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•Recent research on remediation of toxic pollutants by biochar has been summarized.•The production techniques of the biochar have been narrated.•Biochar properties, stability and its ...environmental issues have been analysed.•Applications of biochar in soil fertility and removing pollutants have been reported.•The major stumbling block in biochar production is cost of production.
There is an upsurge enthusiasm for utilizing biochar produced from waste-biomass in different fields, to address the most important ecological issues. This review is focused on an overview of remediating harmful contaminants utilizing biochar. Production of biochar utilizing various systems has been discussed. Biochar has received the consideration of numerous analysts in building up their proficiency to remediate contaminants. Process parameters are fundamentally answerable for deciding the yield of biomass. Biochar derived from biomass is an exceptionally rich wellspring of carbon produced from biomass utilizing thermal combustion. Activating biochar is another particular region for the growing utilization of biochar for expelling specific contaminations. Closed-loop systems to produce biochar creates more opportunities. Decentralized biochar production techniques serve as an effective way of providing employment opportunities, managing wastes, increasing resource proficiency in circular bioeconomy. This paper also covers knowledge gaps and perspectives in the field of remediation of toxic pollutants using biochar.
Peri-urban environments are significant reservoirs of wastewater, and releasing this untreated wastewater from these resources poses severe environmental and ecological threats. Wastewater mitigation ...through sustainable approaches is an emerging area of interest. Algae offers a promising strategy for carbon-neutral valorization and recycling of urban wastewater. Aiming to provide a proof-of-concept for complete valorization and recycling of urban wastewater in a peri-urban environment in a closed loop system, a newly isolated biocrust-forming cyanobacterium Desertifilum tharense BERC-3 was evaluated. Here, the highest growth and lipids productivity were achieved in urban wastewater compared to BG11 and synthetic wastewater. D. tharense BERC-3 showed 60–95% resource recovery efficiency and decreased total dissolved solids, chemical oxygen demand, biological oxygen demand, nitrate nitrogen, ammonia nitrogen and total phosphorus contents of the water by 60.37%, 81.11%, 82.75%, 87.91%, 85.13%, 85.41%, 95.87%, respectively, making it fit for agriculture as per WHO's safety limits. Soil supplementation with 2% wastewater-cultivated algae as a soil amender, along with its irrigation with post-treated wastewater, improved the nitrogen content and microbial activity of the soil by 0.3–2.0-fold and 0.5-fold, respectively. Besides, the availability of phosphorus was also improved by 1.66-fold. The complete bioprocessing pipeline offered a complete biomass utilization. This study demonstrated the first proof-of-concept of integrating resource recovery and resource recycling using cyanobacteria to develop a peri-urban algae farming system. This can lead to establishing wastewater-driven algae cultivation systems as novel enterprises for rural migrants moving to urban areas.
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•Wastewater-grown algal biomass has been questioned for biotech use.•Resource recovery from urban wastewater and use of algal biomass as soil amender.•Soil incubation with wastewater-grown biomass and recycling of treated water.•Desertifilum tharense BERC-3 improved soil fertility and soil microbial activities.•Resource recovery and recycling in peri-urban environments for biomass production.
Biochar is an ample source of organic carbon prepared by the thermal breakdown of biomass. Lignocellulosic biomass is a promising precursor for biochar production, and has several applications in ...various industries. In addition, biochar can be applied for environmental revitalization by reducing the negative impacts through intrinsic mechanisms. In addition to its environmentally friendly nature, biochar has several recyclable and inexpensive benefits. Nourishing and detoxification of the environment can be undertaken using biochar by different investigators on account of its excellent contaminant removal capacity. Studies have shown that biochar can be improved by activation to remove toxic pollutants. In general, biochar is produced by closed-loop systems; however, decentralized methods have been proven to be more efficient for increasing resource efficiency in view of circular bio-economy and lignocellulosic waste management. In the last decade, several studies have been conducted to reveal the unexplored potential and to understand the knowledge gaps in different biochar-based applications. However, there is still a crucial need for research to acquire sufficient data regarding biochar modification and management, the utilization of lignocellulosic biomass, and achieving a sustainable paradigm. The present review has been articulated to provide a summary of information on different aspects of biochar, such as production, characterization, modification for improvisation, issues, and remediation have been addressed.
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•Emerging researches on toxic pollutants removal using biochar has been addressed.•Advanced techniques on biochar production have been articulated.•Obligated properties of biochar for environmental applications have been discussed.•Biochar amendments on ameliorating the soil fertility have been analyzed.•Crucial stumbling block for production and application of biochar were reported.
