Degradation kinetics of butyltin compounds during the bioremediation of contaminated harbour sediments

The present study was aimed at the reclamation of harbour sediments contaminated with butyltin compounds (BTCs) by means of biostimulation and/or bioaugmentation experiments carried out in a 5-L slurry bioreactor. In the biostimulation experiment with inorganic nutrients, almost 50% of TBT was degraded in 20 weeks. In the bioaugmentation experiment with a microbial consortium, no significant degradation of TBT was observed. Conversely, bioaugmentation combined with biostimulation led to a decrease of similar to 50% in TBT after four weeks. A simple kinetic model fitted to the experimental data of BTC concentration allowed us to estimate that 10 weeks are needed to decrease BTC contamination by 90% using a strategy based on both biostimulation and bioaugmentation, and 29 weeks for a strategy using biostimulation only. Overall, our study indicates that strategies based on biostimulation coupled to bioaugmentation can be effective in significantly reducing the concentration of BTCs over relatively short timescales.