Recent progress on the toxic effects of microplastics on Chlorella sp. in aquatic environments.

Microplastics (MPs) are emerging contaminants that have harmful effects on ecosystems. Microalgae are important primary producers in aquatic environments, providing nutrients for various organisms. These microorganisms may be affected by MPs. Therefore, it is important to investigate the toxicity aspects of different MPs on Chlorella species. It can be seen that the BG-11 culture medium was the most commonly used medium in 40 % of the studies for the growth of Chlorella sp. Chlorella sp. grows optimally at a temperature of 25 °C and a pH of 7. Most studies show that Chlorella sp. can grow in the range of 3000-6000 lux. Moreover, various techniques have been used to analyze the morphological properties of MPs in different studies. These techniques included scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and transmission electron microscopy (TEM), which were used in 65 %, 35 %, and 27 % of the studies, respectively. 53 % of the research has focused on the toxic effects of PS on Chlorella sp. Findings show that 41 % of the studies investigated MPs concentrations in the range of 10-100 mg/L, followed by 32 % of the studies in the range of 100-1000 mg/L. The studies found that MPs were used in a spherical shape in 45 % of the cases. The enzymes most affected by MPs were superoxide dismutase (SOD) and Malondialdehyde (MDA), accounting for 48 % of the studies each. Additionally, exposure to MPs increased the activity of enzymes such as SOD and MDA. In general, it can be concluded that MPs had a relatively high negative effect on the growth of Chlorella sp.

Landfill leachates as a significant source for emerging pollutants of phthalic acid esters: Identification, occurrence, characteristics, fate, and transport.

Phthalic acid esters (PAEs) are byproducts released from various sources, including microplastics, cosmetics, personal care products, pharmaceuticals, waxes, inks, detergents, and insecticides. This review article provides an overview of the literature on PAEs in landfill leachates, exploring their identification, occurrence, characteristics, fate, and transport in landfills across different countries. The study emphasizes the influence of these substances on the environment, especially on water and soil. Various analytical techniques, such as GC-MS, GC-FID, and HPLC, are commonly employed to quantify concentrations of PAEs. Studies show significant variations in levels of PAEs among different countries, with the highest concentration observed in landfill leachates in Brazil, followed by Iran. Among the different types of PAE, the survey highlights DEHP as the most concentrated PAE in the leachate, with a concentration of 89.6 µg/L. The review also discusses the levels of other types of PAEs. The data shows that DBP has the highest concentration at 6.8 mg/kg, while DOP has the lowest concentration (0.04 mg/kg). The concentration of PAEs typically decreases as the depth in the soil profile increases. In older landfills, concentrations of PAE decrease significantly, possibly due to long-term degradation and conversion of PAE into other chemical compounds. Future research should prioritize evaluating the effectiveness of landfill liners and waste management practices in preventing the release of PAE and other pollutants into the environment. It is also possible to focus on developing efficient physical, biological, and chemical methods for removing PAEs from landfill leachates. Additionally, the effectiveness of existing treatment processes in removing PAEs from landfill leachates and the necessity for new treatment processes can be considered.

Using Spirulina platensis as a natural biocoagulant for polystyrene removal from aqueous medium: performance, optimization, and modeling.

Microplastics (MPs) are newly recognized contaminants that result from the breakdown of plastics released into aquatic environments. This study focuses on the elimination of polystyrene (PS) using S. platensis, a natural biocoagulant, from aqueous solutions. The research investigated several crucial variables, including the initial level of PS ranging from 100 to 900 mg L-1, pH levels from 4 to 10, the contact time of 20-40 min, and doses of S. platensis ranging from 50 to 250 mg L-1. The analysis of the data revealed that the quadratic model offered the best fit for the experimental results. In the present study, we utilized S. platensis as a novel natural biocoagulant to effectively eliminate PS from aqueous solutions. Process optimization was performed using a Box-Behnken design (BBD). The best-fitting model for the data was the quadratic model. The results displayed that the highest elimination of PS (81%) was occurred at a pH of 4, with a contact time of 30 min, a dose of S. platensis at 250 mg L-1, and a PS concentration of 500 mg L-1. These findings show that S. platensis has a significant effect on removing PS from the aquatic environment. Algae can serve as a convenient and eco-friendly method, replacing chemical coagulants, to effectively remove MPs from the aquatic environment.

