Iranian Journal of

Background and Objective: Supply of safe drinking water to each community is one of the most important challenges in improving the general community’s health. Considering the importance of the research on water quality, identification of water quality research gaps was performed by reviewing the relevant studies through a systematic review for Iran. 
Materials and Methods: In this study 638, 166, 300 and 1000 relevant articles were found on Scopus, SID, Magiran and Iranmedex databases, respectively. Out of 2104 articles, 1394 articles were excluded from the study. Finally, 710 articles were further reviewed.
Results: Monitoring of pollutants by a descriptive study was the main objective of the most studies   (36.62%). Around 13% of the studies were performed on a laboratory scale. Organic pollutants in Iran have been concerned only in 17 provinces, and other provinces have not participated in this regard. Nitrate is studied in around one fifth of the total studies. Heavy metals were also considered as a parameter of concern in the studies carried out on monitoring drinking water resource quality.
Conclusion: This study reflects the research gaps and provides a basis for prioritizing water quality research in Iran. More actions and sound planning should be taken to monitor organic and inorganic pollutants. Chemical and microbial risk assessment, tracing the fate of pollutants and assessment of their ecological effects, investigations on advanced water purification processes, the use of bioremediation methods, identification of biological contaminant using biomarkers and molecular identification techniques are the most important research priorities that require more investigations.
 
 

Background and Objective: Coagulation, which is carried out by mixing coagulants such as alum, ferric chloride and poly aluminum chloride PAC with raw water, is one of the main processes in conventional water treatment plants. Sludge from this process contains high amounts of coagulants with high economic value. Therefore, if these coagulants are recovered, in addition to reducing the risks relate to sludge disposal, the expenses related to the supply of fresh coagulant in water or wastewater treatment plant may decrease.
Materials and Methods: To access related documentation, ScienceDirect, Google scholar and other databases were searched using keywords such as “coagulant recovery”, “water residuals management”, etc. More than one hundred fifty documents were investigated based on the content validity and thematic relation. Gathered contents were classified and summarized under the titles of “recovery methods”, “repeated recoveries”, “recovery regarding economic aspect” and “advantages and disadvantages of methods”.
Results: Use of new methods such as combination of membrane and chemical processes or ion exchange membrane processes leads to the recovery of coagulants with a similar quality to the commercial ones. In case of using conventional and less costly methods such as acid digestion, quality of recovered coagulants is not comparable with those of commercial ones, which are used in water treatment.
Conclusion: Different coagulants recovery methods were investigated to determine the reuse strategies. It is likely that using of recovered coagulants through conventional methods is in accordance with the related regulations of the wastewater treatment plants. Industrial use of novel processes for recovery of coagulants with higher quality needs precise technical and economical investigations.
 

Background and Objective: Bioremediation of contaminants by living microorganisms is a favorable method for elimination or degradation of pollutants to less harmful substances. In the recent decades, cell immobilization technique has been applied to improve biodegradation efficiency and also overcome to free cells disadvantages. The purpose of this review article is to investigate the application of cell immobilization technology with emphsize on polymeric matrices in the aromatic pollutants removal in laboratory scale (shake flask and bioreactor). Also, the performance of free and immobilized cells has been compared in various environmental conditions.
Materials and Methods: In this survey 401, 78, 49, 1450, 0 and 0 relevant articles were found on Scopus, Web of Science, PubMed, Google scholar, SID and Magiran databases, respectively by using keywords such as “Cell immobilization”, “Biodegradation” and “Aromatic. Out of 1978 articles, 1167 articles were excluded from the study. Finally, 811 articles were further reviewed.
Results: According to the previous studies, removal of contaminants by immobilized cells using appropriate matrices is higher than freely suspended cell systems. Also, among the cell immobilization systems, cell entrapment in the polymeric carriers is the most widely used method for the bioremediation of aromatic contaminants.
Conclusion: Regarding the superiority of immobilized cells in comparison with free cells specially in harsh environments, the reuse of immobilized cells and their application in bioreactors as well as their scale up potential, development and application of these methods can be considered by researchers for wastewater treatment in our country.
 

