ABSTRACT
Preliminary treatment processes Preliminary treatment may include several processes, each designed to remove speci›c materials. Selection of what processes are included in pretreatment depends on the collection system (e.g., combined sewer systems, which collect storm water, bring more grit into the inžuent than do sanitary sewers) and the nature or makeup of the wastewater in the community. Moreover, the balance between residential wastewater contents and industrial wastewater contents, and the individual industries that add wastes to the system will be determining factors in process selection for a treatment system.
