Application of UV-rays in removal of polycyclic aromatic hydrocarbons from treated wastewater

Abstract

This study was undertaken to investigate the removal of PAHs by UV-rays from treated wastewater. Samples of wastewater originating from a municipal treatment plant were taken twofold (series I and series II). The initial concentration of PAHs ranged: 0.8 μg/L (in series I) and 1.2 μg/L (in series II), respectively. A standard mixture of 16 compounds was added to the wastewater samples. The amount of individual hydrocarbons in the added mixture was equal to 40 μg/L, (in series I) and 50 μg/L, (in series II), respectively. The samples of wastewater without the added standard mixture were treated as a control samples. All samples of wastewater were exposed to UV-rays during 10, 20, 30 and 60 seconds, respectively. Afterwards, the PAHs concentration in both the wastewater samples containing the standard mixture and in the control samples was determined. Determinations of PAHs concentration in wastewater samples in each series were made in triplicates. A quantitative analysis of PAHs was provided by gas chromatography-mass spectrometry (GC-MS). It was found that exposition to ultraviolet rays resulted in the decrease in the concentration of PAHs in the wastewater samples without added standard mixture up to 65%. The efficiency of the removal of hydrocarbons grouped according to a number of rings was in the range of 0 (for 5- ring and 6-ring of PAHs) to 71% (for naphthalene). It was also found that exposure of wastewater samples to UV-rays resulted in a decrease of PAHs concentration in wastewater samples with the added standard mixture up to 84%. The efficiency of the removal of hydrocarbons grouped according to a number of rings differed significantly (to 94% for naphthalene).

Keywords:

• Wastewater
• UV-rays
• GC-MS
• 16 PAHs - EPA

Acknowledgments

This research was supported by the Committee of Scientific Research grant 3T09C 033 19, BS-402-301/07 and BW– 402-201/09/P.