The approach for carrier retention sieves has evolved based on the practical experience. Early designs used vertically mounted stainless-steel flat-panel sieves. Now uses horizontally configured stainless-steel wedge-wire sieves in aerated MBBR applications, because the position and orientation of the sieve takes advantage of the media and process aeration grid for scouring.
Stainless steel wedge wire screens retain the cultivated biofilm / media in a process-designated reactor while allowing the treated wastewater and sloughed biofilm to flow through to the next treatment phase.
When vertical-mounted flat-panel sieves are used, an air-sparge system should be mounted along the bottom edge of the panels to periodically pulse the sieves and dislodge any accumulated matter.