IRANIAN JOURNAL OF HEALTH AND ENVIRONMENT
Year:2012 | Volume:5 | Issue:3 (17)|Papers Count:12

Background and Objectives: Electro-Fenton process has been widely applied for dye removal from aqueous solution lately. Fenton’s reagent is formed in the electrolysis medium through the simultaneous electrochemical reduction of O2 and Fe3+ to H2O2 and Fe2+ respectively on the cathode surface. In this paper, COD reduction potential and decolorization of real textile wastewater were evaluated by electrochemically generated Fenton reagent process. This wastewater mainly contains non-biodegradable acidic dyes, which are highly resistant against conventional oxidizing agents.Materials and Methods: Electro-Fenton process was carried out in an open and undivided cell in order to evaluate the removal of color and COD from real textile wastewater using graphite felt (cathode) and Pt plate (anode) at room temperature. The effects of current density, flow rate of air, electrolysis time, initial pH, and ferrous ion concentration were investigated for real textile wastewater.Results: The results showed that the optimal experimental conditions obtained in electrochemical studies were as follows: current density=4.8 mA cm-2, pH=3, flow rate of air=1.5 L/min, Fe2+=3mM and reaction time=160 min. Under these conditions, COD removal and decolorization achieved were 63% and 77.2% respectively.Conclusion: According to the results achieved, electro-Fenton process can be used as a pretreatment for degradation of colored wastewater and refractory pollutants. Moreover, this feasible technology improves biodegradability of the textile wastewater.

Background and Objectives: The presence of chemical dyes in the water resources not only pollutes them, but also brings about death of organisms and serious indemnities to the environment through stopping oxygen production and preventing penetration of the sunlight. In this study, we investigated the efficiency of the electrolysis process for decolonization of phenolphthalein and phenol red from aqueous environment.Materials and Methods: The experiments were conducted in an electrochemical reactor having a working volume of 1 liter equipped with 2 graphite electrodes. This study was conducted at laboratory scale. Samples were prepared by dissolving two phenol red and phenolphthalein dyes in drinking water. Then, the effect of operating parameters such as voltage, inter-electrode distance, and NaCl concentration on the complete dye removal was determined considering optimum retention time using Factorial variance analyses and the graphs were plotted using MS Excel software.Results: the results showed that the optimum conditions for completely removal of phenolphthalein was achieved applying a voltage of 48 V, the retention time of 9 minutes, 5 cm inter-electrode distance, and the salt concentration of 1.5 g/l, whereas, complete removal of phenol red was achieved applying a voltage of 48 V, the retention time of 8 minutes, 5 cm inter-electrode distance, and the salt concentration of 2 g/l. Under these conditions, COD removal efficiency for phenol red and phenolphthalein was 85 and 80 percent respectively.Conclusion: This study revealed that electrolysis process is an effective method to remove both phenolphthalein and phenol red dyes from effluent, because it can completely remove the dyes in a short time.

Background and Objectives: Intake of high concentrations of fluoride in drinking water can cause dental fluorosis. In this study, the prevalence of dental fluorosis in rural communities of East Azerbaijan Province was studied.Materials and Methods: 3 villages of Bashsizkooh, Bostanabad (fluoride concentration in drinking water=0.12 mg/L), Nagharehkub, Ahar (current water resource=0.6 mg/L, old water resource= 1.1-1.2 mg/L), and Gharehbolaq, Jolfa (current water resource=0.35 mg/L and old water resource=2.4 mg/L old source) were selected as low, medium, and high exposure to fluoride respectively.All village residents above 6 years old were visited by physician. Quality of water resources was determined by referring to the records archived and through conducting new analysis.Results: Dental fluorosis was observed in 62.7% of the people visited. In 31.5% of participants, fluorosis Grade 1; in 22.4 % of participants, fluorosis grade 2; in 7.7% of participants, fluorosis grade 3; and finally fluorosis grade 4 was observed in 4 patients. Different levels of fluorosis were observed in residents of the villages of Gharebolaq, Nagharehkub, and Bashsizkooh (83.3%, 70.5%, and 32.5% respectively). There was a significant difference in prevalence of fluorosis between villages (P<0.001). Fluorosis was observed in both permanent and temporary teeth. Mean cumulative fluoride index (MCFI) in people with and without fluorosis was 22660.2 and 4743.2 mg, respectively. There was a correlation between this index and fluorosis (R=0.413).Conclusion: In all three villages studied, even Bashsizkooh, different grades of fluorosis were endemic. It is recommended that the responsible authorities take a new measure and approach for the intake of fluoride from drinking water.

