Valorization of Resources from Urban Mined Materials

The following sections are included:

• Preface
• About the Editors
• Contents

Actions to minimize industrial waste can contribute not only to the reduction of environmental impact but also to the conversion of polluting wastes into new sources of income. The valorization of raw materials and consideration of the different regional cultures of production units represent the achievement of the Sustainable Development Goals. There are countless studies on models for decision-making in industrial waste minimization. However, especially in agriculture and agroindustry, where there is high consumption of water and many raw materials are not yet fully valorized, actions need to be differentiated using accessible models and technologies compatible with the different processes carried out at their respective scales. An example of the diversity of scales and processes is seen in the food industry, which includes a range of small-, median-, and large-sized industries. Environmental care coexists on all the different scales; however, models for waste minimization must be compatible despite these differences. In this work, several historical examples of modeling for waste minimization are presented.

This chapter delves into the critical realm of metal recovery from electronic waste (E-waste), addressing the pivotal role it plays in alleviating both resource depletion and environmental pollution. With an intricate exploration of diverse recovery methodologies, such as hydrometallurgy, pyrometallurgy, and emerging bioleaching, the chapter elucidates their environmental considerations and strengths. Essential preliminary processes, including proper E-waste collection, dismantling, and sorting, are highlighted as prerequisites for effective metal recovery. Technological advancements and their impact on enhancing efficiency and yield are underscored, accompanied by an analysis of environmental implications, emissions, and residue management. The economic dimensions of E-waste metal recovery, encompassing market dynamics and potential revenue streams, are comprehensively examined. Emphasizing a circular economy, the chapter advocates for a holistic approach that amalgamates technological innovations, eco-friendly practices, and economic viability to maximize metal recovery and minimize the environmental impact of E-waste. Keywords encompass resource depletion, the circular economy, waste management, clean technology, and the imperative need for sustainable practices. This comprehensive exploration aims to guide stakeholders toward responsible and effective strategies in the intricate landscape of E-waste metal recovery.

Used lithium-ion batteries (LIBs), which contain valuable metals such as cobalt, lithium, manganese, and nickel, are a promising source for future lithium production, with recycling efforts underway. However, lithium recovery is difficult, making LIBs a better source compared to seawater. LIBs contain graphite-coated copper and LiCoO2-coated aluminum electrodes bound with polyvinylidene fluoride (PVDF), serving as conductors through lithium salt-based electrolytes, requiring physical separation and metal enrichment before hydrometallurgical treatment. Flammable electrolytes require discharge and immersion in specific solutions. Hydrometallurgical processes can increase metal concentrations but emit hazardous gases, making them less environmentally friendly. Mechanochemical methods, such as dry and wet milling, can improve lithium and cobalt recovery by inducing structural changes in electrode materials, increasing extraction efficiency, and improving the separation of magnetic materials. Pretreatment techniques for extracting lithium and cobalt emphasize hydrometallurgical recovery through leaching and impurity removal, with a particular focus on the unique challenges posed by lithium extraction due to its stability in aqueous solutions. The economic factors of recycling LIBs depend on recycling rates and metal prices, with hydrometallurgical processes offering the lowest energy consumption and the potential for lithium recovery.

Plastics have become one of the most integral parts of our day-to-day lives; however, after use, plastic waste accumulates on land and in water bodies, which wreaks havoc in the environment by releasing toxic gases. As the usage of plastic increases, it will result in the depletion of natural resources and greater difficulties in managing plastic waste. Accordingly, in this chapter, we focus on various types of resources, such as fuel, gas, energy, and electricity, which are recovered from plastic waste through different waste management technologies such as primary, secondary, tertiary, and quaternary recycling. This chapter is set forth by critically evaluating different types of plastic waste technologies, the products, and their byproducts formed during tertiary treatment. Material and resource recovery of different types of waste plastics through gasification and pyrolysis offers significant environmental benefits by promoting resource extraction and reducing the associated environmental impacts linked to the extraction process.

This comprehensive review presents an in-depth examination of metal recovery processes within liquid extraction systems. Its advantages include high selectivity, efficient separation, and resource recovery potential from waste streams. Liquid extraction relies on the principle of partitioning metal ions between immiscible aqueous and organic phases, influenced by mass transfer kinetics and solvent choice. Beginning with an exploration of the foundational principles of liquid–liquid extraction, including phase equilibria and solute partitioning, the review offers insights into traditional methods while addressing associated challenges. Subsequently, the chapter discusses recent innovations, highlighting their advantages in terms of efficiency, selectivity, and reduced environmental impact. The integration of automation and miniaturization is discussed, showcasing their transformative effects on metal recovery precision and throughput. Additionally, the review highlights the critical importance of sustainability in modern metal recovery, emphasizing eco-friendly practices such as solvent recycling and the use of green extractants. Ongoing research and development efforts strive to enhance efficiency, selectivity, and environmental sustainability, ensuring that this technology will play a crucial role in meeting future critical metal demands. Overall, this chapter provides a comprehensive analysis of evolving metal recovery techniques within liquid extraction systems, offering valuable insights into their applications and potential to address the challenges of sustainable resource management.

