Applying job hazard analysis and William Fine methods on risks identification and assessment of jobs in hot rolling steel, Iran

Background and purpose: Comprehensive evaluation of jobs in industries is a practical and effective method that could identify the jobs and industries with negative effects on the environment. This study identified environmental hazards of hot rolling process and assessing their risks. Materials and methods: An observational study was carried out in which identification of human activity and job’s risks in production hall of Kavir Steel Complex was done according to ISO 14001 approaches (pollutant emissions to air, discharges to water, energy consumption, energy released as heat, wastes, side products, etc) by Job Hazard Analysis method (JHA). Then the risks identified were prioritized and assessed using William Fine method. Results: We identified 205 environmental hazards (in 9 groups) associated with production personnel (n= 81), mechanics and maintenance personnel (n= 44), bed personnel (n= 9), personnel of cleaning services (n= 33), and water plant personnel (n= 38). The highest and lowest rate of risks were due to creation and distribution of wastes (n= 73) and corrosion and depreciation of equipment, (n= 1), respectively. Conclusion: The production personnel were mainly responsible for environmental emissions. The leading causes were stress and anxiety about stoppage of production, payment reduction, and lack of awareness and workers and supervisors on environmental issues. © 2017, Mazandaran University of Medical Sciences. All rights reserved

Optimization of photochemical decomposition acetamiprid pesticide from aqueous solutions and effluent toxicity assessment by Pseudomonas aeruginosa BCRC using response surface methodology

Contamination of water resources by acetamiprid pesticide is considered one of the main environmental problems. The aim of this study was the optimization of acetamiprid removal from aqueous solutions by TiO2/Fe3O4/SiO2 nanocomposite using the response surface methodology (RSM) with toxicity assessment by Pseudomonas aeruginosa BCRC. To obtain the optimum condition for acetamiprid degradation using RSM and central composite design (CCD). The magnetic TiO2/Fe3O4/SiO2 nanocomposite was synthesized using co-precipitation and sol�gel methods. The surface morphology of the nanocomposite and magnetic properties of the as-synthesized Fe3O4 nanoparticles were characterised by scanning electron microscope and vibrating sample magnetometer, respectively. In this study, toxicity assessment tests have been carried out by determining the activity of dehydrogenase enzyme reducing Resazurin (RR) and colony forming unit (CFU) methods. According to CCD, quadratic optimal model with R2 = 0.99 was used. By analysis of variance, the most effective values of each factor were determined in each experiment. According to the results, the most optimal conditions for removal efficiency of acetamiprid (pH = 7.5, contact time = 65 min, and dose of nanoparticle 550 mg/L) was obtained at 76.55. Effect concentration (EC50) for RR and CFU test were 1.950 and 2.050 mg/L, respectively. Based on the results obtained from the model, predicted response values showed high congruence with actual response values. And, the model was suitable for the experiment�s design conditions. © 2017, The Author(s)

Optimization of photochemical decomposition acetamiprid pesticide from aqueous solutions and effluent toxicity assessment by Pseudomonas aeruginosa BCRC using response surface methodology

Contamination of water resources by acetamiprid pesticide is considered one of the main environmental problems. The aim of this study was the optimization of acetamiprid removal from aqueous solutions by TiO2/Fe3O4/SiO2 nanocomposite using the response surface methodology (RSM) with toxicity assessment by Pseudomonas aeruginosa BCRC. To obtain the optimum condition for acetamiprid degradation using RSM and central composite design (CCD). The magnetic TiO2/Fe3O4/SiO2 nanocomposite was synthesized using co-precipitation and sol�gel methods. The surface morphology of the nanocomposite and magnetic properties of the as-synthesized Fe3O4 nanoparticles were characterised by scanning electron microscope and vibrating sample magnetometer, respectively. In this study, toxicity assessment tests have been carried out by determining the activity of dehydrogenase enzyme reducing Resazurin (RR) and colony forming unit (CFU) methods. According to CCD, quadratic optimal model with R2 = 0.99 was used. By analysis of variance, the most effective values of each factor were determined in each experiment. According to the results, the most optimal conditions for removal efficiency of acetamiprid (pH = 7.5, contact time = 65 min, and dose of nanoparticle 550 mg/L) was obtained at 76.55. Effect concentration (EC50) for RR and CFU test were 1.950 and 2.050 mg/L, respectively. Based on the results obtained from the model, predicted response values showed high congruence with actual response values. And, the model was suitable for the experiment�s design conditions. © 2017, The Author(s)

Equilibrium And Kinetics Study Of Reactive Red 123 Dye Removal From Aqueous Solution By Adsorption On Eggshell

