Dynamic and initial head loss in full-scale wastewater filtration and measures to prevent long-term initial head loss

Abstract Dual media sand filters at Henriksdal WWTP began to show high head loss after five years of operation, especially during the fluidization for sorting filter bed backwashing. At that time, were still clean and dynamic loss, due clogging with suspended solids a cycle had its lowest value. Dynamic over lower layer surface in dual was detected some cycles operation. The initial has increased years. This type is constant operation increases only slowly time. It different factors, as precipitation ferric oxide hydroxide nozzle slots on grains bed, accumulation below bottom. Different measures tested reduce or eliminate filters. Results from frequency diagrams showed changing nozzles removing material bottom most favourable actions. Backwashing more frequently sequences also reduced loss.