Continuous Sand Filter

Principle of Operation Raw influent is fed into the base of the sand filled, cone bottomed filter. The flow then rises through the sand so that clean effluent is discharged over the upper weir. The rising flow of the effluent is distributed evenly over the whole cross section of the filter by means of a radial grating system. The contaminated sand falls continuously to the bottom cone outlet from where it is transferred by an external airlift to the wash chamber at the top of the unit. Final backwashing of the sand is then performed by a counter current of clean water before returning to the sand bed in the isolation box. The dirty wash water is discharged over the lower weir for disposal.FeaturesContinuous operation and cleaning High filtration efficiency Superior lift and scouring of sand External airlift for better accessibility No possible contamination of clear water by returning sand Efficient final rinse of sand into the isolation box Manageable reject stream Minimum maintenance cost Adaptability of sand bed depth Flexibility of design Minimum energy requirements No shutdown for backwash No moving parts No backwash material required