Lecturer:

Sewage Treatment

Wastewater Engineering

ECW542

DA/RH

Tower 1/ Aras , Room

Ext.

Learning Outcome

At the end of Week 5 students should be able to

- describe preliminary treatment

- apply knowledge related to preliminarytreatment

PRELIMINARY TREATMENT

Screening, PumpingStation, Grit

and Grease Removal

SCREENING

Remove larger particles, which caninterfere with subsequent equipment orprocesses.

Screening devices can be broadly classifiedas coarse or fine.

Smaller sized openings generate morescreenings and more contaminants onscreenings.

SCREENING

Need to handle, store, dispose of screenings.

Often have screenings of decreasingopenings.

Need to work at low and high flows.

SCREENING DESIGN

Bar spacing, materials of construction anddimensions.

Channel depth, width and approach velocity.

Headloss through the screens (hL = 1(V2-v2/2g)C

Discharge height to accommodate screeningsconveying equipment.

SCREENING DESIGN

Angle of screen.

Materials of construction and coatings foroverall unit.

Screen cover to block wind and improveaesthetics and reduce odor.

Drive unit service factor.

Drive motor size and enclosure (forexample;

totally enclose fan cooled)

Spare parts.

Provision of redundant screen or bypassscreen.

SCREENING DESIGN

THANK YOU