Integrated hybrid treatment for the remediation of 2,3,7,8-tetrachlorodibenzo-p-dioxin

The dioxin isomer 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TeCDD) has been reported as the deadliest compound known to science. Due to its highly recalcitrant nature and low bioavailability, it is stubborn toward bioremediation and chemical treatment. Efforts to degrade it using one single technique have not accomplished the desired results. In this study, we have tried to develop an integrated 2,3,7,8-TeCDD removal process using palladized iron nanoparticles (Pd/nFe) for initial reductive dechlorination under anoxic conditions and subsequent oxidative biomineralization. Using laboratory synthesized Pd/nFe, 2,3,7,8-TeCDD was completely dechlorinated to form the end product dibenzo-p-dioxin (DD). Oxidative degradation of DD was successfully achieved by growing active cells of a dioxin-degrading microorganism Sphingomonas wittichii RW1 (DSM 6014) under aerobic culture conditions. Metabolite identification was done by high performance liquid chromatography (HPLC) and whole cell protein was measured as the indicator for cell growth. To the best of our knowledge, this is the first report on integrated hybrid degradation method for 2,3,7,8-TeCDD.

► Facile synthesis of bimetallic Pd/nFe nanoparticles was carried out in the laboratory.
► 2,3,7,8-TeCDD was completely degraded at ambient conditions by Pd/nFe nanoparticles.
► DD was the sole end product obtained after reduction of 2,3,7,8-TeCDD by Pd/nFe.
► DD oxidation was achieved by sequential biodegradation using Sphingomonas wittichii.