Application of Self Cleaning Rapid Sand Filter in Water Treatment

Document Type : Research Paper

Author

Assist.Prof. Department of Environmental Health-Faculty of Health, Hamedan University

Abstract

Rapid sand filter is one of the most important units in the water treatment plants. It has some difficulties in operation such as backwashing. For the solving of this problem a rapid sand filter has designed and built with the self-cleaning backwashing system. This system consist of 3 main constituents; one galvanized siphon and two galvanized steel tanks. One of them is used for filtration and the other used for the storage of filtrated water in elevation for backwashing the system. Water enter from upside of the filter through the inlet pipe, and collected from the under drainage pipe. Then filter water conduct to the storage tank and exit from outlet pipe. In the beginning, the head loss was low, but because of bed clogging by suspended solids, it increases gradually to the designed head loss (1.2m). Then the system is outed of the service automatically and the backwash is began. The main data for the design of system selected from the hydraulic rules of siphons and rapid sand filter criteria. After essential calculations it was constructed and was started operation. For the hydraulic studies a known volume of storage tank was selected and the time needed for the fill (in filtration stage) and empty (in backwash stage) of water volume with volumetric method were measured. In hydraulic studies the filter surface rate (SOR) was selected about 5-7.5m3/m2/hr (1.39-2.08 lit/sec) and the flow of water in siphon, during the backwashing was measured 8.7 lit/sec. It can be seen that the siphon passes 4-6 times the inlet raw water thus a negative pressure will created in the siphon which causes the water above the sand bed to be discharged automatically and rinse water from elevated tank flow under the sand bed and back wash it. So according to this study self cleaning rapid sand filter is very useful for water filtration, especially in small population community. The construction of system is rapid, simple and economic.  

References

1- AWWA, ASCE, (1990). "Water Treatment Plant Design", 2th ed., USA: Mc Graw-Hill, 145 - 192.
2- Kawamura, S., (2000). "Water Treatment Facilities", 2th ed., USA: John Wiley & Sons, 197 - 210.
3- Hammer, M.J., (1986). "Water and Wastewater Technology", 2th ed. Singapore:Prentice-Hall Inc, 245 - 251.
4- Salvato, J. A., (1992). "Environmental Engineering and Sanitation", 14th ed. USA: Wiley Interscience, 350 - 359.
5- Warren, V., Hammer, M.J., (1993). "Water Supply and Pollution  Control", 5th  ed. , USA: HarperCollins College Publishers, 360–393 .  
6- Corbitt, R.A., (1999). "Standard Handbook of Environmental Engineering", 2th ed. New York: Mc Graw-Hill.
7- Vigneswaran, S., and Visvanathan, C., (1995). "Water Treatment Processes", USA : CRC, 121 - 139.
8- American Water Work Association , (1995). "Water Treatment", 2rd ed. USA: American Water Work Association, 111 - 152.
9- American Water Work Association , (1990). "Water Quality and Treatment", 4th ed. USA: Mc Graw-Hill, 455 – 534 .
10- Giles. R.V., Evett., J.B, and Liu, Ch. (1994). "Fluid Mechanics and Hydraulics", 3rd ed, Schaum's Outline Series, MCGraw-Hill, 127.
Journal of Water and Wastewater; Ab va Fazilab ( in persian )
Volume 15, Issue 2 - Serial Number 2
Serial number: 50
July and August 2005
Pages 14-22

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