Chemical looping combustion of biomass for renewable & non- CO2 emissions energy- status and review

World depends on fossil fuel combustion for thermal energy generation. Fossil fuel combustion leads to the generation of CO2 and ex-tinction of non-renewable resources. To meet the future energy demands replacement of existing technologies should take place in the view of large quantities of GHG’s emissions from fossil fuels and their extinction. Chemical looping combustion (CLC) is primarily a combustion technique with an inherent separation of CO2 from the flue gases. Due to its advantage of negative CO2 emissions, chemical looping combustion got attention of many researchers since last one and half decade. Recent research advancements in the CLC provided a platform for further research and developments in chemical looping combustion of biomass. This paper reviews the CLC of biomass to present the overview of chemical looping combustion technology and its status of biomass utilization as a fuel in CLC reactors

Extraction and Characterization of Microplastics from Organic Solid Matrices and their Remediation

Plastics have become an essential commodity due to their superior engineering properties, durability and low cost to be used by a wide range of commercial products. However, the degradation of plastics due to mechanical, chemical, biological, and photolytic stresses has led to the formation of microplastics (MPs). MPs have risen to the top of environmental concerns due to their affinity to pollute the environment, and to pass to the food chain, threatening human health. In this context, attempts have been made to extract and characterize MPs from aqueous and solid matrices. A problem that not only hampers research but also regulatory decisions is the variety of methods used for the extraction and characterization of MPs, especially in organic solid matrices (OSMs) with organic (OM) \u3e 5%, making the comparison of results difficult. This paper aims to address this need, by critically assessing the methodologies and protocols used for extraction of MPs from OSMs, which includes sample collection, dispersion, OM removal, and separation, as well as the qualitative and quantitative characterization of MPs. Further, current impediments in the accurate characterization of MPs are identified along with recommendations for future developments. Finally, recent efforts by various countries to legislate against certain sources of MPs, as well as issues and novel techniques to remediate MPs from the soil, and wastewater have been highlighted

Municipal solid waste management under Covid-19: Challenges and recommendations

Covid-19 is proving to be an unprecedented disaster for human health, social contacts and the economy worldwide. It is evident that SARS-CoV-2 may spread through municipal solid waste (MSW), if collected, bagged, handled, transported or disposed of inappropriately. Under the stress placed by the current pandemic on the sanitary performance across all MSW management (MSWM) chains, this industry needs to re-examine its infrastructure resilience with respect to all processes, from waste identification, classification, collection, separation, storage, transportation, recycling, treatment and disposal. The current paper provides an overview of the severe challenges placed by Covid-19 onto MSW systems, highlighting the essential role of waste management in public health protection during the ongoing pandemic. It also discusses the measures issued by various international organisations and countries for the protection of MSWM employees (MSWEs), identifying gaps, especially for developing countries, where personal protection equipment and clear guidelines to MSWEs may not have been provided, and the general public may not be well informed. In countries with high recycling rates of MSW, the need to protect MSWEs' health has affected the supply stream of the recycling industry. The article concludes with recommendations for the MSW industry operating under public health crisis conditions

Sustainable environmental geotechnics practices for a green economy

The revitalisation of the global economy after the Covid-19 era presents environmental geotechnics with the opportunity to reinforce the need for a change in paradigm towards a green, circular economy and to promote aggressively the use and development of sustainable technologies and management practices. This paper aims to assist in this effort by concentrating on several thematic areas where sustainability solutions and future improvements are sought. These include the re-entry of construction and demolition of wastes, excavated materials, industrial wastes and marine sediments into the production cycle and the reuse of existing foundations. Despite the recent trend in advanced countries towards recycling and waste-to-energy thermal treatment, landfills still constitute the most common municipal solid waste management practice, especially in low-and-middle-income countries, and technological solutions to improve their environmental footprint are hereby presented. At the same time, remediation solutions are required to address the multitude of contaminated sites worldwide. Advanced developments that incorporate environmental, economic and social dimensions are expounded by the authors, together with sustainable ground improvement solutions for infrastructure projects conducted in soft and weak soils. The topic of thermo-active geostructures concludes this paper, where, apart from their infrastructure utility, these structures have the potential to contribute to the renewable energy source.Published versionThe second author would like to acknowledge the support of the Office of the Associate Provost for Research and Academic Development at Abu Dhabi University, UAE through grant19300540

A review of the occurrence and causes for wildfires and their impacts on the geoenvironment

Wildfires have short- and long-term impacts on the geoenvironment, including the changes to biogeochemical and mechanical properties of soils, landfill stability, surface- and groundwater, air pollution, and vegetation. Climate change has increased the extent and severity of wildfires across the world. Simultaneously, anthropogenic activities—through the expansion of urban areas into wildlands, abandonment of rural practices, and accidental or intentional fire-inception activities—are also responsible for a majority of fires. This paper provides an overall review and critical appraisal of existing knowledge about processes induced by wildfires and their impact on the geoenvironment. Burning of vegetation leads to loss of root reinforcement and changes in soil hydromechanical properties. Also, depending on the fire temperature, soil can be rendered hydrophobic or hydrophilic and compromise soil nutrition levels, hinder revegetation, and, in turn, increase post-fire erosion and the debris flow susceptibility of hillslopes. In addition to direct hazards, wildfires pollute air and soil with smoke and fire suppression agents releasing toxic, persistent, and relatively mobile contaminants into the geoenvironment. Nevertheless, the mitigation of wildfires’ geoenvironmental impacts does not fit within the scope of this paper. In the end, and in no exhaustive way, some of the areas requiring future research are highlighted

Application of municipal plastic waste as a manmade neo-construction material: issues & wayforward.

