Environmental Degradation: Challenges and Strategies for Mitigation

Environmental degradation is directly linked with environmental quality deterioration and depletion of resources. It is the world's most pressing problem and has created many challenges to humans, plants, animals, wildlife, and their habitats due to injudicious use of natural resources like unlimited burning of fossil fuel, water and soil pollution, and emission of harmful gases. The environmental degradation may be caused due to the several factors including pollution, climate, climate change, waste disposal, deforestation, desertification, and overpopulation. Worldwide, many policy initiatives have been born to develop strategies for mitigating and adapting to regulate and minimize restoring environmental degradation. The present chapter aims at (1) presenting an overview of environmental degradation to better understand this global issue, (2) describing different types of environmental degradation, (3) explaining several causes of environmental degradation in detail, and (4) discussing the impacts of environmental degradation and their mitigation measures briefly.

Forests are important terrestrial carbon sinks and help in mitigating the emissions of CO₂, and other greenhouse gases (GHGs). Besides, it provides multiple ecosystem goods and services including livelihood security, socio-economic development, ecosystem functioning, biodiversity maintenance, carbon dynamics, nutrient cycling, and climate regulation. Population explosion, land-use change for agriculture, industry, urbanization, and improper forest management are considered as the major reasons responsible for the acceleration of forest degradation. Shifting cultivation, the traditional land-use technique is another leading cause of global tropical forests degradation. Deforestation and forest degradation set off a series of environmental changes that significantly reduce the valuable provisioning services and also affect locally to global biodiversity. It is responsible for ca. 15% of all GHGs emissions contribute to rising global temperatures, changes in weather patterns, and an increased frequency of extreme weather events. Climate changes can alter wildlife habitats and decrease the availability of food and water. Besides, it is responsible for increased soil erosion, disruption of nutrients and water cycle, disrupted livelihood. Investment in natural ecosystems, through reduced carbon emissions from deforestation and forest Degradation (REDD), and reducing emissions from deforestation, forest degradation, and other forest-related activities (REDD + ) related strategies, contributes significantly to GHGs emissions reduction and forest carbon stocks enhancement. It also generates possible sources of livelihood security for the poor tribal communities that provide financial incentives to prevent deforestation and additional benefits for the conservation, management, and restoration of forests. However, forest landscape restoration (FLR) enhances the ecological integrity of deforested or degraded landscapes and also improves human well-being using nature-based solutions (NbS) such as plantation, agroforestry, erosion control, and natural forest regeneration. In this chapter, major ecological disturbances that cause forest degradation and deforestation have been discussed in detail along with FLR to enhance the ecological integrity of deforested landscapes and some policy interventions.

As one of the fastest-growing economies in the world, Bangladesh is dependent on its agricultural, manufacturing, and energy sectors. Fertile land driving agricultural growth, rapid population growth, low labor cost, and burgeoning local consumption are some of the key factors that are pushing for rapid industrialization in the country. The deeply embedded inertia of the economy to move away from the business as usual scenario is driving more pollution and exhaustion of scarce resources. To act on these challenges necessitates measuring the environmental impact of these economically productive activities. As such, life cycle assessment (LCA) is a globally well-recognized method for evaluating the environmental burden of any product, process, and/or industry. It enables us to discern the hotspots of the environmental impact along the value chain. This chapter presents an in-depth and methodical review of all the LCA studies published to date on the economically and environmentally significant sectors (i.e., agricultural, manufacturing, and energy) of Bangladesh to capture the typology and magnitude of the major environmental impacts caused by these sectors. Subsequently, it presents a comparative picture of all the key environmental impacts caused by these industries/sectors and accordingly attempts to identify the hotspots of harmful anthropogenic activities leading to major environmental degradation in Bangladesh. The investigation unearths several trends in these three sectors. Intensification of agricultural production and its dependency on chemical fertilizers and pesticides are the main causes of exorbitant nitrogen and phosphorus discharge, resulting in eutrophication, biomass devastation, and soil health deterioration. The manufacturing sector is responsible for ecotoxicity, metal depletion, freshwater eutrophication as well as freshwater ecotoxicity. In the energy sector, natural gas power plants were found to be half as harmful as the petroleum and heavy fuel oil-based power plants. The most harmful stage of the power plants’ life cycle is the operational phase where combustion takes place. Among energy technologies using renewable sources, small scale biogas plants were found less polluting than firewood or kerosene-powered stoves and diesel generators. Apart from these, textile and leather tanning industries of Bangladesh were identified for causing significant GHG emissions, acidification, and contamination of the aquatic ecosystem. The recommendations provided in this chapter would guide policy retrofitting for these sectors to ensure sustainable management of natural resources and the environment; therefore, initiating a shift toward responsible production and consumption. This chapter also outlines the knowledge gaps associated with LCA studies relating to these vital sectors of Bangladesh and suggest future research directions for filling those gaps.

