Paper Title
Combined Processes in Wastewater Engineering: Trends, Advances, Challenges, and Future

Abstract
The increasing scarcity of freshwater resources has shifted the focus of water and wastewater treatment from waste disposal to waste minimization, water reuse, and resource recovery. As wastewater becomes more contaminated with persistent and toxic compounds, meeting stricter discharge standards has become challenging. While biological treatment remains widely used, it struggles with non-biodegradable contaminants from industrial effluents, making it difficult to meet regulatory standards. Therefore, advanced treatment technologies are needed to effectively degrade these pollutants while maintaining cost-effectiveness. Although advanced processes offer a promising solution for removing persistent contaminants, they face challenges such as high energy demands, chemical consumption, frequent maintenance, and limited nutrient removal. In response to these challenges, there is a growing emphasis on optimizing the integration of advanced treatments with biological systems to reduce operational and maintenance costs, thereby making combined processes more appealing than standalone treatment methods. When properly integrated, these systems can provide synergistic benefits, achieving pollutant removal efficiencies exceeding 90%. This integration is particularly important for enabling water recycling in industrial applications, supporting cleaner production, and promoting a more sustainable environment. This study explores the latest trends, advancements, challenges, and future directions in the combined processes for wastewater treatment. It will also highlight recent research findings that underscore the potential of these combined approaches to address complex wastewater challenges while advancing sustainability in water management. Keywords - Advanced treatment Processes, Combined processes, High Strength Wastewater, Multicomponent wastewater, Wastewater Engineering.