Phthalate esters pollution in the leachate, soil, and water around a landfill near the sea, Iran.

This investigation aimed to scrutinize the level of phthalate esters (PEs) in the landfill leachate of a coastal city in the north of the Persian Gulf and the sensitive ecosystem (soil and water) around it. Soil (two depths) and water samples were prepared from 5 stations in wet and dry seasons. The studied landfill leachate contained 114-303 µg/L of phthalates. The highest concentration of phthalates was related to bis (2-ethylhexyl) phthalate (3257 ng/g) in the wet season at surface soil (0-5 cm) in the landfill site, while the lowest one (6 ng/g) belonged to dimethyl phthalate at sub-surface soil at 700 m from the landfill in the dry season. A significant change in the level of Σ6PEs in the dry (303 µg/L) and wet (114 µg/L) seasons (P ≤ 0.05) was observed for water samples. The PE concentrations in wet times were higher in all soil depths than in dry times. With increasing depth, the content of phthalates decreased in all studied environments. A direct relationship was observed between the phthalates concentration and the pH value of leachate/water and soil. The PEs concentration was linked to electrical conductivity (leachate: R2 = 0.65, P < 0.01 and surface soil: R2 = 0.77, P < 0.05) and the soil organic content. The ecological risk of di-n-butyl phthalate, benzyl butyl phthalate, bis (2-ethylhexyl) phthalate, and di-n-octyl phthalate in the wet season was greater than one. The results showed that significant levels of phthalate esters are released from landfills to the surrounding environment, which requires adequate measures to maintain the health of the ecosystem and nearby residents.

Utilizing Chlorella vulgaris algae as an eco-friendly coagulant for efficient removal of polyethylene microplastics from aquatic environments.

Polyethylene (PE) microplastics (MPs) are small particles of plastic made from polyethylene, which is a commonly used type of plastic. These microplastics can be found in water sources, such as rivers, lakes, and oceans. They are typically less than 5 mm in size. Chlorella vulgaris (C. vulgaris) is an excellent, simple and inexpensive biocoagulant that can effectively remove a wide range of pollutants through the coagulation and flocculation mechanism. In this study, C. vulgaris algae were used to remove PE MPs. The experiments were designed using the Behnken Box model. The evaluated parameters were the initial PE concentration (100-400 mg/L), the C. vulgaris dose (50-200), and the pH (4-10). The findings showed that increasing the concentration of polyethylene had a positive effect on the efficiency of removal. In addition, the dose of C. vulgaris and pH parameters were inversely and directly related to removal efficiency, respectively. The highest removal efficiency was observed under alkaline conditions. Overall, the maximum PE removal efficiency was 84 % when the concentration of PE was 250 mg/L, the dose of C. vulgaris was 50 mg/L, and the pH was 10. It can be concluded that algae can be used as an environmentally friendly coagulant for effectively removing MPs from aquatic environments.

Investigating the efficiency of oak powder as a new natural coagulant for eliminating polystyrene microplastics from aqueous solutions.

Polystyrene (PS) is a commonly used plastic material in disposable containers. However, it readily breaks down into microplastic particles when exposed to water environments. In this research, oak powder was used as a natural, inexpensive, and eco-friendly coagulant. The present study aims to determine the effectiveness of oak powder in removing PS from aquatic environments. The Box-Behnken model (BBD) was used to determine the optimal conditions for removal. The removal efficiency was evaluated for various parameters including PS concentration (100-900 mg/L), pH (4-10), contact time (10-40 min), and oak dosage (100-400 mg/L). The maximum removal of PS microplastics (89.1%) was achieved by using an oak dose of 250 mg/L, a PS concentration of 900 mg/L, a contact time of 40 min, and a pH of 7. These results suggest that oak powder can effectively remove PS microplastics through surface adsorption and charge neutralization mechanisms, likely due to the presence of tannin compounds. Based on the results obtained, it has been found that the natural coagulant derived from oak has the potential to effectively compete with harmful chemical coagulants in removing microplastics from aqueous solutions.