Agrochemicals in the form of fertilizers and pesticides were thought of as a boon for humankind. However, the advancement of science brought to the fore the fact that chemical fertilizers and pesticides cause considerable harm to soil and subsequently to groundwater. With the burden of feeding a burgeoning global population, modern agriculture is heavily dependent on the extensive use of agrochemicals. Given the fact that the human population will likely reach ~9.7 billion by 2050, the importance of agrochemicals is more than ever before. However, these agrochemicals are inherently persistent in nature and may degrade soil health and the utility of groundwater for various purposes. Soil microbial communities that sustain different nutrient cycles are affected to a great extent by the persistence of these recalcitrant agrochemicals. As humans are dependent on soil and water for their survival, they are also exposed to health hazards stemming from these agrochemicals. Contaminated groundwater, if consumed for a considerable period, may cause many human health problems, including hormone disruption, reproductive abnormalities, and cancer, etc. This chapter aims at reviewing various impacts of chemical fertilizers and pesticides on soil degradation, groundwater, and human health with some reference to Bangladesh perspective and suggesting ameliorative measures that would keep soil and associated ecosystems sustainable and lessen the health hazards for humans.

Contaminants of emerging concern or more precisely, emerging contaminants (ECs) are set of bio-refractory compounds that originate in the water cycle from the technosphere. A more direct pathway is via reuse of treated wastewater that might have residual concentration of ECs that are not easily degraded in the current wastewater treatment practices. In this context, it is pragmatic to firstly understand the pathways of EC release, as well as the physiochemical interactions and transformation of theses ECs in the environment. This understanding of potential impacts can be translated into discharge guidelines for target ECs. This is important, as often variation in discharge standards can dictate the type and degree of treatment required. To understand this stated fact more clearly, this chapter discusses the necessity to undertake removal of the ECs in light of spread and extent of environmental contamination caused by ECs. The advanced oxidation processes that are capable of removal of these pollutants are also being discussed. Thus, attempt has been made to summarize appearance of ECs in aquatic environment, their ecological impacts, and removal methods to produce reusable quality treated water safe for reuse.

Nitrogen pollution from domestic, industrial, and agricultural sources leads to eutrophication and other adverse effects in aquatic systems. Therefore, nitrogen removal from wastewaters before disposal into water bodies is necessary. Many countries have enforced stringent discharge standards as less as10 mg/L as N to control nitrogen pollution. This book chapter reviews the emerging biotechnological processes in controlling nitrogen pollution cost-effectively and helps in meeting stringent discharge standards in contrast to the conventional nitrification–denitrification process. The emphasis of review is on process description and influencing parameters, merits/demerits of each process, and the reactor types employed using the literature reported in the last two decades. Finally, a comprehensive evaluation is done on the process performance for selecting the appropriate process for controlling nitrogen pollution from wastewaters, and recommendations are included.

Anaerobic baffled reactor (ABR) is an expanded septic tank consisting of a series of upflow anaerobic sludge blanket (UASB) processes without granulation for its treatment. The vertical baffled series in ABR stimulates the wastewater to flow through several compartments as it passes from inlet to outlet. Despite the ABR recognition for low operating and maintenance cost and high removal of organic matter and solids, the existing ABR reportedly has more deficient nutrient and pathogen removal performance. This study investigated the reduction of the pathogen from domestic wastewater through the hybrid system of the ABR and upflow anaerobic filter (UAF). Experiments were conducted at the ABR site in Islamic Boarding School in Malang, and untreated sewage was taken from the inlet. The untreated wastewater is fed into lab-scale ABR with a 145 cm × 45 cm × 50 cm dimension with several natural filter media. The rate of the wastewater was 220 ml/min with a detention time of 24 h. The wastewater which flew through ABR was then re-treated using UAF to eliminate the pathogen from wastewater. The hybrid system proved the efficiency of removing 88, 78, 90, 70, 34, and 75% for BOD, COD, TSS, NH₃, PO₄, and total coliform. Therefore, this hybrid treatment can be considered a low-cost treatment to produce an alternative to clean water resources.

