In a pharmaceutical plant, a residual aqueous stream saturated in phenol is produced at a flow rate

of $28\frac{m^3}{d}.$ Its treatment requires a significant operational cost for the plant, as it cannot be

managed by a municipal wastewater treatment plant until its phenol concentration drops below $0\mathrm{.}5$

$\frac{g}{L},$ the maximum allowed concentration at the general collector inlet. The plant currently has an

activated sludge treatment system to meet legal discharge requirements. However, considering the

possibility of integrating the purification of this stream into a waste reuse system is considered.

Phenol is used as a reagent in four sequential reaction stages, all at temperatures between $50$ and

$70C$ and pressurized $($i$.$e$.$ at liquid phase$),$ identified as P$1,$ P$2,$ P$3,$ and P$4.$ Operational conditions

are detailed in the attached table, as the amount of phenol varies for each process. With this data,

the following is requested:

a$.$ Calculate the initial phenol concentration using the functional groups contribution theory.

b$.$ Evaluate if it is possible to achieve a concentration in the stream that allows its discharge to

the municipal collector using a composite curve or if$,$ at least, a relevant reduction is possible.

c$.$ Calculate the efficiency of the phenol treatment required after the integration.

d$.$ Calculate the cost$-$saving obtained using this integration system $($Phenol cost: $800\frac{}{m^3})$