Abstract
An effective removal of suspended solid (SS) by using settled sludge and porous carriers as a filter has been experimentally investigated in a sequencing batch reactor (SBR). In this process, filtration was started in a down-flow mode after the formation of the filter bed, comprising a stratified layer of activated sludge and porous carriers, in a short settling time.
The SS concentration decreased below 10 mg·l-1 after a short recirculating filtration, indicating that this new solid/liquid separation method is more efficient compared to the conventional gravity settling. The SS removal occurred mainly through the sludge bed. Despite the thickness of the sludge bed change with MLSS concentration, the SS removal rate was nearly the same for the MLSS concentration ranging from 1200 to 4500 mg·l-1. The experimental results also showed that there is likely a proper filtration rate range which lead to an efficient SS removal, meanwhile no collapse was observed on the sludge bed.
