Potencial biotecnológico de bactérias na solubilização e adsorção do cobre em descarte eletroeletrônico (placas de circuito impresso).

Abstract

The recovery of electronic waste (WEEE) is linked to the fifteenth goal of the sustainable development goals (SDG) which aims to recover and promote the sustainable use of terrestrial ecosystems. One of the main components of waste electrical and electronic equipment is the printed circuit board (PCB)-(Motherboard) which has valuable metals in its composition that can be recovered including copper. In this context, the aim of the present study was to investigate the bioleaching potential of bacteria in the recovery of copper in disposal of Printed Circuit Boards (PCBs). For that, four bacteria were used (Bacillus subtilis UCP 1594, Pseudomonas fluorescens UCP 1514, Geobacillus stearothermophilus UCP 1520 and Pantoae agglomerans UCP 1581). Initially, bacteria were acclimatized in PCBs ground into small particles and then transferred to AN medium (nutrient agar) with 0.02g, 0.08g and 0.1g.L of PCBs ground. Then, the acclimatized bacteria were submitted to the bioleaching process. The bioleaching process took place in T&K medium added to a 2 cm PCI, in addition to the 10% inoculum (107CFU/mL). The process took place under orbital stirring at 180rpm for 15 days at 37°C. The identification of the potential of bacteria in removing copper from PCBs was evaluated through electrical conductivity, atomic absorption, Scanning Electron Microscopy-(SEM) and Energy Dispersive Spectroscopy-(EDS). According to the results obtained, all bacteria grew in solid medium at the maximum concentration of PCIs tested (0.1g/L) with countless colonies. Furthermore, the maximum concentration (18.98 S/m, 17.58 S/m, 17.31 S/m and 17.98 S/m) of electrolytes in the bioleached solution occurred after 15 days of cultivation of Pseudomonas fluorescens, Geobacillus stearothermophilus, Bacillus subtilis and Pantoea agglomerans, respectively. In addition, from the results of the scanning electron microscopy - SEM it was possible to evidence the formation of corrosion pits by all strains studied. The bacterium Geobacillus stearotermophillus proved to be promising for extracting copper from WEEE with economic potential to stimulate the reuse and reinsertion of metallic copper in the production chain, contributing to the circular economy, sustainability and recycling of electronic waste. Pantoea agglomerans was able to promote the biotreatment of metallic copper, followed by the adsorption of 37.12% of copper by the biomass after 15 days of bioleaching process. Therefore, the bioprocess became a patent because it presents great economic and innovative potential and proposes the application for the technological invention of reuse and reinsertion of metallic copper in the production chain.