Showing 2 results for Biodenitrification
Atieh Ekrami , Lobat Taghavi, Behnam Rasekh , Fatemeh Yazdian,
Volume 13, Issue 50 (3-2023)
Abstract
Aim and Background: 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.
Materials and Methods: 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.
Results: 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.
Conclusion: 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.
Mohammadreza Ahmadiani Moghadam, Fatemeh Yazdiyan, Hamid Rashedi,
Volume 14, Issue 56 (9-2024)
Abstract
Aim and Background: The concentration of nitrate in natural surface waters from agricultural runoff is still a challenging problem in environmental chemistry. One of the promising strategies for denitrification is the use of photocatalysts whose light-centered excited states are able to reduce nitrate to nitrogen gas. The aim of this research is to optimize the nanophotocatalyst based on zinc oxide and titanium by response surface method (RSM) in order to investigate its role in biological denitrification.
Material and methods: The structural and morphological characteristics of the prepared nanophotocatalyst were determined by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and X-ray diffraction (XRD) . The photocatalytic effect of the prepared catalyst was investigated using nitrate solution and acid adsorbent at different concentrations. Two important operational parameters, including temperature (°C) and concentration of nanophotocatalyst carbon-quantum-date/oxygen/titanium dioxide (CQDs/ZnO/TiO2) which affect the denitrification of the bio-microorganism Thiobacillus denitrificans in the presence of nanophotocatalyst, were optimized by the response surface method (RSM). FTIR spectrum confirmed the formation of CQDs/ZnO/TiO2 bonds.
Results: The average diameter of CQDs/ZnO/TiO2 nanophotocatalyst was in the range of 29.31-38.32 nm. Denitrification in the presence of CQDs/ZnO/TiO2 was achieved by increasing the temperature (38.5˚C) and the nanophotocatalyst concentration (0.5 g/L) equal to 62.5%. After determining the optimal conditions, biological denitrification in the presence of nanophotocatalyst was investigated at different nitrate concentrations in the moving bed bioreactor. Based on the results, under batch conditions, the biological denitrification efficiency of Thiobacillus denitrificans in the presence of CQDs/ZnO/TiO2 nanophotocatalyst was equal to 82.1%, while in the bioreactor, the biological denitrification efficiency of microorganisms in the presence of CQDs/ZnO/TiO2 increased to 95%. In other words, the biological denitrification of microorganisms in the moving bed bioreactor was higher in the presence of CQDs/ZnO/TiO2.
Conclusion: According to the results of this study, the CQDs/ZnO/TiO2 nanophotocatalyst in the bioreactor showed higher efficiency in nitrate removal than the discontinuous system. Based on the results, the addition of Ti+4 and Zn+2 metal nanoparticles will enhance biological denitrification and be useful for the development of cost-effective pollutant removal processes.
