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Globally, industrialisation and urbanisation have led to the generation of hazardous waste (HW). Sustainable hazardous waste management (HWM) is the need of the hour for a safe, clean, and eco-friendly environment and public health. The prominent waste management strategies should be aligned with circular economic models considering the economy, environment, and efficiency. This review critically discusses HW generation and sustainable management with the strategies of prevention, reduction, recycling, waste-to-energy, advanced treatment technology, and proper disposal. In this regard, the major HW policies, legislations, and international conventions related to HWM are summarised. The global generation and composition of hazardous industrial, household, and e-waste are analysed, along with their environmental and health impacts. The paper critically discusses recently adapted management strategies, waste-to-energy conversion techniques, treatment technologies, and their suitability, advantages, and limitations. A roadmap for future research focused on the components of the circular economy model is proposed, and the waste management challenges are discussed. This review stems to give a holistic and broader picture of global waste generation (from many sources), its effects on public health and the environment, and the need for a sustainable HWM approach towards the circular economy. The in-depth analysis presented in this work will help build cost-effective and eco-sustainable HWM projects. [ABSTRACT FROM AUTHOR]

The growing energy demand in the context of climate change issues requires the development of green fuels such as hydrogen from water. Piezocatalytic water splitting is promising for producing green hydrogen, yet this process is often limited by low efficiency and low sustainability. Here we developed an efficient method to use wastewater directly for piezocatalytic hydrogen production. Magnetic cerium-doped bismuth ferrite was employed as the piezocatalyst to collect mechanical energy. The performance of hydrogen production was compared using different types of organic wastewaters containing alcohols, organic acids, phenols, and surfactants. Results showed a maximum hydrogen yield of 2114 μmol per g from a 2.5 mg per L alcoholic mixture in wastewater. This high yield is explained by the fact that alcohols act as sacrificial donors to suppress electron site recombination and the reverse reaction. Overall our findings represent a new strategy for piezocatalytic hydrogen production from wastewater. [ABSTRACT FROM AUTHOR]

Biosurfactants have been found capable of replacing synthetic surfactants which include ongoing bioprospecting of biosurfactant-producing bacteria as well as process optimization for maximum biosurfactant production. In this study, five morphologically distinct actinomycete strains isolated from hydrocarbon-polluted soil collected from an oil spill surface in Southeastern Algeria were tested for their ability to produce biosurfactants using preliminary biosurfactant screening assays. The 7SDS strain was selected as the most promising biosurfactant producer due to its greatest oil displacement diameter (7.83±0.15 cm), emulsification index (59.66±0.44%), and enhanced surface tension reduction (30.04±0.51 mN/m); it was identified as Streptomyces thinghirensis 7SDS using 16S rDNA sequence analysis. The 7SDS strain's biosurfactant production was optimized using the Face-centered central composite design (CCD) based on response surface methodology (RSM). To this end, five independent factors, i.e., residual frying oil, used engine oil, whey, CS filtrate, and incubation time, were assessed. The RSM's model predicted a surface tension of 27.48 mN/m using 2.44% (v/v) residual frying oil, 0.35% (v/v) used motor oil, 0.83% (v/v) whey, 0.39% (v/v) CS filtrate, and an incubation time of 219.3 h. The optimized medium produced 8.79 g/L of biosurfactant. The produced biosurfactant allows one to reduce the surface tension of distilled water from 70.86 mN/m to 27.96 mN/m at a critical micelle concentration of 350 mg/L, even over a wide range of pH (2.0–12.0), temperature (4–120 °C), and salinity (2–12%, W/V). Biochemical (Biuret, phenol-sulfuric acid, and phosphate tests) and compositional (FTIR and GC-MS) characterizations confirmed the phospholipid nature of the produced biosurfactant. Interestingly, the produced BS demonstrated significant antimicrobial activity as well as intriguing activity in removing hydrocarbons from polluted soil. Because of their appealing biological properties, strain 7SDS and its biosurfactant are attractive targets for a variety of applications such as biomedicine and environmental ones. [ABSTRACT FROM AUTHOR]

