Question $2$

$($i$)$ ABOD test was done on a $5mL$ sample. It was determined that the initial DO for the sample was $9\mathrm{.}2m\frac{g}{L}$ and the final DO was $3\mathrm{.}8m\frac{g}{L}.$ A seed correction of $0\mathrm{.}59m\frac{g}{L}$ is needed for the sample. Determine the BOD, in $m\frac{g}{L}$ for the sample.

$[2+2$ marks$]$

$($ii$)$ With reference to the above BOD test $($i$),$ define what a 'seed' is as used in an activated sludge system. In addition, list and explain factors two $(2)$ that's necessitate for a 'seed' correction in the same system.

$[2+2+2$ marks $]$