Sustainable Effluent Treatment and Resource Recovery, Volume 2

Green nanotechnology is an emerging field in medicine, engineering, and environmental management. It offers a sustainable approach to treat wastewater effluents by utilizing eco-friendly nanomaterials and nanoscale processes to remove a wide range of contaminants from wastewater. This approach focuses on the development of environmentally benign nanomaterials, such as metal-organic frameworks, graphene, and nanoparticles derived from plants and microorganisms, which can effectively adsorb, degrade, or transform pollutants in wastewater. Green nanotechnology encompasses methods including photocatalytic degradation, adsorption, and oxidation to remove contaminants of emerging concern from wastewater effluents. This green approach can be useful in minimizing the use of corrosive chemicals and the consumption of energy during the treatment of effluents. Furthermore, green nanotechnology encourages using wastewater treatment technologies that are simple, cost-effective, and easy to implement, making them accessible to communities worldwide. The benefits of green nanotechnology in wastewater treatment include improved water quality, reduced environmental pollution, and protection of human health. By providing a sustainable and eco-friendly solution, green nanotechnology has the potential to revolutionize the wastewater treatment industry.

With the rapid advances in veterinary and medical technology as well as global population growth, there has been a corresponding rise in the manufacturing of pharmaceuticals and healthcare items to meet the demand. These different pharmaceutical and personal hygiene products are occasionally discarded in the environment without being treated, which leads to the detection of numerous trace amounts of hormones, antibiotics, and personal care items in water. The disposal of both conventional and novel types of pharmaceutical waste creates various issues, including antibiotic resistance and structural and functional changes to the native gut microbiome. A range of methods has been used to purify wastewater contaminated with pharmaceuticals; however, advanced approaches are still necessary. Nanotechnology-based procedures have many substantial advantages over conventional techniques. Techniques for treating waste water at the nanoscale include nanocatalysts, nanofiltration, and nanoadsorbents. According to research, membrane bioreactors using nanofiltration are more effective than those using reverse osmosis at eliminating different antibiotics. Fouling in membrane bioreactors can be prevented by modifying the membranes with suitable substances. Pharmaceutical chemicals can be rejected due to a variety of factors, including pH, temperature, pressure, pollutant concentration, properties of the rejecting material, charge, and other operating circumstances. Reuse is facilitated by nanoadsorption through recycling. The kinetics of nanoadsorption for pharmacological substances on a surface follows either pseudo-first-order or pseudo-second-order kinetics. The large surface area of nanoparticles, measured by their high Brunauer-Emmett-Teller (BET) surface area to volume ratio, leads to more effective contaminant removal. Therefore, there is a great deal of promise in nanobiotechnology for the removal of new pharmaceutical waste chemicals.

The unregulated disposal of diverse effluents into the environment may lead to deterioration of the water quality endangering both aquatic and terrestrial life. With the advent of industrial revolution, there is a rapid increase in amount of generated effluents majorly contributed by expanding industries and households. While several traditional methods are available, the advancement of innovative technology is essential for wastewater treatment and recycling. Researchers and the wastewater treatment sector have together devised innovative strategies to improve resilience, with biopolymer-based adsorbents emerging as a potential option. In contrast to synthetic polymers, biopolymers such as polylactic acid has advantageous characteristics, including biodegradability, non-toxicity, and biocompatibility. Nonetheless, the adsorption efficacy of pristine PLA is frequently constrained due to its certain properties like hydrophobicity and absence of functional groups, requiring the incorporation of functional fillers to augment their adsorption properties. This chapter summarizes current investigations on the incorporation of various carbon-based nanofillers, organic nanofillers, inorganic nanofillers, and biopolymer-based nanofillers into a PLA matrix. Furthermore, alterations in structural characteristics following the modification of these nanofillers have been examined, and the prospective application of PLA-based nanocomposite membranes for the elimination of harmful pollutants has been addressed. The chapter also discusses the need for scaling-up and socio-economic evaluation and future research direction. Hence, the PLA-based novel composite membranes may play a vital role in advance wastewater treatment technologies.

Industrial effluents play a significant role in environmental pollution; however, these wastes often contain valuable resources including heavy metal ions, volatile fatty acids (VFAs), emulsions, oils, suspended solids and organic nutrients. Treatment of wastewater and recovery of these valuable components from effluents are crucial to minimize environmental impacts and ensure circular and sustainable practices. Membrane-based separation is potentially useful due to its selective pore size-based separation, high removal efficiency with respect to targeted pollutants, elimination of additional chemical requirements and prevention of toxic byproduct formation. Although polymeric membranes are commonly used in industrial effluent treatment, ceramic membrane technology is promising as an efficient and effective solution for remediation of hazardous industrial effluents, and recovery of value-added products. Ceramic membranes have high chemical and thermal resistance, a long lifespan and offer stable permeate flux, owing to efficient fouling management and membrane regeneration potential. In this chapter, the prospects of ceramic membrane-based processes for treatment and resource recovery are addressed with respect to industrial effluents of various sectors including dye recovery from textile effluent, heavy metals recovery from electroplating wastewater, oil and grease removal from petroleum refining and petrochemical processing and recovery of VFAs in membrane bioreactor processes. Limiting aspects like high initial capital costs and maintaining uniform pore sizes while ensuring the membrane is free of defects in large-scale manufacturing are discussed. The future potential of ceramic-polymer composite membranes with respect to engineering pore size, surface morphology and other characteristics are highlighted in view of pilot-scale implementation of such processes.