The aim of this study was to determine the equilibrium and kinetics adsorption of reactive red 123 dye (RR 123) from aqueous solution with chicken’s eggshell as an adsorbent. The initial concentrations of reactive red 123 dye were selected in the range of 25 and 50 mg/L. The target adsorbent was prepared in laboratory conditions and pulverized by ASTM standard sieves. Measurement of the adsorbent surface area was carried out via Brunauer-Emmett-Teller isotherm. The experimental data were analyzed with Langmuir, Freundlich and Temkin isotherm models. The results showed that the calcium components were the main constituents of eggshell (around 95% Ca). The experimental adsorption isotherm was in good concordance with Langmuir and Freundlich models (R2>0.90) and based on the Langmuir isotherm the maximum amount of adsorption (qmax) was 1.26 mg/g. Increase of the eggshell dose and the solution temperature beyond 45ºC led to decrease of the adsorbed dye per mass unit of the adsorbent, but increase of the solution pH up to 9 led to the improvement of dye adsorption. The kinetic studies revealed that the adsorption of reactive red 123 was rapid and complied with pseudo-second order kinetic (R2= 0.99), with the kinetic constant of 0.02 g/mg.min

Mineralization of mefenamic acid from hospital wastewater using electro-Fenton degradation: Optimization and identification of removal mechanism issues

Mefenamic acid (MFA) is a nonsteroidal anti-inflammatory drug widely used for the short-term treatment of mild to moderate pain as well as treatment of primary dysmenorrhea and for decreasing the pain and blood loss during menstrual periods. Since MFA has been detected in raw and sewage water worldwide, the current work deals with the optimizing of removal of MFA from hospital wastewater using the electro-Fenton (E-Fenton) process. A cylindrical Pyrex reactor containing 250 ml of wastewater was employed for treatment investigation. The effects of main variables on the removal process were investigated and the optimum experimental condition was obtained with adequate desirability under the response surface methodology. The obtained results revealed that the removal efficiency of 95.3 was achieved under the optimal experimental condition, including MFA initial concentration of 7.0 mg L�1, the H2O2 dosage of 700 μl/L, the current density of 6.6 mA cm�2, and the reaction time of 12 min. The removal mechanism studies showed that �OH as the dominant radical species plays the main role in E-Fenton process. The MFA removal followed the pseudo-first-order kinetic model. Under the optimum condition of the E-Fenton process, the removal efficiency of MFA from synthetic wastewater was in satisfactory agreement with the real hospital wastewater treatment. © 2019 American Institute of Chemical Engineer

Application of iron impregnated activated carbon for removal of arsenic from water

The presence of arsenic in drinking water is one of the greatest threats to public health. The aim of this experimental investigation was to study the removal efficiency ofAs(v) from water by application of iron-impregnated activated carbon(Fe-AC). Coating of activated carbon with iron salt was carried out by impregnation method and thermo-chemical reactions with using of 100 mM FeCl 3 solution. The Fe-AC was pulverized using ASTM standard sieves with the range of 16-20 mesh. The solid structure and surface characteristics of Fe-AC were determined using conventional techniques. Batch adsorption experiments were carried out with 300 and 600μg/L arsenate. Langmuir, Freundlich and Dubinin-Radushkevich models were used to describe the isotherm and energy of adsorption. The results of this study showed that 2.5 h contact time was enough to achieve the equilibrium. The adsorption of As(v) had a good compliance with Langmuir model (R 2 = 0.995 ) and the maximum adsorption capacity was obtained as 0.024 mg/g. The results of kinetic studies showed that As(v) adsorption on Fe-AC may be limited by film diffusion step (m=0.26). The mean free energy of adsorption (E) calculated from Dubinin-Radushkevich isotherm was found to be 1.52 kj/mol which implies that the adsorption of As(v) on Fe-AC is a physical adsorption. The results indicated that Fe-AC is one of the suitable adsorbents which can be used for the treatment of arsenic contaminated waters

Electro-Fenton approach for highly efficient degradation of the herbicide 2,4-dichlorophenoxyacetic acid from agricultural wastewater: Process optimization, kinetic and mechanism

2,4-Dichlorophenoxyacetic acid (2,4-DPAA) as a commonly used herbicide in agricultural farms causes severe contamination of groundwater and surface water. Herein, a treatment process based on the electro-Fenton (EF) technique was developed for efficient removal of 2,4-DPAA from agricultural wastewater. Response surface methodology (RSM) was employed to optimize the operation conditions and modeling the developed process. The best removal efficiency of 99.2 was achieved at solution pH of 3, initial 2,4-DPAA concentration of 2.6 mg L�1, H2O2 dosage of 470 µL L�1, the current density of 3.5 mA cm�2, and reaction time of 7.5 min, which is in good accordance with the predicted removal efficiency of 98.6 by the model. The developed process was applied successfully for removal of 2,4-DPAA from agricultural wastewater with the actual removal efficiency of 93.7. The values of coefficients of determination (R2), predicted R2 and adjusted R2 were found to be 0.9775, 0.9268, and 0.9690, respectively. Analysis of variance (ANOVA) was conducted to evaluate the competence of the developed model. The obtained high F-value of 114.14 and the very low P-value of <0.0001 confirm that the model is highly significant. The electrical energy consumption was found to be 0.058 kWh.m�3. Employing the radical scavengers and the control experiments based on electrocoagulation and the Fenton process, the main mechanism for 2,4-DPAA degradation is revealed by the in-situ generation of hydroxyl radical throughout the EF treatment process. The kinetic of the developed model followed a pseudo-first-order reaction with a rate constant of 0.4746 min�1. © 2021 Elsevier B.V

