Optimization of Biodenitrification Using Aluminum and Calcium Based Graphene Nanostructures in Bioreactor

 The problem of water pollution is a fundamental and influential issue for the healthy life of humans and bioorganisms. The aim of this study is to optimize aluminum and calcium-based graphene nanostructures by response surface methodology (RSM) in order to investigate their role in biodenitrification. The optimized removal conditions in the bioreactor were investigated.

 Characterization of graphene oxide/aluminum (rGO/Al) and graphene oxide/calcium (rGO/Ca) nanostructures was determined by XRD, SEM and FTIR. The two effective operating parameters of temperature (°C) and concentration (g/L) of rGO/Al and rGO/Ca nanostructures in biodenitrification of Thiobacillus denitrificans microorganism in the presence of nanostructures were optimized by RSM. Chromotropic Acid method was used to measure nitrate.

 The FTIR spectrum confirmed the interaction between RGO-aluminum and rGO/Ca. By SEM analysis, the average diameters of rGO/Al and rGO/Ca nanostructures were observed in the range of 10.24-39.21 nm and 20.86-34.29 nm, respectively. In the presence of rGO/Ca and rGO/Al, with increasing temperature (35°C) and increasing nanostructured concentration (1g/L), removal was achieved for 74.0985% and 77.6905%, respectively. After determining the optimized conditions, the biodenitrification of the microorganism in the presence of nanostructures was investigated in the bioreactor. According to the results, the microorganisms in the presence of rGO/Ca and rGO/Al nanostructures had 74.0985% and 77.6905% biodenitrification, respectively.

 The percentage of biodegradation in the presence of rGO/Al was higher than rGO/Ca and in the presence of rGO/Al was 98%, so this nanostructure in the bioreactor showed higher efficiency in nitrate removal.