Efficient activation of peracetic acid by mixed sludge derived biochar: Critical role of persistent free radicals

Peracetic acid (PAA)-based advanced oxidation processes (AOPs) were increasingly identified as the alternative scheme in wastewater treatment. Cost-effective and easily available catalyst for activation of PAA was in urgent demand for promoting engineering application process. In this study, a new type of biochar catalyst derived from pyrolysis of mixture of primary sludge (PSD) and secondary sludge (SSD) was prepared and showed effective PAA activation ability. The degradation of p-chlorophenol (4-CP) improved with PAA activation by mixed sludge derived biochar (PS-SDBC) than secondary sludge derived biochar (S-SDBC) and primary sludge derived biochar (P-SDBC), and the highest removal efficiency achieved by PS-SDBC with the PSD/SSD ratio of 5/5 (k