Application of a fluidised layer of granular material in the treatment of surface water. Part 2: separation efficiency of the layer

Separation efficiencies attainable with a fluidised layer of granular material (FLGM) when applied for the treatment of different quality surface waters in pilot and full size operations were investigated. It was established that the FLGM can be effective for direct separation of the destabilised impurities and for agitation of systems containing destabilised particles aimed at the formation of readily separable suspension. The separation efficiency of FLGM was found to be, among other factors, influenced by reaction conditions influencing the process of destabilisation of impurities, such as dosage of destabilisation reagent, water temperature, reaction time and measure of FLGM expansion. Furthermore, it was established that incorporation of a FLGM reactor into the treatment process design significantly improved the operational performance of the works, especially in the process configuration of a single-stage separation arrangement. Replacement of silica sand used as the FLGM charge with thermally treated bentonite enabling easier processing of the coated grains as the raw material for production of Al₂O₃ was verified.