HITHERTO ENFORCEMENT OF TUBE DRAINAGE SYSTEM
The first rapid filter with the drainage system concerned was put into service in Krásný Jez u Karlových Varů water treatment works in 1978 (reconstruction of a filter with interbottom). Since then these filters have been put into operation in 33 drinking and service water treatment works. The total filtering area of these filters at present is approximately 6200m2.
A hitherto largest application of rapid filters with the concerned drainage system is a reconstruction of rapid sand filters with interbottom into rapid sand filters without interbottom in the drinking water treatment works in Prague-Podolí. The reconstruction commenced in 1992 and ended in 1995. Thirty-six rapid filters had been reconstructed having a total filtering area amounting to about 2880m2. The mean size of filtering area of the reconstructed filters was 75 m2, the largest filter having a filtering area of 82.5 m2.
The smallest rapid filter of this reconstruction had an area of 0.7m2 (a size suitable for small swimming pools).
Rapid filters with two-layer filtering material (sand + crushed black coal) are operational since 1994 in the drinking water treatment works of Málinec (8 filters by 30 m2 filtering areas) and, since 1999, in the drinking water treatment works of Turček (20 filters by 22.2 m2 filtering areas). Both water treatment works are situated in the Slovak Republic.
Rapid filters with circular plans have been operational since 1998 in the drinking water treatment works of Tlumačov by Zlín (12 filters of O4m).
Simple filtration (without chemical injection) is applied in the sand filters for the atomic-power plant in Jaslovské Bohunice where a gradual reconstruction of 10 water-plant gravity rapid sand filters with interbottoms had been performed into the rapid filters with the concerned tube drainage system between 1982 and 1988. The size of the filtering area of 1 filter is about 60 m2. Further large-scale applications of this type of filtration had been performed in the industrial water treatment works in the Vítkovice Ironworks (307 m2 filtering area) and in the Slovak Republic in VSŽ Košice (720 m2 filtering area) in 1986-7.
An interesting application was the construction of new rapid sand filters in the water treatment works for brewing in Prazdroj, Plzeň, in 1987-8 (4 filters by 20 m2).
The last application is represented by gravity rapid sand filters in the drinking water treatment works in Olomouc- Černovír, built within the framework of the arrangements made after the floods in 1997. Eight rapid filters of filtering area by 31m2 have been in operation since April 2002.