A Biodegradation Bench Study of Cork Wastewater using Gamma Radiation

Abstract Wastewater from cork processing industry present high levels of organic compounds such as phenolics that must be degraded before discharge into the municipal sewer or into public water courses. The aim of this work was to find out if gamma radiation treatment could increase the biodegradability of recalcitrant compounds using a microbial consortium and a mixed solution of four phenolic acids as a model. Chemical and microbiological analyses were performed in non-irradiated (0 kGy) and irradiated (100 kGy) mixed phenolic acids cultures during incubation time. A preliminary HPLC and GC-MS analysis were performed to detect the major phenolic compounds in cork wastewater samples. Results indicated the presence of gallic, protocatechuic, vanillic and syringic acids in cork boiling water and gallic, protocatechuic and vanillic acids in sediment tank samples. The Total Phenolic content (TP) of mixed phenolic acids cultures during incubation time indicated a decrease of 38% for 100 kGy samples. The HPLC analysis suggested that the radiolytic products of syringic and vanillic acids are protocatechuic and gallic acids. The CFU counts pointed out to a decreasing tendency along the incubation time for phenolic acids cultures (0 kGy and 100 kGy) suggesting a non-degradation trend. The selected microbial consortium was not able to metabolize the phenolic compounds solutions at the used conditions. This could be due to the detected radiolytic degradation dynamics of the phenolic acids considering the antimicrobial activity of these compounds.