ABSTRACT
Wastewater contains a wide variety of microorganisms, some of which are pathogens, while others play a signi‹cant role in degradation of organic matter. Bacteria, protozoa, and other microorganisms play an active role in the conversion of biodegradable organic matter to simpler end products that result in stabilization of the waste. This is a continuous process occurring in streams and rivers as natural puri‹cation processes. This is described in more detail in Chapter 4. These natural puri‹cation processes are enhanced and accelerated in engineered biological treatment systems at wastewater treatment plants. For ef‹cient removal of organic matter and other pollutants, it is essential to have a thorough understanding of the nature, growth kinetics, and process requirements of the microorganisms involved and utilized in the biological treatment processes. This chapter will provide an overview of the major groups of microorganisms used in biological treatment of wastewater.
