Catalytic Ozonation of Phenolic Wastewater: Identification and Toxicity of Intermediates

A new strategy in catalytic ozonation removal method for degradation and detoxification of phenol from industrial wastewater was investigated. Magnetic carbon nanocomposite, as a novel catalyst, was synthesized and then used in the catalytic ozonation process (COP) and the effects of operational conditions such as initial pH, reaction time, and initial concentration of phenol on the degradation efficiency and the toxicity assay have been investigated. The results showed that the highest catalytic potential was achieved at optimal neutral pH and the removal efficiency of phenol and COD is 98.5% and 69.8%, respectively. First-order modeling demonstrated that the reactions were dependent on the initial concentration of phenol, with kinetic constants varying from 0.038 min−1 ([phenol]o = 1500mg/L) to 1.273 min−1 ([phenol]o = 50mg/L). Bioassay analysis showed that phenol was highly toxic to Daphnia magna (LC50 96 h = 5.6mg/L). Comparison of toxicity units (TU) of row wastewater (36.01) and the treated effluent showed that TU value, after slightly increasing in the first steps of ozonation for construction of more toxic intermediates, severely reduced at the end of reaction (2.23).Thus, COP was able to effectively remove the toxicity of intermediates which were formed during the chemical oxidation of phenolic wastewaters

Degradation and toxicity reduction of phenol by ultrasound waves

The effects of parameters such as pH, kinetic constants and initial phenol concentration on the sonochemical degradation of phenol and toxicity assay were studied. The experimental results showed that lower pH and lower concentration of phenol favor the phenol degradation. But the rates of phenol degradation under sonication have always been quite low. It is found that the rate of ultrasonic degradation of phenol for initial concentration of 1 mg/L is 0.018 min-1 but later it reduces with increasing of phenol initial concentration substantially and the experimental data fitted well with pseudo first-order reaction rate equation. Bioassay tests showed that phenol was toxic to Daphnia magna and so resulted in quite low LC50 values. Comparison of toxicity units (TU) between phenol and effluent toxicity showed that the TU value for effluent was 1.21 times lower than that obtained for phenol solely. Thus, the toxicity of metabolites formed during the degradation of phenol is lower than the toxicity of phenol itself. KEY WORDS: Phenol, Ultrasound, Sonochemistry, Toxicity assay  Bull. Chem. Soc. Ethiop. 2007, 21(1), 33-38

Adsorption of Arsenic from Aqueous Solutions by Iron Filings and the Effect of Magnetic Field

Aims: Arsenic contamination of natural water resources has become an important environmental problem in the world. The adsorption method by iron filings adsorbent or zero-valent iron was used. The study aimed to evaluate the efficiency of iron filings in arsenite removal from polluted water and to investigate the effect of magnetic field on the process. Materials & Methods: This interventional study was conducted in synthetically polluted water samples with certain arsenic concentrations. With regard to the initial arsenic concentration (0.5 and 2mg/l), iron filings dosages (0, 2.5 and 5g/l), contact times (5, 10 and 15min) and considering the samples before and after magnetic column, 108 samples were prepared. Data was analyzed by paired sample T and one-way ANOVA tests. Findings: The highest mean of removal efficiency at the initial arsenic concentration of 0.5mg/l was seen at the iron filings of 5g/l and 10min contact time (87.7±10.0) and at the initial arsenic concentration of 2mg/l was seen at the iron filings of 5g/l and 15min contact time (86.3±8.4). At the initial arsenic concentration of 0.5mg/l, magnetic field increased the removal efficiency of arsenite at the iron filings dosage of 0g/l and decreased it at the iron filings dosage of 5g/l. The same happened at the initial arsenic concentration of 2mg/l. Conclusion: Arsenic is reduced from the water samples with the iron filings dosage of 5g/l at natural pH. Magnetic field increases the arsenic removal efficiency in the absence of the iron filings and decreases the arsenic removal efficiency in the presence of the iron filings

Application of novel Modified Biological Aerated Filter (MBAF) as a promising post-treatment for water reuse: Modification in configuration and backwashing process

