Enhancing Nitrate Removal With Industrial Wine Residue: Insights From Laboratory Batch and Column Experiments Using Chemical, Isotopic and Numerical Modeling Tools

Agricultural run-off exposes recipient water bodies to nitrate (NO3-) pollution. Biological denitrification is a suitable method for removing NO3- in water resources that can be induced by the use of industrial organic liquid waste as an electron donor source. In light of this, batch and column laboratory experiments were performed to assess the potential of two industrial wine residues (l & iacute;as and v & iacute;nico) to induce biological denitrification of NO3- contaminated water from a constructed wetland and to evaluate the efficiency of these treatments using chemical and isotopic tools. In batch experiments (performed at a C/N ratio of 1.25), v & iacute;nico was not efficient enough in removing N species, attenuating only 35% NO3- and was not used in column experiments. In similar experimental conditions, l & iacute;as completely removed N species from water in both batch and column experiments. The calculated isotope fractionation (epsilon 15NNO3 and epsilon 18ONO3) was the same in both batch and column experiments biostimulated with l & iacute;as and differed from those for v & iacute;nico. The isotopic data confirmed that denitrification was the principal NO3- attenuation pathway in all the experiments. The isotopic fractionation can be later applied to field studies to quantify the efficiency of biologically enhanced denitrification. A numerical geochemical model that accounts for the changes in nitrate, nitrite concentration and isotopic composition due to the degradation of l & iacute;as and v & iacute;nico, including transport in the case of the column experiment, was performed to simulate the experimental results and can be up-scaled in field treatments. Groundwater nitrate pollution is a significant global concern resulting from excessive fertilizer use in agriculture. This pollution poses health risks to humans and ecosystems by contaminating drinking water supplies and aquatic ecosystems. Sustainable remediation of nitrate is necessary to safeguard human health and the environment. Successful field-scale remediation requires laboratory feasibility studies to find the appropriate compounds to reduce nitrate (electron donors) and the best application measures to remove nitrate at a minimum cost. In our research, laboratory experiments were carried out using two industrial wine wastes as electron donors to evaluate their potential to remove nitrate from nitrate-polluted water. Chemical, isotopic, and numerical modeling tools have been used to quantify the amount of nitrate removed. The results indicate that one product successfully removed nitrate and can be implemented in the field as a mitigation strategy, while the other was ineffective and cannot be used. The isotopic fractionation from the laboratory experiments and the numerical model would be subsequently applied in the field to quantify the efficiency of nitrate removal. Wine industry residues induced nitrate attenuation in laboratory batch and column experiments Denitrification efficiency varied with the wine residue type, showing epsilon 15N between -16.5--32.0 parts per thousand and epsilon 18O between -12.1--27.6 parts per thousand A geochemical model describing the trends of the experimental results has been developed and can be used for field applications