Downflow biofilter for organic wastewater

摘要

PURPOSE:To markedly reduce a rise in filtering resistance by providing a fixed bed packed with a granular solid of the same kind or a different kind to the lower part of a packed fixed bed and providing a flow passage, which can diffuse oxygen- containing air bubbles incapable of being introduced into an upper fixed bed among oxygen-containing air bubbles rising through a lower fixed bed to the outside of the system, in the upper fixed bed. CONSTITUTION:A fixed bed B packed with a granular solid is provided to the lower part of a fixed bed A packed with a granular solid and a flow passage C capable of diffusing oxygen-containing air bubbles 9 incapable of being introduced into the fixed bed A among the oxygen-containing air bubbles 9 passing through the fixed bed B by an air diffusing means 5 to flow out and rise from the upper interface of the bed B is provided in the fixed bed A. Since the SS collecting amount in the fixed beds A, B and the amount of bacteria in the fixed bed B increase as the operation is continued over a long time, filtering resistance increases. However, since the oxygen- containing air bubbles 9 flowing out of the upper part of the fixed bed B are diffused to the atmosphere through the air outflow pipe C, the fixed bed A is filled with air to make it possible to prevent a sudden increase in filtering resistance.