Eco-industrial parks (EIPs) are of increasing importance for implementing industrial ecology strategies and are facing increasing challenges in terms of environmental pollution and resource scarcity. As a complex adaptive system, an EIP involves multiple sectors and faces various disturbances that influence its evolutionary trajectories. This study adopts an agent-based model to simulate the material flows and industrial symbiosis process in the EIP, considering the initiative of each company and the ever-changing environment. The proposed EIP model emphasises the heterogeneity of companies and attempts to reflect multiple and dynamic factors that have received less attention in previous studies. This model contains two types of agents, companies and the external environment. A company agent makes decisions and interacts with other agents following its own behaviour rules, while the external environment agent functions to coordinate the material flows and exert influence on the companies. The model has been verified and validated by simulating a 20-year-period development of an empirical EIP in China. The simulation results are assessed by three indicators: eco-connectance, eco-efficiency, and industrial symbiosis indicator. Results showed that during the growing phase, the eco-connectance increased from 0.02 to 0.1 for the non-disturbance situation. The eco-efficiency and industrial symbiosis indicator also realised 78.5% and 74.8% of their total increments. The outcome of this research provides insights for the design of the strategies to improve the industrial symbiosis performance and is of high potential to facilitate EIPs in promoting eco-transformation and sustainable development. [ABSTRACT FROM AUTHOR]

Ash deposition in flue gas heat exchanger affects its heat transfer performance and lifecycle, which becomes a crucial factor restricting the efficient recovery and utilization of flue gas waste heat. In this paper, a numerical method was established to investigate the characteristics of ash deposition in tube bundle heat exchangers. An integrated fouling model including transport, rebound, deposition, and removal of particles was employed to predict the behaviour of particles. Then, the effects of particle diameter and flue gas velocity on collision mass, deposition mass, absolute deposition ratio, and relative deposition ratio were studied. At last, the thermal–hydraulic and ash deposition characteristics of three different tube shapes were compared. The results showed that the low-velocity regions on the circumference were the primary locations of particle deposition, and the medium-diameter particles were the main deposition components. With the increase in flue gas velocity, the deposition mass of large-diameter particles decreased, and that of small-diameter particles increased. The use of an elliptical tube and flattened round tube with an apex angle of 60°had also excellent thermal–hydraulic and anti-fouling performances. Consequently, the ash deposition and wear can be reduced by increasing flue gas velocity, filtering medium and large-diameter particles, and using elliptical and flattened round tubes. [ABSTRACT FROM AUTHOR]

Since 2020, the COVID-19 pandemic has urged event holders to shift conferences online. Virtual and hybrid conferences are greener alternatives to in-person conferences, yet their environmental sustainability has not been fully assessed. Considering food, accommodation, preparation, execution, information and communication technology, and transportation, here we report comparative life cycle assessment results of in-person, virtual, and hybrid conferences and consider carbon footprint trade-offs between in-person participation and hybrid conferences. We find that transitioning from in-person to virtual conferencing can substantially reduce the carbon footprint by 94% and energy use by 90%. For the sake of maintaining more than 50% of in-person participation, carefully selected hubs for hybrid conferences have the potential to slash carbon footprint and energy use by two-thirds. Furthermore, switching the dietary type of future conferences to plant-based diets and improving energy efficiencies of the information and communication technology sector can further reduce the carbon footprint of virtual conferences. Moving conferences from in-person to virtual and hybrid modes may have emissions reductions benefits. Here the authors find that the switch to virtual and hybrid conferencing reduces the carbon footprint by 94% when it comes to the switch to virtual conferencing, and 67% for hybrid conferences with carefully selected hubs. [ABSTRACT FROM AUTHOR]