Background and Objectives: Electric and magnetic fields in the workplace are one of the detrimental factors of power plants, transmission lines, electrical wires, and electrical equipments, therefore, exposure to these fields might be harmful for human health. This study aimed to provide information about intensity of the electromagnetic fields at the high voltage electricity posts and its comparison with the threshold limit value (TLV).Materials and Methods: The study was conducted at one of the high voltage electricity post in Zanjan City having 63, 230, and 400 KV power transmission lines. After identifying stations and measuring the intensity of these fields, GIS maps were prepared and the values were compared with permissible values.Results: The measured magnetic flux density at different parts of the high voltage post showed that the lowest and highest intensity were 1.69 and 153.7 mG respectively which were lower than the ACGIH TLVs.The lowest and highest intensity of the electric field were 0.008 and 38.07 KV/m respectively. The highest value belonged to the 400 KV line, which exceeds the recommended ACGIH TLV (25 KV/m).Conclusion: According to the results, the magnetic field intensity was below the TLVs, but the intensity of electric field measured in the 400 KV line was greater than its TLVs. Thus, the strategies and recommendations for reducing exposure should be taken.

Background and Objectives: Legionella are gram-negative bacteria widely dispersed in natural and man-made water sources. Some Legionella species are pathogenic and could cause respiratory infections. Cultivation technique is the conventional method for the detection of Legionella spp. in aquatic samples. However, the method has low sensitivity and require prolonged incubation period.Therefore, Polymerase chain reaction (PCR) as a rapid method with extreme sensitivity is used. The present study was designed to evaluate the feasibility and sensitivity of PCR method for detection of Legionellas pp. in aquatic samples using three sets of primers.Materials and Methods: In this study, 60 water samples were investigated for the presence of Legionella species using Nested- PCR technique. The sensitivity of this technique was evaluated for the detection of Legionella species in aquatic samples using three primer sets, including (LEG225-LEG858), (LEG448-LEG858), and (LEG448-JRP).Results: The nested PCR assay revealed that detection percentage of Legionella in samples was 70 when LEG448-JRP primers were used, whereas this percentage reduced to 50 and 45 when we applied prime sets of LEG225-LEG858 and LEG448-LEG858, respectively.Conclusion: The results of the study showed that contamination of aquatic samples to the Legionella spp. could be easily and rapidly detected by nested PCR. However, selecting appropriate method for DNA extraction and choosing the primers are important factors in efficiency and sensitivity of detection method.

Background and Objectives: Slaughterhouse wastewater contains various and high amounts of organic matter (e.g., proteins, blood, fat, and lard). In order to produce an effluent suitable for stream discharge, chemical coagulation and electrocoagulation techniques have been particularly explored at the laboratory pilot scale for organic compounds removal from slaughterhouse effluent. The purpose of this work was to investigate the feasibility of treating cattle-slaughterhouse wastewater by combined chemical coagulation and electrocoagulation process to achieve the required standards.Materials and Methods: At present study, slaughterhouse wastewater after initial analysis was tested for survey of coagulation process using Poly aluminum chloride (PAC) at various doses (25-100 mg/L). Then we measured the concentrations of wastewater pollutants (BOD5, COD, TKN, TSS and fecal Coliforms). Later, we transferred the effluent to the electrocoagulation unit and we evaluated the removal efficiency of pollutants in the range 10 to 40 volts of electric potential during 60 min.Results: It was found that the efficiency of chemical coagulation process using poly-aluminum chloride (PAC) as coagulant increases with increasing doses (from 25 to 100 mg/L); we achieved maximum removal efficiency during the chemical coagulation for parameters of BOD5, COD, TSS, and TKN at 100 mg/L of PAC equivalent to 44.78%, 58.52%, 59.9%, and 39.58% respectively.Moreover, the results showed that with increasing the electric potential and reaction time, the yield increases linearly so that maximum removal efficiency at a dose of 100 mg/L PAC, an electrical potential of 40 volts and a reaction time of 60 minutes for the parameters BOD5, COD, TSS, and TKN was 99.18% 99.25%, 82.55%, and 93.97% respectively.Conclusion: The experiments demonstrated the effectiveness of combined chemical coagulation and electrocoagulation processes for pollutants removal from the slaughterhouse wastewaters.Consequently, this combined process can produce effluent compliance with the effluent discharge standards.

