The screening of wastewater is one of the preliminary mechanical treatment to which waste water is subjected at the entrance of treatment plants. It has the goal to separate coarse and medium-fine solids at the inlet, avoiding thus their sedimentation in next stages of plant and clogging of other machineries (pumps, mixers etc.).
In the choice of a screening system, you should consider the following aspects:
- Effectiveness of the device in relation to the potential effects
- The safety and health of employees in charge of the cleaning operations
- The potential harassment caused by odors
- The operations of manipulation and transport of the material to be disposed in landfill
- The options for treatment and disposal.
There are several models of screens, such as, for example: rotary drum, arch with brushes, arch with comb, static, cascade, disk, cochlea etc. In all cases the screen is made of stainless steel or, however, in material suitable to be constantly in contact with water without suffering corrosion. The solids are separated from the water and conveyed to special containers, which must be periodically emptied. The cleaning of the screening surface is automatic, continuous and occurs by brushes, combs or counter current pressured water jets. In the case of a static screen, the cleaning occurs manually. The screening equipment is controlled by pre-set time switches or level sensors.
This technology is an integral part of the treatment process of a Biological plant.