Importance of Mechanical Screen in Sewage Treatment

AS we all know that the mechanical screen is necessary for the wastewater pretreatment. Why? Is it possible without screen? Let’s take a look at the role of the mechanical screen before answer this question, from which we can understand why?

Function and principle

First, the role of grids is to intercept massive suspended or floating solid pollutants. It is a kind of treatment equipment which has protective effect on subsequent treatment structure or pump unit. Its principle is to use a set of parallel metal grids made of metal frame, placed in the sewage channel at an angle, or at the inlet of the pump station catchment pool, to intercept large pollutants.

The function of the filter is to intercept or remove fine suspended solids such as fibers and pulp from sewage. The principle is made by drilling holes in iron sheet or by wire. The diameter of holes is 0.5 - 1.0 mm, which can intercept fine suspended solids.

Structure composition

The mechanical screen is usually including the following parts: grill, grill frame and slag rake.

1. According to the grid gap spacing the screen can be divided to coarse screen (spacing over 40cm), medium screen (space between 15-25mm) and fine screen (space between 4-10mm)

2. According to the way of clean scum can be divided to manual and mechanical, but manual cleaning is mainly responsible for coarse screen.

3. According to the shape can be divided to flat type and curve type, and the flat type is widely used for actual project.

4. According to the characteristic of the structure the screen can be divided to grab screen, circular screen, arc screen, band screen, rotary screen, rotary drum screen and step screen.

Don't underestimate the role of grille which plays a great role in the sewage pre-treatment. It lays a foundation for the early stage of integrated sewage treatment equipment. Therefore, wastewater screening preparation must be done before sewage treatment.