Iranian Journal of

Background and Objective: In countries such as Iran that are facing with water scarcity and water crisis, paying attention to the quantity, quality and sustainable use of water resources is very significant. Petrochemical processes discharge pollutants into the environment, contaminating surface water resources. Therefore, treatment of the wastewater of these industries is necessary. Due to the capabilities of AHP process such as generalization, consideration of various parameters, multi-dimensional selection and quantifying the qualitative parameters by experts, the current study was carried out to select the best wastewater treatment alternative for HDPE plant of petrochemical research and technology company-Arak center based on AHP in 2016.
Materials and Methods: In this study, both sequencing batch reactors (SBR) and extended aeration activated sludge (EAAS) systems based on environmental, technical-functional, economic and management criteria's according to the expert's opinion were weighted. Then, the paired comparisons of the selected wastewater treatment systems for each criterion were developed. Finally, the results were analyzed to select the best wastewater treatment systems for HDPE unit of petrochemical industries using Expert Choice 11 Software.
Results: The results showed that the SBR wastewater treatment system was the best method for the wastewater treatment of HDPE plant of petrochemical research and technology company-Arak center as compared with the ESSA system. Also, consistency ratio was ranged from 0 to 0.10 in all emphases. Based on the results of the sensitivity analysis, the SBR system had the highest priority of economic and environmental criteria. The ESSA system had the highest priority of technical-functional and management criteria.
Conclusion: Based on the results, although ESSA method requires more maintainance and management than the SBR method, due to increasing requirement for the compliance of the output effluent quality with permissible limits and the need for less land for the establishment of the treatment plant, the SBR method was selected to be the most suitable process for HDPE plant wastewater treatment.
 
 

Background and Objective: Indoor air pollution in hospitals could be a serious health threat to the patients, medical staff, and visitors. In previous studies, the importance of paying attention to air quality during the Coronavirus pandemic has been proven. In this study, the effect of visiters' presence under normal conditions and the imposition of hospital restrictions at the time of pandemic on air quality and environmental parameters in a hospital has been evaluated.
Materials and Methods: Air sampling was carried out in Valiasr Hospital of Zanjan in two periods, September 2019 (morning and visiting hours) and during the pandemic in October 2020. All wards inside and the outside of the hospital were examined for air pollutants (PM_2.5, PM₁₀, NO₂, SO₂, CO₂) and environmental parameters (temperature, humidity, and sound levels).
Results: The results of this study showed that except for the sound levels, other pollutants are at an acceptable level. Particulate matter of different sizes in the air of the hospital has a correlation, often with an external source, and has been imported through construction activitie;. However, nitrogen dioxide concentration is dependent on urban traffic. Visiting hours are associated with an increase in the concentration of particulate matter and the sound levels. The pandemic had a positive effect in some wards, on some parameters and often improved the air quality due to the imposing strict health protocols.
Conclusion: This study showed that natural ventilation has a direct effect on the air quality inside of the hospital. It is also suggested that in wards where patients are sensitive or in the need of intensive care, restrictions on commuting and visitation be applied.

Background and Objective: Bioaerosols as small particles enter the body by inhalation and lead to respiratory diseases based on type, concentration, and exposure time. In sensitive workplaces such as medical centers, it is necessary to pay attention to the type and population of these pollutants and the possibility of nosocomial infections. In the present study, the population and type of bioaerosols (bacteria and fungi) in the air of different hospital wards under normal conditions, visiting hours, and Covid-19 pandemic was evaluated.
Materials and Methods: Air sampling was carried out in different wards and ambient air of Valiasr Hospital of Zanjan during September 2019 (morning and visiting hours) and October 2020 (Corona pandemic) using an air sampling pump (Flite 3- SKC Ltd) with a flow of 14.1 L/min and then cultured in Sabaroud dextrose agar and nutrient agar.
Results: The results showed that air pollution in wards such as infectious diseases and clinics in both periods was more than other wards. The microbial density during visiting hours (before the coronavirus outbreak) was almost 30% higher than normal conditions. In October 2020, due to the coronavirus outbreak and reduced traffic, microbial air pollution in the hospital decreased. In both periods of study, the frequency of gram-positive bacteria, especially Staphylococcus species (49%) was higher than other bacteria and among fungal species the frequency of Aspergillus (47%) was higher than others.
Conclusion: This study showed that traffic restrictions caused by the coronavirus pandemic reduce microbial density in hospital space and this achievement can be used in the future with the aim of improving air quality and controlling nosocomial infections.