Background and Objective: The base structure of total petroleum hydrocarbons (TPH) is made of hydrogen and carbon. Widespread use, improper disposal and accidental spills of this compounds lead to long term remaining of contaminations such as organic solvents and poly aromatic hydrocarbons (PAHs) in the soil and groundwater resources, resulting in critical environmental issues. In this study, an oil-contaminated soil was washed using Tween 80 surfactant and the application of photo- Fenton process (UV/Fe2+/H2O2) for treatment of the produced wastewater was evaluated.Materials and Methods: Tween 80 is a yellow liquid with high viscosity and soluble in water. In order to determine of the photo-Fenton process efficiency, we studied effective variables including Fe concentration, pH, H2O2 concentration, and irradiation time. The UV irradiation source was a medium-pressure mercury vapor lamp (400 w) vertically immersed in the solution within 2 L volume glass cylindrical reactor.Results: The results showed that efficiency of COD removal depends on the initial Fe concentration, pH, H2O2 concentration and irradiation time.Under optimum conditions, (Fe: 0.1 mM, H2O2: 0.43 mM, pH: 3 and UV light irradiation time: 2 hours) the removal efficiency of COD was 67.3%. pH plays a crucial role in the photo-Fenton process such that the removal efficiency increased with decreasing of pH.Conclusion: According to the results of this study, under acidic condition, this process is an efficient method for COD removal from the wastewater studied.

Background and Objectives: Pollution of water resources to nitrate is an environmental problem in many parts of the world. This problem possibly causes diseases such as methemoglobinemia, lymphatic system cancer and Leukemia. Hence, nitrate control and removal from water resources is necessary. Considering that application of nanomaterials in treatment of environmental pollutants has become an interesting method, in this research use of Ag-doped TiO2 nanoparticles synthesized through photodeposition produced under UV irradiation was studied for removal of nitrate from aqueous solutions.Materials and Methods: Three nitrate concentrations of 20, 50, and 100 mg/L were considered. In order to determine the effect of Ag-doped TiO2 nanoparticles on nitrate removal, dosages of 0.1, 0.4, 0.8 and 1.2 g/L nanoparticles were used; pH range of 5-9 was also considered. The effect of Ag-doped TiO2 nanoparticles both in darkness and under UV irradiation was studied. Moreover, the presence of chloride and sulfate anions on the system removal efficiency was investigated.Results: The optimum performance of nitrate removal (95.5%) was obtained using nitrate concentration of 100 mg/L, in acidic pH and 0.8 g/L Ag-TiO2. Increase of nanoparticle dosage up to 0.8 g/L, increased the removal efficiency, but for 1.2 g/L dosage of nanoparticles, the removal efficiency decreased. Maximum reduction performance without nanoparticles, under UV irradiation and under darkness conditions were 32% and 23.3%, respectively. In addition, we found that presence of sulfate and chloride anions in aqueous solution reduced efficiency of nitrate removal.Conclusion: Results of this study showed that Ag-doped TiO2 nanoparticles may be efficiently used for nitrate removal from aqueous solutions.

Background and Objectives: Arsenic is one of the most toxically contaminants in groundwater and soils. Due to the ability of bio-accumulation of arsenic III in plants through irrigation with contaminated water and its entrance to the food chain, irreparable hazards would be caused. The aim of this research is the feasibility study of arsenic III removal from polluted water using calcium peroxide nanoparticles synthesized and also studying the effective parameters. Moreover, the adding effect of nanoparticles on the important parameters of irrigation would be assessed.Materials and Methods: In this research, we first synthesized CaO2 nanoparticles through chemical precipitation and then studied the arsenic removal efficiency from contaminated water samples.Nevertheless, the impact of the effective parameters including pH, initial arsenic III concentration, and CaO2 nanoparticles concentration were investigated. Finally, relevant results to nanoparticles effect on the important irrigation water quality parameters were presented.Results: Our results showed that synthesized particles were in the range of 25-50 nanometers.In addition, the efficiency of the CaO2 nanoparticles in arsenic III removal was 88 percent under following conditions: irrigation pH range 6.5-8.5, nanoparticles dosage 40 mg/L, arsenic initial concentration 400 mg/L, and 30 minuts retention time. Moreover, the nanoparticles synthesized did not have any undesirable impact on significant parameters in irrigation water.Conclusion: Generally, it can be concluded that CaO2 nanoparticles based on the in situ chemical oxidation had significant effect on the reduction of arsenic III until lower than recommended standards for irrigation water. High rate of process and relatively short reaction time, and having no negative effects on the significant parameters of irrigation indicate that CaO2 nanoparticles have significant potential in removal of arsenic III from contaminated water.