A variety of effectual, non-polluting, and economical nanomaterials have been developed, having special capabilities for the potential purification of industrial effluents. Improper disposal of effluent generated from different industries or mining activities affects the ecosystem through increased metal pollution and biodiversity loss. It has significant detrimental effects on the health of aquatic ecosystems through increased nutrient loads that can lead to eutrophication and temporary oxygen deficits and also a serious negative impact on ecosystems due to heavy metals (HMs) bioaccumulation in the food chains. Nano-metal silicate tubes (NMSTs) synthesized through the silica garden route are considered important materials for the removal of HMs from industrial effluents. The present chapter is emphasized on nano calcium silicate precipitation tubes (CaSPT) as HMsl (Zn(II), Cd(II), Cu(II), Pb(II), and Cr(III)) adsorbents in an aqueous medium to identify its application as water purifier after thorough physicochemical characterization. With the increase in initial metal ion concentration, the absorption process moved towards irreversibility. Adsorbent dose and its initial concentration has significant impacts on adsorption, and it varies non-linearly. CaSPT was identified as a superior adsorbent of HM ions as compared to the conventional non-tubular calcium silicate tube due to its high surface area. Nano CaSPT was successfully applied in an effluent sample collected from the electroplating industry to remove Cr(III), Zn(II), and Pb(II).

Wet processing (dyeing) of textiles consumes large quantities of water and during processing, considerable quantities of dyes remain unfixed, thus generating coloured effluent. Textile industry is a major contributor to environmental pollution and the second-highest source of water pollution in the world. Thus, dye-containing textile effluents should be properly treated (decolourized) until they reach the regulatory discharge limits. Dye decolourization techniques can be classified into three main categories: physical (membrane-filtration, sorption techniques, etc.) chemical (coagulation or flocculation, electro flotation, electrokinetic coagulation, conventional oxidation methods, irradiation, or electrochemical processes, etc.) and biological methods (using microorganisms or their enzymes). Chemical and physical decolourization have shown efficient colour removal in certain dyes. However, generation of large quantities of sludge that requires further treatment or disposal and the high cost are the main drawbacks of these methods. On the contrary, biological techniques are considered as attractive solutions for textile effluent decolourization due to low-cost, sustainability, and public acceptability. Biological decolourization of dyes can be a result of either biosorption or biodegradation or both. Release of coloured effluents containing dyes into the environment may result in health issues and environmental pollution. When coloured effluents get into water bodies, light penetration through water is reduced and thus affects the photosynthetic activities of aquatic flora, thereby severely limiting the food sources for aquatic organisms. Dyes are toxic to flora, fauna and humans and further, degradation of dyes may deplete dissolved oxygen levels in water and consequently affect aquatic organisms.

The rapid increase in uncontrolled anthropogenic activities, human population, industrialization, and deforestation etc., has created a huge pressure on our environment and natural resources. These have caused environmental degradation (i.e., the deterioration of the various aspects of environment including soil, water, and air) through exploitation of natural resources involving both biotic and abiotic aspects. At present, the deterioration of the environment has touched almost every corner of the earth in one way or the other. The effect of such degradation can be seen on the air and water quality, health of plants, animals, human beings, etc. Therefore, we need to promote sustainable usage of our existing natural resources without further exploitation. In addition, alternative technologies (e.g., bioremediation, nanoremediation, thermal oxidation, phytoremediation, etc.) should be encouraged which will not only help in restoring the deteriorated resources but also avoid further damages to the ecosystems. In this chapter, we have discussed various aspects of pollution resulting to environmental degradation, and have highlighted the possible remediation technologies that can be used to minimize environmental degradation. Thus, the purpose of this chapter is to provide an overview of the ongoing remediation technologies along with their applicability, efficiency and, limitations that should be improved.

