendments (1996), landfills have indeed been widely used all around the world for treating various wastes. The landfill's biological and biogeochemical processes are believed to be originated about 2 to 4 decades ago. Scopus and web of Science based bibliometric study reveals that there are few papers available in scientific domain. Further, till today not a single paper demonstrated the detailed landfills heterogenicity, chemistry and microbiological processes and their associated dynamics in a combined approach. Accordingly, the paper addresses the recent applications of cutting-edge biogeochemical and biological methods adopted by different countries to sketch an emerging perspective of landfill biological and biogeochemical reactions and dynamics. Additionally, the significance of several regulatory factors controlling the landfill's biogeochemical and biological processes is highlighted. Finally, this article emphasizes the future opportunities for integrating advanced techniques to explain landfill chemistry explicitly. In conclusion, this paper will provide a comprehensive vision of the diverse dimensions of landfill biological and biogeochemical reactions and dynamics to the scientific world and policymakers. © 2023 Elsevier Ltd

E-waste management has become a global concern because of the enormous rise in the rate of end-of-life electrical and electronic equipment's (EEEs). Disposal of waste EEE directly into the environment leads to adverse effects on the environment as well as on human health. For the management of E-waste, numerous studies have been carried out for extracting metals (base, precious, and rare earth) following pyrometallurgy, hydrometallurgy, and biometallurgy. Irrespective of the advantages of these processes, certain limitations still exist with each of these options in terms of their adoption as treatment techniques. Several journal publications regarding the different processes have been made which aids in future research in the field of E-waste management. This review provides a comprehensive summary of the various metal recovery processes (pyrometallurgy, hydrometallurgy, and biometallurgy) from E-waste, along with their advantages and limitations. A bibliometric study based on the published articles using different keywords in Scopus has been provided for a complete idea about E-waste with green technology perspective like bioleaching, biosorption, etc. The present study also focussed on the circular economic approach towards sustainable E-waste management along with its socio-economic aspects and the economic growth of the country. The present study would provide valuable knowledge in understanding E-waste and its different treatment processes to the students, researchers, industrialists, and policymakers of the country.

Carbon dioxide (CO2) emissions from a variety of sources, such as transportation, fossil fuel burning, and cement manufacturing facilities, are widely regarded to be the root cause of global warming. The rising CO2 levels call for immediate improvements in CO2 capture, extraction, and utilization technology. Methods for capturing and converting CO2 into useful products have included the use of microbial enzymes, nonporous materials, metal-organic frameworks (MOFs), chemicals, and hybrid membranes. However, these methods possess limitations that make the scale up and commercialization challenging. Scientists are concentrating on maximizing CO2 utilization by incorporating CO2-philic components into enzyme-chemical-material combinations, due to the high solubility of CO2. Here, the focus is on the chemistry of CO2-philic materials, enzymes and biomolecules engaged in CO2 conversion, and the hybrid micro-reactors that contain material and enzymes integrating together to convert the CO2 into value-added products (organic acids, bioelectricity, carbonates, carbamates, methane, methanol, etc.). The difficulties and obstacles inherent in creating and sustaining such systems have also been highlighted

Microplastics (MPs) have attracted wide attention all over the world as a remarkable pollutant. While MPs are spreading throughout several complex environmental matrices, various experiments till date have been preliminary concentrate on aquatic ecosystems. Terrestrial sources namely solid waste-origin have remains unexplored, although they contribute largely for aquatic microplastics origin. Simultaneously, terrestrial systems under human activity, like healthcare units, are likely to be polluted by various plastic ingredients. Solid waste MPs sources primarily include sanitary landfilling, food waste, wastewater treatment end-product (sludge), tire wear, textile washing and paint failure. These microplastics caused adverse impacts on ecosystem, environment, and health. Accordingly, the present study addressed solid waste MPs’ occurrence and sources, identification, quantification, characterization, fate, and degradation pathways for developing comprehensive management strategies following the principles of circular economy. In particularly, this paper critically demonstrated solid waste MPs sources, solid waste MPs sampling followed by identification and quantification by adopting combined chemical ( e.g., spectroscopy viz., Fourier transform infrared (FTIR) spectroscopy, and Raman spectroscopy), physical ( e.g., microscopy such as transmission or scanning electronic microscopy, TEM or SEM) and thermal analyses. Additionally, the strengths and limitations of each analytical technique are discussed critically with practical aspect. Further, the MPs related national and international regulations or laws and their subsequent relevance to solid waste MPs management with future challenges are discussed very critically. Finally, the outcomes of the review paper will be valuable to different stakeholders for effective policy implementation.