Biostimulation of microbial reductive dechlorination of polychlorinated biphenyls in marine sediments of the Venice Lagoon

Microbial reductive dechlorination of polychlorinated biphenyls (PCBs) is often limited by the lack of electron donors, particularly hydrogen, for which the dechlorinating microorganisms compete with others. In this work, two organic acids (pyruvate and lactate), two agro-industrial wastes rich in simple sugars (sugar beet molasses and cheese whey) and a polylactate were tested as electron donors in order to stimulate the microbial reductive dechlorination of PCBs in a marine sediment of Venice Lagoon spiked Aroclor 1254. Polylactate partially inhibited all microbial activities, while pyruvate, molasses and cheese whey remarkably stimulated methanogenesys without affecting sulfate-reduction and PCB dechlorination. Finally, lactate partially inhibited sulfate-reduction, stimulated methanogenesys and increased the PCB reductive dechlorination rate of approximately 45% as compared to untreated controls, thus appearing to be the most promising electron donor for the enhancement of PCB microbial reductive dechlorination in the marine sediments of Venice lagoon.