Wastes are unceasingly generated in the world, and most of them can be recycled, reused, or recovered to promote a circular economy. Among waste treatment approaches, the anaerobic digestion (AD) process has been considered as an ideal process due to its ecological benefits (reduction of unpleasant odor, pathogens accumulation, or greenhouse gas emission), social and economic advantages, and energy saving. In addition to biogas production, this process can be used to produce various bioproducts, such as biopolymers, bioplastics, biomass, biofertilizers, and biolipids. Interestingly, the AD process residue or digestate is a nutrient-rich by-product that can be used as a biofertilizer for agronomical purposes to balance N-P cycle in the soils. Despite of numerous benefits of AD, less than 1 % of waste is treated by this process. This process has the potential to be integrated with other waste treatment approaches to increase waste treatment efficiency. Therefore, it is essential to focus on each advantage and clarify ambiguity in order to satisfy more countries for employing AD for waste treatment. In this review, various benefits of AD are evaluated; and its potential impacts on particularly agriculture are examined in detail. Additionally, potential biomass and wastes that can be used for anaerobic digestion worldwide are deliberated. Besides, a critical perspective has been developed on the economic, environmental, and social evaluation of the benefits of AD and, as a final point, focused on an integrated circular cascading approach. © 2024 Elsevier Ltd

Background: Aquaculture relies significantly on effective aeration systems to ensure optimal conditions for aquatic organisms. This 96-day study investigates the dynamic relationship between Oxygen Transfer Rates (OTR) and seasonal variations, with a specific focus on the impact of seasonal dynamics and the placement of paddle wheel aerators. The study recognizes the pivotal role of Total Dissolved Solids (TDS) and Total Suspended Solids (TSS) as key water quality parameters influencing aeration efficiency. Methodology: A series of water circulation experiments were conducted at regular intervals to assess mixing rates, revealing a nuanced trajectory ranging from 27.05 to 14.22 m³/kWh. The study scrutinized the influence of TDS and TSS on these rates. Additionally, water velocity variations, ranging from 0.45 to 1.67 m/s, were examined, highlighting density-dependent changes, particularly evident post four weeks of operation. Oxygen stratification analysis provided insights into deviations in Dissolved Oxygen (DO) concentrations, with particular attention to climatic aberrations. Rigorous statistical analyses, including chi-squared, Pearson correlation, Gaussian distribution checks, and student's t-tests, validated the methodological robustness and data reliability. Significant findings: Employing a Seasonal Auto Regressive Integrated Moving Average (SARIMA) model, the study achieved a remarkable 97 % accuracy in forecasting DO levels for the subsequent 96 days. Real-time validation, complemented by a Chi-square goodness of fit test, reaffirmed the model's reliability, establishing congruence between observed and forecasted values. This research underscores the critical roles of strategic aerator placement and seasonal considerations in optimizing pond aeration efficiency, providing substantive insights for the sustainable management of aquaculture ecosystems. © 2024 Taiwan Institute of Chemical Engineers

Biogas production through anaerobic digestion (AD) is one of the complex non-linear biological processes, wherein understanding its dynamics plays a crucial role towards process control and optimization. In this work, a machine learning based biogas predictive model was developed for high solid systems using algorithms, including SVM, ET, DT, GPR, and KNN and two different datasets (Dataset-1:10, Dataset-2:5 inputs). Support Vector Machine had the highest accuracy (R2) of all the algorithms at 91 % (Dataset-1) and 87 % (Dataset-2), respectively. The statistical analysis showed that there was no significant difference (p = 0.377) across the datasets, wherein with less inputs, accurate results could be predicted. In case of biogas yield, the critical factors which affect the model predictions include loading rate and retention time. The developed high solid machine learning model shows the possibility of integrating Artificial Intelligence to optimize and control AD process, thus contributing to a generic model for enhancing the overall performance of the biogas plant. © 2024 Elsevier Ltd

Microalgae paves the way towards a negative emission technology; however, single-pot systems combining nutrient removal and wastewater treatment are scarce in the literature. In this study, three different types of wastewater (university, municipality, and dairy industries) were studied using microalgae towards treatment and nutrient removal using Scenedesmus sp. and Chlorella sp. The experiments were carried out in 20 L reactors, for 9 days, where in achieving a maximum of algal growth rate of 770 and 725 mg/L for Scenedesmus sp. and Chlorella sp., respectively. Of the three wastewaters, dairy wastewater had the highest influent COD (3488 mg/L), which was reduced by 92% after 9 days. The pigment content was highest after 6 days (0.22 ± 0.03%), and there was no significant improvement after 9 days, suggesting a trade-off between nutrient removal, photosynthetic performance, and COD reduction. Microalgae act as a sustainable solution and negative emission technology to solve the crisis of wastewater treatment, nutrient removal and production of high-value products. Graphical abstract: (Figure presented.) © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2024.

