Central composite design applied to paracetamol degradation by heat-activated peroxydisulfate oxidation process and its relevance as a pretreatment prior to a biological treatment

In this study, the degradation of paracetamol (PCT) by thermo-activated peroxydisulfate (PDS) and the feasibility of coupling thermo-activated peroxydisulfate to activated sludge culture were examined. The effect of the relevant parameters on the thermo activated peroxydisulfate process, namely temperature, PDS concentration, initial pH and initial PCT concentration was investigated. As observed, the solution pH did not have a significant effect on the PCT degradation. The temperature increased the degradation of PCT, while an increase of the initial PCT concentration impacted negatively its degradation yield. The PDS concentration showed an optimal value of 8 mM. The operating parameters were then optimized by using a central composite design (CCD). After performing a screening of the various factors, response surface analysis led to the following optimal conditions for the yield of PCT degradation: 0.33, 5 mM, pH = 6 and 68 degrees C for the initial PCT concentration, the initial peroxydisulfate concentration and the temperature respectively, leading to the removal of 94.2% of PCT. Under these conditions, the BOD5/COD ratio increased from 0.008 initially to 0.34 after 10 h. Showing a significant improvement of the biodegradability; consequently and even if the limit of biodegradability (0.4) was not achieved, a biological treatment could be promisingly considered.

Automated summary

The study demonstrated that thermo-activated peroxydisulfate could effectively degrade paracetamol, achieving a 94.2% removal rate of PCT by optimizing operational parameters. Furthermore, coupling activated sludge culture with thermo-activated peroxydisulfate significantly enhanced the biodegradability of PCT, providing favorable conditions for biological treatment.