| 摘要 |
The invention deals with a method of cleaning the filter medium of a gravity sand filter and a filter system. The filter medium is placed on the divider, under which compressed air is brought, permeating through openings in the divider to the filter medium and on the way to its surface releasing turbidity to the water layer above the filter medium. Compressed air brought under the divider pushes filtered water out of the space under the divider to the filtered water tank. Time necessary for initial fragmentation of turbidity in the filter medium and for a subsequent reduction of pressure under the divider is shorter than the time necessary for pushing so much water out of the space under the divider to release air out of the divider area to the filtered water tank. The filter system comprises a filter vessel with a divider permeable for water, a filter medium placed on the divider, an outlet pipe leading from the filtered water space under the divider to the tank of the filtered water pump, a filtered water pump and a tank of the turbid water pump, a turbid water pump and a compressed air inlet leading under the divider. The outlet pipe has an inflow near the bottom of the sand filter vessel and an outflow to the filtered water tank at the level of the minimum level of water in the sand filter vessel. The turbid water inflow to the turbid water tank is located above the surface of the filter medium and below the minimum level of water in the sand filter vessel. The capacity of the outlet pipe is higher than the supposed flow through the filter medium and the flow of the outlet pipe is smaller than the flow of the compressed air inlet. |
