ABSTRACT
Wastewater in sewers is, in general, a high-rate system for microbiological transformations. Wastewater is a very complex microbiological system including a great number of microorganisms divided into specific classes. These microorganisms occur in the water phase, in biofilms (slimes), in sewer deposits, and at walls exposed to the sewer atmosphere. Several fractions of organic matter that are substrates for these microorganisms are found in wastewater. Furthermore, inorganic compounds can microbiologically be transformed.
