On$-$line process monitoring and control is often a requirement for a standard bioreactor design as

they are a necessity in order to obtain meaningful experimental results. Temperature, $pH,$ and

dissolved oxygen level are key physical variables in running fermentation experiments in

bioreactors. Sketch a two$-$dimensional $(2$D$)$ schematic of a typical bioreactor system inclusive of

the following control loops:

$($i$)$ Dissolved oxygen level $($aeration and agitation$)$

$($ii$)$ Temperature via circulation of thermo$-$stated water in the jacketed layer

$($iii$)pH$ via addition of acid$/$base

$($iv$)$ Feeding of substrates via peristaltic pump