Attributional life cycle assessment study examines the environmental impact of raw materials, machinery, and unit operations. In the present work, an attributional life cycle assessment (LCA) was employed to assess the environmental and greenhouse gas impacts of a shrimp feed production system. A commercial shrimp feed mill in Tamil Nadu, India, provided inventory data for one-ton shrimp feed (functional unit) for a Cradle-to-Gate evaluation using environmental impact methodologies, specifically Impact 2002+ in SimaPro® (V9.3.0.3) software. The results showed that human health (0.003357 DALY), ecosystem quality (2720.518 PDF × m2 × yr), climate change (2031.696 kg CO2 eq), and resources (71019.42 MJ primary) were the most significantly impacted. The human health category was found to be the most prominent after normalization and weighting (0.47 pt), and strategies were suggested accordingly. The GWP20 and GWP100 measures for long-term climate change were calculated to be 8.7 and 7.33 kg CO2 eq, respectively. Cast iron used in machinery production (GWP 20–15.40%, GWP100–134.5%) and electricity use (GWP 20–6.13%, GWP 100–6.9%) accounted for sizable portions of the burden. Feed production is estimated to contribute 0.2% of global CO2 emissions within the proposed global context. These findings are significant regarding economically and environmentally sustainable shrimp feed production worldwide. © 2023 Elsevier Inc.

Background: Aquaculture relies significantly on effective aeration systems to ensure optimal conditions for aquatic organisms. This 96-day study investigates the dynamic relationship between Oxygen Transfer Rates (OTR) and seasonal variations, with a specific focus on the impact of seasonal dynamics and the placement of paddle wheel aerators. The study recognizes the pivotal role of Total Dissolved Solids (TDS) and Total Suspended Solids (TSS) as key water quality parameters influencing aeration efficiency. Methodology: A series of water circulation experiments were conducted at regular intervals to assess mixing rates, revealing a nuanced trajectory ranging from 27.05 to 14.22 m³/kWh. The study scrutinized the influence of TDS and TSS on these rates. Additionally, water velocity variations, ranging from 0.45 to 1.67 m/s, were examined, highlighting density-dependent changes, particularly evident post four weeks of operation. Oxygen stratification analysis provided insights into deviations in Dissolved Oxygen (DO) concentrations, with particular attention to climatic aberrations. Rigorous statistical analyses, including chi-squared, Pearson correlation, Gaussian distribution checks, and student's t-tests, validated the methodological robustness and data reliability. Significant findings: Employing a Seasonal Auto Regressive Integrated Moving Average (SARIMA) model, the study achieved a remarkable 97 % accuracy in forecasting DO levels for the subsequent 96 days. Real-time validation, complemented by a Chi-square goodness of fit test, reaffirmed the model's reliability, establishing congruence between observed and forecasted values. This research underscores the critical roles of strategic aerator placement and seasonal considerations in optimizing pond aeration efficiency, providing substantive insights for the sustainable management of aquaculture ecosystems. © 2024 Taiwan Institute of Chemical Engineers

Lignocellulosic biomass is the richest regenerative resource in nature. Especially in the context of continuous consumption of fossil energy and environmental pollution, it is urgent to use lignocellulosic biomass to prepare clean energy such as biofuels. But lignocellulose has a strong natural barrier against degradation, which needs to be pre-treated by physical, chemical and microbial means and then converted into biofuels and other high value-added products at lower cost and higher efficiency. This chapter mainly describes the pretreatment techniques of lignocellulose in recent years, including traditional physical methods, chemical methods and biological methods. And the mechanism of each pretreatment method is briefly introduced, and its advantages and disadvantages are analysed and summarized. At the same time, the economic feasibility and influencing factors of these technologies are discussed and analysed. Finally, the development and application of lignocellulosic pretreatment technology are prospected and suggested, aiming at providing some reference for the more efficient development and utilization of cellulose. © 2025 Elsevier Ltd. All rights reserved.

