| dc.description.abstract | Background: Antibiotics are among resistant organic compounds and commonly,
cannot be eliminated by conventional wastewater treatment processes. Then,
concentrations are often found at nano to micro grams per liter in water resources.
In recent years, use of advanced oxidation processes for decomposition and
mineralization of resistant organic compounds have attracted the attention of many
researchers. One of them is the catalytic ozonation process. The use of catalysts
eliminates the major problems of the single ozonation process, such as low
solubility and stability of ozone in water and slow reaction with some organic
compounds. In addition, catalysts such as iron shavings and activated carbon have
advantages such as availability, high stability and reusability. Therefore, the main
objective of this study was to investigate the performance of catalytic ozonation
using iron shavings and activated carbon/iron shavings as catalyst in removal of
sulfamethoxazole from effluent of biological treatment system.
Material and Methods: In order to conduct this research municipal wastewater
treatment plant effluent of Gharamalek, Tabriz was used as the reaction
environment. After passing the effluent samples through a 0.45 μm filter, a specific
concentration of SMX (1, 3, 5 and 20 mg/l) was spiked to the samples. The effect
of pH (3, 7 and 10) was also evaluated at reaction times of one to 60 minutes.
Process efficiencies, effects of tert-butanol, COD and the amount of sediment
formed by the catalytic ozonation process were investigated for all pHs, in the range
of one to 60 minutes. The effects of matrix, TOC, LC-MS/MS, soluble ozone and
off-gas were measured at neutral pH for one to 60 minutes. Finally, the
experimental data were analyzed using SPSS software (IBM SPSS Statistics 19,
SPSS Inc., USA).
Results: The results showed that the efficiency of ozonation process in removal of
SMX at any pH was higher than that of the catalytic ozonation by iron shavings.151
The TOC removal efficiency was also not significantly different between the two
processes after 60 minutes of reaction (p>0.05). However, the rate of COD removal
in the catalytic process was higher than that of ozonation and the concentration of
COD reached from 122 to 11 mg/l at the end of the reaction. The amount of iron
precipitation mud in catalytic ozonation by iron shavings was also lower in alkaline
(3.1 mg) than in acidic (5.3 mg) and neutral pH (10.3 mg). The overall comparison
of the three processes studied also showed that the catalytic ozonation process by
iron shavings/activated carbon had the highest efficiency in the removal of SMX
(99.84% at 10 min), COD (96% at 60 min) and TOC (85% at 60 min).
Conclusion: The results showed that the mixture of iron shavings/ activated carbon
as a catalyst had better efficiency in SMX removal and mineralization. In addition,
although the efficiency of the catalytic ozonation by iron shavings in SMX removal
was lower than that of the single ozonation, nonetheless, using of iron shavings as
a low cost catalyst with increasing COD removal rate has environmental and
economic value in ozonation of wastewater containing organic resistant
compounds. | en_US |
