The application of advanced oxidation process (AOP) in the treatment of wastewater contaminated with oil was investigated in this study. The AOP investigated is the homogeneous photo-Fenton (UV/H2O2/Fe(+2)) process. The reaction is influenced by the input concentration of hydrogen peroxide H2O2, amount of the iron catalyst Fe(+2), pH, temperature, irradiation time, and concentration of oil in the wastewater. The removal efficiency for the used system at the optimal operational parameters (H2O2 = 400 mg/L, Fe(+2) = 40 mg/L, pH = 3, irradiation time = 150 min, and temperature = 30 °C) for 1,000 mg/L oil load was found to be 72%. The study examined the implementation of artificial neural network (ANN) for the prediction and simulation of oil degradation in aqueous solution by photo-Fenton process. The multilayered feed-forward networks were trained by using a backpropagation algorithm; a three-layer network with 22 neurons in the hidden layer gave optimal results. The results show that the ANN model can predict the experimental results with high correlation coefficient (R (2) = 0.9949). The sensitivity analysis showed that all studied variables (H2O2, Fe(+2), pH, irradiation time, temperature, and oil concentration) have strong effect on the oil degradation. The pH was found to be the most influential parameter with relative importance of 20.6%.
The bioremediation of 2,4‐dichlorophenoxyacetic acid (2,4‐D) contaminated soil was studied in a roller slurry bioreactor operated under aerobic conditions. The performance of the roller slurry bioreactor was tested for different concentrations of 2,4‐D in sandy loam soil (200, 300, and 500 mg/kg soil). Sewage sludge was used as an inexpensive source of microorganisms which is available in large quantities in wastewater treatment plants. The results show that all biodegradation experiments demonstrated a significant decrease in 2,4‐D concentrations. Removal efficiencies of 100, 99, and 97% for the initial concentrations of 200, 300, and 500 mg 2,4‐D/kg of soil were obtained after ten days, respectively. Abiotic conditions (reactor without microorganisms) were also performed to investigate the desorption efficiency of contaminants from soil to liquid phase. Different amendments as the surfactants sodium dodecyl sulfate, rhamnolipid and glass beads (with 10% load) were used in the roller slurry bioreactor to reduce the incubation time and to enhance the bioremediation efficiency. The results show that there was no reduction in the incubation time and no significant enhancement in the degradation efficiency of 2,4‐D in soil for these amendments.
The solar photocatalytic degradation of diuron, which is one of the herbicides, has been studied by a solar pilot plant in heterogeneous solar photocatalysis with titanium dioxide. The pilot plant was made up of compound parabolic collectors specially designed for solar photocatalytic applications. The influence of different variables such as, H2O2 initial concentration, TiO2 initial concentration, and diuron initial concentration with their relationship to the degradation efficiency were studied. Hydrogen peroxide (H2O2) found to increase the rate of diuron degradation. The best removal efficiency of heterogeneous solar photocatalytic TiO2 system was found to be 46.65 % and for heterogeneous solar photocatalytic TiO2/ H2O2 system was found to be 80.65 %. Based on these results, the solar photocatalytic degradation by TiO2/ H2O2 system could be a useful technology for the treatment of effluents containing diuron.
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