Treatment of industrial effluent combining sustainability and high efficiency is the need of the hour. Conventional effluent treatment techniques suffer from energy-intensiveness, low output efficiency, risks of secondary contamination apart from bearing an array of treatment steps. This makes it imperative for a paradigm shift in the process development and design of wastewater treatment plants to cater to the stringent environmental conditions and challenges of the future. Novel technology solutions like integrated membrane separation, photocatalysis, nanotechnology focusing on complete pollutant degradation without generation of toxic residues and scoring high on the eco-friendliness aspect offers promising options to deliver broad-spectrum effluent remediation. This chapter explores novel green alternatives. The chapter also studies the pros and the cons of conventional ETP and evaluates their newage modifications. This is followed by an in-depth discussion of the crux of emerging novel technology solutions, scope of their application and possible integration with prevailing separation techniques. Finally, strategies like waste valorization patterns of process intensification in design were discussed for sustainable and cost-effective technology development.

Water is crucial component that determines living forms including plants and animals as well as human beings and its availability and quality is one of the major factors for domestic, agriculture, industries, transportation and other activities. Thus, the water quality becomes as a central concern on determining the life quality and the economy any country. Besides, urbanization, mechanization and waste disposals including industrial effluents are essential factors usually influence the water quality in a specified area. Present environmental problems are mainly encountered due to the disposal of unprocessed, and raw industrial effluents containing various toxic chemical to the environment specially water bodies (rivers).

Indifferent to point source pollution that was usually discharged into surface water from a known site, such as pipe effluent, diffuse pollution happens when contaminant goes into surface water by means of surface runoff, soil infiltration or rainfall, causing in the depreciation of surface water quality. The most common example of diffuse pollution is the leaching of pesticides and fertilizer from agricultural activities. In this context, ecological engineering practices, namely constructed wetlands and vegetated ditches, may play a paramount role in providing the sustainable solution for this issue. Though constructed wetlands have been widely used for many years, vegetated ditches have started been practiced only recently. Therefore, this review is done with the aim to illustrate the practice of vegetated ditch in treating diffuse pollution that leads into the degradation of surface water quality. This paper will highlight the application of vegetated ditch in treating diffuse pollution, the effectiveness of the system as well as the mechanisms of contaminant removal. Furthermore, this review will critically evaluate the challenges faced by vegetated ditch implementation as well as the recommendations needed for the enhancement of the system.

Japan is susceptible to several natural disasters, including earthquakes and typhoons. Thus, the government, local governments, businesses, other organisations, and individuals are faced with the challenge of responding quickly to restore the systems. However, depending on the scale of the disaster, recovery can be expensive and arduous. The Great East Japan Earthquake in March 2011 and the COVID-19 pandemic are significant disasters. It is now difficult to establish a natural, economic, and social environment before disasters. In particular, social rather than physical and financial damage is more complex to measure. Often, it is not possible to restore the situation to the pre-disaster conditions. Presuming that people cannot secure a safe environment, they will need to live in a new area, even if it is only temporary. Even if safety can be ensured, the inability to belong to a traditional community can significantly impact people of all ages. Therefore, it is essential to maintain the same pre-disaster living environment, build convenience, strengthen disaster prevention, and priorities the environment. Moreover, community development in which the people are directly engaged, is required.

Ever increasing the demand of petroleum diesel, environmental degradation, fuel-hike and depleting petroleum stashes encourage the study of alternate fuel to diesel engines. Several low-cost and accessible bio-resources and agro-industrial waste are available for alternate liquid fuel production including the biodiesel. Biodiesel production from plant-based materials became more and more attractive in the recent years, due to the increasing economic concerns and environmental awareness about the use of conventional diesel fuel. Many researches have ascertained better emissions in biodiesel because of its higher proportionality of O₂ content, cetane rating and lubricity. Besides, domestic production of biodiesel from edible oils leads the food oil crisis. Hence present research emphasis waste cooking oil for biodiesel production to minimize the environmental pollution and cost. 

