Optimization of Persulfate Dosage for Enhanced Remediation of Soil Contaminated with Polycyclic Aromatic Hydrocarbons

The remediation of soils contaminated with polycyclic aromatic hydrocarbons (PAHs) is significantly hindered by their inherent chemical stability, which severely limits the efficiency of conventional bioremediation strategies. To address these limitations, this study proposes an integrated strategy combining persulfate activation with microbial remediation. Building upon previous research findings, we established an empirical formula for determining the optimal persulfate dosage: Y=3.65×CPAHs+0.41×CTOC+2.70, where TOC denotes total organic carbon. The validity of this empirical formula was systematically evaluated through comprehensive experiments using both simulated and field-collected PAH-contaminated soils. For simulated PAH-contaminated soils (PS1, PS2, and PS3) and actual contaminated soil, the calculated optimal persulfate dosages were 6.0%, 6.3%, 8.0%, and 5.4%, respectively. Experimental validation demonstrated close alignment between predicted and observed optimal dosages, with actual values ranging from 6.0% for PS1, 6.0%–8.0% for PS2, 8.0%–10.0% for PS3, to 5.0% for actual contaminated soil. Microbial community analysis revealed that optimal persulfate dosage conditions promoted the dominance of genus Oceunobacillus in the soil microbiome. Furthermore, the oxidative processes appeared to enhance mutualistic interactions within microbial cooccurrence networks, suggesting a synergistic effect between chemical oxidation and biological degradation. The optimal dosage of persulfate demonstrates dual functionality: (1) direct degradation of PAHs through chemical oxidation, and (2) enhancement of biological degradation processes in contaminated soils. These findings provide a scientifically robust framework for determining persulfate dosage in PAH-contaminated soil remediation, offering practical guidance for field applications while optimizing the synergy between chemical and biological remediation processes.