Iranian Journal of Health, Safety and Environment (IJHSE)
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Photocatalytic Removal of Methylbenzene Vapors by MnO2/Al2O3/Fe2O3 Nano composite
Get PDFMethyl benzene, which has carcinogenic effects, is a volatile organic compound that is widely used in various industries. Nano composites of Mno2/Al203/Fe203, which is a new photocatalyst, have not been applied to remove contaminants from air streams. Therefore, the aim of the present study was to investigate the photocatalytic removal of ethyl benzene by using this nano composite activated by visible light. Morphological characteristics of the synthesized Nano composite in a sol-gel method are determined through XRD, FTIR, and SEM. Through the photocatalyst process and by the use of visible light radiation, the synthesized Nano composite is used to degrade ethyl benzene in the gas phase. In order to estimate the main effects and interaction ones and to optimize the experiment numbers, the response surface method was used. Operational parameters investigated in the study are the initial concentration of contaminants, relative humidity, and the residence time, which were considered in three levels; further, the experiments were designed by Design Expert version 9 software. The results show the Nano composite particle sizes were less than 82 nanometers. The findings also indicate that relative humidity and residence time were effective parameters in removal efficiency of ethyl benzene. This Nano composite, at the optimal conditions, was capable of removing 98.72% of the pollutants, with an initial content of 300 ppm. MnO2/Al2O3/Fe2O3 Nano composite is a suitable catalyst to remove ethyl benzene from air streams. Among the features of the Nano composite are reaction at room temperature and lower production dangerous byproducts, which are the main advantages of this Nano composite as compared with other nano composites
Comparing of Four Ergonomic Risk Assessment Methods of HAL-TLV, Strain Index, OCRA Checklist, and ART for Repetitive Work Tasks
Get PDFThis study is aimed to compare the results obtained from four risk assessment methods, videlicet HAL-TLV, Strain index, OCRA checklist, and ART. These musculoskeletal disorders assessment tools are generally used in the studies as well as in the field of occupational health. In this study, the data was collected via assessments of 30 tasks by 9 raters in poultry slaughter, assembly, and container production industries using four methods of upper limb musculoskeletal disorder risk assessment. In order to determine the level of agreement between the risk assessment methods, the Spearman's rank correlation coefficient and Cohen's weighted kappa were used, according to which the highest agreement and correlation were found between ART and OCRA checklist methods, while the HAL-TLV and OCRA checklist exhibited the lowest agreement and correlation. The difference between the risk classification results of the studied methods could be due to the difference of definitions of the risk variables; therefore, selecting the assessment tools for assessing the task risks in the working environment must be in accordance with the assessment objectives and complexity of the work tasks
Removal of Remazol Black B Dye by Electrocoagulation Process Coupled with Bentonite as an Aid Coagulant and Natural Adsorbent
Get PDFColoured discharge effluent into aquatic ecosystems may be carcinogenic and mutagenic besides aesthetic problems. In this work, the ability to remove (Remazol Black B) coloured water using electrocoagulation process is equipped with iron and aluminium electrodes with bentonite as a coagulant aid and natural adsorbent has been investigated. Remazol Black B was selected as a model dye and the treatment process was performed in a batch of electrocoagulation (EC) cell using iron and aluminium electrodes and bentonite. Experiments were conducted at 5 levels of various operational parameters at bench scale. The initial dye concentration was varied between 200-1200mg/L, pH ranging from 2-10; the retention time was between 0-60 minutes, the voltage studied was in the range of 5-30 V and the electrical conductivity was 0.25 to 2 Siemens/cm. Results showed that the use of electro-Aluminum and Iron, under optimum conditions of pH 2 and 4, the concentration of dye1000mg/L, the voltage of 30V and 30 min have the maximum dye removal of about 99% and 91%, respectively. Results showed that both electrode voltages increase the efficiency of the above process in paint removal with decreasing pH from 10 to 2 and increasing the voltage from 5 to 30 V. Results show that by electrocoagulation Process Coupled with Bentonite as an Aid Coagulant could be used as well as an effective method for dye removal from colored wastewater
Using the Absorptive-Dissipative Silencer in Air Conditioning Systems of an Office Environment in Order to Provide Acoustic Comfort