In this study, an attempt was made to assess the knowledge, attitude, practices regarding pesticide handling and acute toxicity symptoms of pesticide use among the farmers of mid Brahmaputra Valley of Assam. The study included a sample size of 90 farmers taken from 6 villages of Sonitpur district of Assam, India. The farmers include both full-time and part-time agriculturists. Data collection was done through a questionnaire survey. Of the total samples, 82.2% used chemical pesticides and majority acknowledged them as harmful. Despite awareness of the health risk by the handling of pesticides, 75.68% reported not using any personal protective measures. 13.51% stated that they did not have separate work clothing, neither they washed them separately. Of the pesticides used, 52% belong to WHO class II (moderately hazardous), 8% belong to class III (slightly hazardous), and 4% belong to class Ib (highly hazardous). We had found that 59.46% of the farmers complained of Acute Pesticide Poisoning (APP), 24.32% sometimes complained of APP whereas 16.22% never complained of APP. The main self-reported toxicity symptoms include headache, nausea, burning of eyes, vomiting, shortening of breath, vision disturbance, and excessive sweating. The study revealed that lack of adequate knowledge and risky behavior during handling; storage and disposal of pesticides were a common scenario among the farmers. The use of pesticides in modern times cannot be stopped but certainly can be checked with proper training and Government initiatives.

Synthetic chemicals were used as pesticides for killing numerous pests. There are various classes in which insecticides are one of the types which are responsible for causing dangerous effect on human beings. Due to their efficacy, these insecticides gained popularity, and easy access has made them popular among farmers. Chlorpyrifos is a type of insecticide having broad spectrum effect which makes it a favourable candidate against numerous pests. When it is being used, it remains in the environment for several years, contaminating the quality of soil and the groundwater. The chlorpyrifos pesticide is used rigorously in farming practices. Chlorpyrifos inhibits acetylcholine esterase enzyme causing convulsion, paralysis and ultimately death. Deleterious effect of the chlorpyrifos pesticide has led researchers to ponder about its efficient and eco-friendly degradation/removal process. Biological method of degradation involves microbes where enzymes play a crucial role in degradation of chlorpyrifos. Laccase is an enzyme having broad substrate specificity and explored for chlorpyrifos degradation in its free and immobilized form. And it has been observed that enzyme immobilized onto a suitable support shows more efficiency than the free enzymes. Moreover, the immobilized enzyme can be reused multiple times. So far, numerous carriers or supports have been reported. However, role of nanoparticles in immobilization is in infancy. Large surface area, eco-friendly nature and inexpensive characteristics may enhance the degradation efficiency by retaining the enzymes intact and enhancing the reusability. This chapter will focus on laccase enzyme, their sources of generation, characteristics and application. Further, the chapter would highlight the application of nanoparticle in pesticide degradation and its role as a carrier for enzyme immobilization. Lastly, the chapter would discuss about the mechanism of action of laccase immobilized nanoparticle in pesticide degradation.

Deforestation and forest degradation are impairing the amplitude of forests to produce various ecosystem products and services, livelihood security, and its contribution towards mitigating the greenhouse gas emissions and climate change. Indian forests support the sustenance needs of ~300 millions of tribal people and forest dwelling rural populations. India is experiencing an increased pace of deforestation and destruction of forest resources leading to overall forest degradation in the past few decades. Around 40% of the Indian forests are degraded and over-exploited, 70% have lost the natural regeneration potential, and 55% are prone to fire. India is one of the parties to all the potentially notable world’s agreements and conventions encompassing forests and their degradation prevention. India has committed to accomplish restoration of 21 Mha of damaged, degraded, and deforested lands by 2030 under the Bonn Challenge. The forestry sector constitutes an important part of India’s Nationally Determined Contribution (NDC) and can be achieved through several ongoing programmes such as the National Mission for a Green India, National Afforestation Programme, compensatory afforestation, and plantations to increase the area under forest in the country. India’s forestry sector is committed to establish a supplementary forest cover as a terrestrial carbon sink of 2.5–3.0 billion tonnes of CO₂ equivalent under the Paris Agreement by 2030. Besides, investment in natural ecosystems, through reduction in carbon emissions from deforestation and forest degradation (REDD), and reducing GHGs emissions from deforestation, forest degradation, and other forest related activities (REDD+) related strategies, contribute significantly to a reduction in GHGs emissions and improvement of carbon storage capacity of natural forests. It also helps in generating alternative income sources for the rural, tribal, and forest-dependent communities that will give essential financial inducements to avoid deforestation and to provide supplementary livelihood advantages from the protection and restoration of forest ecosystems. This chapter will particularly focus on the tropical forest, as it is currently experiencing the highest rates of deforestation and over-exploitation.

