Analysis of the method of calculating high resistance drainage of rapid filters

Summary

The methods of calculating high resistance drainage distribution systems for rapid filters are considered. In the practice of designing filtration plants in Russia several approaches to the structural concept of drainages that provide for equilibrium distribution of wash water in area have been worked out. It is shown that the method proposed by VNII VODGEO is the most substantiated; therefore it seems advisable to restore the recommendations on the use of this method in the practice of designing filtration plants in the regulatory documents. The analysis of the practical use of different approaches to the most useful method of calculating high resistance drainages for rapid filters shows the need to take into account a whole complex of indicators in these calculations. The most important among them is the indicator of drainage open ratio as well as assumed values of original flow rate of wash water in collectors (channels) and branches that determine the value of recovered head.

Key words

rapid filter , drainage-distribution system , wash uniformity , drainage open ratio , backwash loss