Evaluation of the Performance of an Activated Sludge Bioreactor for the Sulfide Removal in the Presence of Nanoparticles: Kinetic Study and Respirometry Test

In this project, experimental investigations were performed to measure the bio-kinetic parameters of the sulfide removal using an activated sludge bioreactor (ASBR) in the presence of nanoparticles. For this aim, silica nanoparticles (NPs) and exfoliated graphene oxide (GO) nanosheets were synthesized and characterized using FTIR, XRD, and TEM analysis. Then, three types of bioreactor systems, including activated sludge without nanoparticles (AS), in the presence of SiO2 NPs, and GO nanosheets, were utilized for different ranges of sulfide concentrations. The variation of pH values in the ASBR systems was investigated during the kinetic experiments. Respirometry tests were employed to calculate the maximum yield factor (Y) and endogenous decay coefficient (kd) in Monod’s model and the maximum cell growth rate during the sulfide removal. Moreover, different kinetic models, including Monod, first-order, second-order, Moser, and Contois, were compared. The values of the R2 coefficient (0.992, 0.927, and 0.976 for AS, SiO2, and GO bioreactor systems, respectively) showed that the Monod model was appropriately fitted with the experimental data, and the SiO2 sample had the best condition for both sulfide removal and biomass growth and GO sample had the worst performance.