Disposal of the enormous amounts of municipal plastic waste, MPW, generated by contemporary society has resulted in a severe threat to the inland and marine environments. In order to reduce this menace, different thermal treatment techniques of MPW (viz., incineration, gasification, and pyrolysis) are being considered and practiced. However, apart from the exorbitant cost associated with the implementation of these techniques, to achieve eco-friendly results, MPW ideally should be devoid of heavy metals, chlorine, moisture and inerts. With these limitations in view, modalities to utilize MPW, as a manmade neo-construction material that acts as a binder and/or filler for manufacturing various end-products (read composites) viz., tiles, cement concrete, paver blocks/bricks, and wood-plastic composites, have also been explored by earlier researchers. Though this practice will be a panacea for sustainable development of the present-day society, various issues associated with the (i) suitable quality and composition of MPW, (ii) incompatibility between the binder and filler, and (iii) inappropriate process(es) adopted, due to which the resultant end-products entail inferior characteristics, need to be evaluated critically. With this in view, (i) review of the engineering properties of the end-products manufactured from MPW binders and fillers, and (ii) the issues and the way forward associated with the management and utilization of MPW, as a manmade neo-construction material, have been critically synthesized and presented in this manuscript. It is believed that such a discussion would be instrumental to utilize the MPW as a sustainable construction material

Effect of physico-chemico-biological and operational parameters on composting of organic fraction of municipal solid waste and gaseous products emission: review

Composting enables microbial decomposition of biodegradable organic fractions of municipal solid waste (OFMSW) and converts them into a valuable resource having profuse application in agriculture and horticulture. The efficiency of composting, primarily, would depend upon physico-chemico-biological properties of the feedstock (moisture content, particle size and organic matter) and operational parameters (temperature, aeration rate and frequency, presence of bulking agents and microorganisms). However, lack of appropriate selection of the initial physico-chemico-biological properties of municipal solid waste (MSW) and inadequate maintenance of operational conditions during composting results in generating low-quality end products with undesirable characteristics, such as phytotoxicity and nutrients-deficiency. Also, the release of toxic elements, greenhouse gases and volatile organic compounds (odorants) into the environment are other major issues related to composting technology, which need immediate attention of the researchers. Hence, a critical synthesis of the literature has been conducted to understand the effect of different (i) physical (particle size, moisture content), (ii) chemical (pH, elemental composition), (iii) biological (type of microorganisms, enzymatic activities) and (iv) operational (temperature, aeration strategy, turning frequency, addition of bulking agents) parameters on the composting of OFMSW and emission of major gaseous products. Furthermore, by utilizing the available data in the literature, several trends have been developed to depict the impact of substrate characteristics and operational conditions on compost quality and emission of gaseous products. These relationships would be instrumental in devising general recommendations on the selection of initial properties of MSW to (i) obtain superior quality compost and (ii) reduce the emission of harmful gaseous products during composting

Characterization and utilization of landfill-mined-soil-like-fractions (LFMSF) for sustainable development: a critical appraisal

Unscientifically Created Landfills and Dumps, UCLDs, pose a severe threat to geoenvironment due to uncontrolled release of greenhouse gases and toxic leachate, accidental fire(s) and occasional slope failure(s). Further, UCLDs also become a socio-economic burden on the municipalities through the consumption of enormous land of the modern-day cities and creation of unhealthy living conditions for the surrounding populace. However, an increase in demand for the land to settle the ever-growing population of such cities and to meet the infrastructural requirements, the habitable boundaries of these cities are expanding, and hence mining of the UCLDs, termed as landfill mining, LFM, is being advocated. Apart from this, LFM facilitates the recovery of resources such as metals, plastics, glass and paper from the landfill mined residues, LMRs. Despite these advantages, LFM faces a significant challenge due to the creation of huge volumes of fine-fractions, separated from the LMRs, also known as ‘Landfill-Mined-Soil-like-Fractions’, LFMSF, which primarily is a conglomeration of organics, soils, debris and smaller chips of metals, plastics, and glass. Unfortunately, utilization of the LFMSF, as a manmade resource, has still not become a well-accepted practice. This is mainly due to the lack of understanding of the characteristics of the LFMSF that are mostly site-specific. With this in view, synthesis of the literature dealing with the issues related to the characterization and utilization of the LFMSF was conducted. It has been realized that by developing and following adequate characterization protocols and guidelines, the LFMSF can be utilized as a manmade resource for sustainable development, without impacting the geoenvironment adversely