Observation and model analysis for the bacterial community structure of activated sludge

Abstract

This chapter provides both experimental and theoretical approaches to elucidate the community structures of activated sludge. Activated sludge process is a wastewater treatment process and is widely used all over the world for the purification of wastewater. It is mainly composed of bacteria, and the specific capability of each bacterium is responsible for the overall performance of the process. Protista and bacteria are the dominant microorganisms that constitute the activated sludge. Previously, there used to be a little information about the bacterial communities and their roles because of the absence of the techniques to analyze the bacterial communities but recently, molecular biological techniques have made it possible to analyze the bacterial constituent of the activated sludge; however, still there are no details of the characteristics of each bacterium. These molecular biological techniques are based on the information of ribosomal RNA sequences. Fluorescent in situ hybridization was used to clarify the composition of the bacteria at a group level in activated sludge samples. The chapter concludes that the actual activated sludge of a broad range of operating conditions has similar bacterial group composition in spite of the difference of regional and climate conditions. The most possible source of bacteria for activated sludge is raw sewage.