Adsorption of tetracycline on polyvinyl chloride microplastics in aqueous environments.

Microplastics (MPs), as carriers of organic pollutants in the environment, have become a growing public concern in recent years. Tetracycline (TTC) is an antibiotic that can be absorbed by MPs and have a harmful effect on human health. Therefore, this study was conducted with the aim of investigating the adsorption rate of TTC onto polyvinyl chloride (PVC) MPs. In addition, the adsorption mechanism of this process was studied using isothermal, kinetic, and thermodynamic models. For this purpose, experimental runs using the Box-Behnken model were designed to investigate the main research parameters, including PVC dose (0.5-2 g/L), reaction time (5-55 min), initial antibiotic concentration (5-15 mg/L), and pH (4-10). Based on the research findings, the highest TTC adsorption rate (93.23%) was obtained at a pH of 10, a contact time of 55 min, an adsorbent dose of 1.25 g/L, and an antibiotic concentration of 10 mg/L. The study found that the adsorption rate of TTC followed the pseudo-second-order and Langmuir models. Thermodynamic data indicated that the process was spontaneous, exothermic, and physical. Increasing ion concentration decreased TTC adsorption, and distilled water had the highest adsorption, while municipal wastewater had the lowest adsorption. These findings provide valuable insights into the behavior of MPs and organic pollutants, underscoring the importance of conducting additional research and implementing measures to mitigate their detrimental effects on human health and the environment.

Biodegradation of crystal violet dye by Saccharomyces cerevisiae in aqueous medium.

Crystal violet (CV) is an azo dye with cationic nature, belonging to the triphenylmethane group. This study was designed to optimize CV removal by S. cerevisiae from aqueous solutions using BBD model. Harvested cells of S. cerevisiae were locally obtained from Iran Science and Technology Research Organization (ISTRO). The decolorization tests were performed in a laboratory container containing a 100 cc of reaction solution under different variables, including yeast dose (0.5-1.5 g/L), pH (4-10), dye concentration (10-100 mg/L), and the reaction time of 24 h. After stirring with a magnetic shaker at a speed of 400 rpm, 10 cc of each sample was taken and centrifuged at 4000 rpm for 10 min to separate the biomass from dye solution. Then, the supernatant was filtered and finally the remaining CV was measured by a spectrophotometer at λmax 590 nm. After the optimization of the factors mentioned above, the removal efficiency of this dye was investigated at the reaction times of 0.5-72 h. The findings indicated that CV removal ranged from 53.92 to 84.99%. The maximum CV removal was obtained at the CV concentration of 100 mg/L, the pH of 7, and the S. cerevisiae dose of 1.5 g/L. The findings showed that the elimination efficiency is directly related to the initial CV concentration, pH, and S. cerevisiae dose. However, during the reaction time, the elimination efficiency decreased slightly. The findings of this study proved that CV can be removed from aqueous solutions with an easy and low-cost method based on the use of indigenous microorganisms.

Modification of Chlorella vulgaris carbon with Fe3O4 nanoparticles for tetracycline elimination from aqueous media.

Tetracycline (TTC) is an antibiotic commonly prescribed to treat bacterial infections in animals and humans because of its low toxicity and antibacterial activity. This study focuses on the removal of TTC from an aqueous media using an activated carbon of Chlorella vulgaris modified with Fe3O4 magnetic composite (ACCV/Fe3O4 mc). The isothermal and kinetic models were studied to understand the adsorption mechanism. The Box-Behnken model was used for experimental design, and the main research parameters were ACCV/Fe3O4 mc mass (0.2-0.8 g/L), reaction time (10-60 min), TTC concentration (5-30 mg/L), and pH (3-11). The highest TTC removal rate of 90.47% was obtained at a pH of 7, a time of 60 min, an ACCV/Fe3O4 mc mass of 0.5 g/L, and an antibiotic concentration of 5 mg/L. TTC removal was fitted with the pseudo-second-order and the Langmuir model. The Langmuir adsorption capacity of TTC was computed to be 26.18 mg/g. The results show that the ACCV/Fe3O4 mc adsorbent significantly removes TTC from the aqueous solution.

