Microbial extracellular polymeric substances based-technology for selenium removal from drinking and wastewater using CSTR and UASB reactors

Selenium (Se) is a naturally occurring trace element in the earth's crust.

Microorganisms and their metabolites, such as extracellular polymeric substances (EPS) play a major role in the redox transformation of metalloids in the environment.

However, how EPS affects Se oxyanions redox cycling in drinking water and wastewater, what the underlying mechanisms, especially electron transfer mechanisms between EPS and Se, and which components of EPS are involved in Se redox transformation are unclear.

Especially concerning electron transfer mechanisms between EPS-Se oxyanions to form BioSeNPs and which redox-active components of EPS are involved in the redox cycling of Se oxyanions. How EPS-mediated reduction of Se affects the isotopic fractions of Se during the reduction process.

To what extent do these pure cultures strain-derived EPS-Se oxyanions reduction mechanisms apply to the Continuous Stirred Tank Reactor (CSTR) and an Up-flow anaerobic sludge blanket (UASB) reactor system for water and wastewater treatment, respectively.

In this research, we plan to set up in situ and in vitro microcosms combined with electrochemical and spectroscopic techniques to examine 1) the key agents and structural components of EPS involved in the reduction of Se(IV/VI), 2) the electron transfer mechanisms between EPS and Se oxyanions for the reduction of Se(IV/VI); 3) the significance of the Se reduction to the environmental fate and recovery of BioSeNPs in CSTR and UASB reactor.

The roles of EPS-mediated reduction processes on the isotopic fractions of Se.

The results from this project will be vital to clarifying the role of microbial EPS and their components in the BioSeNPs cycle and developing biotechnologies to remediate and recover environmental Se.