Migration of PAHs in food industry sludge to the air during removal by UV and TiO2

- Treated sludge from food industry was characterized for PAHs.
- A device was designed and applied successfully during the removal of PAHs.
- PUF was used here for the first time to determine evaporated PAH from food sludge.
- Effects of temperature, UV and TiO2 on removal and evaporation of PAH were determined.
- Removed and evaporated PAH ratios varied between 69-95% and 25-95%, respectively.

This study was conducted to investigate the evaporation ratios of polycyclic aromatic hydrocarbons (PAHs) from the food industry treatment sludge. Five PAH compounds having different ring numbers were targeted. The effects of temperature, UV and TiO2 on PAH evaporation were also studied. All applications were performed in a specially designed apparatus. The air in the apparatus was vacuumed to collect the evaporated PAHs on the PUF cartridges. Then, these PUF cartridges were extracted for determination of PAHs. The PAH concentrations were measured by a gas-chromatography mass-spectrometer (GC-MS). 91% of the initial ∑5 PAHs in the sludge was evaporated into the air at the end of the UV application. However, this value decreased to 21% when UV was not employed. Initial and final PAH levels in the sludge were measured to determine the removed PAHs which refer to the addition of degraded and evaporated PAHs. The results indicated that the UV-TiO2 application at high temperatures was considered an appropriate PAH removal method because it restricted the evaporation of PAHs while it removed high levels of PAHs. PAHs were mainly removed from the sludge by degradation rather than evaporation with this application.