This book provides a very basic overview of microorganisms relevant to wastewater treatment plant operator. It easy-to-understand language it provides explanations and descriptions of helpful and harmful bacteria, protozoa, and metazoa, algae, and fungus -- and their specialized function in the treatment process, helping the operator to effectively manage the Plant bacterial process. Color photos and illustrations are included within the book and on the supplemental CD-ROM for quick identification under the microscope.