Fenno - Gravitational Sand Bed Filters

We design and manufacture sand filters based on gravitational pressure. The filters are installed in steel or concrete basins. Inlet water is brought into the filter through piping and automatic valves or through a channel and automatic closing plates. The thickness of the sand bed is slightly more or less than 1.5 metres. The sand bed is flushed with pressurised backwash air and pressurised backwash water. The durations and intervals of air and water flushing of the sand bed vary according to the sludge type. Flushing air and water are fed in evenly through special nozzles placed in the flushing piping or intermediate floor underneath the bed. Flushing sludge is discharged into the overflow channel by rising the water level during flushing. The sludge is led out of the channel into the sludge or reject water process. The operation of the filters is controlled by automatic valves and/or automatic closing plates.