Keywords: biological aerated filters, biological treatment, biofilters, municipal sewage, burned clay pellets, wastewater treatment, hydraulic loading rate, aeration ratio, overloading, backwashing, media height
Treatment of municipal sewage by Biological Aerated Filter (BAF) using burned clay pellet as media
The high-strength municipal sewage was treated by the two-stage Biological Aerated Filter (BAF) pilot system with microorganism carrier of burned clay pellet. The effects of hydraulic loading rate, aeration ratio, overloading, backwashing and the height of media on the performance of BAF were investigated. In higher hydraulic loading and lower ratio of aeration, the two-stage BAF may decrease effluent COD, NH2+-N and SS to less than 50 mg/L, 8.0 mg/L and 20 mg/L respectively. Moreover, the operation stability was not affected remarkably by the instantaneous overloading and periodical backwashing. The backwashing step by step was proposed to save energy and infrastructural investment. In addition, the dynamic expressions for the COD and NH2+-N removal were deduced respectively.