Adsorption of Organic Stormwater Pollutants onto Activated Carbon from Sewage Sludge

Adsorption filters have the potential to retain suspended pollutants physically, as well as attracting andchemically attaching dissolved compounds onto the adsorbent. This study investigated the adsorption ofeight hydrophobic organic compounds (HOCs) frequently detected in stormwater e including fourpolycyclic aromatic hydrocarbons (PAHs), two phthalates and two alkylphenols e onto activated carbonproduced from domestic sewage sludge. Adsorption was studied using batch tests. Kinetic studiesindicated that bulk adsorption of HOCs occurred within 10 min. Sludge-based activated carbon (SBAC)was as efficient as tested commercial carbons for adsorbing HOCs; adsorption capacities ranged from 70to 2800 mg/g (Cinitial \ubc 10e300 mg/L; 15 mg SBAC in 150 mL solution; 24 h contact time) for each HOC. Inthe batch tests, the adsorption capacity was generally negatively correlated to the compounds\u27 hydrophobicity(log Kow) and positively associated with decreasing molecule size, suggesting that molecularsieving limited adsorption. However, in repeated adsorption tests, where competition between HOCs wasmore likely to occur, adsorbed pollutant loads exhibited strong positive correlation with log Kow. Sewagesludge as a carbon source for activated carbon has great potential as a sustainable alternative for sludgewaste management practices and production of a high-capacity adsorption material