Hydroxypropyl-β-cyclodextrin improves the removal of polycyclic aromatic hydrocarbons by aerobic granular sludge

Polycyclic aromatic hydrocarbons (PAHs) as polar organic pollutants, their potential harm to the environment has caused widespread concern. This study describes a simple method to prepare modified aerobic granular sludge (AGS) by hydroxypropyl-β-cyclodextrin (HP-β-CD). Using HP-β-CD modified AGS as the adsorbent, the removal of specific PAHs: Fluoranthene (Fla) reached 95% comparing to 80% of the unmodified AGS. The removal of Fla was related to initial concentration, temperature and ion concentration (Na⁺, Mg²⁺). The removal efficiency of Fla reached 96.27%, 94.26% and 93.69%, when initial concentration of Fla was 10, 15 and 20 μmol/L. At temperatures of 15°C, 30°C and 45°C, the removal efficiency of Fla (15 μmol/L) gradually improved from 87.20% to 94.84% and 95.73%. The presence of Na⁺ and Mg²⁺ ions led to the deterioration of PAHs removal. With the increase of Na⁺ and Mg²⁺ concentrations, the removal efficiency of modified AGS on PAHs decreased by 3.9% and 6.5%, respectively. These findings indicate the potential application of cyclodextrins as the active sites of a complex modified polymer network for PAHs wastewater treatment.