Abstract

GONZALEZ-SUAREZ, Aimeé; PEREDA-REYES, Ileana; OLIVA-MERENCIO, Deny  and  MONTALVO-MARTINEZ, Silvio Jacinto. Speciation of iron, nickel and cobalt in the anaerobic biodegradation of rice straw. Rev.fac.ing.univ. Antioquia [online]. 2021, n.101, pp.55-63.  Epub Sep 16, 2021. ISSN 0120-6230.  https://doi.org/10.17533/udea.redin.20200366.

The bioavailability of Fe, Ni and Co and its impact on the mono-digestion of rice straw with addition of a natural nutrient source were assessed. The chemical forms and the degree of bioavailability of Fe, Ni and Co were investigated in two reactors during 311 days of experimentation at 37°C. The reactor (R2) was supplemented with 1 g/L of mineral once a week. The control reactor R1 was limited in mineral during the study. The greatest methane yield of 238 mL/g VS was obtained with mineral supply with an increment of 45% respect to reactor without metals (164 mL/g VS). The sequential extraction confirmed that 70, 88 and 75% of Fe, Ni and Co were mainly in bioavailable forms (interchangeable and carbonate), respectively, with mineral supply in R2. Fe and Co were mainly associated to the carbonate and oxidizable fractions (43% and 41% respectively), while the Ni concentrations were not detected during the experimentation. As a result, the methane yield in R2 increased by 45%, with a potential bioavailability (Ni ˃ Co ˃ Fe) higher compared to control reactor (Co ˃ Fe). Trace elements deficit in R1 result in the reduction of metal-binding forms until the end of experiment, with a negative impact on methanogenic community.

Keywords : Biogas; metals; mineral; productivity; waste treatment.

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