Sustainable Effluent Treatment and Resource Recovery, Volume 1

In this modern era, the growing concern over global water scarcity is driving researchers to explore advancements and innovative methods in current water treatment technologies. Nanomaterials and nanocatalysts have gained importance for their exceptional properties, such as greater surface area, unique composition, adjustable morphology, and enhanced charge transfer capabilities, which contribute to their superior removal efficiencies, positioning them as promising solutions for novel strategies. Particularly, the greener and more sustainable synthesis of nanomaterials has unlocked new avenues for effluent treatment due to its eco-friendly, low toxicity, maintenance of mild reaction conditions, high efficiency, and advantageous and cost-effective platform compared to other conventional methods. Green-fabricated nanomaterials serve as nano-scale adsorbents and photocatalysts and can be assessed in the elimination and degradation of effluent from water sources. The vital impact of green synthesis lies in the involvement of numerous phenolic antioxidants in plants and microorganisms that serve as reducing agents and capping agents for the preparation, including nanorods, nanotubes, nanowires, nanoflowers, and quantum-dot nanomaterials. This chapter discusses the importance of green technology in the fields of water and wastewater treatment. Additionally, the chapter delves into various techniques used in the green synthesis of nanoparticles. The subsequent section emphasizes recent advancements in effluent removal using green-synthesized nanomaterials and nanocatalysts, providing a mechanistic understanding of their role in effluent treatment. Finally, the chapter addresses the environmental impact of green nanomaterials and discusses future challenges in this field.

In response to the growing incidence of disease and pandemic worldwide, there has been a significant increase in pharmaceutical production and usage. However, this has resulted in a corresponding rise in pharmaceutical waste, such as benzafibrate, hydrocortisone, atenolol, carbamazepine, tetracycline, and ibuprofen, which have been detected in water resources and have had negative impacts on the environment and health. Various methods have been studied to remove these pollutants. Recently, adsorption and photocatalytic methods have gained popularity due to their efficiency, cost-effectiveness and eco-friendly nature; particularly because they utilize non-hazardous or less toxic reagents. This chapter provides a comprehensive overview of the current state-of-the-art green synthesis methods used in the production of metal oxide-based nanomaterials such as copper oxide, iron oxides, silver oxide, titanium dioxide, and zinc oxide, which have been applied for the adsorption and photocatalytic treatment of pharmaceutical effluents. This chapter also discusses the challenges of treating treatment of pharmaceutical effluents and the mechanisms of adsorption and photocatalytic degradation using metal oxide-based nanomaterials. Additionally, the potential for resource recovery from e-waste is also explored as a source of precursors for metal oxide nanomaterials, which can help mitigate e-waste. Finally, the chapter addresses the toxicity of metal oxide-based nanomaterials, highlighting the risks associated with inhalation, ingestion, and skin contact. This is an important consideration when working with metal oxide-based nanomaterials, as some these nanomaterials can cause harm to both humans and the environment.

Aquatic environments are increasingly contaminated by heavy metals, dyes, and other hazardous waste released by industrial, domestic, and commercial sources. Effective treatment of effluents from these point sources remains a significant environmental challenge. Among various remediation approaches, photocatalysis has emerged as one of the most effective methods for treatment of effluents. This chapter presents an overview of recent advances in two-dimensional graphene-based nanomaterials (GBNs) for wastewater treatment. GBNs have attracted attention as a feasible material for environmental remediation applications due to exceptional characteristics, including mechanical, surface, electrical, structural, thermal, and optical properties. This chapter explores several GBNs and examines their properties and green synthesis techniques. We focus on the use of GBNs in photocatalytic effluent treatment, including the elimination of heavy metals, bacteria and viruses, pharmaceutical contaminants, and organic and inorganic pollutants. We also provide a comparison of GBNs with other nanomaterials for effluent treatment in terms of cost and performance. Furthermore, an in-depth assessment of the advancements and technologies found for employing GBNs in wastewater treatment is discussed, and the advantages and disadvantages of GBNs are highlighted, along with ways to enhance their qualities and properties to optimize them for wastewater treatment. Overall, this chapter offers a comprehensive analysis of the new paradigm of GBNs for environmental remediation, including insight into how they might affect wastewater treatment.

