EFFECT OF NONIONIC SURFACTANT ON THE DEGRADATION OF GLASS-SORBED PCB CONGENERS BY INTEGRATED CHEMICAL BIOLOGICAL TREATMENT

A study was conducted on the effect of a nonionic surfactant on the efficiency of the integrated chemical-biological treatment (ICBT) of polychlorinated biphenyls (PCBs) sorbed to the glass walls of the experimental vessels. The addition of surfactant associated with the chemical oxidation was proposed to overcome two limitations of biodegradation of hydrophobic compounds: adsorption to surfaces, and lack of solubility and thus availability to the microorganisms. Two C-14-labeled PCB congeners, 2-chlorobiphenyl and 2,2',4,4'-tetrachlorobiphenyl, were used as the test compounds. The integrated chemical-biological treatment consisted of sequential applications of Fenton's reagent (5% H2O2, 1 mM FeSO4) at pH 4.0 (with and without nonionic surfactant Novel II 1412-60) and the inoculation with a mixed culture of Pseudomonas sp., strain LB400, and Alcaligenes eutrophus, strain H850, at pH 8.0. The chemical treatment in the presence of surfactant affected the removal of the congeners bound to the glass surfaces of the experimental test systems. As indicated by high-pressure liquid chromatography analysis, these PCBs were converted to unidentified soluble products that are hypothesized to be partial oxidation products. No parent test compounds were detectable in the system after chemical treatment with or without surfactant. The addition of the mixed culture of PCB-degrading bacteria after completion of chemical treatment in the presence of surfactant resulted in the removal of approximately 45% of 2-chlorobiphenyl and 32% of 2,2',4,4'-tetrachlorobiphenyl in the form of (CO2)-C-14. This compared to 29% and 23% without the addition of surfactant, respectively. We suggest that the combination of surfactant-induced desorption and chemical oxidation would increase the availability of hydrophobic pollutants for microbial degradation.