Biological Aerated Filter (BAF) reactors due to their plentiful biomass, high shockability, high efficiency, good filtration, availability and lack of need for large land areas, are enjoying from great importance in advanced wastewater treatment. Therefore, in this study, Polystyrene Coated by Sand (PCS) was produced as a novel media and its application in a modified down-flow BAF structure for advanced wastewater treatment was assessed in two steps. In step one, the backwash effluent did not return to the system, while in step two backwash effluent returned to increase the water reuse efficiency. The backwash process was also studied through three methods of Top Backwashing (TB), Bottom Backwashing (BB), as well as Top and Bottom Backwashing Simultaneously (TBBS). The results showed that return of backwash effluent had no significant effect on the BAF effluent quality. In the second step similar to the first one with slight differences, the residual average concentrations of TSS, BOD5, and COD at the effluent were about 2.5, 8.2, and 25.5 mg/L, respectively. Additionally, in step two, the mean volume of disposal sludge/volume of treated water (v(ds)/v(tw)) decreased a large extent to about 0.088. In other words, the water reuse has increased to more than 99.91. The backwash time in methods of TB and BB were 65 and 35 min, respectively; however, it decreased in TBBS methods to 25 min. The concentrations of most effluent parameters in this system are in concordance with the 2012 EPA Agriculture Standards, even for irrigation of Non-processed agricultural crops and livestock water consumption. (C) 2017 Elsevier Ltd. All rights reserved

One-Pot synthesis, characterization and adsorption studies of amine-functionalized magnetite nanoparticles for removal of Cr (VI) and Ni (II) ions from aqueous solution: Kinetic, isotherm and thermodynamic studies

Background: Discharge of heavy metals such as hexavalent chromium (Cr (VI)) and nickel (Ni (II)) into aquatic ecosystems is a matter of concern in wastewater treatment due to their harmful effects on humans. In this paper, removal of Cr (VI) and Ni (II) ions from aqueous solution was investigated using an amino-functionalized magnetic Nano-adsorbent (Fe3O4-NH2). Methods: An amino-functionalized magnetic Nano-adsorbent (Fe3O4-NH2) was synthesized by compositing Fe3O4 with 1, 6-hexanediamine for removal of Cr (VI) and Ni (II) ions from aqueous solution. The adsorbent was characterized by Scanning Electron Microscope (SEM), Transmission Electron Microscopy (TEM), powder X-Ray Diffraction (XRD), and Vibrating Sample Magnetometry (VSM). Also, the effects of various operational parameters were studied. Results: According to our finding, Fe3O4-NH2 could be simply separated from aqueous solution with an external magnetic field at 30 s. The experimental data for the adsorption of Cr (VI) and Ni (II) ions revealed that the process followed the Langmuir isotherm and the maximum adsorption capacity was 232.51 mg g-1 for Cr (VI) at pH = 3 and 222.12 mg g-1 and for Ni(II) at pH = 6 at 298 °K. Besides, the kinetic data indicated that the results fitted with the pseudo-second-order model (R2: 0.9871 and 0.9947 for Cr (VI) and Ni (II), respectively. The results of thermodynamic study indicated that: standard free energy changes (�G�), standard enthalpy change (�H�), and standard entropy change (�S�) were respectively -3.28, 137.1, and 26.91 kJ mol-1 for Cr (VI) and -6.8433, 116.7, and 31.02 kJ mol-1 for Ni (II). The adsorption/desorption cycles of Fe3O4-NH2 indicated that it could be used for five times. Conclusions: The selected metals' sorption was achieved mainly via electrostatic attraction and coordination interactions. In fact, Fe3O4-NH2 could be removed more than 96 for both Cr (VI) and Ni (II) ions from aqueous solution and actual wastewater. © 2016 The Author(s)

Influence of bioaugmentation on biodegradation of phenanthrene-contaminated soil by earthworm in lab scale

Background: Use of earthworm to eliminate the phenanthrene from the soil (bioaccumulation) is developed as an economical method. Bioaugmentation of microorganism was used for promotion of bioaccumulation by earthworm. The aim of this study was to determine the bioaccumulation or biodegradation of phenanthrene by Eisenia fetida and bacterial consortium in polluted soil. Methods: The amount of 0.4 kg of the polluted soil in the ratio of 10 and 30 mg phenanthrene per kg of dry soil was transferred into each pot. Afterwards, bacteria and earthworms were added to each pot in separate and combination. The samples were kept under field conditions, and the retention concentrations of phenanthrene were analyzed after 8 weeks. Results: Results showed that the Eisenia fetida was able to significantly remove phenanthrene from the polluted soil samples. Bioaccumulation and bioaugmentation alone have the removal efficiency of 60.24 and 50.3, respectively. In the combined mode, phenanthrene removal efficiency was 63.81. Conclusions: The current study indicated that the use of earthworms, could improve both phenanthrene bioavailability and microbial activity, which led to enhancing removal of carbon-based pollutants. ©2014 Asgharnia et al