Integrating sustainability into business functions of organisations is a challenge faced by practitioners. They need to understand what aspects must be considered to achieve effective sustainability implementation. Few studies review current sustainable business models and reveal essential aspects that must be possessed by these models. This study aims to discuss the available sustainable business models and identify the main features of the models. Conceptual research is applied in this study to synthesise the current sustainable business models in the literature. The study reveals nine main aspects to consider, including sustainability, information technology, circular economy, value chain, core values, value creation, organisational values, performance management, and stakeholder engagement. The proposed framework would help the practitioners to capture important aspects of the sustainability implementation. These aspects would guide them to effectively embed sustainability into an organisation's business functions and fulfil stakeholder expectations. [ABSTRACT FROM AUTHOR]

Malaysia is in a transition state towards a more developed country which stresses on sustainable development. The Malaysia government has introduced several policies related to the installation of renewable energy to secure its energy demand, which has an annual growth rate of 8.1%. In the Iskandar region in Johor, low-carbon development projects have been continuously implemented under the low-carbon society blueprint for Iskandar Malaysia. The selected village, Layang-Layang, is located within a palm oil plantation and is part of Malaysia rural transformation centre (RTC) project where a community-composting pilot plant was successfully set up in 2016. This study analysed the environmental and economic performance of the community-composting project. A total of four scenarios is analysed regarding their environmental performance (greenhouse gas emission) and the economic returns of investment. Scenario A served as the baseline study where all the municipal waste is sent to a landfill site. Scenario B involved the current pilot-scale composting plant practised by 100 residents in Layang-Layang. Scenario C considered the scaled-up composting scenario (3000 residents) based on the data from scenario A and B in Layang-Layang. Scenario D considered the treatment of the municipal wastes (3000 residents) to generate biogas via anaerobic digestion (AD) where the digestate was used for composting. In this study, co-composting of food waste from a residential area with the green waste from the plantation showed a reduction potential of 96.79% (Scenario C) on greenhouse gas (GHG) emission as compared to the landfill (Scenario A) and a reduction of 99.67% on GHG emission for the integrated AD and composting system (Scenario D). The scaled-up composting in scenario C was more attractive for investment as compared to scenario D. Scenario C showed a shorter minimal year for the return of investment (3.09 years) as compared to Scenario D (6.17 years) with electricity generation from biogas. [ABSTRACT FROM AUTHOR]

This work is aimed at developing knowledge about the possibilities of a circular economy arising from the processing of metallurgical slag, which in a number of indicators is close to natural formations. The possibility of manufacturing ceramic catalyst carriers from natural raw materials and industrial waste (metallurgical slags) using powder metallurgy is considered. Properties of metallurgical slags are studied by X-ray diffraction analysis, methods of simultaneous thermal analysis (thermogravimetry/differential thermal analysis), optical microscopy and scanning electron microscopy. Studies have revealed the similarity of the structure and properties of natural raw materials and studied metallurgical slag. It was established that the studied metallurgical slags could be used as an additional component to the zeolite–bentonite base to create a ceramic carrier for the catalyst. The scheme of manufacture of catalyst carriers from natural raw materials and metallurgical slag. [ABSTRACT FROM AUTHOR]

Mitigation of greenhouse gases (GHG) emissions is desirable without compromising the economic growth. This paper reviews the recent trends to mitigate GHG emissions in the key sectors of energy and solid waste. The energy sector is the key admitter for global GHG emissions, and a range of optimisation and modelling tool has been developed to minimise the GHG emissions and overall cost, especially for the implementation of renewable energies such as biofuel and biogas. A few carbon sequestration technologies such as the carbon capture and storage (CCS) and biochar application have been reviewed. The review included the challenges and knowledge gaps regarding the utilisation of CCS, such as the storage capacity, long-term policy framework, high costs and the potential risk. Although solid waste contributes about < 5% of the global GHG emissions, effective solid waste management remained a great challenge in many fast-growing cities in Asia. Considering the high organic portion (> 40%) in the municipal solid waste for many developing countries in Asia, composting has been proposed as a viable treatment technology to convert waste-to-wealth. A range of waste management tools, including scenario analyses on different waste technologies, optimisation of waste collection routes, multi-criteria decision tools, is reviewed to support the decision-making for solid waste management. A range of environmental management system (EMS) has been adopted by organisations to improve product quality, reducing production cost and improves reputation of firms. An environmental policy such as tax exemption could be helpful to promote the adoption of EMS that could be costly. CO2 and material flow footprint tools, such as water-energy-materials nexus, are applicable at a city and regional level. The tools are used to mitigate GHG emissions by developing the mechanisms with shared markets of virtual resource flows (carbon, water, food, energy) between the trading partners regionally and internationally. [ABSTRACT FROM AUTHOR]

