Influence of hydraulic loading rate on performance and energy-efficient of a pilot-scale down-flow hanging sponge reactor treating domestic wastewater

Abstract The hydraulic loading rate (HLR) is a vital factor affecting the biological attached growth processes. Herein, a pilot-scale down-flow hanging sponge reactor (DHS) with a capacity of 0.5 m3/d was investigated under different HLRs (5.56 and 11.12 m3/m2.d). The DHS reactor was operated at an organic loading rate of 1.2 kgCOD/m sponge 3 .d. The results showed that COD removal attained 60.4 ± 11.4% at HRL of 5.56 m3/m2 d while this removal increased to 78% during the steady stage of operating at HLR of 11.12 m3/m2.d. Total suspended solid (TSS) was moderately removed with the efficiencies of 69.7%–75.6%. High NH 4 + -N removal of 80% was attained during operation, indicated that the nitrification process was mildly sensitive to change of HLR. This proposed technology brings a beneficial economic in decreasing energy consumption. This study suggested a viable treatment solution of the DHS using natural air ventilation, which favors low-income areas.