Mechanical treatment equipment
The initial stage of wastewater treatment is screens or a rake section – one of the most important stages of mechanical treatment. Wastewater entering the treatment plant contains solid inclusions, such as wood, sticks, cotton waste and other debris. Before further mechanical treatment (grit removals, primary sedimentation tanks), all this garbage must be trapped and removed from the sewage to protect the subsequent stage of biological treatment, as well as expensive equipment (pumps, mixers, aeration system, etc.) – screens perform this function.
Screens or rakes consist of steel bars (slats, racks) and are placed in a channel through which water flows. The bars are located at a certain distance from each other, called a bar spacing. A number of installed bars form a so-called filter screen.
Garbage, trapped in the screens, is removed from the filter by a rake and sent to a screw conveyor. The conveyor conveys the waste into the screw washing machine and thick it, reducing the volume. The filtrate, when pressed, is dumped into the channel after the screens, and the compact waste is stored in a container for subsequent removal. In some cases, crushers are installed at the pump sumps or before screens to grind large debris.