| 摘要 |
A filter underdrain module for an underdrain system for a granular media filter. The module is an elongated, integrally constructed, self-contained unit having an enclosed interior and having a substantially flat, substantially rectangular exterior top wall. The water and air for simultaneous backwashing and scouring the filter media are separately conveyed by conduits within the module, and separately discharged into the filter support bed or directly into the filter media, as the case may be. The discharge openings for the water and air are located in the top exterior wall of the module. The discharge openings for water are all substantially the same shape and size, and substantially uniformly spaced along the length and breadth of the module. The same is preferably true of the air discharge openings. Various preferred embodiments are disclosed, including dual ducts for one or both of the separate conduits for cleaning water and scouring air. An underdrain system using the module is disclosed. Various dimensional ratios for such a system are given, as well as various rectangular grid patterns for positioning the water and air discharge openings in the top wall of the module.
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