Biodegradation potential of photocatalyzed surfactant washwater

Enhanced release of hydrophobic compounds from a soil matrix can be achieve d by use of soil-washing or soil-flushing using various surfactants. Howeve r, the surfactants used in achieving the desorption of organic contaminants may also cause a problem in subsequent removal/disposal of these contamina nts. UV radiation in the presence of TiO2 as a pretreatment step to achieve initial (or partial) breakdown of naphthalene and Sodium Dodecyl Sulfate ( SDS) using batch experiments indicated that 56% to 88% naphthalene degradat ion occurred within 30 minutes to one hour. Preliminary results on the estimate of the batch aerobic biodegradation pot ential of photocatalyzed washwater containing naphthalene and SDS suggested that SDS was the major carbon and energy source for an activated sludge en richment culture and an enrichment culture obtained from microorganisms at a contaminated site. Continuous-flow stirred tank reactors (CSTRs) wit with a solids retention time (SRT) of 4 days were not effective, but an SRT of 8 days was successful in biodegrading the naphthalene and surfactant. These results indicated that photocatalytic treatment as a pre-treatment step fo llowed by a biodegradation step may offer potential in cleaning up surfacta nt washwaters containing organic contaminants.