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

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. [ABSTRACT FROM AUTHOR]