A performance evaluation of a new iron oxide-based porous ceramsite (IPC) in biological aerated filters.

A novel medium containing iron oxide-based porous ceramsite (IPC) and commercial ceramsite (CC) was used in two laboratory-scale upflow biological aerated filters (BAFs) to treat city wastewater to compare their efficacy in wastewater treatment. The IPC BAF and CC BAF were operated in water at 20-26°C, an air/water (A/W) ratio of: 3:1 and hydraulic retention times (HRTs) of 7, 3.5, 1.75, and 0.5 h and the removal of ammonia nitrogen (NH3-N), total nitrogen (TN), total organic carbon (TOC), and phosphorus (P) were studied. Our results indicated that IPC BAF was superior to CC BAF in terms of TOC, TN, NH3-N, and P removal. IPC had higher total porosity and larger total surface area than CC. The interconnected porous structure of IPC was suitable to microbial growth, protozoan, and metazoan organisms were primarily found in the accumulated biofilm layer. Biomass, in the biofilm layer, was detected at three distinct distances (300, 900, and 1500 mm) from the bottom of the inlet filter, again indicating that the IPC was more suitable for biomass growth. The presence of biomass improves the simultaneous removal efficiency of nitrogen and phosphorus in the IPC BAF. Thus, our findings support IPC as a material for use in filter media in wastewater treatment BAFs.