Background and Objective: Global market growth of reverse osmosis (RO) has led to an increase in annual disposal of membrane wastes. Therefore, evaluation of membrane waste management strategies is important to reduce their adverse environmental impacts. Due to the widespread domestic RO membrane market and their economic considerations, this study aims at investigation the direct recycling methods of RO membranes to extend their life cycles.
Materials and Methods: Academic search engines and citation databases such Scopus and PubMed was used to retrieve relevant papers. Selected documents were analyzed and compared in three aspects of technical, economic and environmental issues. 
Results: Direct recycling of RO is performed with fouling removal and degradation of polyamide layer (PA) using oxidizing agents like KMnO₄ and NaOCl. The degradation rate of the PA layer is controlled by optimizing the oxidant concentration during the oxidation process. Factors such as the type of membrane used, its storage conditions, the operating units’ conditions and the final expected product will determine the required concentration-time values. Strategies to reduce these values are very important from an economic and environmental point of view. Decreasing the concentration of oxidizing agent reduces the chlorinated and halogenated compounds emitted from the oxidizing unit which subsequently lessen their harmful environmental impacts and reduces the energy consumption required for treatment.
Conclusion:  The conversion of RO membranes to porous filters is technically possible by optimizing the conditions. In addition, the proper choice of RO membrane and final product type lead to economic and environmental productivity.

Background and Objective: Recently, microplastics (MPs) have been found in the aquatic and terrestrial environments, air, and food. Other pollutants can be transported by MPs and pose a threat to the human, animal, and environment. Measurement and evaluation of microplastics can either increase knowledge about them or boost understanding of their possible harmful effects. However, no standard method has been established to measure microplastics and the measurement of microplastics has been done by various methods in different published studies. The aim of current study was to investigate different methods of measuring microplastics in water and wastewater environment and identifying the strengths and weaknesses of these methods.
Materials and Methods: The present review study was conducted during the winter 2021, by searching the papers cited in PubMed, Google Scholar, Web of Science, and Scopus databases using the keywords "Microplastic", "Water", "Drinking-water", "Wastewater", "Surface", "Bottled-water" and "Marine" and selecting articles published between 2015 and 2021 in reputable journals.
Results: The main stages of MPs measuring in various studies included sampling and sieving, pretreatment and digestion, density separation, counting and Identification of MPs by their chemical composition.
Conclusion: Digestion using H₂O₂, density separation using NaCl, counting by stereomicroscope, and Spectroscopy using FTIR and micro-RAMAN are the most widely used methods in the studies related to detecting MPs in water and wastewater environment. However, different methods of measuring and identifying microplastics have made comparing the results of studies difficult and it seems that efforts should be made to standardize these methods.

Background and Objective: Understanding the factors contributing to the mortality of COVID-19 patients can provide comprehensive information for preventive decisions and public health, and will help in better management of the epidemic. In this regard, the present study was conducted with the aim of identifying and introducing risk factors affecting the mortality of COVID-19 patients by modifiable and non-modifiable factors.
Materials and Methods: In this review study, according to the objectives of the study, related papers on risk factors affecting the mortality of COVID-19 patients were searched and collected in the international databases of Web of Science, Scopus, Embase, PubMed, and Google scholar. Then the results were extracted and reported by modifiable and non-modifiable factors.
Results: The results showed that almost all studies conducted in this field address non-modifiable risk factors such as age, sex, and underlying diseases including cardiovascular disease, diabetes, hypertension, respiratory diseases, cancer, self-diseases, autoimmune, and neurological diseases. Although few studies have been conducted on modifiable risk factors, lack of early admission or long waiting for hospital admission, occupancy of hospital beds and ICUs, as well as lack of equipment in hospitals were associated with increased mortality in these studies.
Conclusion: Regarding the situation of different countries in this epidemic, improving the control of the COVID-19 epidemic and reduce the mortality rate is possible by considering modifiable factors and taking appropriate measures. According to the results of studies, allocating sufficient financial, personnel and equipment resources can be effective in reducing COVID-19 mortality. However, controlling the COVID-19 epidemic to reduce morbidity and mortality as well as its economic and social consequences is possible by integrated management in the country. Also, using the experiences and guidance of the World Health Organization and successful countries, and stability in measures with a comprehensive approach should be considered.

