STUDY ON THE PERFORMANCE OF AN UP-FLOW AERATED BIOFILTER (UAB) IN MUNICIPAL WASTE-WATER TREATMENTS

A comprehensive wastewater treatment system that accomplishes oxidatio n of organic matter, nitrification, and denitrification was developed, and its characteristics and performance were investigated. A municipa l wastewater was treated by an up-flow aerated biofilter (UAB), in whi ch biofilms were developed on stainless meshes installed horizontally. This UAB exhibited a great potential ability of oxidation of organic matter, SS stabilization, and nitrification due to a unique aeration m echanism giving high DO concentrations with relatively low aeration ra tes. Another unique feature of the UAB was that attached biofilms on s tainless meshes physically filtered out and/or adsorbed suspended soli ds in the wastewater in addition to the biological oxidation of organi c matter. A stable nitrification could be achieved at HRT = 10 hours c orresponding to a hydraulic loading of 86 L m(-2) d(-1) and at a ratio of aeration rate to wastewater flow rate (A/W) of 2, which is conside rably low as compared to aeration rates of typical activated sludge sy stems. This UAB system also could handle relatively high hydraulic loa ding rates. The UAB used in this study still have enough space to inst all more stainless meshes so as to reduce hydraulic loading rates resu lting in the reduction of HRT and aeration rate, which leads to improv ement of the system performance as well as reduction of the running co st.