TVOCs and BTEX concentrations in the air of south pars special economic energy zone

cold season were higher than those in warm season. High concentrations of Benzene in cold and warm seasons were used to identify areas of high exposure risk.survey TVOCs and BTEX in the air of South Pars Special Economic Energy Zone in 2014. Materials and methods: In a cross-sectional study sampling and analysis was done by NIOSH 1501 method. The study was carried out in 336 activated carbon tubes and personal sampling pump in 6 sampling stations during one year. The compounds were extracted by solvent carbon disulfide and analyzed using Gas Chromatography- Flame Ionization Detector (GC-FID). Data analysis was performed in SPSS Ver.18 applying Kruskal-Wallis, Fligner test and ANOVA. Results: The mean concentrations of TVOCs and TBTEX were 229.34 and 31.23 µg/m3 in cold season and 212.19 and 29.89 µg/m3 in warm season, respectively. The mean concentrations of Benzene in all stations were 11.72 µg/m3 which were higher than the threshold levels recommended by Iranian Clean Air Act and US Environmental Protection Agency (USEPA). The ANOVA results showed a significant difference between the concentration of pollutants and hour, month and sampling stations (P<0.05), but no significant difference was found between the concentration of pollutants and seasons (P>0.05). Conclusion: The concentrations of measured pollutants in cold season were higher than those in warm season. High concentrations of Benzene in cold and warm seasons were used to identify areas of high exposure risk. © 2016, AMazandaran University of Medical Sciences. All rights reserved

A comparative study of the disinfection efficacy of H<inf>2</inf>O<inf>2</inf>/ferrate and UV/H<inf>2</inf>O<inf>2</inf>/ferrate processes on inactivation of Bacillus subtilis spores by response surface methodology for modeling and optimization

Abstract Although chlorination can inactivate most of the microorganisms in water but protozoan parasites like C. parvum oocysts and Giardia cysts can resist against it. Therefore, many researches have been conducted to find a novel method for water disinfection. Present study evaluated the synergistic effect of H2O2 and ferrate followed by UV radiation to inactivate Bacillus subtilis spores as surrogate microorganisms. Response surface methodology(RSM) was employed for the optimization for UV/H2O2/ferrate and H2O2/ferrate processes. By using central composite design(CCD), the effect of three main parameters including time, hydrogen peroxide, and ferrate concentrations was examined on process performance. The results showed that the combination of UV, H2O2 and ferrate was the most effective disinfection process in compare with when H2O2 and ferrate were used. This study indicated that by UV/H2O2/ferrate, about 5.2 log reductions of B. subtilis spores was inactivated at 9299 mg/l of H2O2 and 0.4 mg/l of ferrate concentrations after 57 min of contact time which was the optimum condition, but H2O2/ferrate can inactivate B. subtilis spores about 4.7 logs compare to the other process. Therefore, the results of this research demonstrated that UV/H2O2 /ferrate process is a promising process for spore inactivation and water disinfection. Keywords Disinfection Bacillus subtilis spores UV radiation/ H2O2 /ferrate Response surface methodology (RSM) Central composite design (CCD

A comparative study of the disinfection efficacy of H2O2/ferrate and UV/H2O2/ferrate processes on inactivation of Bacillus subtilis spores by response surface methodology for modeling and optimization

Although chlorination can inactivate most of the microorganisms in water but protozoan parasites like C. parvum oocysts and Giardia cysts can resist against it. Therefore, many researches have been conducted to find a novel method for water disinfection. Present study evaluated the synergistic effect of H2O2 and ferrate followed by UV radiation to inactivate Bacillus subtilis spores as surrogate microorganisms. Response surface methodology(RSM) was employed for the optimization for UV/H2O2/ferrate and H2O2/ferrate processes. By using central composite design(CCD), the effect of three main parameters including time, hydrogen peroxide, and ferrate concentrations was examined on process performance. The results showed that the combination of UV, H2O2 and ferrate was the most effective disinfection process in compare with when H2O2 and ferrate were used. This study indicated that by UV/H2O2/ferrate, about 5.2 log reductions of B. subtilis spores was inactivated at 9299 mg/l of H2O2 and 0.4 mg/l of ferrate concentrations after 57 min of contact time which was the optimum condition, but H2O2/ferrate can inactivate B. subtilis spores about 4.7 logs compare to the other process. Therefore, the results of this research demonstrated that UV/H2O2 /ferrate process is a promising process for spore inactivation and water disinfection. © 2018 Elsevier Lt