فهرست مطالب

  • Volume:6 Issue:3, 2019
  • تاریخ انتشار: 1398/05/10
  • تعداد عناوین: 8
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  • Amir Hossein Baghaie*, Forough Aghili Pages 151-156
    Background
    Soil pollution with heavy metals seriously threatens soil quality, food safety, and human health. This study was conducted to determine the soil pollution level and ecological risk assessment of different heavy metals in agricultural soils around Nakhlak Pb-Zn mine, located in Anarak district, Nain county of Isfahan province.
    Methods
    A total of 50 soil samples were collected from agricultural land around Nakhlak mine and analyzed to determine the concentrations of Pb, Cd, Zn, Ni, Cu, and Mn. The geo-accumulation index (I geo), enrichment factor (EF), and potential ecological-risk index (Er) were used to assess the level of soil pollution with heavy metals.
    Results
    The mean concentrations of Pb, Cd, Zn, Ni, Cu, and Mn were 355, 2.72, 347, 26, 36, and 505 mg/kg, respectively, which were higher than the background values of world soils. Based on the Igeo index, the study area was moderately to heavily contaminated with Pb and Zn, uncontaminated to moderate contaminated with Cd and Cu, and uncontaminated with Mn and Ni. According to the EF values, the study soil was moderately contaminated with Mn, Ni, and Cu, significantly contaminated with Cd and Zn, and highly enriched with Pb. The RI values showed a moderate level of heavy metals
    contamination in the study soil.
    Conclusion
    According to the results, the ecological risk of heavy metals for ecosystem in agricultural lands around Nakhlak Pb-Zn mine is moderate. However, the contamination status should be considered periodically.
    Keywords: Soil, Lead, Zinc, Risk assessment, Pollution
  • Amirreza Talaiekhozani*, Abbas Heydari Chaleshtori, Farhad Banisharif, Zeinab Eskandari, Mohammad Nasiri, Farham Aminsharei, Junboum Park, Shahabaldin Rezania, Maryam Bazrafshan Pages 157-170
    Background
    Industrial dyes are toxic and carcinogenic, therefore, they should be removed from wastewater. The aim of this study was to investigate the removal of acid orange 7 Dye from wastewater using ultraviolet (UV) radiation, MgO nanoparticles, ultrasonic method alone and in combination with each other.
    Methods
    The effects of some factors such as temperature, pH, hydraulic retention time (HRT), UV power, and concentration of MgO nanoparticles on the removal of Acid Orange 7 dye from synthetic wastewater using different methods were investigated. Also, adsorption isotherms for MgO nanoparticles and kinetics for UV radiation were investigated.
    Results
    The optimum HRT was 55 minutes while the temperature was not effective in dye removal using the ultrasonic method. Under optimum conditions for UV irradiation method (HRT = 70 minutes, UV power = 170 mW/cm2, and temperature = 10˚C), 58% of the dye was removed. However, under optimum conditions for MgO nanoparticles method (HRT = 15 minutes, temperature = 20˚C, and ratio of MgO nanoparticles to the initial dye concentration = 67.2), 82% of the dye was removed. By combining these methods, the dye removal efficiency was significantly increased. The combination of ultrasonic method and MgO nanoparticles had no significant effect on increasing the dye removal efficiency from wastewater. It was revealed that dye removal using UV radiation can be described by the first-order kinetics.
    Conclusion
    According to the results, UV radiation has a synergistic effect on the dye adsorption process by MgO nanoparticles. Therefore, the combination of these methods can be effective for the removal of dye from wastewater.
    Keywords: Azo compounds, Ultraviolet rays, Ultrasonic method, Nanoparticles, Waste water, Kinetics
  • Majid Askari Hesni*, Seyed Aliakbar Hedayati, Amir Qadermarzi, Mojtaba Pouladi, Somayeh Zangiabadi, Nabat Naqshbandi Pages 171-177
    Background
    Aquaculture wastewater contains high levels of phosphate and nitrate. The reuse of this water requires standards beyond the secondary standards to eliminate more organic pollutants from aquaculture effluents. In this research, the removal of these pollutants from wastewater using Chlorella vulgaris and Fe3O4 nanoparticles in the reactor space was investigated.
    Methods
    This study was conducted on fish farms effluent in the laboratory system. For this purpose, a 5-L semi-industrial reactor with a mixer blade, porous plate, and a compressor was designed. Chlorella vulgaris samples were collected from the natural environment and cultured in the laboratory environment. Also, Fe3O4 nanoparticles were prepared from Iranian Nano Pishgaman Company to make the desired solution. During the experiment (3 weeks), samples were taken weekly (in one phase) from the effluent. Dissolved oxygen (DO), pH, nitrate (NO3), and phosphate (PO4) factors from the influent and effluent of the farms were measured. The statistical data were analyzed using SPSS version 21 and Excel 2013.