Investigation of microplastic pollution in Torghabeh River sediments, northeast of Iran.

Rivers are the route of transfer of microplastics from upstream to downstream areas and seas. Microplastic tracing in river sediments can provide a better reflection of long-term microplastic pollution. This study aimed to investigate the occurrence and distribution of microplastic contamination in the Torghabeh River sediments in Khorasan Razavi (Iran). Sediment samples were collected from four sites along the river. Microplastic particles were classified according to type, shape, and color. The average microplastic concentration was 8 ± 2.82 particles per 100 g of dry sediments. Most of the microplastics detected in river sediments were in the form of filaments and fragments. A total of 32 polymers were identified and isolated from sediments. According to Raman spectroscopy results, polystyrene had the highest abundance compared to polyester, polyethylene, and other polymers. The predominant shape of the microplastics in the river sediment was filament and fragmented. It can be concluded that the areas that were exposed to human activity contained more microplastic contamination. The present investigation can also provide baseline information for the study of riverine ecosystems.

Health impacts quantification attributed to ambient particulate matter in the nearest Iranian city to the main dust source.

Urban air contamination is one of the ten most dangerous parameters for human health, which causes cardiovascular disease, respiratory, metabolic diseases, and decreased lung function. Air Q is a reliable software for studying the impacts of atmospheric contaminants on human health, and today, it is widely used in the environment. The purpose of this research was to quantify the mortality and morbidity rates that corresponded to ambient particulate matter (PM) in Rigan City. To perform this, the Air Q software was used. The findings reflected that the yearly mean values of PM10 and PM2.5 are 264.83 and 50.45 µg/m3. The findings indicated that the PM10 and PM2.5 content in Rigan was above standard levels described by WHO. The total number of deaths, cardiovascular deaths, and respiratory deaths due to PM in Rigan were estimated as 70.3, 45.8, and 10.7 persons, respectively. Hospital admissions for cardiovascular and respiratory diseases correlated to PM10 were estimated at 154.2 and 59 persons, respectively. Acute myocardial infarction associated with PM2.5 was 2.7 persons. Overall, the data in this study may be helpful to national and regional policymakers who are responsible for managing and preventing atmospheric contamination and assessing the costs of health risks.

Assessment of the health risk and geo-accumulation of toxic metals in agricultural soil and wheat, northern Iran.

The current work was conducted to study the concentrations of heavy metals (HMs) in farming soil and wheat and compute their geological and health indexes, including geo-accumulation index (Igeo), chronic daily intake (CDI), hazard index (HI), hazard quotient (HQ), and cancer risk (CR). In general, 256 samples were collected from agriculture soil (AS) and wheat in Kalaleh and Aq Qala areas, northern Iran. The average rates of Cd, Cu, Pb, and Zn were detected to be 0.28, 25.24, 15.44, and 60.33 mg·kg-1, respectively, for AS and 0.01, 8.85, 0.73, and 33.81 mg·kg-1 for wheat, respectively. Based on the results, the HQ and HI levels for investigated HMs were lower than l. So, the health risk of HMs exposure for adults and children was low. CR levels for Pb in AS for both children and adults were observed greater than the threshold value. Accordingly, lead-contaminated soil will be carcinogenic if ingested by children. On the other hand, the exposure to Pb (through wheat) and Cd (through both soil and wheat) had the acceptable CR level for all groups. As a result, for an extended period, there are no significant health consequences for children and adults.

Impact of exposure to ambient air pollutants on the admission rate of hospitals for asthma disease in Shiraz, southern Iran.