There are contrasting opinions on the utilisation of microbial inoculant (MI) as a bioremediation technology for composting. The effectiveness can be affected by a diversity of factors, and the reproducibility of results can be a great challenge. This study aims to review the effectiveness of MI, specified as isolated or cultured single and consortium micro-organisms, for composting, with the main component of lignocellulosic waste (LW) and the organic portion of municipal solid waste (OPMSW). The potential for the enhancing effect of each parameter, i.e. compost quality parameters: pH, germination index, nitrogen content, phosphorus content, potassium content, C/N ratio; composting parameters: temperature, odour, enzymatic activities, organic matter content, microbial population, volume reduction, humification, is discussed and evaluated. Based on 13 analysed parameters, the use of MI tends to exert a significant positive effect on the composting of LW compared to that of OPMSW. There has not been a full consensus on the efficiency of MI for composting as it varies on a case-by-case basis. A decision framework is required for the application of MI for different composting scenarios. This overview proposes MI technology, which has been generally less practical than optimising the physicochemical parameters of the composting due to the higher variation in the composting efficiency. Comprehensive comparison studies between the two approaches are needed for further verification which can contribute to the support of composting as a clean technology. The unnecessary uses of resources (e.g. MI, electric, fuel) can consequently be avoided for environmental footprint minimisation. [ABSTRACT FROM AUTHOR]

An introduction to topics discussed within the issue is presented, including "Utilization of Waste for Large Capacity Productions of Phosphorus-Containing Products Based on the System Analysis Methods," by Arkadiy Bessarabov and colleagues, "Synthesis of Resource Conservation Network With Sink-Source Interaction," by Cheng-Liang Chen and colleagues, and "Spatial Information Systems for Emission Reduction," by Kálmán I. Kovács.

Asia-Pacific (APAC) has been the world's most dynamic emerging area of economic development and trade in recent decades. Here, we reveal the significant and imbalanced environmental and socio-economic effects of the region's growths during 1995–2015. Owing to the intra-regional trade of goods and services, APAC economies grew increasingly interdependent in each other's water and energy use, greenhouse gas (GHG) and PM2.5 emissions, and labor and economic productivity, while the environmental and economic disparity widened within the region. Furthermore, our results highlight APAC's significant role in globalization. By 2015, APAC was engaged in 50–71% of the virtual flows of water, energy, GHG, PM2.5, labor, and value added embodied in international trade. While the region's final demand and trade grew less resource- and emissions-intensive, predominantly led by China's transformations, APAC still lags behind global averages after two decades. More joint efforts of APAC economies and attention to sustainable transformation are needed. The environmental and socio-economic implications of the growth in welfare and trade in Asia-Pacific (APAC) remain unclear. Here the authors show that over the past two decades (1995–2015), owing to intraregional trade, the APAC economies have grown increasingly interdependent in natural resource use, air emissions, and labor and economic productivity. [ABSTRACT FROM AUTHOR]

The author discusses the role of industry-academia partnership to the advancement of the science and engineering of deployable technologies. He cites the Panel Discussion "Academia-Industry Collaboration in Sustainable Development" at the 8th Conference on Sustainable Development of Energy, Water and Environment Systems (SDEWES 2012) in Ohrid, Macedonia which highlighted the incentives for collaboration of academia-industry. He also notes successful stories of academia-industry partnership.

An introduction to the articles discussed within the issue is presented, including articles on environmental policy decision-making support systems and analysis, and articles on environmental policies implementation into clean technologies process design and analysis.