Mechanical treatment is indispensable as the first process step of preliminary treatment of wastewater, both for STP inlets and other fields of application, such as process water treatment.
Disturbing coarse material has to be removed in order to protect the subsequent steps against damage/pollution or to relieve them. It is the goal to completely separate floating, settling and suspended material, depending on the bar spacing, and remove the material prior to discharging it into a container.
The hygienic conditions, operation safety and the fact that there are nearly any maintenance works are factors becoming more and more important.
For municipal STPs an additional screenings washing is recommendable as regards the denitrification, in order to lead the soluble organics again to biological treatment.