Multifaced features and sustainability of using pure oxygen in biological wastewater treatment: A review

In most wastewater treatment plants, biological treatment degrades organic matter. Aeration is a key parameter that directly affects dissolved oxygen concentration, fouling, mixing of solids, and operation costs. Although air is efficient with most types of wastewater, pure oxygen can provide a more economical and efficient dissolved oxygen supply, especially for high-strength wastewater. This review discussing pure oxygen-based aeration can be applied in various biological treatment techniques, making it a promising technology in wastewater treat-ment. Thus, this review covers the deep discussion of pure oxygen effects on wastewater treatment, challenges, advantages, and disadvantages, as well as its impact on microbial community structure and multifaceted assessment, which are essential methodological tools for wastewater treatment efficiency during wastewater life cycle assessment to attain a sustainable circular (bio)economy. To date, this topic has not been thoroughly reviewed. Therefore, this review may be one of the few reviews that discuss and provide an overview of the integration of pure oxygen in wastewater treatment. Pure oxygen-based wastewater treatment is recommended as an intelligent approach for nitrification, denitrification, and organic removal in most biological wastewater treatment techniques. Hence, this review found that further studies are required to develop a pure oxygen technology that is combined with new biofilm technologies to achieve higher treatment efficiency, lower treatment costs, and application with different types of wastewater that may pave the way for optimal biological treatment efficiency of different types of wastewater.