Removal of trivalent chromium in tannery wastewater by biotic-abiotic process based on Yarrowia lipolytica and Candida fluvialisis

Tanneries are recognized for generating highly polluting toxic wastes, including chromium, a metal that receives great attention due to the negative effects on biota and humans. Despite the existence of different physical and chemical methods for its treatment, these are not well received due to the high costs and complexity of the technologies. In order to evaluate the removal capacity of trivalent chromium with microorganisms from wastewater from leather tanning, acidophilic, chromium-resistant microorganisms were isolated in culture media prepared from the salts required for the tanning process. Subsequently, two native yeasts were selected, by their greater abundance, identified as Yarrowia lipolytica and Candida fluviatilis, which were used together to inoculate the batch type biotreatments, which consisted of Erlenmeyer flasks, packed with sand of 2.5 to 6 mm thick, containing tanning water at a concentration of 1021 mg Cr (III) / L, chemical, physical and biological controls were included. After 21 days of incubation, 97.5 % of the chromium was removed in the biotreatments, with an increase in pH. This research demonstrated the importance of the interaction of biotic and abiotic factors to enhance the removal of chromium in acid waters from tanneries. The results are novel for the treatment of tanning effluents, reducing the concentration of trivalent chromium by a biological method that in turn increases the pH, reaching permissible values and taking advantage of the own biodiversity of these effluents, benefits that make possible their later utility on a larger scale.