Background and Objectives: Along with the rapid development of human life, controlling harmful effects of microorganisms would be unavoidable. The objective of this study was to evaluate antibacterial efficacy of zinc oxide nanoparticles on different microbial strains.Material and Methods: This experimental study was done using gram negative and gram positive bacteria in nutrient media. Nanoparticle characterization was determined using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM). Bacterial sensitivity to nanoparticles was tested using a disk diffusion test and minimum inhibitory concentration (MIC).Time-kill studies and other tests were carried out using 108 CFU/mL of bacteria at baseline. A point of zero charge, pHzpc, of nanoparticle was investigated using the batch equilibration method.Obtained data were managed by SPSS Ver.16 and were analyzed through the Pearson, analysis of variance (ANOVA) and Student’s independent t-tests.0.05 was selected as significant level for all tests.Results: Characterization results from XRD, SEM, and TEM showed that particles are in nano range and they do not contain any discernible crystalline impurity. The average ZnO nanoparticles diameter was 20 nm. The pHZPC for ZnO was found to be 7.51. The P. aeruginosa strain exhibited larger diameter inhibition zone (DIZ) to ZnO nanoparticle compared with other strains. Population of P.aeroginosa for 2 x MIC concentration was reduced to zero in the presence of nano ZnO within 150 min. The bacterial CFU had significant difference with contact time, nanoparticles loading, and bacterial strain (P<0.001).Conclusion: This study demonstrated that antibacterial activity of ZnO can be a candidates for the elimination of gram negative and gram positive bacteria, particularly in nasocomial infection agent control.

Background and Objectives: Nitrate is one of the most groundwater pollutants in world. Reduction of nitrate to nitrite by microorganisms cause serious health hazards. Nitrate can be eliminated using either adsorbtion or reduction. In this study, we investigated the adsorption of nitate on zeolite and the feasibility of removal improvement using supported zero valent nano iron on zeolite via the reduction process.Materials and Methods: The study was done in two phases; investigation the zeolite and modified zeolite with zero valent nano iron in nitrate removal from water. First, we determined the optimum pH and time then the effect of adsorbent and nitrate concentration was investigated in one factor at the time. The adsorption isotherm was calculated according to the optimum condition. The physical characteristics of adsorbents were determined using SEM and TEM.Results: The morphology investigation of adsorbent showed that the particle size of supported zero valent nano iron on zeolite was approximately 30-50 nm in diameter. The best conditions were; pH 5, contact time of 120 min and 15 g/L for zeolite, while pH 3, contact time of 50 min and 7.5 g/L for supported zero valent nano iron on zeolite. The isotherm equations revealed that nitrate adsorption follows Langmiur in both cases.Conclusion: The supported zero valent nano iron on zeolite could be considered as a high potential adsorbent for nitrate because it has several adsorbent sites, and Fe0 as a function for nitrate reduction.

Background and Objectives: Background and objectives: Wind-induced particulate air pollution from iron ore pilescan causes environmental and economic problems for steel industries. In this experimental study, the effectiveness of various additives in reducing particulate air pollution from iron ore piles was investigated in a laboratory wind tunnel.Materials and Methods: The experimental set up consisted of a prismatic pile and a wind tunnel. Four different wind speeds of 4.3, 5, 7 and 11 m /s was used in the study Municipal water, quick lime (2%), seawater, treated industrial wastewater and Polylatice (0.25%) were used as additives to stabilize the upper layer of the pile.Results: Emission factors for non-stabilized (without additive) piles at 4.3, 5, 7 and 11 m/s wind speeds were 46.7, 73.2, 1025.4 and 13768.7 g/m2, respectively. Stabilized piles with 2.6, 2.7, 2.8, 2.7 and 2.8 percent additive (moisture content of the upper layer of the pile) for municipal water, Polylattice (0.25%), treated industrial wastewater, seawater and quick lime (2%) indicated a decrease of 99.4%, 100%, 99.3%, 99.5% and 99.5% particulate emission reduction, respectively.Conclusions: Proper selection and use of additives on iron piles has the potential for decreasing more than 99% of the wind-induced particulate emissions. Operational factors such as covered area, spray frequency, pile geometry, seasonal adjustments related to ambient temperature and humidity, wind speed and operator education need to be an integral part of the pollutant reduction program.