PAH oxidation at supercritical and subcritical conditions

One of the biggest problems caused by rapid population growth and industrialization is water pollution. While clean and potable water is decreasing globally, the concentration of organic substances such as polycyclic aromatic hydrocarbons (PAH) in wastewater is increasing day by day. In this study, the removal efficiencies of fluoranthene and benzo(a)pyrene, which are classified as priority pollutants, in high organic load by supercritical water oxidation (SCWO) and PAH formation were investigated. SCWO experimental conditions were realized using constant pressure (22.5 MPa), the temperature was between 300 ˚C and 450 ˚C, the time was between 5 and 15 minutes, and the oxidant ratio (DOD) was between 0.5 and 2. The specific PAH concentrations of the samples and the qualitative analysis of other organic compounds were performed by gas chromatography-mass spectrophotometry (GC-MS). The removal efficiencies of the samples in terms of chemical oxygen demand (COD) were examined and statistical ANOVA analyzes were performed. The lowest COD removal efficiencies were found to be 46% (22.5 MPa, 375 ˚C, 10 min, and DOD 1.25), and the highest was 93% (22.5 MPa, 450 ˚C, 10 min, and DOD 0.5). The most influential variable on the COD removal efficiency was observed as DOD. PAH removal data were determined as 99.9% and 100% for fluoranthene and benzo(a)pyrene.