    Results
    The amounts of nitrate and phosphate were decreased by about 80.76 and 80.55% in the biological reactor, whereas these amounts were 70.52 and 70.48% in the nanoparticle reactor, respectively. Also, there were significant differences in the amounts of NO3 and PO4 between the control treatment and weekly treatment (P < 0.05).
    Conclusion
    Based on the results, both reactors were able to reduce nitrate and phosphate from aquaculture wastewater, but the efficiency of the biological reactor was higher than that of the nanoparticle reactor.
    Keywords: Nitrate, Phosphate, Fe3O4 nanoparticle, Chlorella vulgaris, Biological refinement
  • Seyed Mostafa Aghili*, Nasser Mehrdadi, Behnoush Aminzadeh, Mohammad Ali Zazouli Pages 179-184
    Background
    One of the useful applications of Dewatered sludge (DWS) of municipal wastewater treatment plants (WWTPs) is its use as manure in agriculture; therefore, its quality characteristics should be specified. The aim of this research was to determine biological and physicochemical characteristics of DWS of Sari WWTP and compare them with standards, and also to investigate its potential use in agriculture.
    Methods
    Sludge samples were taken from the sewage sludge of Sari WWTP. Sampling and analysis of samples parameters including fecal coliform, salmonella, helminth ova, carbon, nitrogen, C/N, phosphorus, organic matter, potassium, moisture, electrical conductivity, and PH, were performed during four seasons with three replications based on the standard method.
    Results
    The fecal coliform, salmonella, and helminth ova of the DWS were 2.37×106 ± 1.06×106 MPN/1 g d.s weight, 47±12.92 MPN/4 g d.s weight, and 466±61.85 number/4 g d.s weight, respectively, therefore, the DWS of Sari WWTP was categorized in the class B of the EPA standard. The amounts of C/N, organic matter, carbon, nitrogen, phosphorus, potassium, moisture, electrical conductivity, and PH were obtained to be 12.7±1.15, 42.4±3.27%, 24.6±1.89%, 1.94±0.13%, 2.35±0.6%, 0.57±0.13%, 82±3.12%, 1.34±0.21 ds/m, and 7.41± 0.45, respectively.
    Conclusion
    The DWS of Sari WWTP has a good fertility value but it cannot be safely used in agriculture and should be improved for class A by the Processes to Further Reduce Pathogens (PFRP), especially by composting.
    Keywords: Sewage sludge, Agricultural use, Fertilizer, Pollution control, Dewatered sludge
  • Ali Abdul Rahman, Al Ezzi*, Salam H. Alhamdiny Pages 185-190
    Background
    Several important designs have been applied to remove toxic and hazardous organic substances like phenol and phenol compounds from wastewater, but there is a need to seek an alternative design to effectively remove organic pollutants from water to less hazardous compounds and a costeffective system.
    Methods
    A modified internal loop airlift reactor was designed to remove the organic pollutants in synthetic wastewater using an efficient and cost-effective treatment technique by means of a synergistic effect of combination oxidation, stripping, and adsorption. The influence of the current style was experimentally examined in the treatment of synthetic phenol contaminated wastewater. The practical device was tested under different airflow rates range (2-15 L/min) through gross difference retention period (5-60 minutes) at a various molar ratio of phenol to hydrogen peroxide ranging from 1:10 to 1:20.
    Results
    It was revealed that the preferred molar ratio of phenol to hydrogen peroxide equals to 1:20. Moreover, the airflow rate is 15 L/min with longer retention period of 60 minutes, indicating the maximum removal efficiency (89%) of phenol from the synthetic wastewater.
    Conclusion
    Successful removal of phenol from water by the removal efficiency of 89% boosts the success of the executed design as well as the scenario of conducting the synergistic processes (stripping, oxidation and adsorption) in one device and also increases the chances of solving environmental problems via treating wastewater before recycling and releasing it into natural water sources.
    Keywords: Waste water, Hydrogen peroxide, Oxidation, Stripping, Adsorption, Phenol
  • Md. Abu Rayhan Khan, Mosummath Hosna Ara*, Palash Kumar Dhar Pages 191-202
    Background
    Contamination of soil with heavy metals is an alarming issue around the world. Therefore, this study aimed to assess the contamination status of heavy metals in the soil of Mongla industrial area, Bangladesh.
    Methods
    Soil samples were randomly collected from 20 sites and digested by wet digestion method. The concentrations of heavy metals (Mn, Fe, Cu, Zn, Cd, and Pb) were determined using atomic absorption spectrophotometer (AAS). The quality of soil was assessed based on the contamination factor (CF),
    geoaccumulation index (Igeo), enrichment factor (EF), and ecological risk index factor (ERIF) analyses.