Lignocellulosic biomass is the most abundant and sustainable feedstock available globally. As a source of the polysaccharides, cellulose and hemicellulose, it can be converted into biofuels and other ...platform chemicals. This article highlights some important aspects that needs to be focused upon for the commercial development of lignocellulosic biorefineries. Although, lignocellulosic biomass offers clear value in terms of its green advantages and sustainability, there has been very low commercial success at industrial production levels. This can be attributed to a few key factors such as an irregular biomass supply chain, inefficient or complex pre-treatment and saccharification technologies, and scale up challenges leading to high capital and operating expenditures. Moreover, techno-economic studies performed on lignocellulosic biorefineries have revealed that process complexity is the most detrimental factor prohibiting scale-up. Although there have been several research efforts funded both by the public and private sectors, biomass valorization into biofuels and chemicals remains a technical and economical challenge. This review examines the global drivers towards the advancements of lignocellulosic biorefineries, technical and operational challenges for industrialization and future directions towards overcoming them.
•Commercialization of lignocellulosic biomass refineries needs efficient value chain.•Sustainable feedstock supply can be gained with biomass source diversification.•New pre-treatment technologies can enhance yield and accelerate industrial scale-up.•Novel enzyme cocktails can improve extraction and hydrolysis of polysaccharides.•Industrial scale-up requires development of efficient co-processing techniques.
An ever increasing demand for animal protein products has posed serious challenges for managing the increasing quantities of livestock manure. The choice of treatment technologies is still a ...complicated task and considerable debates over this issue still continue. To build a clearer picture of manure treatment framework, this study was conducted to review the most frequently employed manure management technologies from their state of the art, challenges, sustainability, environmental regulations and incentives, and improvement strategies perspectives. The results showed that most treatment technologies have focused on the solid fraction of manure while the liquid fraction still remains a potential environmental threat. Compared to other waste to energy solutions, anaerobic digestion is the most mature technology to upgrade manure's organic matter into renewable energy, however the problems associated with high investment costs, operating parameters, manure collection, and digestate management have hindered its developments in rural areas in developing countries. Bio-oil production through hydrothermal liquification is also a promising solution, as it can directly convert the wet manure into biofuel. However, lipid-poor nature of manure, operational difficulties, and the need for downstream process to remove nitrogenous compounds from the final product necessitate further research. Livestock manure management (both solid and liquid fractions) under biorefinery approach seems an inevitable solution for future sustainable development to meet circular bioeconomy requirements. Much research is still required to establish a systematic framework based on regional requirements to develop an integrated manure nutrient recycling and manure management planning with minimum environmental risks and maximum profit.
•Challenge and future perspective of manure management technologies are discussed.•Manure management technologies were compared from environmental viewpoints.•Role of different groups involve in manure management circular loop was established.•Product is the vital link of the policy, technology and environment assessment.
In this study, the key gaps of food waste prevention have been addressed in the context of the emerging circular economy. First, current terminology related to food waste was reviewed and clarified, ...in particular, the terms food surplus, waste and losses. This work highlights why the clarity of these definitions is crucial for the sustainability of future food waste management systems, especially in the context of circular economy. Through a simple matrix, definitions are linked to the concepts of edibility and possibility of avoidance, leading to six distinct categories of food waste: i) edible, ii) naturally inedible (pits), iii) industrial residue, iv) inedible due to natural causes (pests), v) inedible due to ineffective management and vi) not accounted for. Category I encompasses surplus food only; category II-V food waste and category VI food losses. Based on this, an updated pyramid for food waste hierarchy is proposed, distinguishing surplus food and a new category for material recycling, in order to reflect the future food waste biorefineries in the circular bioeconomy. Nutrient and energy recovery are two separate categories and the terms recovery and recycling are clarified. Finally, a circular economy framework is presented for food surplus and waste, considering closing the loop throughout the whole food supply chain, in connection with the concept of strong and weak sustainability. This is presented along with a review of key EU policies related to food waste and examples of initiatives from the Member States.
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•Unclear definitions and frameworks for food waste prevent efficient minimization.•Six categories distinguishing edibility and level of avoidance were created.•Waste hierarchy expanded by material recycling and nutrient recovery.•Framework to close the loop of food waste in the supply chain included•Three tools for harmonized and simplified food quantification and management
•Biorefinery and bioprocessing are sustainable ways for resource conservation.•Circular bioeconomy significantly reduces food waste accumulation.•In depth studies are necessary to close knowledge ...gaps in field of food waste valorization.•The major stumbling block in resource recovery from food waste is cost of production.
