Bubble Bead® Filters have an “hourglass” shaped internal geometry with a constricted washing throat, although some models may appear to be cylindrical. These filters contain no moving parts for agitation of the bead bed.
During continuous filtration, water from the rearing tank enters the unit at the bottom through a slotted inlet pipe, passes upward through the bead bed which floats in the upper filtration chamber, and exits through a slotted discharge pipe at the top.
The inlet pipe also serves as the sludge discharge line during backwashing. The filter is equipped with an air inlet below the center of the washing throat. Four valves (inlet, sludge, air, and discharge) control the filter’s operation. Check valves are sometimes used on the air inlet and water outlet lines to simplify backwashing.