Green synthesis, which relies on natural materials and sustainable processes, has emerged as an efficient strategy with reduced environmental impact. Micro-/nanoparticles and polymeric materials obtained from renewable sources, including plant extracts, biomass, and agricultural residues, exhibit unique properties that make them highly effective in effluent treatment. This chapter reviews recent progress in the green synthesis of micro-/nanoparticles, biopolymers, and polymeric materials, with particular emphasis on their applications in wastewater remediation. The review highlights that: (1) although the synthesis routes for micro-/nanoparticles and polymeric materials differ, they converge on the common objective of minimizing environmental impact through sustainable practices; (2) the performance of these materials in water and effluent treatment strongly depends on the optimization of synthesis parameters; and (3) integrating multiple synthesis strategies offers promising pathways for developing novel materials that combine the advantages of micro-/nanoparticles and polymers/biopolymers. Future investigations should focus on refining these processes to further enhance efficiency and broaden their applications, particularly in effluent treatment and related fields.

The factors that characterize the development of the processes of the design, synthesis, and application of nanoparticles represent one of the most fascinating branches of green nanotechnology. It offers a better option than the previously employed physical and chemical techniques which are more harmful to the environment and generally more expensive. Among the different types of biological agents that can be used for green NP synthesis, plant-based methods have been the favourite choice of many scholars in the world. This chapter examines asset recovery from industrial emissions using a novel approach that provides cost and environment-friendly nano sorbent, using polymers adsorbing toxins. The increase in the population across the world has brought about heavy water pollution problems mainly arising from heavy metals, dyes, textile effluents, microorganisms, and organic and chemical waste. There are several techniques to get rid of these pollutants. The chapter regards green synthesis techniques like the use of plant extract, microorganisms, and renewable sources to replace conventional chemical techniques. While in the other hand, the available polymeric materials developed possess areas of reinforcement towards adsorption, filtration, and degradation of organic waste contaminated from wastewater. The recently developed polymer and nanocomposite materials have a high surface area, high porosity, and various functional groups which make them more effective in wastewater treatment. Experimental studies will be focused on the initial adsorption of contaminants followed by filtration tests and biodegradation tests of the adsorbent materials. The present chapter reviews the developed green synthesis methods for polymeric materials and nanocomposites aimed at wastewater treatment applications.

Bio-nanotechnology, the integration of biological systems with nanotechnology, offers innovative solutions for environmental challenges, particularly in effluent treatment. Toxic compounds that pose serious risks to human health and ecosystems are frequently found in wastewater from industries including textiles, chemicals, and medicines. Traditional wastewater treatment methods, while effective, often involve high energy consumption, chemicals, and complex processes. Bio-nanotechnology addresses these issues by leveraging nanoparticles (NPs) and biological agents to enhance the efficacy and sustainability of effluent treatment. Nanomaterials, such as metallic, carbon-based, and polymeric NPs, exhibit unique physicochemical properties, including high surface area, reactivity, and adsorption capacity, which make them highly effective in removing pollutants. These NPs can adsorb, degrade, or transform toxic contaminants, including heavy metals, organic dyes, and endocrine-disrupting chemicals from wastewater. The effluent treatment process can be enhanced by the synergistic effects of using biological agents, such as enzymes and bacteria, in combination with NPs. Bio-nanotechnology enables the development of biosensors for real-time monitoring of effluent quality and finding trace levels of contaminants. Additionally, bio-nanomaterials can be designed for specific effluent types, increasing the precision and value of treatment. Although promising, the large-scale application of bio-nanotechnology in effluent treatment requires addressing challenges such as nanoparticle stability, environmental impact, and cost-effectiveness. Nonetheless, the potential of bio-nanotechnology in achieving efficient, eco-friendly, and economically viable effluent treatment solutions holds great promise for the future of environmental sustainability.

Enzymes are essential for treating industrial effluents because of their efficacy, selectivity, and environmental friendliness. These biocatalysts provide a viable alternative to traditional physicochemical approaches by reducing complex organic and inorganic contaminants to smaller, non-toxic molecules. Textile dye decolourization, phenolic chemical breakdown, oil residue cleanup, and heavy metal detoxification are all possible applications. Advances in enzyme engineering and immobilization techniques have increased their durability and ability to be reused, making them commercially feasible for large-scale operations. This chapter examines the effects of enzymes on various industrial effluents, as well as the benefits and drawbacks of enzyme-based effluent treatment systems and their novel uses across diverse industries.

