فهرست مطالب

Advances in Environmental Health Research - Volume:7 Issue: 4, 2019
  • Volume:7 Issue: 4, 2019
  • تاریخ انتشار: 1398/07/09
  • تعداد عناوین: 6
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  • Reza Shokoohi, Abdollah Dargahi, Ghobad Ahmadidoost *, Mohammad Jamil Moradi Pages 203-212
    The combination process of UV/ S2O82-/Al2O3 leads to the production of radicals and radical hydroxyls, which could decompose and remove various pollutants, such as phenol. The present study aimed to investigate the photocatalytic efficiency of aluminum oxide nanoparticles and persulfate compilative processes in the removal of phenol. This experimental study was conducted in a discontinuous reaction chamber with a useful volume of one liter. In this process, we assessed the effects of the initial pH parameters (3, 5, 7, and 9), initial concentration of phenol (10, 20, 30, 50, and 100 mg/l), concentration of persulfate anions (20, 30, 40, 50, and 60 mg/l), reaction time (5 and 120 minutes), and dose of Al2O3 nanoparticles (10, 20, 30, and 40 mg/l). The applied pilot was composed of a low-pressure mercury lamp (55 Watt), which was inside the steel chamber. The obtained data were fitted to the pseudo-first- and pseudo-second-order reaction kinetics. According to the findings, the process had high efficiency in the removal of phenol. In optimal conditions (pH:5, persulfate concentration: 50 mg/l, nanoparticle dose: 40 mg/l, reaction time: 60 minutes), the efficiency of the process was determined to be 95% at the initial phenol concentration of 10 mg/l, which was fitted with first-rate kinetics (R2=0.98). Furthermore, the highest efficiency was observed in the photocatalytic process of aluminum oxide nanoparticles and persulfates in the optimal conditions of exploitation. Therefore, persulfate could be used as an appropriate oxidizer with aluminum oxide nanoparticles for the removal of phenol.
    Keywords: Photocatalytic Process, aluminum oxide, Persulfateoxidation, Phenol, Aqueous solution
  • Ali Reza Zarei *, Ali Moloudi Pages 213-224
    In the present study, nickel and iron (Ni/Fe) bimetallic nanoparticles (Ni-Fe NPs) were produced in the presence of activated carbon (AC) to prepare supported Ni/Fe bimetallic nanoparticles (Ni-Fe NPs/AC). The NPs were modified using cetylpyridinium chloride and used for the simultaneous adsorption and degradation of perchlorate. Synthesized Ni-Fe NPs/AC was characterized using FE-SEM, EDS, and XRD. The influential factors in the removal of perchlorate by Ni-Fe NPs/AC were optimized based on experimental design. According to the results, adsorption and degradation efficiencies were 96.98% and 78.81%, respectively, which could be achieved to the efficiency of nearly 100% by increasing the process time to 110 minutes. Reaction kinetics complied with the pseudo-first-order characteristics. Moreover, the rate constant of adsorption and degradation were estimated at 0.0848 and 0.0199 min-1 at 303 K, and the activation energy for adsorption and degradation was 42.39 and 12.47 kJ/mol, respectively. The proposed method could effectively remove perchlorate from well water and industrial wastewater. Therefore, Ni-Fe NPs/AC could be an effective nanomaterial for the complete degradation of perchlorate. This novel method could also remove persistent organic and inorganic pollutants and promote the industrial application of bimetallic NPs in environmental remediation.
    Keywords: Perchlorate, Adsorption, Reductive degradation, Activated carbon, Ni, Fe bimetallic nanoparticles
  • Saeid Fallahizadeh, Marzieh Vaezzadeh *, Dariush Naghipour Pages 225-232
    Today, heavy metal contamination is a major environmental concern across the world. Some of the common heavy metal pollutants in industrial wastewater include lead, copper, cadmium, and nickel. This study aimed to compare the efficiency of duckweed in the removal of heavy metals from aqueous solutions in combined and separate forms. This applied, fundamental research was conducted based on empirical studies. Heavy metal solutions were prepared at the concentrations of 5, 10, and 25 mg/l, and duckweed (weight: 0.2, 0.4, 0.8, and 1.2 g) was added to the prepared solutions (100 ml). Plant weight in the combined solution was four times higher than the separate solution. After the contact time of five, 10, and 15 days, heavy metal residues in the solutions was measured using ICP-OES. According to the results, heavy metal removal from the separate solutions differed with the combined solutions. Both systems were compared in terms of the contact time, initial heavy metal concentration, and removal order. The obtained results indicated that the removal efficiency of heavy metals was higher in the combined solutions compared to the separate solutions. Increased initial concentration also reduced removal efficiency in the separate solutions, while the removal rate remained constant in the combined solutions. Moreover, the heavy metals in the combined solutions were removed within a shorter time. The removal sequence of the heavy metals from separate solutions was lead>cadmium>nickel>chromium at the maximum removal time. In the combined heavy metal solutions, such removal rate sequence was not observed.
