Insights into the relationship between denitrification and organic carbon release of solid-phase denitrification systems: Mechanism and microbial characteristics

Abstract

Solid-phase denitrification is a promising alternative denitrification technology when facing a shortage of carbon sources. Nevertheless, it is still unclear whether there is a certain interaction between the denitrification process and the carbon release process in a solid-phase denitrification system. In this study, the concept of “Self-adaptation” was proposed for the relationship between denitrification and carbon release. At various influent nitrate loads, the PCL-supported denitrification system achieved an average nitrate removal rate of over 90.59 ± 7.01 % and a maximum denitrification rate of 0.67 ± 0.06 gN/(L·d). Microorganisms can spontaneously regulate the carbon release rate of PCL in response to changes in influent nitrate load, demonstrating “self-adaptation” of the PCL-supported solid-phase denitrification system. Regulation of carbon release rate via the “Self-adaptation” was achieved by changes in extracellular depolymerase activity. Acidovorax_sp. played a key role in “Self-adaptation”, for its function of both denitrification and PCL degradation.