Get PDFAir conditioning systems are the main source of background low frequency noise in administrative buildings, restaurants, classrooms, and hotels. There are different ways to reduce the low frequency noise. Silencers are generic tools which are utilized for controlling noise produced by air conditioning systems. Sound assessment and frequency analysis were performed in accordance with standard methods to evaluate the exposure of workers in separate work stations. In the next step, an absorptive- dissipative silencer which its inner side was covered by convoluted acoustical foam was implemented in the ventilation system. The exposure of employees was re-evaluated. Moreover, Preferred Noise Criterion (PNC) and Speech Interference Level (SIL) were two acoustic indices used for assessing the effectiveness of the silencer. Before implementing the silencer, the sound pressure level in the rooms was between 57.8 and 61.1dBA with a peak frequency at 125Hz. The implemented silencer with dimensions of 1.4 ×1×1m, and inlet and outlet area of 0.45×0.45m was able to reduce the sound pressure level of about 13 to 14.2dB. Further, the PNC and the SIL indices were reduced to 14.33 and 15.31dB, respectively. The implemented absorptive- dissipative silencer reduced the sound pressure level of about 13.6dBA. Moreover, PNC and SIL indices are two important indices which can be used for assessing the level of comfort in office buildings
Evaluation of Exposure to BTEX in Hookah Smokers and Carcinogenic and Non- Carcinogenic Risk Assessment
Get PDFTo investigate the demographic characteristics, concentration of Benzene, Toluene, Ethyl benzene and Xylenes (BTEX) in output smoke and health risk assessment in hookah smokers in hookah cafés, Iran. We checked hookah cafés in the different parts of Hamadan city and analyzed location and social station of each cafés in 2016. Finally, 20 cafés selected and five samples on each cafés (total of 100 samples). BTEX compounds were sampled in output smoke from mouth smokers using charcoal and analyzed by GC- MS according to NIOSH1501 method. The quantitative risk assessment of exposure to BTEX as recommended by the United State Environmental Protection Agency method was used. The smokers' demographic characteristics collected using a self-designed questionnaire. The average concentrations of benzene, toluene, ethyl benzene, o, m-Xylene and p- Xylene were 6.45, 7.02, 10.07, 7.21 and 8.36 mg/m3, respectively. The mean cancer risk for benzene was estimated as 529 × 10-5 and mean non-carcinogenic risks for toluene, ethyl benzene and o, m-Xylene and p–Xylene (TEXs) were 17.57, 5.03, 24.03 and 27.88, respectively. Hookah smoking is prevalent among youths and smokers are exposed to benzene level higher than the threshold limit value recommended by ACGIH. Cancer risk for benzene and non-carcinogenic risk for TEXs were much higher than recommended limits. Thus, in order to prevent diseases stemming from hookah smoking, urgent and increased notification about its adverse health effects and intensified regulatory laws are needed to decrease hookah smoking in hookah cafés
Human Injuries Risk Assessment of Medium Voltage Electrocution using Bow Tie Model in Fuzzy Environment (Case Study: Golestan Province Electricity Distribution Company)
Get PDFIndividuals involved in development, repair and maintenance activities of power transmission and distribution are at high risk of electrocution. The purpose of this research is to calculate the human injuries risk of medium voltage electrocution accidents using Bow Tie model in fuzzy environment. Therefore, existing evidences and documents was investigated, and accident causes was determined using the FTA technique. Then, their outcomes were identified by using ETA and William Fine method, and Bow Tie diagrams were drawn based on the results. After that, because of inadequate data, the fuzzy logic was used to calculate the probability of the root causes and outcomes of the accident. The probability of the middle causes and top event was also calculated by probabilistic equations. The results showed that in terms of frequency, medium voltage electrocution accident with probability of 2.2E-4 is one of the significant accidents in the electricity distribution activities, as well as the outcome of "permanent total disability or death of one person" and "with no injury", are the maximum and minimum outcome of the mentioned accident with the probability of 2.1E-6 and 1.29E-10, respectively. These outcomes with the risk of 1.05E-8 and 1.29E-10 are also considered as highest and lowest risk, respectively. "Permanent total disability or death of one person" is the most important outcome of medium voltage electrocution accident, in terms of both frequency and risk. "Lack of installing earth system" and "absence of double insulation" are the most important root causes of accidents. Finally, the results of this research can facilitate financial and human resources planning, and also, the use of Bow Tie in the fuzzy environment can resolve risk assessment problem greatly in the uncertainty and lack of inadequate data
Anionic Surfactant Removal Using Electrochemical Process: Effect of Electrode Materials and Energy Consumption
Get PDFThe aim of this study was the investigation of electrochemical process for sodium dodecyl sulfate (SDS) removal from aqueous solutions using different electrode materials. The influence of operating parameters such as current density, solution initial pH, surfactant concentrations, retention time, supporting electrolyte concentrations, electrode materials (aluminum, titanium, galvanized steel, stainless steel) and electrical energy consumption were evaluated. The obtained results indicated that the stainless steel electrode was more efficient than other electrodes. Maximum SDS removal was obtained 94.98% at the optimum condition of initial pH 7.0, 60 min retention time, 3.125 mA/cm2 current density, 100 mg/L initial SDS concentration and 0.2 g/L NaCl concentration. The electrical energy consumption of stainless steel, aluminum, titanium and galvanized steel was achieved 4, 3.68, 12 and 4.48 KWh/m3, respectively. It was found that the electrochemical reaction using stainless steel plate electrodes was efficient in SDS removal from aquatic environments
