Removal of heavy metal ions from washing solutions by matrix structures of ferrobacteria

Because of anthropogenic loading, heavy metal ions (Zn, Cd, Cr, Cu, Ni, etc.) enter natural waters along with insufficiently treated industrial wastewater, vehicle washes, and rainwater - toxic carcinogens characterized by high biochemical activity, ability to migrate and complex. Existing methods of their removal are mainly based on physicochemical and baromembrane methods are quite expensive and difficult to operate. The development of biotechnology allows us to consider bacteria, fungi, yeast as a tool for removing these contaminants from natural waters and washing solutions of electroplating production. Currently, many genera of bacteria and fungi are known to be capable of removing heavy metal ions from solutions, in particular, microorganisms of the genera Aeromonas, Bacillus thuringiensis, Escherichia, Pseudomonas. Enterobacter, Thiobacillus ferrooxidans; мицелии грибів Aspergillus flavus, Aspergillus niger. The paper provides an analytical review of publications on this topic. Known mechanisms of accumulation of heavy metal ions by bacteria and mycelial fungi are described. The aim of the work is to investigate the possibility of removing Cr6+, Cu2+, Zn2+, and Ni2+ ions from washing solutions by matrix structures of ferrobacteria. The objects of research were aqueous solutions containing Cr6+ ions (0.8 mg/dm3) and washing solutions from the galvanic production workshop. The work presents the research methodology and pilot plant schemes. Matrix structures of ferrobacteria acted as the reagent-precipitant Gallionella та Lepthothrix. The possibility of removing Cr (VI) cations adsorbed by matrix structures of bacteria of the genera Gallionella and Lepthothrix from diluted solutions has been established. The kinetics of Cr6+ extraction by matrix structures at different concentrations per unit volume of the studied solution have been studied. It was established that the maximum cleaning effect was achieved at a sediment concentration of 200 mg/dm3, the lowest at a concentration of C=40 mg/dm3. The dependences of the cleaning efficiency of galvanic production washing waters from IVM (Cu2+ up to 16 mg/dm3, Zn2+ up to 50 mg/dm3, Ni2+ up to 1.3 mg/dm3) on the sediment of matrix structures of ferrobacteria were determined. It has been established that to remove IVM from washing waters, a stepwise introduction of a precipitating reagent with a dose of 300 mg/dm3 at each stage should be used. When using fresh ferrobacterial sediment as a precipitating reagent, biominerals, cells, and polymer matrix structures that have a crystalline structure and a large specific surface area take an active part in the adsorption process of heavy metal ions.