The rapid global population growth, industrialization, and intensive farming practices have significantly increased wastewater production, presenting critical environmental and public health risks. Untreated wastewater, rich in nutrients, chemical contaminants, and harmful microorganisms, is frequently discharged into natural water bodies, causing pollution, loss of biodiversity, and contamination of potable water sources. Effective management strategies, including sustainable treatment solutions, are essential to mitigate the adverse environmental impact of wastewater. This chapter highlights the complexities of wastewater, which includes contaminants such as pesticides, heavy metals, pharmaceuticals, and radioactive chemicals, often originating from various household, industrial, and runoff sources. Traditional mechanical treatments can remove visible impurities, but chemical pollutants remain a challenge. Bioremediation, particularly through fungi, offers an environmentally friendly and cost-effective approach to wastewater treatment. Fungi are well-suited for this task due to their resistance to high contamination levels, and their ability to utilize pollutants as growth substrates. Their unique metabolic properties, including the production of metal-binding proteins and catabolic enzymes, allow them to degrade a wide range of toxic substances, such as heavy metals, pharmaceuticals, and organic pollutants. Furthermore, fungi are crucial in biogeochemical transformations, which enhance soil fertility and plant growth. This chapter explores the potential of fungal remediation (mycoremediation) in treating wastewater, alongside other innovative residual waste processing techniques, such as incineration, gasification, and advanced oxidation processes (AOP).