Treatment of Synthetic Wastewater Containing Reactive Blue 19 by Electrolysis Process

Background: Disposal of untreated wastewater in the textile industries to environmental according to toxic pollutants, organic matter and available colors in them for human and other creatures' health is harmful. On the other, wastewater treatment conventional methods of textile industry are often extensive and lack of the desired performance. In this research was investigated efficiency of electrolysis process by graphitic electrode for the removal of reactive blue 19 dye from synthetic wastewater. Materials and Methods: For performance of test has used from a reactor made of Plexiglas with 3 liter capacity which was equipped with two graphite electrodes. The effect of operational parameters such as voltage, initial dye concentration and total dissolved solids (TDS) rate, was investigated. Dye concentration in samples was determined by spectrophotometer UV-Visible in 592 nm wavelength. Results: According to obtained results in optimum conditions (Voltage 24V, initial dye concentration 10 mg/L, TDS 3500 mg/L and time 2 min) Removal efficiency was equal to 98.6%. The results were indicative decreasing of removal efficiency with increasing of dye concentration and decreasing of voltage. Conclusion: Electrolysis process using from graphite electrode is efficient method for removal of reactive blue 19 dye from textile industries dye wastewater

Application of Solar Irradiation / K2S2O8 Photochemical Oxidation Process for the Removal of Reactive Blue 19 Dye fromAqueous Solutions

"n "n "nBackgroundandObjectives: Dyes are organic compoundswith complex structures,which due to toxicity, carcinogenicity and nonbiodegredabity, this type of pollutants is one of the most important pollutants of the environment. The goal of this researchwas to study the feasibility of the application of solar irradiation in presence of potassium persulfate (K2S2O8) for the removal of Reactive blue19 (RB19) from synthetic wastewater."nMaterials andMethods: This researchwas carried out in laboratory scalewith using of 200ml volume of batchphotoreactor.The effectsofoperatingparameters suchas concentrationofK2S2O8,pH,photoexposure time and preliminary concentrations of dye on decolorization have been evaluated.Different concentrations of pollutant inwastewaterwere prepared by solution of variousmasses of RB19 on tapwater. The reactors were exposedwith natural solar irradiation as aUVAsource from11 amto 14 pm.Themaximumabsorbtion wave length of this dye (!max) was determined by spectrophotometer (Unico, 2100). The measurement of dye concentrations was determined with using of standard curve and its best line equation"nResults:Analysis of absorbtion spectra showed that the !max of RB19 is 592 nm. The average intensity of the UVA irradiated from solar system was 54.6 µW/Cm2. The results of decolorization process showed that 38.2%of this dye can be removed within 3 hr in the presence of potassium persulfate and decreasing of pH leads to the elevation of dye removal efficiency. Based on these findings, the efficiency of dye removal with 3h photoexposure time and pH ranges of 4,6 and 8 were found to be 98.2 88.5 and 78.5%, respectively.Also, the results showed that increasing of K2S2O8 dosage leads to elevation of dye removal efficiency in 3h photoexposure time and K2S2O8 dosages within 1-5mmol/L, with the removal efficiency of 75,86,92,95 and 98.5%, respectively.Analysis of data indicates that the kinetic of the removal of RB19 with this process is a first order reaction which its rate constant is 0.01min-1."nConclusion: Due to the operation problems presented in heterogeneous photocatalitical processes such as catalysts separation and high costs of operation and maintenance of these processes caused by manmade sources of irradiations; homogeneous photocatalitical process with using of potassium persulfate associated with natural solar irradiation can be used as a suitable process for the removal of dyes from textile industries wastewaters

Removal Of Methylene Blue Dye From Textile Simulated Sample Using Tubular Reactor And TiO2/Uv-C Photocatalytic Process

In this study, photocatalytic degradation of methylene blue was examined using different concentrations of TiO2 nano-particles (diameters less than 21 nm) and ultraviolet (UV-C) radiation in a tubular reactor. Different concentrations of catalyst (0.3-1.2 g/L), different pH conditions (3, 7 and 9) and dye concentration (15, 30 and 60 mg/L) as well as sample rotation level (125 mL/min) were studied. The sample passed 1-7 times through the quartz reactor exposed to UV-C ray (constant intensity = 2.8 mW/cm2) (every rotation time was 8 min). Results of this research showed clearly that methylene blue is significantly degradable by TiO2 and UV-C radiation. Increasing dye concentration resulted in decreased efficiency and thus, as more samples passed through quarts tube, removal efficiency increased. Methylene blue with concentration of 15 mg/L and after 7 rotations in the reactor (56 min) was removed with the efficiency of 98%. Subsequent to dye removal, 47% of initial COD decreased simultaneously