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Polychlorinated Biphenyls (PCBs) are mutagenic, carcinogenic, and persistent organic pollutants of the marine and coastal environment. No previous research has precisely used barnacles as potential PCBs bioindicators in the Caspian sea. The present survey was done to add the PCBs concentrations amongst the barnacle and sediment samples collected from 5 important Iranian ports besides the Caspian sea. Barnacle and sediment samples were collected from Astara, Anzali, Caspian, Kiashahr, and Chamkhaleh ports. Samples were transferred to the laboratory and analyzed for the presence and concentration of PCBs using GC-MS. Eighty different types of PCB were detected in the examined samples. PCBs concentration ranged from 02.00±00.10 to 53.00±00.60 ng/g. PCB-77 (53.00±00.60 ng/g in Chamkhaleh, 53.00±01.20 ng/g in Caspian, 53.00±02.40 ng/g in Anzali, and 53.00±2.7 ng/g in Astara ports) had the highest concentration in barnacle samples. PCB-52 (53.00±00.70 ng/g in Chamkhaleh port) had the highest concentration in sediment samples. PCB-114 had the lowest concentration amongst the barnacle (02.00±00.10 ng/g in Astara port) and sediment (03.00±00.20 ng/g in Anzali port) samples. This study is the first report evaluating the presence and concentration of PCBs in barnacle in the Caspian Sea. The role of barnacles and sediments as biomonitors of PCBs was determined. It seems necessary to set strict rules to prevent pollutants from entering the Caspian Sea. [ABSTRACT FROM AUTHOR]

The ninth olefin plan of Arya Sasol Petrochemical Company (A.S.P.C.) is regarded the largest gas Olefin Unit located on Pars Special Economic Energy Zone (P.S.E.E.Z). Considering the importance of the petrochemical unit, its environmental assessment seems necessary to identify and reduce potential hazards. For this purpose, after determining the scope of the study area, identification and measurement of the environmental parameters, environmental risk assessment of the unit was carried out using Environment Failure Mode and Effect Analysis (EFMEA). Using the noted method, sources causing environmental risks were identified, rated and prioritized. Beside, the impacts of the environmental aspects derived from the unit activities as well as their consequences were also analyzed. Furthermore, the identified impacts were prioritized based on Risk Priority Number (RPN) and severity level of the consequences imposed on the affected environment. After performing statistical calculations, it was found that the environmental aspects owing the risk priority number higher than 15 have a high level of risk. Results obtained from Low Density Polyethylene Unit revealed that the highest risk belongs to the emergency vent system with risk priority number equal to 48. It is occurred due to imperfect performance of the reactor safety system leading to the emissions of ethylene gas, particles, and radioactive steam as well as air and noise pollutions. Results derived from secondary assessment of the environmental aspects, through difference in calculated RPN and activities risk levels showed that employing modern methods and risk assessment are have remarkably reduced the severity of risk and consequently detracted the damages and losses incurred on the environment.

Events such as the emission of toxic gases are possible on floating roof storage tanks. Since gasoline is a high-consumption and volatile product stored in adjacent oil depots or large cities, it is necessary to assess their emission risk. Given that the multi-criteria methods allow the identification of and assessment of the indicators well and allow the participation of expert experts, so the FAHP method has been used to identify and assess the risk before the emission of toxic gases. The results showed the importance of 7 factors among 36 factors, 3 of which were related to equipment error. The DOW'S CEI method was used to assess the emission risk if the event occurred. This method provides safe boundaries based on Emergency Response Planning Guidelines (ERPGs), where the results indicate the settlement placement around the oil repository in the range of the predicted concentration at all three levels of ERPG. [ABSTRACT FROM AUTHOR]

Background: This study aimed at developing and using a semi-quantitative method for analyzing safety resilience in the chemical industry. This cross-sectional, descriptiveanalytical study aimed to develop a semi-quantitative method for analyzing resilience. Methods: This study was carried out based on the Delphi method including 18 experts in chemical and process engineering as well as the health, safety and environment (HSE) engineering in 2018-2020. Results: The development of the semi-quantitative method for analyzing safety resilience took place after three rounds of the Delphi study. In this Delphi study, all the members of the experts' panel approved the three components of preparedness, likelihood, and severity with an 80% acceptance level. The results of the field study revealed 131 hazardous elements. The maximum and minimum values of resilience were found to be 500 and 100 belonging to failure in utility and failure in the distributed control system, respectively. Conclusion: The developed semi-quantitative method has acceptable reliability for the analysis of safety resilience in the chemical industry. Therefore, the analysis in the chemical industry can be considered an effective, necessary decision-making instrument for predicting and preventing dangers threatening the process, manpower, and nature of the chemical industry. [ABSTRACT FROM AUTHOR]

