A laboratory-scale oxic biofilm reactor using loofah sponge as support material was carried out to study its start-up characteristics and the optimum operation parameters in removing organic matter and nitrogen from domestic wastewater. It took no more than 10 days to complete microbiological cultivation and acclimation, indicating that the natural loofah sponge was a superior support material compared with some conventional ones. The influence parameter experiments showed that the hydraulic retention time (HRT) had a significant influence on the COD and NH3-N removal efficiencies, the average COD and NH3-N removal efficiencies were 83.7 and 96.9% respectively when the temperature was 25 ± 2 °C, the influent flow rate was 0.21 L/h and the HRT was 7.5 h. The loofah sponge biofilm system had a strong tolerance to organic shock loading in the present experiment. Additionally, it was found that domestic wastewater could be preferably treated with 88.9% of COD and 98.7% of NH3-N removal efficiencies with the corresponding influent concentrations of 260.0 and 26.8 mg/L, respectively. The observations obtained in the present study indicated that the loofah sponge was an excellent natural support material, potentially feasible for the present system for the treatment of the decentralized domestic wastewater.
Keywords: domestic wastewater, hydraulic retention time, loofah sponge biofilm, shock loading