From a biodegradability study on $2$ nitrifying$*$ laboratory scale activated sludge biological systems, both at $20$ degC,

one treating the raw WW at $12$ days sludge age, the other treating the settled WW at $6$ days sludge,

the filtered effluent COD, TKN$,$ FSA, TOC, TP and OP concentrations were measured, i$.$e$.$

Raw WW $45$ mgCOD$/$l $1\mathrm{.}5$ mgTKN$-$N$/$l $0\mathrm{.}38$ mgFSA$-$N$/$l $15\mathrm{.}0$ mgC$/$l $7\mathrm{.}55$ mgTP$-$P$/$l $7\mathrm{.}55$ mgOP$-$P$/$l

Set WW $45$ mgCOD$/$l $2\mathrm{.}0$ mgTKN$-$N$/$l $0\mathrm{.}85$ mgFSA$-$N$/$l $15\mathrm{.}0$ mgC$/$l $6\mathrm{.}94$ mgTP$-$P$/$l $6\mathrm{.}94$ mgOP$-$P$/$l

$(*$ One in which all the available FSA is nitrified to nitrate leaving little FSA in the effluent, i$.$e$.$ one in which the effluent

FSA concentration is zero. Also all the biodegradable soluble organic N$,$ Nobsi, will have been degraded, so that the

filtered effluent TKN is all soluble unbiodegradable organic N i$.$e$.$ Nouse $=$ Nousi.$)$

$4$a$.$ Accepting these concentrations, estimate the unbiodegradable soluble COD and TKN fractions in the raw and settled sewage.

$4$b$.$ From this same experiment, the unbiodegradable particulate COD fraction $($fS$\text{'}$up$)$ was calculated $($later in the course we

shall see how this is done$)$ to be $0\mathrm{.}133$ and $0\mathrm{.}021$ mgCOD$/$mgCOD for the raw and settled sewages

respectively. With these fS'up values and the measurements from $1$ to $4$ above, characterize the raw and settled sewage

COD into their soluble and particulate biodegradable and unbiodegradable COD fractions and concentrations, and also

the influent TKN into its FSA, and organic C and N fractions, the latter into its soluble and particulate biodegradable and

unbiodegradable C and N fractions.

Use a COD$/$VSS ratio $($fcv$)$ of $1\mathrm{.}481$ mgCOD$/$mgVSS$,$ TKN$/$VSS ratio $($fn$)$ of $0\mathrm{.}10$ mgN$/$mgVSS$,$

TOC$/$VSS $($fc$)$ of $0\mathrm{.}518$ mgC$/$mgVSS and P$/$VSS $($fp$)0\mathrm{.}025$ mgP$/$mgVSS for the influent

unbiodegradable particulate organics $($Supi or XIi$)$ and that the unbio soluble organic P $($Pousi$)$ is $0\mathrm{.}00$ mgP$/$l$.$