    Keywords: Aqueous solutions, Duckweed, heavy metals
  • Fariba Mohsenzadeh *, Akram Ranjbar Pages 233-240
    Alpha-naphthol is a two-ring aromatic hydrocarbon with toxic and mutagenic properties. Bioremediation technology is considered to be an efficient, economical, and environmentally friendly approach to the remediation of the sites contaminated with polycyclic aromatic hydrocarbons. In this study, six fungal species of the Trichoderma genus were cultured in potato dextrose agar (PDA) media containing 10-200 mg/kg of α-naphthol for the adaptation of the fungal strains. The removal of α-naphthol was assessed 30 days after the growth of the adapted fungal colonies at various concentrations of α-naphthol (50, 100, and 150 mg/kg). According to the obtained results, all the fungi could grow in the culture media containing α-naphthol, removing α-naphthol from the media. The highest removal efficiency belonged to T. viridescens, while the lowest removal efficiency belonged to T. koningii. In addition, the growth ability of the fungi was determined based on the colony diameters, and the results indicated the highest and lowest colony diameters in case of T. koningii and T. viridescens, respectively. In other words, an inverse correlation was observed between the fungal growth rate and α-naphthol removal efficiency. On the other hand, the results of enzyme activity assay demonstrated that the activity of peroxidase and catalase increased with higher α-naphthol contamination. The highest enzyme activity was observed in T. viridescens, growing in the media containing 150 mg/kg of α-naphthol, which indicated a marked correlation between α-naphthol removal efficiency and enzyme activity. Therefore, it could be concluded that T. viridescens had the highest enzyme activity and α-naphthol removal efficiency.
    Keywords: α-Naphthol, Pollution, Trichoderma, Bioremediation, Enzymatic activity
  • Mohammad Reza Turkan, Saeid Saeidijam, Mahdi Reyahi Khoram * Pages 241-248
    The present study aimed to evaluate the treatment efficiency of the modified Ludzack-Ettinger (MLE) process using the conventional activated sludge (CAS) in Tafresh city, located in Iran during October-December 2016 (before upgrading) and October-December 2017 (after upgrading to the MLE process). The measured parameters in the study included chemical oxygen demand (COD), five-day biochemical oxygen demand (BOD5), nitrate-nitrogen, total suspended solids, phosphate, dissolved oxygen, ammonium-nitrogen, and pH. According to the obtained results, the treatment efficiency of the MLE process based on the BOD5 and COD was 92.11% and 91.20%, respectively. On the other hand, the treatment efficiency of the CAS process (before upgrading) based on the BOD5 and COD removal was 48.55% and 56.76%, respectively. Therefore, it could be concluded that the MLE process was able to successfully upgrade wastewater treatment services.
    Keywords: Activated sludge, Tafresh city, Treatment Plant, Wastewater
  • Rouhollah Shokri, Reza Jalilzadeh Yengejeh, Ali Akbar Babaei *, Ehsan Derikvand, Ali Almasi Pages 249-259
    Antibiotics are among the major concerns in terms of environmental control due to their cumulative properties, adverse health effects on humans, and development of drug resistance. The present study aimed to investigate the efficiency of the combination of UV/H2O2 and moving-bed biofilm reactor (MBBR) systems in the removal of azithromycin from aqueous solutions using the response surface methodology (RSM). In the UV/H2O2 process, a low-pressure mercury vapor lamp with the power of eight Watts, wavelength of 254 nanometers, and intensity of 1.02 mw/cm2 was used to determine the effects of pH, azithromycin concentration, hydrogen peroxide concentration, and contact time on the removal efficiency of azithromycin. According to the obtained results, the highest removal efficiency in the UV/H2O2 process was obtained with the azithromycin concentration of 2 mg/l. Therefore, 2 mg/l of azithromycin was selected as the optimal concentration with the highest removal efficiency. Following that, the optimal concentration of azithromycin was injected into the MBBR reactor. In the combined process of UV/H2O2 and MBBR, the highest removal efficiency of azithromycin was 91.2%. Therefore, it could be concluded that the combined system of UV/H2O2 and MBBR had the highest efficiency in the removal of azithromycin from aqueous solutions.
    Keywords: Advanced oxidation processes, Moving Bed Biofilm Reactor, Antibiotic Azithromycin, Response Surface Methodology