Background and Objective: Dolochar is the residual ash from the production of sponge iron in the process of direct reduction of iron ore by the coal-based method. In Iran, this waste is transported to the nearest landfill. However, these methods are a major environmental concern due to the fineness of the waste and the presence of heavy metals in its composition. The aim of the present study is to investigate the methods of reusing dolochar in order to solve the environmental problem and further use it as auxiliary materials in applications such as road construction and wastewater treatment.
Materials and Methods: In depth investigation of the word “Dolochar” in Science Direct, SID, and MagIran databases showed that there is no long history of reusing it. Only 14 English articles were found, all of which were used in research; Therefore, the present article deals with the issue of reusing Dolochar in Iran for the first time.
Results: By reviewing previous studies, reuse of Dolochar has been classified into five sections. Dolochar use in wastewater treatment (removal of copper, chromium, paint, phosphate, nitrate, surfactant), removal of chromium from mine effluent (more than 94%), as a synthesis gas, as a filter medium (three times better than sand filters) and it is also used in construction and road construction (alternatives to aggregates).
Conclusion: The high capacity of Dolochar in waste absorption and wastewater treatment shows that it is necessary to reuse it in Iran instead of burying or leaving it in the environment.

Background and Objective: The purpose of this study is to identify and comprehensively evaluate international studies related to bioaugmentation and biostimulation methods for the remediation of soils contaminated with petroleum compounds.
Materials and Methods: This systematic review study was conducted in April 2022. The present systematic review study was conducted to address two main questions: 1) Is biostimulation an effective process in the bioremediation of soils contaminated with petroleum hydrocarbons; and 2) Is bioaugmentation an effective process for bioremediation of soils contaminated with petroleum hydrocarbons? Global electronic databases (PubMed, Web of Science, and Scopus) were used to identify relevant studies. After a comprehensive review of studies, 123 studies consistent with the purpose were selected.
Results: The results showed that biostimulation methods can have profound changes in bacterial, Archaebacteria, and soil fungal communities in terms of activity, frequency, and composition. In general, the nutrients and electron receptors added in the biostimulation process improve soil microbial activity, increasing the overall abundance of bacteria, and fungi and promoting selective replication of bacterial, archival, and fungal polyaromatic hydrocarbons (PHC) destroyers. The use of bioaugmentation technology in an environment contaminated with petroleum hydrocarbons has a positive effect on the refining process. However, it is necessary to precisely select the appropriate microbial strains. The most important factor in the removal of hydrocarbons in the soil is the selection of oil-decomposing microorganisms that can survive in high concentrations of pollutants.
Conclusion: Therefore, the result indicated that biostimulation and bioaugmentation can efficiently improve the THP removal efficiency in contaminated soil by considering the environmental conditions.
 

Background and Objective: The presence of toxic compounds, including phenol, due to industrial development, poses a threat to the environment. Utilizing hairy roots has emerged as a potential method to remove these toxins. This review aims to explore the efficacy of hairy roots in absorbing phenol pollutants and the influencing parameters.
Materials and Methods: This study was conducted using a descriptive-review method based on existing literature gathered from databases such as Science Direct, PubMed, and Google Scholar. The focus of the study was on the purification of phenol using hairy roots. Keywords such as Phytoremediation, Hairy root, Phenol, and Transgenic roots were used for data collection.
Results: Results show successful phenol removal by hairy roots, potentially attributed to abundant production of peroxidase enzymes. Various factors, such as hydrogen peroxide (H₂O₂), incubation time, pH, plant species, and pollutant concentration, impact phenol removal efficiency. Notably, plants like Brassica napus, rich in peroxidase enzymes, exhibit high efficiency in removing phenol pollution up to 500 mg/L, with H₂O₂ and within a pH range of 4-9.
Conclusion: In conclusion, hair roots possess significant adsorption capacity for phenol. However, phenol concentration, contact time, pH, and temperature influence their performance. Therefore, further research is required to explore optimal conditions for phenol removal.
 

Background and Objective: Breast cancer is the most common malignancy in women worldwide. Cadmium is one of the most persistent and toxic heavy metals, exposure to which may lead to an increased risk of breast cancer. This study aims to quantitatively summarize the available evidence for the relationship between cadmium exposure and the risk of breast cancer using a systematic review and meta-analysis.
Materials and Methods: In this research, observational studies that investigated the relationship between cadmium and breast cancer until May 2022 and were published in international databases were searched and retrieved. To determine the heterogeneity, the statistical tests Chi² and I² were used, to determine the presence of publication bias Egger's and Begg's tests were used, and to detect the root of the heterogeneity, meta-regression, and sensitivity analysis were used.
Results: In this study, it was observed that compared to the base group, the relative risk of breast cancer in people exposed/exposed to a dose higher than the base level of cadmium is equal to 1.10 (95% CI: 1.06-1.14; p ≤ 0.001), therefore, a statistically significant relationship was observed between exposure to cadmium or exposure to levels exceeding the baseline and developing breast cancer. In investigating the possibility of publication bias, the result of Egger's test was equal to (p ≥ 0.001), and the result of Bagg's test was equal to (p = 0.099).
Conclusion: According to the available evidence, exposure to cadmium leads to an increase in the risk of breast cancer, and this increase in risk is statistically significant.
 