Asthma is a common chronic respiratory disease in the world. Short-term exposure to ambient air pollutants is closely related to acute respiratory diseases and asthmatic symptoms. The purpose of this research was to estimate the correlation between exposure to three air pollutants (O3, NO2, and SO2) and hospital admission because of asthmatic disease (HAAD) in the city of Shiraz, southern Iran. The data were collected from the two real-time monitoring stations located in this city. The acquired information was used for developing predictive models by the AirQ software. The findings of this study were reported for two age groups (<15 and 15-64 years old). The highest levels of O3, NO2, and SO2 were obtained 187.33 µg/m3, 34.1 µg/m3, and 491.2 µg/m3 in 2016, respectively, and 227.75 µg/m3, 92.26 µg/m3, and 190.21 µg/m3, respectively, in 2017. Among the mentioned pollutants, the yearly average concentration of SO2 was 8.62 times more than the WHO guideline, during the studied times. The number of extra cases of HAAD for <15 years and 15-64 years caused by the air pollutants in Shiraz were estimated to be 273 and 36, respectively, in 2016, and 243 and 30 for 2017, respectively. The results of this work displayed that air pollutants have caused respiratory problems in Shiraz city. The AirQ model is a facile and potential tool for the prediction of asthma disease to reduce the health risk of atmospheric pollutants in the worldwide.

Quantification of mortality and morbidity attributed to the ambient air criteria pollutants in Shiraz city, Iran.

According to the epidemiological surveys, ambient air pollution has directly related to mortality and different diseases such as cardiovascular and respiratory defects. Among the atmospheric contaminants, criteria air ones (NO2, O3, PM2.5/10, SO2) demonstrated that have particular importance in the community disease. The overall goal of this paper was to study the impact of criteria air contaminants on the health of the inhabitants of Shiraz city, Iran. To accomplish this, the AirQ2.2.3 software was applied. The results of the study revealed that the annual average NO2, SO2, PM2.5, PM10, and O3 concentrations are 39.98, 27.6, 14.35, 46.16, and 120.03 µg/m3 in 2016 and 30.27, 23.97, 16.45, 51.65, and 52.58 µg/m3 in 2017. The total International Classification of Diseases (ICD), cardiovascular, and respiratory mortalities caused by air contaminants in Shiraz was predicted as 911, 628, and 182 cases in 2016, and 346, 370, and 82 cases in 2017, respectively. Sulfur dioxide (SO2) had the greatest rate of total mortality with the attributable equivalent of 4.3% in 2016, but this value has been decreased to 0.42% in 2017. The findings of this research revealed that air contamination has caused problems in Shiraz city according to the predicted results. The findings of this work provide useful data for regional and national health policymakers, who should take decisions to develop strategies for control air contaminants and estimate the cost-effectiveness of interventions.

Analysis of quality and quantity of health-care wastes in clinical laboratories: a case study of Ilam city.

Generation of health-care wastes is one of the major concerns in health-care institutions worldwide due to direct and indirect impact on human health and environment. The purpose of the present work was to estimate the quantity and quality of clinical laboratory wastes in the city of Ilam, Iran. In this cross-sectional study, randomly eight clinical laboratories including five in private sector and three governmental clinical laboratories were selected for sampling according to the purpose of the study. The results showed that the total amount of waste generation was 27,700.90 kg/year. The average amount of health-care wastes generation in Ilam city was 0.2 kg/person/year. The portions of general, pathologic, sharp, infectious, and pharmaceutical and chemical wastes were 37, 5, 2, and 56% (by weight), respectively. As a considerable amount of waste is generated in clinical laboratories of Ilam city, therefore, it is necessary to implement integrated plans for the proper management of these wastes. Thus, sufficient training and education programs must be developed for all clinical staffs and that the existing training and education procedures should also be promoted.

Data on the removal of turbidity from aqueous solutions using polyaluminum chloride.

Polyaluminum chloride (PAC) is claimed to be superior to conventional coagulants because of higher removal of particulate and/or organic matters as well as inherent advantages of lower alkalinity consumption and lesser sludge production. 1000 mL of the reaction mixture was examined using parameters, including PAC dose (5-10 mg/L), pH (4-9), and turbidity (1.9 NTU). The content was stirred at 120 rpm for 1 min. Thereafter, the turbidity of water samples was measured using a P2100 turbidimeter. Data indicated that the maximum removal efficiency of turbidity (97.74%) obtained under the PAC doses of 4 and 10, and the pH of 8. There is not a significant relationship between the different dosages of PAC (P-value > 0.05), but the influence of pH on the removal of turbidity was significant (P-value < 0.05). Based on the dataset, the removal efficiency of turbidity was depended on PAC and pH.

