Example $1.$

Please analyse water softening cycle. There should be soften water having $2me\frac{q}{L}C{a}^2$ and $9me\frac{q}{L}Na$ with superficial velocity of feed $10c\frac{m}{m}in.,2m.$ column is used. $CR{T}^2=2e\frac{q}{L},{}_e=0\mathrm{.}4.$ Determine feed period

Example $2.$

For the data of Ex$.1$ assume that bed is regenerated by $25$ mass $\%$NaCl at superficial velocity $0\mathrm{.}5c\frac{m}{m}in.$

Find time required to regenerate the bed.

Example $3.$

We'd like to soften water having $3me\frac{q}{L}M{g}_{2+}$ and $5me\frac{q}{L}Na+$ with superficial feed velocity $8c\frac{m}{m}in$ and $3m$ column is used with $CRT=1e\frac{q}{L},{}_e=0\mathrm{.}4.$

Find feed period.