Using the Fuzzy Grey Relational Analysis Method in Wastewater Treatment Process Selection
Get PDFDue to the variety of treatment processes, the decision to choose the best treatment process is difficult. This paper describes a fuzzy grey relational analysis (GRA) method for selection of the optimal wastewater treatment process. The rating of all alternatives and the weight of each criterion is described by linguistic variables, which can be expressed in triangular fuzzy numbers. Then, a vertex method is used to calculate the distance between two triangular fuzzy numbers. According to the concept of the GRA, a fuzzy relative relational degree is defined to determine the ranking order of all alternatives by calculating the degree of fuzzy grey relational coefficient to both the fuzzy positive ideal solution (FPIS) and fuzzy negative ideal solution (FNIS) simultaneously. Furthermore, a case study is carried out and solved by both methods (i.e., GRA and fuzzy GRA) to show the feasibility and effectiveness of the proposed method. In the case study, five anaerobic wastewater treatment alternatives are evaluated and compared against technical, economic, environmental and administrative criteria and their sub-criteria. Finally, the related results of ranking alternatives from two methods are compared with each other's. By using both Fuzzy GRA and GRA, ABR process has been selected as the first priority and the best anaerobic process. The frequency count assessment of the Iran's industrial parks' WWTPs which have used this method and their performance, proved the priority of this method
Health risk assessment of heavy metals in indoor dust from Bushehr, Iran
Get PDFEnvironmental contamination with heavy metals is one of the main concerns on a global scale and the risk related to exposure to heavy metals present in indoor dust is considered as a serious threat to human health. Therefore, the purpose of the current research was to evaluate the heavy metals concentrations in indoor dust and their potential risks in urban areas in Bushehr city, Iran. Fifty-four indoor dust samples were collected from different buildings including lab rooms, offices, school rooms and households within the Bushehr City, during May – July 2016 and analyzed using ICP-AES (Arcousmodel, Germany). The sum of hazard quotient (hazard quotient (HQs) for heavy metals for adults declined in the order of Cr > Cd > Cu >Ni > Zn > Pb for the household while the order of ΣHQ for trace metals for adults in offices is Cr > Cd > Ni >Cu > Zn > Pb. Moreover, the values ΣHQ for trace metals for children declined in the order of Cr > Cd > Zn > Ni > Cu > Pb for the schools while the order of ΣHQ for trace metals for children in households is Cd > Zn >Cu > Cd > Ni > Cr > Pb. For all heavy metals, the HQs was about an order of magnitude higher for children than for adults. These findings can be attributed to the more vulnerability of children to the toxic substances
Comparison of the Performance of AOP Method Using O3/H2O2 in the Presence of TiO2 and ZrO2 Nano Particles Stabilized on Pumice for the Removal of Pentachlorophenol from Aquatic Solution: Kinetic Studies
No full textPentachlorophenol is one of the resistant phenol compounds has classified in the group of the primary pollutants due to its high toxicity and carcinogenic potential. The aim of this study is determining the efficiency of advanced oxidation process method using O3/H2O2 in the presence of TiO2 and ZrO2 nano-particles stabilized on pumice for the removal of PCP from aquatic solutions. This experimental study was performed in a batch reactor at laboratory scale. In this study, the effects of reaction time, initial concentration of PCP, pH, concentration of catalysts and H2O2 and also the amount of decline in chemical oxygen demand (COD) after the process were investigated. The concentration of PCP in the sample was determined using spectrophotometer at wavelength of 500 nm and, in the end, the results were analyzed using SPSS software and according to repeated measures analysis and statistical test of comparative ordered pairs with confidence interval of 95%. Scanning electron microscope (SEM), fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD) images of modified pumice were taken and the kinetic degree of the processes was also determined. The results indicated that the PCP removal by the both processes increased with increasing reaction time, catalyst concentration, H2O2 concentration and pH and reduced with decreasing initial PCP concentration. The maximum removal efficiencies by the two processes: O3/nZrO2/H2O2 and O3/nTiO2/H2O2 were 100 and 95%, respectively, in the optimum conditions. The results illustrated that the two studied processes followed the pseudo-second -order kinetic model. Further, the findings revealed that the both processes mentioned in this study were of high capability in removing PCP and they could be used as an appropriate process in removing this organic material