Microplastics (MPs) are emerging contaminants of growing concern in wastewater treatment plants (WWTPs), which serve as both critical sinks and inadvertent sources of these persistent pollutants. This chapter explores the potential of bioremediation as a sustainable strategy for MP removal, critically examining microbial and enzymatic degradation pathways across different stages of WWTPs. It synthesizes current knowledge on bacteria, fungi, algae, and higher eukaryotes capable of MP degradation while emphasizing their relevance within the operational context of biological treatment, tertiary polishing, and sludge stabilization units. Key strategies such as bioaugmentation, biostimulation, and enzyme-assisted treatment are evaluated with case studies and conceptual models, highlighting integration challenges related to retention time, biodegradation efficiency, and ecological compatibility. Advanced configurations like enzymatic membrane reactors and hyperthermophilic composting are presented as promising yet underexplored solutions. The chapter concludes with a critical reflection on the limitations of current bioremediation efforts, advocating for pilot-scale testing, microbial consortia engineering, and techno-economic assessments to enable scalable application in WWTPs. This comprehensive synthesis provides both foundational insights and forward-looking perspectives on deploying biotechnology for MP mitigation in engineered wastewater systems.

Industrial effluents contain organic and inorganic compounds which pose hindrances in safe disposal of waste water, if inappropriately/inadequately treated before their release in the natural environment. Microbial systems have long been recognized as attractive alternatives for treating industrial wastewaters as they offer a safe and environmentally compatible approach to waste treatment. With efforts being made to minimize waste generated, circular economy approaches are being explored and applied to conventional waste treatment strategies. Microalgae are promising candidates for valorization of industrial effluents as they offer distinct advantages including lower energy consumption than that required for traditional waste treatment methods. Treated effluents can be used to produce biofertilizers, sources of bioenergy, etc., and efforts to extract valuable products from waste using microalgae continue. Here we discuss the potential of microalgae in waste valorization with an aim to provide an important insight into what microalgae can offer to environmental sustainability. The future potential and challenges for this approach are also addressed.

The industrial revolution, through heavy mining and the widespread use of synthetic dyes, has led to a global threat from heavy metal contamination and other toxic pollutants. Other than industrial effluents and mining, the primary sources of soil pollution are insecticides and paint. Synthetic colors have largely replaced natural ones because they are more resistant to chemicals, light, heat, and changes in pH. Although synthetic dyes offer clear advantages over natural colors, they cause significant environmental harm, particularly to aquatic systems. Heavy metal and synthetic dye contamination is a serious issue that directly and indirectly harms crops, humans, other organisms, and the environment; thus, cleaning up polluted soils and aquatic systems is important. Despite ongoing efforts through techniques like vitrification, thermal desorption, and chemical leaching, heavy metals and dyes remain a persistent environmental problem due to their continued use and a lack of proper removal technology. Plants and microbes use inexpensive, environmentally friendly processes, known as bioremediation, to remove heavy metals and dyes. Microorganisms perform this by metabolizing and decomposing environmental contaminants. The breakdown of heavy metals and dyes by biological agents involves numerous strategies. Microbes use methods such as biosorption, bioleaching, biomineralization, biotransformation, and intracellular accumulation, while plants employ techniques like phytoextraction, phytovolatilization, and phytodegradation. Research has shown that using genetically engineered microorganisms with enhanced bioremediation capabilities, biomining with hybrid technologies, and omics-based methodologies is a beneficial and interesting approach to the bioremediation of these contaminants. This chapter reviews different bioremediation strategies involving plants, microbes, and their combination use to address contamination from heavy metals and dye.

Bio-nanotechnology is an emerging interdisciplinary field that integrates biological systems with nanotechnology to address environmental challenges, particularly in industrial effluent treatment. The rapid growth of industries has led to the excessive release of toxic pollutants into water bodies, which causes severe ecological and health issues. Conventional effluent treatment methods like chemical and physical processes have limitations in terms of efficiency, sustainability and cost-effectiveness. Bio-nanotechnology offers a promising alternative by utilizing bio-based nanomaterials for effective wastewater remediation. These nanomaterials are derived from biological entities like microorganisms and plants. They possess unique properties such as high surface area, reactivity and biocompatibility, which make them ideal for adsorption, catalysis and degradation of harmful contaminants. This review explores the latest advancements in bio-nanotechnology for effluent treatment, focusing on the biogenic synthesis of nanomaterials and their applications in removing heavy metals, dyes and organic pollutants from industrial wastewater. It also examines the environmental benefits of using bio-nanomaterials, including their potential for biodegradability and lower toxicity compared with synthetic alternatives. Furthermore, challenges related to large-scale production, potential environmental risks and regulatory frameworks are also discussed. The article concludes that, while bio-nanotechnology holds great potential for revolutionizing industrial effluent treatment, further research is necessary to optimize its implementation for broader industrial use, ensuring sustainability and cost-efficiency. This review mainly highlights bio-nanotechnology as a sustainable and efficient approach that offers a greener solution for industrial effluent management and contributes to environmental preservation.