Oil removal from water in parallel plate gravity-type separators

Abstract Aspects of oil removal by gravity separation in parallel plate separators have been investigated both theoretically and experimentally. Attention has been paid to the possible influence of retention time distribution, co- or countercurrent flow (in tilted plate separators) and to the effect of perforation of the plates. Perforation enables an easy removal of separated oil in horizontal plate separators. It appears that the overflow rate-related to the horizontal projection of the real plate area-determines the performance of a plate separator in all these cases. A residence time distribution will lower the separation efficiency only when it is caused by a velocity profile over the width of the tank or by an extremely unequal distribution of the influent over the plates. A tilted full plate separator and a horizontal perforated plate separator with the same overflow rate perform equally well as to separation efficiency; only secondary, practical reasons will determine the choice between either construction.