Comparative Study of the Contaminant Removal Efficiencies from Municipal Wastewater by an Aerobic Biofilm System Using Natural Gravels and Recycling Materials as the Contact Media

摘要

This study aimed to evaluate the contaminant removal efficiencies from municipal wastewater by an aerobic biofilm system using different materials as the contact media. A pilot-scale biofilm system was constructed using natural gravels at the size between 5 and 10 cm as well as the recycling materials of (1) construction and demolition waste (C&D waste), and (2) oyster shells. The municipal wastewater used was collected from a drainage channel. The retention times for the experiments were 4, 6 and 8 hours. The use of C&D waste demonstrated a better capability of removing suspended solid (SS), biological oxygen demand (BOD) and ammonium-nitrogen (NH3-N) in municipal wastewater. For SS, BOD and NH3-N, the removal efficiencies using C&D waste as the contact media were calculated as 76.4%, 73.8% and 82.2.0% at the retention time of 8 hours and 12.2 L/min aeration rate, respectively. The increase in system retention time resulted in the improvement of BOD, SS, and NH3-N removal. By considering the project life span of 20 years of this facility, using recycling materials as the contact media might reduce the unit treatment cost for municipal wastewater from 1.47 NTD/ton to 1.17-1.15 NTD/ton compared to that using gravel as the contact media.