Assisted Bioremediation Approaches - Biostimulation and Bioaugmentation - Used in the Removal of Organochlorinated Pollutants from the Contaminated Bottom Sediments

Abstract

The prospects of using the biostimulation and bioaugmentation treatment for the removal of the polychlorinated biphenyl (PCBs) from contaminated sediment collected from the sewage canal in the surroundings of a former PCB manufacturing plant in Slovakia is described. The eleven bacterial strains isolated in our previous work from sewage Strážsky canal sediments were able to aerobically degrade significant amounts of PCBs. Five of the bacterial isolates obtained were used in bioaugmentation treatment individually as single strains and within the eight artificially prepared consortia consisting of two or three strains. Bioaugmentation by a single strain was performed in other set of experiments combined with the addition of nonionic surfactants (Triton X and Tween 80) to increase bioavailability of PCBs and with the addition of terpenes (carvone and limonene) to induce required enzymes. <br />The highest biodegradation of PCBs in biostimulation treatment was obtained using all three studied factors – addition of nitrogen, phosphorus, and oxygen to the indigenous microorganisms naturally present in the contaminated sediment. The highest biodegradation of PCBs in bioaugmentation experiments was obtained with the individual bacterial isolates (one Gram-positive and one Gram-negative), and with a laboratory prepared consortium consisting of three selected bacterial isolates. Addition of surfactant Tween 80 led to a higher biodegradation of PCBs than that of Triton X. Bioaugmentation treatment using the addition of single bacterial isolate and surfactant Tween 80 improved elimination of the evaluated indicator PCB congeners to the highest extent and thus appeared to be the most perspective technique for possible field bioremediation.