ABSTRACT
So far we have only considered processes with dispersed growth, that is, where the microorganisms are suspended in the liquid medium. Another category of biological processes are the so-called attached growth processes, where the microorganisms grow attached to a solid support medium. e main advantage of attached growth processes is that higher biomass concentrations can be obtained than in suspended growth processes; therefore, an attached growth process can obtain the same treatment eciency with a lower reactor volume. In an ideal attached growth process where all the microorganisms are attached to the support and there are no suspended cells, there would be no need of solid-liquid separation aer the biological reactor. However, usually a small fraction of the microorganisms detach from the support and are present in the euent and therefore need to be separated before discharge of the wastewater.