The global goal of achieving net-zero emissions by 2050 depends heavily on advancements in energy storage technologies. Lithium-ion batteries (LIBs) play a crucial role in this effort, powering electric vehicles and modern energy storage systems. Widespread adoption of LIBs has led to a growing volume of spent LIBs, posing challenges in waste management and resource conservation. Efficient recycling and resource recovery are essential to reduce environmental footprint, minimize dependence on raw materials and create a sustainable supply chain. Valuable materials, including Li, Co, Ni, and graphite, can be recovered through recycling, minimizing reliance on virgin resources and lowering production costs. However, the widespread use of recycling technologies is limited by high costs, technical difficulties, and inefficient collection systems. Overcoming these challenges requires innovative recovery methods and stronger regulations. This chapter provides an overview of the structure, components and composition of LIBs, including the anode, cathode, electrolyte, and separator. It explores state-of-the-art recovery technologies and techniques for extracting valuable materials from spent LIBs, such as electrolytes, graphite, and metals. Furthermore, the chapter examines the challenges and opportunities associated with resource recovery strategies and discusses future perspectives on LIB recycling.

Effluent treatment is a critical environmental challenge, with escalating global industrial and municipal discharges contributing to global water pollution. Photocatalysis, an advanced oxidation process leveraging light-activated catalysts, has emerged as a promising solution for treating diverse effluents. This chapter comprehensively explores recent advances in photocatalytic processes for effluent treatment, focusing on the development of innovative photocatalysts. The chapter begins by introducing the types of effluents, including biological, organic and inorganic effluents. The advantages of photocatalytic treatment over conventional methods are outlined to provide a strong foundation for understanding its potential. Recent advancements in the applications of photocatalytic processes in effluent treatment are examined in detail, covering the degradation of organic effluents, the removal of heavy metals, and the disinfection of pathogens. We describe the key parameters that influence the efficiency of photocatalysis, such as catalyst type, light intensity, pH, and effluent concentration. Highlight the fundamental principles and reaction pathways involved in photocatalytic degradation, particularly the role of different catalysts. Finally, the chapter identifies the challenges, such as catalyst deactivation and scalability, and proposes future research directions to address these limitations. Overall, this work highlights the transformative potential of photocatalytic processes in achieving sustainable and efficient effluent treatment solutions.

Photocatalysis has emerged as a promising and sustainable advanced oxidation technology for wastewater treatment, due to its capacity to degrade and mineralize a diverse array of organic pollutants under mild conditions. Recent advancements in material science have notably propelled the progress of innovative photocatalysts, improving the efficiency and practicality of this approach for real-world applications. This study provides an in-depth evaluation of current advances in reactor design and process optimisation techniques for photocatalyst-based effluent treatment. Engineering methods that enhance mass transmission, light utilisation, and system performance are the focus of attention. Furthermore, we assess techniques for modelling to forecast and enhance treatment results and investigate the incorporation of sophisticated photocatalytic materials into scalable reactor designs. Significant issues like catalyst recovery, operational stability, and scalability are critically examined in the discussion, along with potential future applications. By highlighting these developments, this study aims to make it easier to design affordable, highly effective photocatalytic systems for sustainable water treatment.

Hydroxyapatite (HAp) is a flexible and environmentally acceptable adsorbent for wastewater treatment. It has the capacity to remove a wide range of pollutants, including pesticides, organic contaminants, various dyes (cationic, azo, anionic), heavy metals and metalloids. The sustainability and environmental friendliness of the green applications for HAp are highlighted in this review. Important methodologies, including biomimetic synthesis, plant extract-assisted manufacturing, and microbial-mediated approaches that improve the structural and adsorption characteristics of HAp are covered. The article explores the mechanics of pollutant adsorption, emphasizing the functions of porosity, ion exchange, and surface functional groups in pollutant removal. Recent advances in in-silico studies and computational optimization are addressed, with details on how to design tailored HAp adsorbents with improved functionality. The applicability of computational tools for predicting adsorption efficiency and synthesis parameter optimization is explored. These tools involve molecular dynamics (MD), density functional theory (DFT), and machine learning (ML) models. The challenges with HAp adsorbents, such as regeneration and scale-up, and proposed solutions are also addressed in this paper. This emphasizes the combination of green chemistry concepts with computational tools as a means of creating high-performing and reasonably priced adsorbents for environmentally friendly wastewater treatment. Ultimately, this article provides a comprehensive understanding of the synthesis, optimization, and application of eco-friendly HAp adsorbents, paving the way for innovative solutions in environmental remediation.

Effluent treatment plays a vital role in minimizing environmental pollution, but the complexity and variability of wastewater make process optimization challenging. Traditional treatment systems often struggle with nonlinear behaviors, inconsistent influent characteristics, and emerging contaminants. This chapter explores the transformative role of soft computing and artificial intelligence (AI) in improving the efficiency, adaptability, and sustainability of effluent treatment. Key techniques such as Artificial Neural Networks (ANNs), Fuzzy Logic (FL), Genetic Algorithms (GAs), Particle Swarm Optimization (PSO), Decision Trees, Random Forests, and Support Vector Machines (SVMs) are discussed in detail. Real-world applications and hybrid approaches demonstrate how these tools enhance control, monitoring, and predictive capabilities across various treatment technologies, including membrane bioreactors, adsorption systems, and electrocoagulation. We conclude by highlighting challenges, opportunities, and future trends toward fully automated and self-optimizing wastewater treatment systems.