As noted in Example 8-2 , the headloss was too high. Rework the example without the 100–...

As noted in Example 8-2 , the headloss was too high. Rework the example without the 100–140 sieve fraction to see how much this would improve the headloss characteristics. Assume that the fraction above sieve size number 8 does not contribute to the headloss and that recalculation of the percentages is not required.

Example 8-2

Estimate the clean filter headloss in Ottawa Island’s proposed new sand filter using the sand described in Example 8-1, and determine if it is reasonable. Use the following assumptions: loading rate is 216 m³/d · m² , specific gravity of sand is 2.65, the shape factor is 0.82, the bed porosity is 0.45, the water temperature is 10^oC, and the depth of sand is 0.5 m.

Example 8-1

A sand filter is to be designed for the Ottawa Island’s new water treatment plant. A sieve analysis of the local island sand is given below. Using the sand analysis, find the effective size, E, and uniformity coefficient, U.