Recently, persulfate (PS) has received a lot of interest as an alternative to \({H}_{2}{O}_{2}\) for advanced oxidation processes. On the other hand, and among different activation techniques, ultrasonic (US) activation has emerged as a new method that has gained popularity in recent years. To that end, the combination of US and PS is a potential organic wastewater treatment option. In this study, the oxidation of a model bio-recalcitrant contaminant, Rhodamine B (Rh B), which is a basic dye widely used in the textile and food industry, were investigated, using the thermal activation of persulfate in the presence of low frequency ultrasonic waves (ƒ = 50/60 Hz and P = 30 W). Several variables were considered for the effect of degradation including the initial concentration of the dye, the concentration of the oxidant, the volume of the solution, the temperature, and the effects of both organic and inorganic additives. The experimental results showed that 100% of discoloration efficiency was achieved within 90 min under optimum operational conditions. Among the anions and cations that are added to the medium, certain species exhibited a positive effect on the discoloration efficiency of RhB, while others inhibited its elimination. On the other hand, certain additives were found to significantly accelerate the discoloration efficiency of RhB. Overall, the results of this work indicate that the T/US/PS oxidation system is a potent and promising process for the degradation of Rhodamine B.