| 摘要 |
PURPOSE: An upflow type sand filter is provided to reduce the scales of backwash treatment facilities and to reduce loads to sewage and wastewater treatment processes by reducing the amount of backwash water. CONSTITUTION: An upflow type sand filter includes a water level gauge(125), a compressed air supplying pipe(135), a first automatic valve, a rejecting pipe(160), a second automatic valve(182), and a controller. The water level gauge is arranged at a feed water inlet(121). The compressed air supplying pipe supplies compressed air to an air lift pipe such that sand for washing feed water floats toward a washing chamber(150). The first automatic valve is combined with the compressed air supplying pipe. The rejecting pipe is connected to the washing chamber. Backwash water for washing sand is drained through the rejecting pipe. The second automatic valve is combined with the rejecting pipe. The controller controls the automatic valves. [Reference numerals] (AA) Compressed air; (BB) Feed water; (CC) Treated water
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