    Results
    The average concentrations of Mn, Fe, Cu, Zn, Cd, and Pb were obtained to be 258.08 ± 51.61, 3736.90 ± 322.17, 19.55 ± 6.49, 66.76 ± 18.32, 0.59 ± 0.13, and 10.40 ± 1.49 mg kg-1, respectively, which were below the permissible limit. The highest value of CF (0.74 ± 0.16), Igeo (0.35 ± 0.34), EF (24.86 ± 6.27), and PERIF (22.11 ± 4.81) was observed for Cd. The pollution of CF, Igeo, EF, and ERIF was classified as very severely polluted, unpolluted to moderately polluted, strongly to extremely polluted, and slightly polluted, respectively, with these heavy metals due to anthropogenic activities. One-way ANOVA indicated a significant difference between Zn and Cd concentrations (P < 0.05), whereas Pearson correlation showed a positive correlation between Zn-Pb (P = 0.01) and Fe-Zn (P = 0.05).
    Conclusion
    There are different classes of contamination with heavy metals in the study area. Therefore, necessary steps should be taken and people’s awareness of the soil pollution should be raised.
    Keywords: Soil pollution, Heavy metals, Contamination factor, Geoaccumulation index, Enrichment factor, Ecological risk index factor
  • Marzieh Bagheri*, Esmail Mardani Pages 203-213
    Background
    Today, due to increasing usage of dyes in various industrials and their destructive effects on health and environment, it is necessary to remove them from industrial wastes. Although there are few studies on the use of rice bran modified with polyaniline (RB/PANI) for removal of different dyes, but the effect of this adsorbent on the removal of Acid Orange 7 (AO7) dye has not been evaluated yet. Therefore, this study was conducted to investigate the removal of AO7 dye by RB/PANI as an adsorbent.
    Methods
    The adsorbent characteristics were determined using scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. Also, the adsorbent surface area was measured by Brunauer–Emmett–Teller (BET) technique. The method of one-factor-at-a-time was used to optimize various factors including pH, temperature, and adsorbent dosage.
    Results
    The optimal values for the factors affecting AO7 dye removal were calculated. It was revealed that the maximum dye removal was obtained at pH = 3, temperature = 25˚C, dye concentration = 30 mg/L, adsorbent dosage = 30 mg/L, and contact time= 60 minutes. The maximum removal percentage for RB/PANI was 97.13%. It was also revealed that Langmuir isotherm is the best fitted isotherm model.
    Conclusion
    According to the results, the polyaniline-modified rice bran could be used as an excellent adsorbent for the removal of AO7 from aqueous solutions. The maximum dye removal efficiency for AO7 was obtained at pH = 3. Also, it was revealed that AO7 dye removal follows the pseudo second order kinetic model and it is a spontaneous process.
    Keywords: Temperature, Adsorption, Coloring agents, Kinetics, Thermodynamics
  • Mohammad Mehdi Amin, Majid Hashemi, Karim Ebrahimpour, Afsane Chavoshani* Pages 215-224
    Background
    Due to the complexities involved in the extraction of micropollutants, the information regarding micropollutants like paraben in wastewater and sludge is scarce. The aim of this study was to adopt a microwave-assisted dispersive liquid-liquid micro-extraction (MADLLME) method for the
    extraction of parabens in municipal wastewater treatment plant (WWTP).
    Methods
    A mixed stock solution of methyl-, ethyl-, propyl-, and butyl-parabens with concentration of 10 mg/mL were prepared in methanol. To validate this method, the limit of detection (LOD), limit of quantification (LOQ), linearity, and m/z were measured. To adopt this method in different condition, the effect of pH (3, 7, 9, and 12), microwave power (180, 300, 450, and 600 W), solvent type (methanol, acetone, methanol/water, acetone/water), and 1 g folorisil were assessed. After adopting MADLLME method, the paraben fate of this WWTP was evaluated through mass loading and emission.
    Results
    The optimum performance of MADLLME method was observed at pH = 7, microwave power= 450 W, reaction time = 30 s, and methanol as the solvent. The total concentrations of four paraben metabolites in the WWTP ranged between 2505 ng/L in influent, 1953 ng/L in effluent, and 8.03 ng/g at wet weight sludge samples. The total mass loading and emission of four parabens in this WWTP was 0.672 mg/d/1000 people and 0.186 mg/d/1000 people, respectively.
    Conclusion
    MADLLME method seems to be an excellent alternative, as a green extraction technique, for determining various groups of emerging micropollutants in different matrices.
    Keywords: Paraben, Environment, Municipal sludge, Dispersive liquid-liquid micro-extraction, Microwave-assisted extraction