Innovative slow-release organic carbon-source material for groundwaterin situdenitrification

Slow-release organic carbon-source (SOC) material, a new kind of electron donor for in situ groundwater denitrification, was prepared and evaluated in this study. With starch as a biologically utilized carbon source and polyvinyl alcohol (PVA) as a frame, this material performed controllable carbon release rates and demonstrated stable behaviour during the simulated denitrification process. Raman spectrum analysis showed that the PVA skeleton formed cross-linking network structures for hydrogen-bonded water molecules reset in low temperatures, and the starchy molecules filled in the interspace of the skeleton to form a two-phase interlocking/disperse phase structure. In a static system, carbon release processes followed the Fickian law with (1.294–6.560) × 10−3 mg g−1 s−1/2 as the release coefficient. Under domestication and in situ groundwater simulation conditions, SOC material played a favourable role during denitrification, with 1.049 ± 0.165 as an average carbon–nitrogen ratio. The denitrification process followed the law of zero-order kinetics, while the dynamics parameter kN was 0.563–8.753 gN m−3 d−1. Generally, SOC material was suggested to be a potential carbon source (electron donor) suitable for in situ groundwater denitrification.