Pilot study of biobeds application for the remediation of citrus agro-industrial wastewaters

ABSTRACT

Agro-industrial wastewaters from citrus packaging plants are a significant source of pollution. Looking for a solution, lab-scale biobeds were evaluated for the remediation of fungicides from citrus agro-industry wastewaters. They were constructed under controlled conditions, using an ‘in-house’ designed bio-mixture containing soil, peat and cereal bran (1:1:2). The degradation of imazalil, prochloraz, propiconazole and pyrimethanil was studied individually, as a mixture and in real wastewater from a citric packing house facility. The pesticide behaviour was assessed using a novel validated dispersive sample preparation. The extraction was performed with ethylacetate and a salting out step with sodium tetraborate. The clean-up was performed with MgSO₄ and Al₂O₃. The instrumental determination was carried out by LC-MS/MS in MRM acquisition mode. When studied separately, all the pesticides were dissipated. Particularly, propiconazole showed a 90% concentration reduction after 60 days. Two metabolites of prochloraz of environmental concern: 2,4,6-trichlorophenol and N-formil-N’-propil-N’-2(2,4,6 trichlorophenoxy) ethyl urea were detected, and their chemical structures were confirmed through mass spectrometry experiments. The bio-mixture was also efficient in dissipating the four pesticides when applied together in a single biobed. Real wastewaters from a citric agro-industry containing pyrimethanil and imazalil were tested using the same conditions. Both compounds dissipated 50% and 79% respectively, within 70 days.

KEYWORDS:

• Citrus
• postharvest fungicides
• agro-industrial wastewater
• biobeds

Acknowledgments

The Join Centre FAO/IAEA/RALACA for the purchasing of the Standards. The authors are grateful to Citrícola Salteña and San Miguel Citrus Company for the kindness to provide the effluents for the study and ENZUR S.A to provide the pesticide commercial formulates. Dra.S.Niell for the general revision of the English language.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

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Additional information

Funding

This work was supported by the National Agency for Investigation and Innovation under Grant [ANII-FMV-2016-1-125537]. The authors are thankfully to PEDECIBA Química for the research support to SR, RH, VC, HH and NB.