Background and Objective: Given the concern about the presence of microplastics in the air and settled dust, and the lack of a standard approach for their detection, it is necessary to investigate the methods and techniques used to study this type of pollution in Iran. Therefore, this study aimed to systematically review the methods and techniques used for sampling, quantification, and characterization of microplastics in the air and settled dust in indoor and outdoor environments in Iran.
Materials and Methods: In this systematic review, the keywords Microplastic*, Air*, Atmosphere*, Dust, Indoor, Outdoor, Iran, and their corresponding Persian equivalents were searched until Dec 1, 2023, in Scopus, PubMed, Web of Science, Google Scholar, Magiran, and SID databases. Obtained articles from the databases were analyzed in order to find the eligible ones.
Results: Overall, 175 articles were found in the initial search, and after removing the duplicates and nonrelevant, 13 eligible articles were included in the study. In most of the studies, the samples were digested with H₂O₂, and the microplastics were mainly analyzed using a variety of microscopes and µRaman spectroscopy. The abundance of microplastics in the indoor environment was much higher than in the outdoor environment.
Conclusion: The results of this study showed that there is the required equipment for the sampling and analysis of microplastics in air and settled dust in Iran, and these pollutants have been detected in both indoor and outdoor environments.
 

Background and Objective: Rapid aging and climate change are two major global challenges of the 21st century. This study was conducted to identify the effects of climate change on the health of older adults.
Materials and Methods: This systematic review was conducted by comprehensively searching the Scopus, PubMed, and Web of Science electronic databases using the keywords elderly, aging, older people, health, and climate change, in English. Articles from 2014 to February 2023 following the PRISMA checklist were examined. Studies were included if they were published in English, had full text available, and focused on a population of people over 60 years old.  Simulated studies were excluded.
Results: The quality of these studies was reported to be moderate to good according to the STROBE checklist. The results showed that climate change negatively impacts the physical, mental and social health of the elderly. It causes an increase in the prevalence of cardiovascular, kidney, and respiratory diseases, as well as depression. Additionally, it leads to a reduction in daily activities, an increase in hospitalization rates and higher mortality. Among various climate changes, the increase in temperature poses the greatest to the health of older adults.
Conclusion: Climate changes, particularly the rise in temperature, have the most significant negative impact on the physical health of older adults. Therefore, there is a pressing need for increased focus on environmental sustainability, the development of public health intervention policies, and the implementation of adaptive strategies to mitigate the effects of extreme temperatures for older adults.
 

Background and Objective: The initial step in managing methane emissions is quantification. This study aims to comprehensively investigate the methods for estimating and measuring methane gas emissions in municipal solid waste landfills.
Materials and Methods: This systematic review includes studies published in English and Farsi between January 2005 and May 2023. English-language articles were included from  PubMed, Web of Science, and Scopus databases, while Persian-language articles were included from SID, Majiran and Google Scholar.
Results: After evaluating the studies, 90 studies providing information on methods for measuring and estimating methane gas emissions in urban landfills were selected. The results showed that emission estimates based on widely used models like LandGEM and IPCC, despite being lower in cost and providing faster results, are often associated with relatively high uncertainty. Therefore, quantitative and qualitative methods of direct measurement are preferred for accurately determining methane emissions from landfills. The most commonly used methods for measuring greenhouse gases, especially methane from landfills, include direct reading equipment and closed flux determination chambers.
Conclusion: Estimating greenhouse gas emissions from primary sources allows responsible authorities to understand the current status of methane emissions and to formulate reduction strategies. The findings of estimated methane emissions from landfills can differ significantly from the actual measurements in some situations. Therefore, while these estimation methods are  useful, fast and cost-effective tools, their inherent uncertainties should be considered when using them.