The problem of wastewater and solid waste disposal is ubiquitous in today’s world. Different technologies are being researched upon for the treatment of wastewater. The backdrop of resource crunch and stricter environmental norms has generated the impetus for a paradigm shift in wastewater management. Greener and sustainable approaches are being explored that focuses on resource conservation and recycling of water. The waste-to-wealth technologies scoring high on technological viability and economic feasibility fronts provide a fresh research avenue for practical implementation. In this chapter, the efficacy of some of the most promising conventional and novel separation options for value added product recovery from wastewater have been discussed. The crux of the technology, applicability and the possible resources that can be recovered was studied vis-a-vis the pros and cons. Finally, evaluations of the industrial scale up potentially and commercialization status of the technologies was  reviewed.

Environmental degradation and socio-economic issues are the most significant areas of great concern. In an industrial area, it has direct linkages and visible results on the social fabric. An in-depth understanding of the environment and its degradation reveals that the impact could be caused on air, water, land and any other contributory component of the earth system, either biotic or abiotic. Since the socio-economic impacts are from among the many, in this chapter of book, the author has tried to concentrate and describe the socio-economic aspects only that deals with the sustainability concerning the Indian mining industry. In recent decades, rapid industrialization, progressive development has left innumerable and alarming impacts on the ecology and environment and it is evident that to progress holistically, environment protection and societal development must go hand-in-hand. No strategy to tackle the environmental challenges is complete without the coverage of societal parameters; hence, this topic in the book has relevance and benefits. The socio-economic dimensions of the environment are immensely helpful in terms of raising the standard of living, employment generation and literacy enhancement which are, of course, very serious issues for society. As evident, different regions have different parameters for the community and region development, it is necessary that an in-depth and site-specific understanding shall be made. In this chapter, the author has defined the methodology of socio-economic impact assessment and evaluation, the framework for environmental sustainability to tackle the environmental degradation menace, industry–community relation, etc., emphasizing that mining enterprises are useful for the societal development of rural areas, where mines are generally located. To cater for the progress of society, we must address the social issues and challenges more diligently. By doing so, the major issues of industrial unrest can be addressed properly for the masses. It should also be realized that socio-economic environment impact evaluation and analysis, ignored mostly, shall be handled on priority.

The chapter analyses the short-run and long-run effects of international trade on the environment. For this purpose, the bounds testing method to cointegration is applied to a small island country setting of Mauritius and over the period 1980–2018. The result shows that that trade has adversely impacted on the environment. In addition to that, higher economic growth is as well observed to generate higher CO₂ emission. Furthermore, the CUSUM and CUSUM square confirm the stability of the model for Mauritius.

The consistent usage of plastic products has resulted in a proportionate rise of global plastic waste generation predominantly from domestic and industrial sectors. Effective management of plastic waste has become crucial to deal with complex environmental challenges imposing damage to our natural resources. This is an attempt to assess different existing collection, disposal, and treatment technologies for plastic waste management. With the challenges and limitations imposed by factors influencing the inadequate handling of plastic waste, this is an attempt to highlight recent advancements that emerged out lately to tackle the issue along with their environmental implications. Widely adopted treatment and disposal methods like material recycling with and without plastic waste separation, thermo-chemical recycling, pyrolysis, heat recovery incineration, and landfilling are compared, and problems associated with their efficacy are proffered to identify research and investment opportunities. The key drivers leading to plastic waste mismanagement in nature and its impact on the social, economic, and environmental dimensions from developed and developing economies are explored. Future scopes and technological outlook on an effective plastic waste management system in an environmental and resource compatible perspective have been discussed.

