The invention provides a process for treating a loaded solvent stream having a time-varying contaminant concentration, the process comprising the steps of: (a) providing a plurality of hold-up tanks; (b) feeding the loaded solvent stream in dependence on its contaminant concentration to one or more of the hold-up tanks and; (c) allowing lowed solvent to flow from the plurality of hold-up tanks to obtain a smoothed loaded solvent stream having a reduced time-varying contaminant concentration. The invention further provides a treating unit comprising a circuit for circulating a solvent stream, which circuit includes a device for smoothing contaminant peak concentrations, said device comprising a plurality of hold-up tanks each hold-up tank having at least one inlet and an outlet equipped with an outlet valve, the device further comprising an inlet distributor allowing the control of solvent flow to one or more of the hold-up tanks.