Air pollution is one of the most important problems of urban life. Since a large proportion of airborne pollutants originate from industry, it is important to address emission removal systems. One of the growing industries is the production of aluminum, which requires attention and planning since emits dangerous pollutants such as particulate matter, SO 2 , NOx, dioxins, furans, mercury chloride, and fl uorine compounds. The present study investigates the production life cycle of this metal and analyzes the production of gaseous pollutants and particles in different production units. Large amount of pollution is produced in the alumina production and the aluminum electrolysis units, which in the best case, for the production of one ton of fi nal aluminum, Emit 1.07, 4.73, and 1.32 kg of particulate pollutants, sulfur dioxide, and nitrogen dioxide respectively. In the next step, in the search of the optimal system for controlling particulate pollutants, SO2, NOx caused by aluminum production, by reviewing the research background and related articles and books, ranked these systems using ELECTRE, TOPSIS and SAW methods. Sedimentation chamber, internal separators, cyclones, fabric fi lters, electrostatic precipitators, and wet collectors in particle removal and condensation, absorption, adsorption, incineration, and wet washing in SO 2 and NO x removal were reviewed and compared. The results show the superiority of cyclones in particle removal, wet washing system for removing SO 2, and adsorption for removing NO X .
In large cities, several hundred cubic meters of municipal wastewater is produced every day, which because of high levels of pollution, needs to be treated either for disposal or secondary use. Some of the most important indicators and pollutants that should be reduced to the standard range are VOC, TSS, TDS, BOD 5 , nitrogen, phosphorus, heavy metals, and pathogens. Wastewater treatment plants, which have different capacities and procedures depending on the type and characteristics of the infl uent and effl uent, have large budgets of several hundred million for their life cycle. These costs include construction, maintenance, operation, chemical and biological materials, energy, and amortization. The costs associated with these environmentally essential infrastructures vary according to their treatment processes. This issue leads environmental engineers and policymakers to economic evaluation of various methods. This study with the help of CapdetWorks2.5 software has discussed three different methods of Complete Mixed Activated Sludge (CMAS), Aerated lagoon, and Oxidation Ditch in wastewater treatment plants in terms of operating costs. Evaluation and implementation of the decision-making system were conducted using Analytic Hierarchy Process (AHP). The results of the analysis showed that aeration ponds are the most optimal option in terms of operating costs with a value of 47.3%. The other two studied methods, namely CMAS and Oxidation Ditch, have a value of 24.9% and 27.9%, respectively.
With the growth of industrialization and urbanization in megacities, some emerging disasters occur such as air pollution mortality, increasing cancer risks, decreasing life expectancy, descending prosperity, and Human Development Indexes (HDI). In addition, with the raising population of cities, the quantity and quality of air pollutions are increased based on vehicle application rate, industrial activities, agricultural efforts and etc. In this research, with the application of Dose-Response Functions in air pollution, some parameters such as chronic disease-based mortality, life expectancy reduction based on chronic and acute effects, and ozone gas health risks are computed in a case study of Mashhad city, Iran. The outcomes have illustrated the life expectancy is reduced in a case study around 8.22 and 8.51 years for men and women, respectively. Plus, the results of statistical health scrutinizing have demonstrated that the mortality of chronic effects based on air pollution emissions is calculated around 20 percentages in the case study. Likewise, with the application of two different methods in Multi-Criteria Decision Making (MCDM) containing Analytic Hierarchy Process (AHP) and ELimination Et Choice Translating Reality (ELECTRE) the responsibility of each pollution is determined. As per the mentioned computations, Particle Matter 2.5 (PM 2.5 ) has the most role in increasing the health risk of air pollution in Mashhad City, Iran.
Industrial wastewater treatment is of high priority due to the presence of an extraordinary concentration of dangerous pollutants. Similar to urban wastewater treatment plants, there are plenty of options while designing industrial ones which need various analyses and researches to choose correctly. One of the most effi cient ways to solve this problem is to implement Economic and Sensitivity Analysis. This research has studied designing an industrial wastewater treatment plant utilizing three different biological treatment methods (including Sequential Batch Reactors (SBR), plug-fl ow activated sludge with a secondary clarifi er, and step aeration activated sludge with a secondary clarifi er). It also measures the sensitivity of performance cost parameters to factors affecting the suspended growth unit. The results of the economic analysis showed that using SBR has the highest construction cost of $ 70,200,000 and the highest total cost of 96,900,000. Sensitivity analysis showed that by adjusting design retention time and variance between heterotrophic microorganism decay rate and the reality, using activated carbon-based systems could signifi cantly reduce total annual costs.
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