Calculate the clean$-$bed through a deep $-$bed filter with $1\mathrm{.}5$m anthracite coal$($ effective size$=1\mathrm{.}1)$ over $0\mathrm{.}3$ m sand $($ effective size$=0\mathrm{.}5$ mm$)$ at a filtration rate of $15$ m$/$hr and temperature of $15$ degree celcius. Pw $=998\mathrm{.}4$ kg$/$m$^3,$ u$=1\mathrm{.}14*10^-3$ kg$/$m$.$s$.$ Midpoint from table $11\mathrm{.}5$

anthracite coal: Kv$=228,$ Ki$=4\mathrm{.}4,$ e$=0\mathrm{.}50$

Sand; Kv$=112,$ Ki$=2\mathrm{.}2,$ e$=0\mathrm{.}42$