The Next Frontier of Biological Nutrient Removal

The negative impact of nutrients such as nitrogen (N) and phosphorus (P) on receiving water bodies such as eutrophication and algal blooms led to development of biological nutrient removal (BNR) processes. Many of these initial BNR processes utilized existing infrastructure and involved alternate configurations and operational approaches for conventional activated sludge processes (ASP). Increasing population growth and subsequent impacts on climate and natural resources such as water have led to a need for more robust and sustainable approaches. As BNR technologies have continued to evolve to meet these ever-increasing demands, the next generation of solutions has focused on more efficient use of energy and oxygen and reduced footprint by introducing process intensification technologies. These technologies utilize attached growth and alternative biokinetic pathways to provide higher rate treatment in a smaller footprint or to provide different treatment pathways that are more favorable in terms of inputs (oxygen) or outputs (end products). These processes also provide advantages when treating recalcitrant or potentially inhibitory waste streams such as those found in petro-chemical applications. This presentation will encompass a brief overview of the conventional biological removal processes, a discussion of the optimization strategies, and a focus on looking forward to the emerging BNR technologies. Several of these next frontier technologies that will be discussed include membrane-aerated biofilm reactors (MABR), aerobic granular activated sludge, and short-cut nitrogen removal processes. As these technologies are transitioning into mainstream applications, the developers and the technical community continue to seek new applications in which their unique characteristics and advantages can be applied.