Heavy industries play a crucial role in the economic growth of India through their contribution towards meeting demand, including exports and GDP. Every functional unit of the production process related to hard-to-abate industries has to depend upon power sources for manufacturing the final product. The major power source for heavy industries namely power plants, iron and steel, cement, paper, and fertilizer are coal. During the process of energy conversion from coal through combustion, they produce a large amount of greenhouse gases. As production capacity is increased to meet the growing demand, it is essential to mitigate carbon emissions. There are many routes adopted by various sectors to decarbonize the production process. These include the use of alternative fuels, using the best available techniques, carbon capture utilization, and storage. Most of these techniques have shown positive impacts after implementation. In this study, the production process of each sector is analyzed to find the hotspots, the mitigation strategies followed by each industry, and mainly the use of green hydrogen as a power source. It elaborates on the routes of production of green hydrogen, the major challenges in the implementation part, the policy making of green hydrogen in India, its relationship to heavy industries, and how green hydrogen plays a role in net-zero emission goals. © 2024 American Chemical Society.

Due to resource scarcity, current industrial systems are switching from waste treatment, such as wastewater treatment and biomass, to resource recovery (RR). Biofuels, manure, pesticides, organic acids, and other bioproducts with a great market value can be produced from wastewater and activated sludge (AS). This will not only help in the transition from a linear economy to a circular economy, but also contribute to sustainable development. However, the cost of recovering resources from wastewater and AS to produce value-added products is quite high as compared to conventional treatment methods. In addition, most antioxidant technologies remain at the laboratory scale that have not yet reached the level at industrial scale. In order to promote the innovation of resource recovery technology, the various methods of treating wastewater and AS to produce biofuels, nutrients and energy are reviewed, including biochemistry, thermochemistry and chemical stabilization. The limitations of wastewater and AS treatment methods are prospected from biochemical characteristics, economic and environmental factors. The biofuels derived from third generation feedstocks, such as wastewater are more sustainable. Microalgal biomass are being used to produce biodiesel, bioethanol, biohydrogen, biogas, biooils, bioplastics, biofertilizers, biochar and biopesticides. New technologies and policies can promote a circular economy based on biological materials. © 2023 Elsevier Ltd

Bioenergy with carbon capture and storage (BECCS) is gaining attention as an energy source and the most effective path to achieve negative CO2 emissions by photosynthesis and capturing CO2. However, BECCS has certain challenges and limitation which needs to be addressed to make the technology feasible. Concerns about food security, land, water use, and the possibility of large-scale implementation are critical in commercialization. As an emerging field, BECCS will need dynamic research and development over the next few decades, as well as strong policy backing, to clinch that it can be implemented on time for fulfilling the Paris agreement targets. The goal of this critical review is to find the impending obstacles that BECCS is facing, as well as the approaches to overcome them, while also emphasizing the advances in the field over the last decade. Detailed technology assessment is provided for a better understanding. © 2023 Elsevier Ltd

Hydrogen is considered as the fuel of the future not only because of its high energy density but also due to its zero-carbon emission potential during combustion. However, to achieve sustainable growth, the hydrogen generation process must be techno-economically feasible and have minimum carbon footprint. The techno-economic analysis (TEA) of various hydrogen generation process aids in identifying the effective bio-hydrogen generation process at minimal cost thereby aiding in faster dissemination of the system by attracting investors. Among the various techniques available for bio-hydrogen production, gasification was found to be most economical ($1.2/kg H2) followed by anaerobic digestion process ($1.25/kg H2). Meanwhile, after carrying out the life cycle analysis (LCA) of the different bio-hydrogen generation process, it was found that generation of bio-hydrogen by gasification of eucalyptus wood produced least carbon foot of −1.6 kg CO2eq./kg H2. Thus, the TEA and LCA of different biohydrogen production process also helps to identify the bottlenecks haunting the penetration of hydrogen in energy market which can be overcome by framing effective policies by the governing agencies. © 2023 Elsevier Ltd

Carbon capture storage and utilization (CCSU) has the potential to become a key tool to mitigate climate change, thus, aiding in achieving the objectives of the 2015 Paris Agreement. Even though the relevant remediation technology has achieved technical maturity to a certain extent, implementation of CCSU on a larger scale is currently limited because of non-technical parameters that include cost, legalization, lack of storage reservoir, and market mechanism to penalize CO2 emitter. Among these, cost emerges as the primary barrier to the dissemination of CCSU. Hence, necessary policy frameworks and incentives must be provided by governing agencies to enable faster dissemination of carbon capture and utilization (CCU) and carbon capture and storage (CCS) globally. Meanwhile, strict implementation of a carbon tax across nations and market demand for products generated using captured CO2 can aid in the fast adoption of CCU and CCS. This review assessed the economic feasibility and sustainability of CCS and CCU technologies to identify the barriers to commercializing these technologies. © 2023 Elsevier B.V.

