The potential and realistic hazards after a solar-driven chemical treatment of benzene using a health risk assessment at a gas station site in Korea

Abstract

In order to evaluate the potential use for ex situ remediation, a solar-driven, photocatalyzed reactor system was constructed and applied for the treatment of groundwater contaminated with benzene using selected advanced oxidation processes (AOP) processes, such as H₂O₂/solar light, TiO₂ slurry/solar light and immobilized TiO₂/solar light. However; to date, there have been few attempts to characterize the potential impact of residual levels of benzene on human health after treatment. Some papers have focused on the application of treatment methods of benzene, but most have not considered the effects of realistic hazards and human health. Therefore, potential and realistic hazards of benzene to human health were investigated at a gas station site using a risk-based assessment approach. Among the different remediation actions, the solar light/TiO₂ slurry/H₂O₂ system (Action 5) showed higher removal efficiency than the solar light/TiO₂ slurry (Action 3) and the solar light/immobilized TiO₂ (Action 2) systems for the treatment of benzene. The Action 5 remediation method achieved 98% degradation, and lead to a substantial increase in the removal of benzene due to the synergetic effect of TiO₂ with the oxidant, H₂O₂. Also, using the realistic and potential hazard assessment instead of the point estimation of concentration after benzene treatment, the total health risk exceeded the target risk value (1 × 10^{− 6}). However, the 95th percentile target cancer risk, found using a probabilistic analysis (Monte Carlo method), was around 1 × 10^{− 6}, indicating a low potential carcinogenic risk. Therefore, it was concluded that no adverse health risk was unlikely to be posed if the Action 5 system, which included the addition of TiO₂ and H₂O₂, or if an increased reaction time was applied. In addition, continuous efforts and proper actions must be taken on the “Soil and Groundwater Remediation Action” based on the risk assessment in Korea.

Keywords:

• TiO₂
• H₂O₂
• benzene
• ex situ remediation
• health risk
• groundwater