Woodchip bioreactors for saline leachates denitrification can mitigate agricultural impacts in mediterranean areas: The Campo de Cartagena-Mar Menor environmental issue

Leachates from intensive agriculture containing high nitrate have been identified as a major cause of the severe eutrophication crisis that impacts Mar Menor (SE Spain), the largest hypersaline coastal lagoon in the Medi-terranean basin. A best management practice for removing NO3--N is denitrifying bioreactors. This is the first study to assess the efficiency of citrus woodchips bioreactors in treating agricultural leachates that flow to the Mar Menor via surface discharges. Denitrification capacity, woodchip degradation (by weight loss), formation of potentially harmful compounds, and greenhouse gas (GHG) emissions were assessed. Three bioreactors (6 m x 0.98 m x 1.2 m) filled with citrus woodchips (3 m(3) d(-1) per bioreactor) through which the untreated ditch water over 1.5 years. Bioreactors were operated at 8 h, 16 h, and 24 h hydraulic residence time respectively, in each bioreactor. The main characteristics of the ditch water were: pH approximate to 7.5-8.0, electrical conductivity approximate to 5-8 dS m-1, dissolved organic carbon approximate to 6-10 mg L-1, and NO3--N approximate to 22-45 mg L-1. Bioreactors were highly efficient in reducing NO3--N. The average RNO3 in effluents was for the complete experimental period 8 g N m(-3) d(-1), 10.9 g N m(-3) d(-1), and 12.6 g N m(-3) d(-1) for 8, 16 and 24 h residence time, respectively. Nitrate reduction efficiency was modulated by seasonal changes in temperature, with an increasing efficiency in warmer periods (maximum approximate to 85-90% for all hydraulic residence time) and decreasing in colder ones (minimum approximate to 12%, 23% and 41% for hydraulic residence time 8, 16 and 24 h respectively). Woodchips degradation was greatest during the first six months (average approximate to 29% weight loss) in the material above the water level, attributable to aerobic mineralization of the organic carbon, while weight loss was approximate to 11% in woodchip media continuously below the water level. Dissolved organic carbon, sulfide, ammonium, and soluble phosphorus concentrations in the effluents were mostly low, although some peaks in concentrations occurred. Design consideration must be taken to avoid environmental impacts due to the occasional presence of harmful compounds in the effluents.

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Diaz-Garcia C. Martinez-Sanchez J.J. y Alvarez-Rogel J. Woodchip bioreactors for saline leachates denitrification can mitigate agricultural impacts in mediterranean areas: The Campo de Cartagena-Mar Menor environmental issue. Elsevier B.V., 2023. https://doi.org/10.1016/j.jenvman.2023.117292

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Resource type Article
Date of creation 2024-11-05
Date of last revision 2024-11-05
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Metadata identifier de7545bc-ef39-5ac8-89ac-2ee5701b607b
Metadata language Spanish
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High-value dataset category Earth observation and environment
ISO 19115 topic category biota
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Name of the dataset creator Diaz-Garcia, C., Martinez-Sanchez, J.J. y Alvarez-Rogel, J.
Name of the dataset editor Elsevier B.V.
Other identifier DOI: 10.1016/j.jenvman.2023.117292
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Email of the dataset creator cdiazg@illinois.edu
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