Page 7 - Simplified Wastewater Treatment Fundementals_Preliminary Treatment.exe

Preliminary Treatment

Screening

Screening is a barrier which catches large debris and rags, extracting what has been

captured from the wastewater.

Screens come in many forms including: manual Bar Screens, self-cleaning Climber

Screens, Step Screens, Perforated Screens and Rotary Screens.

There are 3 classifications of Screens. Coarse, Medium and Fine.

Coarse Bar Screens resemble prison bars or a fence. The bars have a 2-inch gap. Coarse

Screens are intended to capture large debris like wood boards, tree limbs, pieces of pipe

and large rocks.

Coarse Bars Screens are not intended to capture all the rags.

Coarse Screens are manually raked and can serve as an emergency

influent bypass in times of overwhelming flow into a facility.