Biological Character Research Of The Activated Sludge/Biofilm Process Treating Municiple Wastewater In North Area

Activated sludge/biofilm process represents a renewable process with the combination of activated sludge process and biofilm process. Applying activated sludge/biofilm process for treatment of domestic wastewater captures the benefits in terms of releasing water source shortage, solving the conflicts between water supply and demand as well as realizing recycling uses of water resource. However, little is currently studied on the characteristics of microorganisms in activated sludge/biofilm process, particularly on the natures of bacteria at low temperature. Therefore, in order to put forward the solution to the problems related to hybrid biological sytem, this study mainly focused on intensive investigations on the characteristics of miroorganisms in the reactor using domestic wastewater as influent.The results demonstrated that at normal-temperature conditions, both total nitrogen removal efficiency and COD elimination efficiency in anoxic stage increased when recirculation ratio was increased. At low-temperature conditions, concentration and activity of activated sludge and biofilm were found to increase with the increase of recirculation ratio.The activity of suspended sludge and biofilm were observed to decrease due to the increase of the amounts of biomass, thus decrease of organic loading in the system. At low-temperature conditions, overall activity of suspended sludge and biofilm was sustained to be at a relative stable state. Nevertheless, in comparison with that at normal-temperature condition, the activity of bacteria showed a sharp decrease, and no relationship between suspended sludge and biofim was found. Temperature had a significant affection on the amounts of microorganisms, that was both the amounts and activity of bacteria was decreased when temperature decreased.Making use of the SEM method, the characters of microorganism in the hybrid biofilm treatment system were compared. The results were that, the bacteria face of the activated sluge and biofilm is plentifulat the common temperature. And at the low temperature, the filament increased significantly in the activated sludge and the biofilm detached but the existence of biofilm guaranteed the treatment...