The energy sector accounts for three-quarters of the greenhouse gas emission happening around the world. So, it is necessary to move toward a sustainable fuel with minimal carbon emissions to mitigate the rise in global temperature. Bioenergy is considered an effective resource to satisfy the rising global energy demand with minimal carbon emissions. The presence of proven and well-mature technology to convert biomass into various forms of fuels and chemical products provides an upper hand to bioresources over other energy sources. However, the rise in the cost of feedstocks, transportation cost of low-density bioresources, and lack of reliable biomass supply chain network has made them least preferred when compared to solar and wind energy technologies. Hence, it is important to access the scope for commercialization of biomass-based products, which will aid in framing policies to create a sustainable market for them. © 2024 Elsevier Inc. All rights reserved.

The global nations are under pressure to develop a renewable and environmentally friendly fuel/technology from sustainable feedstock, such as woody biomass, to reduce greenhouse gas emissions and meet the energy demand. But several factors must be addressed to achieve the daunting task, which includes technological advancement, financial viability, environmental sustainability, and finally government backing in the form of sensible regulations and increased public awareness. To reduce the world's reliance on fossil fuels and ensure a sustainable future, biofuel policies are crucial. The production of biofuel from woody biomass makes the system not only to reduce the cost of the feedstock but also to decrement the dependency on first-generation feedstocks, which dominates the present biofuel market. Hence, this chapter deals with the need for governing bodies to draft an effective policy for the successful adoption of woody biomass-based biorefinery technologies to mitigate global emissions and to fulfill the growing energy demand thereby enabling a sustainable economy. © 2023 Elsevier Inc. All rights reserved.

Bioenergy resources, when harvested sustainably, have the potential not only to satisfy the growing energy demand but can also aid in achieving a negative carbon footprint. The Intergovernmental Panel on Climate Change (IPCC) has also identified bioenergy resources as an effective tool to achieve zero emissions by 2050 because biomass can be valorized into various products, namely, producer gas, syngas, bioethanol, biomethanol, biochar, bio-oil, etc. by adopting different conversion pathways, thus, aiding in the reduction in consumption of fossil fuel, thereby decreasing the anthropogenic greenhouse gas (GHGs) emission into the atmosphere. However, it is necessary to analyze the economic viability of these biorefinery systems for the faster penetration of these products into the global market and to identify the bottleneck haunting its faster dissemination. In this regard, this chapter analyses the technical and economic factors which affect the biorefinery of woody biomass by employing thermo-chemical and bio-chemical conversion processes. © 2023 Elsevier Inc. All rights reserved.

With the huge energy demand inevitably exacerbates the non-renewable resources depletion and ecological-social challenges, renewable energy has become a crucial participant in sustainable strategy. Biorefinery emerged as a sustainable approach and recognized promising transformation platforms for products, to achieve circular bioeconomy which focuses on the biomass efficient and sustainable valorization, promotes resource regeneration and restorative. The emerged biowaste biorefinery has proved as sustainable approach for integrated bioproducts and further applied this technology in industrial, commercial, agricultural and energy sectors. Based on carbon neutral sustainable development, this review comprehensive explained the biowaste as renewable resource generation and resource utilization technologies from the perspective of energy, nutrient and material recovery in the concept of biorefinery. Integrate biorefinery concepts into biowaste management is promise for conversion biowaste into value-added materials and contribute as driving force to cope with resource scarcity, climate changes and huge material demand in circular bioeconomy. In practice, the optimal of biorefinery technologies depends on environmentally friendly, economic and technical feasibility, social and policy acceptance. Additionally, policy interventions are necessary to promote biowaste biorefinery implements for circular bioeconomy and contribute to low-carbon cleaner environment. © 2022 Elsevier Ltd