The bactericidal effect of simultaneous titanium oxide on common hospital bacteria.

Bacteria prevalence has increased in health centers and hospitals. Infection control can decrease the number of bacteria. Bacteria cause 90% of nosocomial infections and fungi, viruses, or protozoa are less involved. Bacteria control can decrease the number of diseases. The Simultaneous titanium oxide (SMTiO) is a new method of disinfection. This process degrades bacteria by producing hydroxyl radical. The present study was conducted with the aim of analyzing the bactericidal effect of simultaneous titanium oxide on common hospital bacteria. In this study, SMTiO system was placed under a laminar hood. Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, Pseudomonas aeruginosa, and Citrobacter freundii were selected as common hospital bacteria. Treatment operations were conducted at the bacteria concentration 106 cells/mL and the exposure times of 1 to 48 h. Then, the bacteria colonies were counted and removal rate calculated separately each of the bacteria. Finally, data analysis was conducted by using one-way ANOVA. Results showed that E. coli and C. freundii had the highest removal rate (40%) and the lowest removal (14%), respectively. Results confirmed that SMTiO can degrade Gram-positive and Gram-negative bacteria, but its effects were lower on Gram-positive bacteria. Results showed that removal efficiency increased gradually during exposure periods. We recommend that future studies should analyze the structure of bacteria after the treatment with SMTiO.

Optimization of diazinon biodegradation from aqueous solutions by Saccharomyces cerevisiae using response surface methodology.

Diazinon is an organophosphate compound that inhibits the activity of acetylcholinesterase. Standards of the World Health Organization and Environmental Protection Agency for diazinon concentration in water are 0.1 and 9 × 10-6 mg/L, respectively. The aim of this study was the optimization of diazinon biodegradation from aqueous solutions by Saccharomyces cerevisiae using the response surface methodology (RSM). Harvested cells of S. cerevisiae were locally purchased from the Iranian Research Organization for Science and Technology. To obtain the optimum condition for diazinon biodegradation using RSM, input parameters included the initial concentration of diazinon (0.01-10 mg/L), concentration of S. cerevisiae (0.5-5%), pH (4-10), and retention time (1-30 h). The research study had a central composite design where one of the methods was RSM. According to the results, the observed values of the removal efficiency of diazinon were variable in the range of 23-96. The highest removal rate was obtained as 96% under the initial diazinon concentration of 2.5 mg/L, S. cerevisiae concentration of 3.88%, pH of 5.5, and retention time of 22.75 h. The results displayed that the removal efficiency of diazinon had a direct relationship with the concentration of S. cerevisiae and retention time, and an inverse relationship with pH and the initial concentration of diazinon. We can conclude that S. cerevisiae has the ability to remove diazinon with the lowest cost and a high efficiency.

Cardiovascular, respiratory, and total mortality attributed to PM2.5 in Mashhad, Iran.

Poor air quality is one of the most important environmental problems in many large cities of the world, which can cause a wide range of acute and chronic health effects, including partial physiological disorders and cardiac death due to respiratory and cardiovascular diseases. According to the latest edition of the national standard for air quality, maximum contamination level is 15 µg/m(3) per year and 35 µg/m(3) per day. The aim of this study was to evaluate cardiovascular, respiratory, and total mortality attributed to PM2.5 in the city of Mashhad during 2013. To this end, the Air Q model was used to assess health impacts of PM2.5 and human exposure to it. In this model, the attributable proportion of health outcome, annual number of excess cases of mortality for all causes, and cardiovascular and respiratory diseases were estimated. The results showed that the number of excess cases of mortality for all causes and cardiovascular and respiratory diseases attributable to PM2.5 was 32, 263, and 332 µg/m(3), respectively. Moreover, the annual average of PM2.5 in Mashhad was obtained to be 37.85 µg/m(3). This study demonstrated that a high percentage of mortality resulting from this pollutant could be due to the high average concentration of PM2.5 in the city during 2013. In this case, using the particle control methods, such as optimal use of fuel, management of air quality in urban areas, technical inspection of vehicles, faster development of public transport, and use of industrial technology can be effective in reducing air pollution in cities and turning existing situations into preferred ones.