PRODUCTION OF BACTERIAL NANOCELLULOSE FROM WASTE BREWER'S YEAST FOR ADSORPTION AND RECOVERY OF Cu(II), Fe(III), Ni(II) and Co(II) FROM MINING EFFLUENTS
bacterial nanocellulose;Gluconacetobacter hansenii;adsorption;optimization;mining
Brazil is one of the main producers and exporters of iron ore in the world, with a production of 358.0 million tons in the year 2021. Due to the large volume of production, there is, consequently, the generation of a large volume of liquid waste that needs be treated before being disposed of in the environment, as they have a high content of heavy metals. However, the treatments, hitherto known, are expensive and complex. An economical and environmentally viable alternative for the treatment of these residues is the use of bacterial nanocellulose as an adsorbent of the heavy metals present in the composition of the residues, due to its properties of biocompatibility and biodegradability. However, further studies are needed to increase production efficiency, changing fermentation parameters and evaluating the use of alternative substrates. The Brazilian brewing industry produces around 14.0 billion liters of beer a year and, with that, a large volume of nutritionally rich waste. With its high nutritional value, the residues are excellent substrate candidates for bacteria producing bacterial nanocellulose, adding value to them. Given this scenario, the present research project aims to (i) the static production of bacterial nanocellulose using the brewing industry waste as a substrate, (ii) the obtainment of an adsorbent composed of bacterial nanocellulose for the treatment of waste from the mining industry and (iii) recovery of heavy metals and iron oxide from mining industry effluents for reuse in industries. It was possible to obtain approximately 1532 mg of bacterial nanocellulose through the batch system. As an adsorbent, the material showed to be very promising, obtaining a maximum adsorption capacity for the metals Co (II), Ni (II) and Cu (II) of, respectively, 0.0739, 0.2504 and 0.3945 mg· g-1. For the same metals, the removal rate of the synthetic solutions studied was, respectively, 62.56, 39.13 and 61.64%