Air dispersion modeling is an important tool to improve air quality. The main objective of this research was focused on the simulation of CO emission from stacks at the Tehran Oil Refinery Complex, Iran. The AMS/EPA Regulatory Model (AERMOD) was developed to simulate the CO dispersion from stacks between the years 2018 and 2019. The results of the model on the maximum volume of CO concentration at 1hr and 8hr for hot and cold temperature were equal to 109 μg/m3, 32 μg/m3, 360 μg/m3, 254 μg/m3, respectively. Simulated values of CO emissions were compared to those obtained area measurement campaign at 4 receptors. Maximum concentration of CO in cold period of times was more than hot period of times. This can be attributed to low air turbulence. Our analysis demonstrated that the AERMOD modeling system is applicable for air quality simulation in the near future for CO. Simulation output showed that were all centered in against mountain and the middle of simulation area where the emission sources concentrated, and it is probably because the air pollutions were topography and source oriented. Finally, study results indicate that the simulated concentration of CO based on AERMOD, does not exceed concentration limit, set by the Iranian Ambient Air Quality Standard. It verified that CO release from oil refinery stacks don't have any significant impact on nearby communities. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the environmental risk of Balarood Dam in Iran at constructional phase. The scientific methods used in this research were the Environmental Failure Mode and Effects Analysis (EFMEA) and VIKOR. In the process of environmental risk assessment, the EFMEA method was used first to calculate the risk priority number (RPN) for each environmental aspect. The identified risks were ranked based on RPN values in the next stage. Comparison of the RPN values showed that the risk of pollution of Balarood River, with a RPN of 125, is in the first priority. In addition, the environmental risks, identified during the follow-up phase, were weighted by entropy method based on severity, occurrence probability, and extent of pollution.Then, the VIKOR method, as one of the multicriteria decision-making (MCDM) methods, was run to evaluate and prioritize the potential environmental risks. The risk of water pollution under high, medium and low conditions, with a weight of 1,300, 1,000 and 700, was identified as the most important risk of dam construction. Accordingly, the most important corrective action, proposed to mitigate the high priority environmental risks, is to prevent the discharge of sanitary and industrial wastewater into the river. [ABSTRACT FROM AUTHOR]

Oil and gas production is an inherently hazardous activity due to the large volume of flammable and explosive hydrocarbons stored or processed in a facility. Therefore, formal risk assessments are necessary for various phases of the asset life cycle because they help personnel identify, evaluate, and control the hazards that could result in loss of life, injury, pollution, property damage, or business disruption. The aim of this study was to assess the risk of fire and explosion (F&E) in the Gas Treating Unit of a gas refinery using the DOW'S fire and explosion index in order to examine the influence of the controlling methods. Accordingly, the important processes of the subunits in the Gas Treating Unit were identified based on the important influential parameters such as process pressure, temperature, and material value. In the next step, the most important parameters affecting the fire and explosion index were calculated for each subunit. In each case, the corresponding control methods were identified and their effects were investigated. The results revealed that 5 subunits out of the 5 studied had a severe risk of fire and explosion. The feed gas K.O DRUM (Knock-out Drum) was the most critical subunit of the Gas Treating Unit, given an F & E index value of 235.62. According to the research findings, the controlling methods could reduce the F&E index but not less than 98.7. [ABSTRACT FROM AUTHOR]

The beet sugar industry generates large volumes of wastewater with high levels of chemical oxygen demand (COD) and color content, which are discharged into the nearby environment without adequate treatment. The aim of this study was to investigate the treatment possibility of this wastewater by using the photo-Fenton oxidation combined with a coagulation process. Central composite design and response surface methodology were used to evaluate the relationships between color and COD reduction and the photo-Fenton oxidation parameters (i.e. Fenton's reagent dosage, pH, and reaction time). The combined treatment results showed 59% of COD and 83.9% of color removal were obtained at optimum conditions (pH: 6.2; Fe2+ dosage: 20 ppm; H2O2 dosage: 1500 ppm; and reaction time of 15 min). Finally, the results of gel permeation chromatography showed that low molecular weight fraction of the wastewater impurities is more degraded than high molecular weight fraction during oxidation/coagulation process. Therefore, the results obtained from this study showed that an appropriate combined method for the treatment of beet sugar industry wastewater can be designed and implemented. [ABSTRACT FROM AUTHOR]

Air pollution is considered as a destructive toxin of the nerves and ecosystems. Many schools are located in high-traffic streets in Tehran metropolitan, Iran. This study aimed at determining air pollution critical areas and impacts of this pollution on ecosystem and mental function of children at sensitive period of brain development. This was a descriptive-applied research in terms of methodology. According to data obtained from 22 stations for air quality monitoring in Tehran and average annual concentration of AQI pollutants, Tehran air pollution zoning has done in 2017 using Spline interpolation method through Arc GIS-10 and map of critical and healthy areas was drawn. Second step was undertaken using Wechsler test for 90 female students at age of 8-10 living in two areas. In the first area, air pollution was critical and the second area had a healthy air. Cognitive and depression disorders scored based on Wechsler and N-Back tests, respectively. Personal health indices obtained from health record of students to analyse their relation with cognitive disorder using ANOVA tests. Regions 22 and 20 were the most healthy and polluted areas, respectively. Girl children had different verbal, functional and general intelligence in these areas; there was a significant relationship between pollution or cleanness of each area and children's IQ. In addition, there was a direct and significant relation between air pollution and ecological effects. Thus, required actions should be taken to prevent the pollution of air and the impairment complications in cognitive functions. [ABSTRACT FROM AUTHOR]