Characterization of effluents from a tannery industry: a case study of Córdoba province, Argentina

Tannery effluents are considered to be severe pollutants around the world. The characterization of such effluents is a very important task in order to verify the compliance with legal requirements of the discharge and, if necessary, to optimize their treatment. In this study, we used the effluents from a local tannery (Córdoba, Argentina) that had implemented only a primary treatment. The effluents were periodically collected during one year to assess their physical, chemical, and microbiological characteristics, as well as their toxicity. The physical and chemical characteristics showed variations independently of the sampling time, although, in general, a high nutrient load was the most frequent finding. Moreover, parameters such as chemical oxygen demand, biochemical oxygen demand, total nitrogen, total phosphate, total phenols, Cr(VI) and settleable solids exceeded the limit set by the provincial legislation for the discharge of effluents into surface water bodies. The effluents were also characterized by a high count of bacteria, where pollutant-tolerant and some pathogenic bacteria were found. In sampling 9, Bacteroidetes, Firmicutes and Proteobacteria represented up to 93 % of the total number of sequences obtained, with Paludibacter, Tissierella Soehngenia, Proteocatella and Proteiniclasticum as the most abundant genera. In concordance with these results, all samples showed toxicity according to L. sativa and AMPHITOX bioassays. Altogether, data from this report indicate the need to optimize primary treatment of the effluents, as well as to include complementary treatments in order to reduce the negative environmental impacts of the release of this kind of runoffs.