Enhanced biodegradation kinetics in the copper-polluted sediment through bioaugmentation with water spinach and peanut husk-derived biochar

Abstract

Stenotrophomonas maltophilia is a copper-tolerant bacterium that is used for improving the resilience and efficacy of microorganisms engaged in degrading substrate under high copper contamination. Examination of reaction kinetics indicates that the original consortia, Stenotrophomonas maltophilia and the mixed culture, follow a first-order reaction. The Michaelis-Menten model suggests that elevated copper concentrations exert stress on the original bacterial population and Stenotrophomonas maltophilia. However, when a mixed culture is employed during the bioaugmentation process, it brings about an enhancement in microbial resistance and performance. This study demonstrates that the poor performance of indigenous bacteria in media that are highly contaminated with copper can be improved by adding exogenous copper-tolerant bacteria. Furthermore, poor mass transfer in sediments can be improved by adding plants and biochar. This strategic addition serves a dual purpose: it increases the affinity of the substrate for sediments characterized by poor mass transfer and alleviates the inhibitory effects induced by copper. In addition, high percentages of Firmicutes, Bacteroidetes, and Euryarchaeota within the biochar matrix were verified to expedite the substrate biodegradation process even at high copper concentrations. The findings in this work provide an important basis for the future design of in situ bioremediation systems for heavy metal-contaminated sites.