Performance of Substrates Removal in Biological Aerated Filter with Shell Carriers

摘要

Shell as one kind of mariculture product wastes contain more than ninety percent calcium carbonate, possess coarse surface, and can be used as biofilm carrier. Especially, shell provides calcium ion under sub-acidity condition, which can remove phosphorus by biologically induced phosphorus precipitation. It was investigated in present research that the role of shell for substrate removal in wastewater. Shells with averaged 5 cm diameter were filled in the biological aerated filter (BAF) with 9.3% of filling rate. Averaged chemical oxygen demand (COD) removals were 79.2%, 81.6% and 88.6%; averaged total phosphorus (TP) removal were 36.1 %, 37.0% and 42.7% under the conditions of hydraulic retention time (HRT) 4 h, 8 h and 12 h, respectively. It was found obvious erosion trace on the used shell surface after ninety eight days operation, this result may suggest that shell carrier released calcium ions under biological induced role and air and fluid friction, which formed phosphorus precipitation and discharged with waste sludge.