ENHANCING BIOREMEDIATION OF CRUDE OIL CONTAMINATED SOIL BY COMBINING WITH PHOTOCATALYTIC PROCESS USING TiO2 AS CATALYST

Abstract

One of the continuous environmental problems is hydrocarbon contamination caused by the activity of the petroleum industry. Although many contaminated sites were successfully cleaned up by bioremediation treatment, a number of field reports indicated that biological treatment was sometimes found to be very slow or incomplete mineralization occurred. Lack of bioavailability has been identified as one of the important factors that may inhibit a fast and complete degradation process. Enhancement of chemicals biodegradability during chemical oxidation gives a presumption to investigate the ability of combined photo-catalytic process using TiO₂ under sunlight illumination and biodegradation. This study was expected to overcome the limitation of hydrocarbon bioavailability. The experiments were conducted in a reactor made of 25 cm x 15 cm x 10 cm glass pans microcosms by varying TiO₂ concentration from 0.5, 1, 2, to 3% (w/w) and two control reactors: biostimulation and natural attenuation. During the 12-week study, several parameters were analyzed, including the main parameters: TPH gravimetric, heterotrophic bacteria, petrophylic bacteria, and other parameters, such as pH, moisture content, organic carbon, total nitrogen, and UV intensity. The results showed that the addition of photocatalyst TiO₂ was adequately significant in enhancing TPH removal rates. However, the increasing concentration of TiO₂ added to the reactors did not always show proportionality to the increasing of TPH degradation rates. TPH degradation rates were influenced by indigenous petrophylic bacteria activities and energy derived from UV light. The highest TPH degradation rate was found when 2% (w/w) of TiO₂ added.