Removal of Polycyclic Aromatic Hydrocarbons from Water Using Mn(III)-Based Advanced Oxidation Process

Floods have the potential to resuspend polycyclic aromatic hydrocarbons (PAHs) laden sediments and potentially impact drinking water intakes. This work identifies optimal operating conditions for the PAH removal from water using a combined permanganate (Mn(VII))/bisulfite advanced oxidation process (AOP). PAHs in aqueous solutions containing humic acid (HA) were treated using a combination of permanganate and bisulfite at different molar ratios. Results showed that the Mn(VII)/bisulfite AOP was an effective method to remove priority PAHs, but the dosage needs to be carefully controlled to avoid excessive by-products and reduce treatment costs. The optimal reaction conditions [C[16PAHs]:C[KMnO4]:C[NaHSO3]=1:30:60 (m[16PAHs]:m[KMnO4]:m[NaHSO3]=1:22:29) and 10 min<=reaction time<30 min] were identified within a wide pH range (5.0-8.0). High removal efficiencies (85%-100%) were achieved for typically refractory high molecular weight PAHs, including pyrene (PYR), chrysene (CHRY), benzo[a]anthracene (B[a]A), benzo[b]fluoranthene (B[b]F), benzo[k]fluoranthene (B[k]F), benzo[a]pyrene (B[a]P), and dibenzo[a,h]anthracene (D[ah]A). The concentration of B[a]P was reduced to below 0.2 μg/L from an initial concentration of 0.8 μg/L in less than 30 min, and a 2 mg-OC/L concentration of HA had minimal effect on the effectiveness of AOP. The maximum concentration level of B[a]P is specified as 0.2 μg/L, according to National Primary Drinking Water Regulations issued by the EPA. Overall, the Mn(VII)/bisulfite AOP represents a promising technology for PAH removal to below minimum EPA drinking water standards in emergency scenarios, although the control of the dosages of permanganate and bisulfite is required.