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DOI : ,    Vol.6, No.2, 53 ~ 63, 1998
Title
Selection of Dual Media Size Distribution based on Settling Velocity
최승일Suing Il Choi,원동찬Dong Chan Won
Abstract
A method of combining size distribution of dual media has been investigated. The method has been based on the sphericity and the settling velocity of sand and anthracite. The settling equation was developed considering sphericity. The sphericity and settling velocity of sands and anthracites were measured at different six. The settling velocity of sand and anthracite were matched to find the pairs of sand and anthracite which has same settling velocity. The diameter of sand was determined as d10 and the diameter of paired anthracite was determined as d90. Then the sand and anthracite size distribution were revealed based on the uniformity coefficient. Actual combination was modified to match d10 of sand and of d80 anthracite. The media composed by the modified guide line were well separated after backwash while the media composed by the usual guide line at Korean water standards showed about 50% of mixing and those by USA rule showed about 25% of mixing. The developed guide line has several combination based on the different sand effective size.
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