The use of bacteria-attached polysulfone nanofibers in the treatment of wastewater containing Cr(VI) and reactive dyes

In this thesis, Clavibacter michiganensis (GQ466171) bacteria that has high bioremediation ability were attached to polysulfone nanofiber (PSU-Nf) and the Cr(VI) and Reactive Blue (RB) removal efficiency of the produced nanobiocomposite material was determined. In the first stage of the study, the maximum number of bacteria attached to Nfs produced in random (diameter: 954.07 ± 222.86 nm) and aligned morphology (diameter: 784.01 ± 174.61 nm) and Cr(VI) removal efficiencies were determined. Accordingly, the Cr(VI) removal efficiency for PSU-Nf mats in random morphology was %89.66 ± 0.17, while it was %87.93 ± 0.17 for PSU-Nf in aligned morphology. As a result, Nfs produced in random morphology were selected for the production of bionanocomposite materials. The incubation time required for maximum bacteria to attach to the nanofiber was determined as 4 days (2.54×106 CFU/mL). In the next stage of the study, bioremoval studies were carried out in an environment containing 20 ppm pollutants in order to determine the optimum conditions. The optimum conditions for Cr(VI) were found to be pH 8, 24 hours of contact time, 23 °C of temperature and 100 rpm of agitation rate, and therefore the highest Cr(VI) removal was determined as %94.15 ± 0.2. The optimum conditions for RB were found to be pH 8, 15 hours of contact time, 30 °C of temperature, 100 rpm of agitation rate, and the highest removal efficiency was determined as %100. After the optimization conditions had been determined, removal studies were carried out with bacteria-attached PSU-Nf napkins and, as a result, the Cr(VI) removal efficiency was %96.79 ± 0.2; the RB removal efficiency was found to be %100 after 13 hours of contact time. The reusability of bacteria-attached nanofibers is an economically important factor. For this reason, the reusability properties of bacteria-attached PSU-Nfs were determined up to 5 cycles. After the 5th cycle use of PSU-Nfs, the removal efficiency was calculated as %70.37 ± 0.34 for 10 ppm Cr(VI) and %51.85 ± 2.07 for 20 ppm RB. The results showed that the nanobiocomposite material continued to remove successfully even after the 5th cycle. In addition, bacteria-attached PSU-Nf mats were stored at 4 °C and 23 °C for up to 30 days and their post-storage removal efficiencies were tested. The results show the potential use of bacteria-attached PSU-Nf mats even after long-term storage in wastewater treatment has very high removal efficiency.