Potencial de descoloração e biodegradação de corantes azoicos alimentícios por células de bacillus sp. Es-1 imobilizadas em alginato de sódio.

Abstract

Dyes are widely used in many industries, such as food, textile, pulp and paper production and cosmetics. With the accelerated growth of the world population the production of industrialized food is continuous and ends up generating large volume of effluents that can cause serious pollution if released to the environment without proper treatment. In the food industry, azo dyes are commonly used and can remain in wastewater. To biodegrade these wastewater dyes can be used bioremediation by microorganisms, since it is considered a very advantageous remediation technology to recover ecosystems when compared to other technologies. In this sense, bacteria function as efficient and inexpensive biological agents to biodegrade these compounds. This study aimed to perform a bibliometric mapping on the bioremediation of azoic dyes by microbial cells immobilized in the Scopus, Web of Science and Science Direct and evaluate the potential of free and immobilized bacterial cells in sodium alginate in the degradation of azo dyes Amaranth and tartrazine. The microorganisms were isolated from a sample of effluent from a beverage industry located in the Rio Pardo Valley, Rio Grande do Sul. For the screening of bacteria the effluent was added to a nutrient medium plus tartrazine to 200 mg L-1 that was incubated under static conditions and stirred at 35 ºC for 96 h. From the media where the discoloration of tartrazine was observed, the bacteria present were isolated. Were isolated in pure culture 8 bacteria whose colonies showed distinct morphological characteristics. The bacterium identified as Bacillus sp. ES-1 and Amarante dye, which showed discoloration in less time, were selected for degradation studies with free microorganism cells and immobilized in sodium alginate. At 156 h of culture, the immobilized cells of the microorganism showed a discoloration rate of 86% at 150 h while the free cells had an efficiency of 81% at 144 h. The presence of phenol and indole in the analyzes by GC-MS indicated the partial biodegradation of the dye. In the analysis by FTIR were observed elevations in the amide band for both treatments indicating the bioreduction of the azo bond of the dye and a higher rate of discoloration by the free cells of the bacterium. It was concluded that the bacterium Bacillus sp. ES-1 showed good potential for discoloration and that the use of a hybrid process (free cells + immobilized cells) could be an effective, low cost and environmentally friendly approach for the removal of dye from industrial effluent.