$1.$ A batch aerobic digestion test was performed on waste activated sludge

from a pilot plant treating a soluble wastewater. The temperature was

$20\backslash$deg C and the pH was maintained at a value above $6\mathrm{.}5.$ The results are

presented in Table SQ$12\mathrm{.}1.($a$)$ Determine the concentrations of the volatile

and fixed nonbiodegradable suspended solids. $($b$)$ Determine the decay

coefficients for both volatile and fixed suspended solids.

A completely mixed aerobic digester is to be designed to treat the waste

solids characterized in Study Question $6.$ The solids will be thickened to

$10,000$ mg$/$L prior to digestion but no additional thickening will be practiced

in the digester. The winter operating temperature will be $1$O$"$C$,$ and

the temperature correction factor, $8,$ is $1\mathrm{.}04.$ The flow rate of the thickened

solids will be $500$ m$3/$day$.($a$)$ What SRT is required to provide $38\%$ VSS

destruction during winter operating conditions? $($b$)$ The temperature of

the bioreactor can be elevated to $25\backslash$deg C by insulation and selection of the

oxygen transfer device. What SRT is required to achieve a $38\%$ VSS

destruction at this temperature? $($c$)$ What is the SOUR of the digested

solids at $25"$C$?($d$)$ What is the oxygen requirement for the aerobic digester?

$($e$)$ What volume must the digester have at $25"$C$?($ f $)$ Assuming

that FSS are lost during digestion in a first order manner, what is the

percent reduction in TSS at $25"$C$?(8)$ How much power is required to

mix the bioreactor at $25"$C$?$