Please help me to draw and explain nicely. Explain two factors that could contribute to the changes of $pH$ in microbial fermentation

process. Draw a two$-$dimensional schematic on how to realize a feedback control loop to

control $pH$ value of a reactor content in a stirred bioreactor system.

$..,$ Anaerobic process is a complex chain of subsequent and interacting degredation steps for

production of a biogas. Biological monitoring and process control of such anaerobic process

is highly important. Illustrate an anaerobic digester schematic that includes the following

features: $-$

An open loop control of a pump for feed input to the reactor

A feedback temperature control loop

An online gas analyzer that is linked to the output of the digester