The ENTADT grit separator is used at the raw inlet and should be positioned downstream of the sewage screens. These screens will have medium fine spaces .Where two stage screening is applied ENTADT system can be installed after the medium spaced screen thus offering protection to the fine thus screening mechanism from abrasive detritus.
The collection tank is a wide shallow channel of square proportions. The inlet channel is near parallel to the inlet side of the tank and has a series of vertical baffles to assist with the distribution of flow entering the collection tank.
The chamber design enhances the equalization of the flow across the chamber. Flow is in a singular direction across the tank to the outlet side. The outlet is a sharp edged weir which has a drowned discharge during the higher flow rates. The normal form of hydraulic control is a Standing Wave Flume, this doubles as the means of flow measurement. The characteristics of the flume are ideal to control the critical crossflow velocities within the trap. The flume will be positioned downstream of the Crossflow chamber in accordance with its specific requirements.
A recessed, circular sump is formed. The level floor of this sump is the bed upon which the grit and other similar solids will settle. This accumulation of solids is collected and transported by a slowly rotating scraper mechanism supported on the bridge spanning the tank. The collected solids are delivered to a hopper on the periphery of the tank; from here the grit is separated and dewatered by a Classifier.
Various methods of grit classification are available. These are selected by preference, site limitations and in some instance the effectiveness of the primary screening.
Efficient operation will be achieved when the velocity over the whole range of flow is maintained at a specific value. It is at this velocity that grits of the specified size and specific gravity will be collected. Sizing, positioning and hydraulic control are of the utmost importance.