Grit Unbalance in Sewage Flow Division

by Yoshiaki Yoshimi,
Thomas E. Stelson,

Serial Information: Journal of the Sanitary Engineering Division, 1963, Vol. 89, Issue 2, Pg. 61-86

Document Type: Journal Paper


When sewage flows from a single inlet conduit to multiple grit chambers, large unbalances in liquid-grit distribution may occur. The slower moving bottom water that carries most of the grit is more easily diverted and will tend to concentrate in side channels at asymmetric bifurcations. Model tests support the proposed method of analysis of flow division distribution and show the complexities of the problem. Several arrangements for correcting unbalance are tested: (1) A vertical wall to advance the point of division and to reduce the effect of lace of symmetry; (2) top vanes that deflect top water into the side channel and force bottom water to move straight ahead; and (3) spiral motion that orients grit in the inlet conduit and alters flow division patterns. None of the tested systems cures all cases of unbalance, but all are effective for appropriate uses.

Subject Headings: Flow distribution | Sewage | Inlets (waterway) | Conduits | Asymmetry | Bifurcations | Walls | High-rise buildings

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