RECTANGULAR CLARIFIERS: THE FORGOTTEN STEPCHILD

INTRODUCTION The prevalent opinion in the wastewater treatment community is that the square clarifier is the poorest shape for a secondary clarifier. This is blamed on both its geometry and its inherent mechanical problems. That leaves us with either circular or rectangular shaped clarifiers. Again, if put to a vote, most engineers and operators probably believe that the circular clarifier is superior to the rectangular clarifier . . . . . for a whole host of reasons. The author, based on his field experience testing clarifiers of all shapes and sizes, will present a case for the rectangular shape. The purpose of this paper is not to say one is better than the other, but simply to show that the rectangular clarifier, if properly designed or modified, can perform with the best of them.