The prominent dyes present in the textile industry are azo, anthraquinone, and methylene blue (MB). These dyes are more resistant to degradation. The treatment imparted for the removal of color in the textile industry is divided into physicochemical and biological methods. Inexpensive agricultural wastes act as adsorbents for eliminating dyes from the solution. Adsorption methods are frequently employed to remove specific types of contaminants from water, particularly those that are difficult to biodegrade. For the removal of colors from wastewater, biological treatment and adsorption on activated carbon are currently gaining popularity. Though commercial activated carbon is the preferred adsorbent for color removal, its widespread use is constrained by its comparatively high cost, which prompted research on alternative non-conventional and affordable adsorbents. This review aims to compile the disparate information that is currently available on a variety of possibly affordable adsorbents for dye removal. It includes many recently published data that reveal that inexpensive biosorbents and nanofillers have excelled at removing dyes from textile wastewater.

Solid waste management is increasingly challenging due to rapid urbanization, exponential population growth, and industrial expansion, making it one of the most pressing global issues today. A nation’s overall solid waste output, which results from numerous agricultural, urban, cultural, social, and religious activities, causes environmental (air, water, and soil) pollution as well as health issues for its people. This in turn significantly damages the Earth’s ecological environment. Agricultural Floral Waste (AFW) encompasses all types of solid organic waste generated from various human activities in fields and urban areas, making its management crucial. Every year, India generates about 500 million tons of farm waste, and Indian households waste 50 kg of food per capita. In financial terms, the harvest and post-harvest losses of major agricultural and allied produce amount to Rs. 92,651 crore yearly. In India, between 70 and 80% of solid waste is organic waste. Any organic waste, including floral debris, when dumped outdoors can lead to environmental issues since the decomposition process encourages the growth of germs. Appropriate handling of floral waste disposal will contribute to both the achievement of almost 60% of the UN’s Sustainable Development Goals and a decrease in environmental pollution. Kenya and China have been turning flower waste into compost, but the United States and Europe are burning flower debris, which adds to air pollution. Efficient management can lessen environmental stress and yield a variety of beneficial resources such as compost, biogas, biochar, natural dyes, and perfumes. Therefore, to address the potential challenges associated with implementing the sustainable management of AFW in many parts of the world, including India, a thorough investigation is urgently needed.

The nutritional value of milk and dairy products is manifested in the nature of effluents with a high organic load, resulting from the water used in equipment cleaning processes, as well as in the by-products of the production of cheese, butter, and other derivatives. On the other hand, the dairy industry also presents itself on different scales, ranging from family-owned businesses to large conglomerates; in all cases, this sector coexists with the need to reduce the pollutant load of its production process. In general, the industry complies with environmental regulations through the waste treatment system. In this chapter, from the perspective of clean technologies, systems for minimizing and valuing waste are suggested for the main industrial waste in the dairy sector through an a priori analysis based on a comparison between the investment required in each proposal and the environmental and economic benefits. The proposals are built based on published scientific work on the possibilities of recovering this waste. The suggestions from the different systems are offered as a contribution for this productive sector’s vision of transforming what is considered polluting into a new income opportunity.

Many manufacturing items require specific elements, including, for example, low-carbon technologies such as wind turbines, electric cars, and catalytic converters. The growing global population and aspirations for a better life have raised concerns about the security and accessibility of valuable elements. These economically important metals need appr priate, environment-friendly recovery technology from increasing waste repositories, which will help both in hazard avoidance and as a potential source for industry. Phytoextraction, also known as phytomining, is a green and innovative method for recovering metals from waste, mainly focusing on resource supply, while contributing to hazard mitigation. In this context, plants have been found to be capable of phytomining platinum group metals (PGMs) to create stable metal nanoparticles that are useful in various industrial reactions. The use of mine tailings or waste mining waters for metal adsorption in plant beds is followed by controlled pyrolysis to produce stabilized PGM nanoparticles for het-erogeneous catalysts. The proposed solution to the global issue of metal depletion can lead to the creation of a new range of naturally derived catalysts. This review explores a multidisciplinary approach to evaluating metal sustainability, highlighting key aspects such as metal lifecycle analysis, waste sources, phytoextraction, and potential green chemical applications.

The following section is included:

• Index