DEVICE AND METHOD FOR PREVENTING CLOSURE OF FILTER MATERIAL IN BIOLOGICAL FILTER TANK

摘要

PROBLEM TO BE SOLVED: To prevent the closure of a filter material in the biological filter tank of a sewage septic tank. SOLUTION: At a time of the back washing of a biological filter tank, the hollow filter material X of a filtering treatment zone M and the hollow filter material X of an aerobic treatment zone N are brought to a fluidized contact state to be subjected to washing treatment and a part of the hollow filter material X of the filtering treatment zone M is floated toward the upper part of an air diffuser S while a part of the hollow filter material X of the aerobic treatment zone is sedimented toward the lower part of the air diffuser to mix both filter materials of the treatment zones M, N. This operation is repeated to properly replace the hollow filter materials X in the tank up and down to convert the treatment functions thereof.