The Ganges, Brahmaputra and Meghna rivers are the three main rivers contributing to the formation the GBM (Ganges–Brahmaputra–Meghna) delta system. The delta system undergoes several environmental challenges both natural and manmade. A significant portion of population from different nations is directly and indirectly dependent on these three rivers for their sustenance. As transboundary rivers, they suffer a lack of transnational cooperation in terms of river protection and sustainable management. This review article analyses the environmental challenges in the GBM delta system to better understand the critical issues related to sustainable delta management. It also focuses on the transboundary issues and their solutions through cooperation, knowledge sharing and other joint activities between nations. The Ganges, Brahmaputra and Meghna rivers suffer from different forms of pollution. Significant sources include domestic, industrial and agricultural affluents along with direct defecation, bathing, washing, solid waste dumping and throwing of ritualistic burnt dead bodies into river water. The level of pollution creates havoc in aquatic ecosystem and leaves the water unusable for humans as well. The significant growth of population in these regions has modified the land cover of the GBM delta system. The rise in agricultural land, dams and other hydraulic structures has modified the erosion and sedimentation dynamics of the Ganges, Brahmaputra and Meghna rivers. As a result, the cases of riverbank erosion, riverbed siltation and river course shifting are also rising. The rivers also struggle with the various types of natural disasters like cyclones, storm surges, floods, droughts, salinity intrusions, coastal erosions and tidal bores. There is also a lack of understanding and cooperation between countries when it comes to sustainable delta management. To top it off, other issues like extreme poverty, lack of education, dependency on nature-based agricultural practices have also clouded the long-term development of the delta system and its people. The above-mentioned challenges require holistic and integrated action plans among respective nations. This can be achieved through effective policy dialogues, transnational protection and conservation plans, information sharing, co-learning, joint research programs, transstate accountability and technological advancements which can be ensured by each of the participating nations. The Ganges–Brahmaputra–Meghna (GBM) delta system extends for more than hundreds of kilometres along the Bay of Bengal coastline. The Ganges and Brahmaputra River drains roughly around 75% of the Himalayan mountain range. These two rivers carry around 1.1 GT/yr of sediment and dump on the Bengal Basin. This amount is equal to around 6–8% of the total sediment input dumped on the oceans globally. These rivers are extensively affected by different types of pollutions, erratic flood intensities and altering tidal characteristics. They also suffer from river stage fluctuations in the downstream riparian regions due to the construction and operation of hydraulic structures in the upstream regions. This study provides a critical analysis of the present issues and challenges regarding the active rivers of the GBM delta system and recommends a holistic and sustainable management plan for the protection and conservation of the rivers by analysing previously published research works and secondary datasets. The Ganges, Brahmaputra and Meghna river basins experience various point and non-point pollutions. The downstream regions face a higher rate of pollution than the upstream ones. As the rivers approach the delta mouth, land use patterns and land covers change due to increased rate of urbanization, industrialization, agricultural practices and climate change effects. Their flow is also being controlled by several upstream hydraulic structures like dams, barrages and reservoirs. Consequently, the river basins face many natural and anthropogenic disasters. The combined effect of these issues elevates the vulnerability of the downstream delta mouth population and destabilizes their socio-economic conditions. These crises can be solved through transnational cooperation, regional capacity building and sharing of information between upstream and downstream riparian countries. Inclusive and flexible strategies with appropriate policy dialogue may lead to amendments of current agreements which may eventually create a sustainable platform to overcome the environmental challenges of the Ganges–Brahmaputra–Meghna delta system.

Given the dire state of the planet where scarce resources are being exhausted and “waste” is carelessly disposed of, we can find a hero within the concept of the circular economy—a model which aims to achieve a closed loop scenario by recycling the wastes back into the useful economic and ecological flows. Bangladesh, despite her growing population, lacks a dependable institutional waste management system, so the government should apply the concept of circular economy to modify and reconstruct it into a sustainable model. Organic food waste is the major constituent of household waste, containing nutrients and chemicals with too great of an influence on the chemical cycle to simply be disposed of. The current primary waste disposal method followed in Bangladesh is undesirable landfill dumping and such an easily recyclable component like food waste must not follow that path and should be re-circulated back into the loop instead. Currently, there are no comprehensive studies on food waste in Bangladesh to be used for policy guidance. Hence, proper quantification with composition of food wastes is essential to determine the reprocessing potential and provide policy guidance to restructure the existing inefficient waste management system into a sustainable one within the purview of circular economy concept. This chapter attempts to quantify the food waste generation of Bangladesh and explores the various options of available modern technology and methods to recover and reuse food waste. Circularity is the perfect instrument to promote decoupling and achieve sustainability, so its prospect and significance in food waste recycling shall be investigated.