Sustainable development of circular bioeconomy concept is only possible upon adopting potential advanced technologies for food waste valorization. This approach can simultaneously answer resources and environmental challenges incurred due to capital loss and greenhouse gases accumulation. Food waste valorization opens new horizons of economical growth, bringing waste as an opportunity feedstock for bio processes to synthesize biobased products from biological source in a circular loop. Advanced technologies like Ultrasound assisted extraction, Microwave assisted extraction, bioreactors, enzyme immobilization assisted extraction and their combination mitigates the global concern caused due to mismanagement of food waste. Food waste decomposition to sub-zero level using advanced techniques fabricates food waste into bio-based products like bioactive compounds (antioxidants, pigments, polysaccharides, polyphenols, etc.); biofuels (biodiesel, biomethane, biohydrogen); and bioplastics. This review abridges merits and demerits of various advanced techniques extended for food waste valorization and contribution of food waste in revenue generation as value added products.
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•Gasification prevents the generation of harmful gases such as NOx and SOx.•LCB gasification is a significant technology to reduce reliance on fossil fuels.•The low energy required ...makes the gasification process very cost-effective.•Utilizing LCB in BE framework with the help of gasification was investigated.
The energy deficiency issues and intense environmental pollution have exacted the production of biofuels which are both renewable and sustainable and can be used to displace fossil fuels. The raw material for manufacturing second-generation biofuels is lignocellulosic biomass (LCB), which is widely available. LCB bioprocessing to produce high-value bio-based products has been the subject of attention. Biomass gasification is a powerful technology to achieve sustainable development goals, reduce reliance on fossil fuels, and reduce environmental concerns. This paper, will provide an overview of the LCB structures and the gasification process. Also, consistent with the concept of “circular bio-economy”, this study focuses on the role of LCB gasification in the environmental impacts, and how gasification can be effective in the pathway of circular bio-economy. The current challenges to gasification and biorefinery and future perspectives are also presented.
Spirulina biomass accounts for 30% of the total algae biomass production globally. In conventional process of Spirulina biomass production, cultivation using chemical-based culture medium contributes ...35% of the total production cost. Moreover, the environmental impact of cultivation stage is the highest among all the production stages which resulted from the extensive usage of chemicals and nutrients. Thus, various types of culture medium such as chemical-based, modified, and alternative culture medium with highlights on wastewater medium is reviewed on the recent advances of culture media for Spirulina cultivation. Further study is needed in modifying or exploring alternative culture media utilising waste, wastewater, or by-products from industrial processes to ensure the sustainability of environment and nutrients source for cultivation in the long term. Moreover, the current development of utilising wastewater medium only support the growth of Spirulina however it cannot eliminate the negative impacts of wastewater. In fact, the recent developments in coupling with wastewater treatment technology can eradicate the negative impacts of wastewater while supporting the growth of Spirulina. The application of Spirulina cultivation in wastewater able to resolve the global environmental pollution issues, produce value added product and even generate green electricity. This would benefit the society, business, and environment in achieving a sustainable circular bioeconomy.
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•Chemical-based medium used in commercially viable production is not sustainable.•Many studies reported in supporting and enhancing Spirulina growth in wastewater.•Change in the concept of utilising wastewater by coupling with treatment technology.•Explore sustainable, alternative low-cost culture media: vermicompost and seawater.
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•MES cathode for better bacterial growth and CO2 delivery is reviewed.•Strategies are provided for energy-efficient anodic electron generation.•MES chain-elongation suitable for ...high-value product formation and extraction.•MES integrated with other bioprocesses can be promising to sustain circular economy.
Recycling CO2 into organic products through microbial electrosynthesis (MES) is attractive from the perspective of circular bioeconomy. However, several challenges need to be addressed before scaling-up MES systems. In this review, recent advances in electrode materials, microbe-catalyzed CO2 reduction and MES energy consumption are discussed in detail. Anode materials are briefly reviewed first, with several strategies proposed to reduce the energy input for electron generation and enhance MES bioeconomy. This was followed by discussions on MES cathode materials and configurations for enhanced chemolithoautotroph growth and CO2 reduction. Various chemolithoautotrophs, effective for CO2 reduction and diverse bioproduct formation, on MES cathode were also discussed. Finally, research efforts on developing cost-effective process for bioproduct extraction from MES are presented. Future perspectives to improve product formation and reduce energy cost are discussed to realize the application of the MES as a chemical production platform in the context of building a circular economy.
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