Tracing the role of endogenous carbon in denitrification using wine industry by-product as an external electron donor: Coupling isotopic tools with mathematical modeling

JOURNAL OF ENVIRONMENTAL MANAGEMENT

卷:207

Article

Carrey, R.¹  Rodriguez-Escales, P.^2,3  Soler, A.¹  Otero, N.^1,4 

[1] Univ Barcelona, Fac Ciencies Terra, Dep Mineral Petr & Geol Aplicada, Grp Mineral Aplicada & Medi Ambient, C Marti & Franqubs S-N, E-08028 Barcelona, Spain

[2] Univ Politecn Cataluna, Dept Civil & Environm Engn, Jordi Girona 1-3, ES-08034 Barcelona, Spain

[3] UPC, CSIC, Hydrogeol Grp, Associated Unit, Barcelona, Spain

[4] Generalitat Catalunya, Barcelona, Spain

关键词: Denitrification;    Stable isotopes;    Modeling;    Endogenous carbon;    Wine by-product;    Porous media;   

DOI  :  10.1016/j.jenvman.2017.10.063

来源: Elsevier

【 摘 要 】

Nitrate removal through enhanced biological denitrification (EBD), consisting of the inoculation of an external electron donor, is a feasible solution for the recovery of groundwater quality. In this context, liquid waste from wine industries (wine industry by-products, WIB) may be feasible for use as a reactant to enhance heterotrophic denitrification. To address the feasibility of WIB as electron donor to promote denitrification, as well as to evaluate the role of biomass as a secondary organic C source, a flow-through experiment was carried out. Chemical and isotopic characterization was performed and coupled with mathematical modeling. Complete nitrate attenuation with no nitrite accumulation was successfully achieved after 10 days. Four different C/N molar ratios (7.0, 2.0, 1.0 and 0) were tested. Progressive decrease of the C/N ratio reduced the remaining C in the outflow and favored biomass migration, producing significant changes in dispersivity in the reactor, which favored efficient nitrate degradation. The applied mathematical model described the general trends for nitrate, ethanol, dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) concentrations. This model shows how the biomass present in the system is degraded to dissolved organic C (DOCen) and becomes the main source of DOC for a C/N ratio between 1.0 and 0. The isotopic model developed for organic and inorganic carbon also describes the general trends of delta C-13 of ethanol, DOC and DIC in the outflow water. The study of the evolution of the isotopic fractionation of organic C using a Rayleigh distillation model shows the shift in the organic carbon source from the WIB to the biomass and is in agreement with the isotopic fractionation values used to calibrate the model. Isotopic fractionations (epsilon) of C-ethanol and C-DOCen were -1 parts per thousand and -5 parts per thousand (model) and -3.3 parts per thousand and -4.8 parts per thousand (Rayleigh), respectively. In addition, an inverse isotopic fractionation of +10 parts per thousand was observed for biomass degradation to DOCen. Overall, WIB can efficiently promote nitrate reduction in EBD treatments. The conceptual model of the organic C cycle and the developed mathematical model accurately described the chemical and isotopic transformations that occur during this induced denitrification. (C) 2017 Elsevier Ltd. All rights reserved.

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