mohammadreza mehrasbi

During the early days of COVID-19 pandemic, due to the shortage of N95 respirators in hospitals and healthcare centers, the reuse of N95 respirators was posed as a crisis capacity strategy. Several studies have evaluated the efficacy of various decontamination methods on N95 respirators of well-known and approved brands. However, fundamental question is whether decontamination and reuse methods can be applied to all types of respirators.

Six types of respirators were selected from well-known and lesser-known brands which their manufacturers claimed to be N95. The selected respirators decontaminated with dry heat, ultraviolet germicidal irradiation, and ethylene oxide methods in seven consecutive cycles and their particle filtration efficiency and pressure drop were measured before and after each decontamination cycle.

As the initial measurements revealed, 4 respirators (group A) showed a sharp drop in efficiency and also, negative efficiency in removing 2.5 and 4 µm particles in most of the experiments. In these respirators (group A), the maximum efficiency in removing 0.5 µm particles was 74.4 %, while the last two respirators (group B) achieved an efficiency of 98 %. Subsequent experiments following the decontamination process revealed that the non-authentic N95 respirators within group A which were not resistant to decontamination. However, the second group demonstrated a removal rate of over 95 % of particles ranging from 0.5 to 10 µm after six consecutive decontamination cycles using all three methods. The results demonstrated that ultraviolet germicidal irradiation and ethylene oxide methods could eradicate the covid-19 virus from respirators.

The results indicated that decontamination can be successfully applied to original N95 respirators, not low-quality respirators, even under critical conditions.

The contamination of food with heavy metals is a significant concern for humans. Among food products, milk and dairy products have received more attention due to their widespread consumption at all ages, particularly among children. The aim of this study is to determine the concentration of lead and cadmium in milk and dairy products in Zanjan.

132 samples of milk, doogh, yogurt, and cream were collected from Zanjan city during the winter and summer of 2020-2021. The lead and cadmium levels in the samples were quantified using microwave digestion and graffiti furnace atomic absorption spectrophotometry.

The average concentrations of lead and cadmium in traditional milk, industrial milk, doogh, full-fat yogurt, low-fat yogurt, and cream samples were 96.23, 89.91, 78.79, 49.79, 53.74, 106.08, and 2.76, 2.07, 2.59, 1.09, 1.34, 5.60 µg/kg, respectively. The mean lead concentrations in milk and dairy products during winter were significantly higher than those during summer, whereas the mean cadmium concentrations during summer were higher than those during winter for all dairy products.

The lead and cadmium concentrations in most of the samples exceeded the WHO-FAO standards of 20 and 2.6 µg/kg for lead and cadmium, respectively. Therefore, prompt action is necessary to address this issue.

Consumption of tea and herbal teas is increasing worldwide due to their beneficial substances and daily antioxidant properties. However, in unfavorable environmental conditions, biological contamination can occur and cause a variety of diseases in humans and animals. In the meantime, fungal infection is of special importance as it produces secondary metabolites (mycotoxins). Mycotoxins affect various tissues of the body and their acute and chronic toxic effects can have serious problems for public health. Health risk varies in terms of mycotoxins and depends primarily on the geographical area and economic status of the population. This review examines the published articles about determining the presence of mycotoxins in herbal teas and teas and transfer to infusions 1997-2019 using high technique apparatus. The collected information was obtained from PubMed, Science Direct, Scopus, and Web of Science. This review decided to investigate the mycotoxins levels in tea and herbal tea and then consider different and effective proposed methods of removing or reducing mycotoxins.

Recalcitrant organics remediation from water resources continues to be a significant environmental problem and there is a continued effort to demonstrate practicable and economical treatment options for pollution removal.

In this study, the efficiency of the permeable reactive barrier (PRB) in a column reactor using zero-valent iron (ZVI) particles and sand mixture in the removal of methyl tert-butyl ether (MTBE) from aquatic phases was investigated. The system performance was MTBE removal while initial pH,reaction time, pollutant content, catalyst load, hydraulic loading rate (HLR), and the reaction rate constant were independent variables.

The results showed that the process efficiency decreased by increasing pH, HLR, and pollutant concentration. In this case, the optimal conditions were obtained at pH = 7, HLR = 0.23 m3/m2·d, and C0 = 1 mg/L, which achieved a remarkable removal efficiency up to 90.32%. The high nitrate concentrations and hardness as intervening factors reduced process efficiency to less than 44.61 and 51.4%, respectively. The lack of interfering factors had a considerable effect on the reaction rate of MTBE reduction, which is approximately 2.65 and 4.11 times higher than that in the presence of calcium hardness and nitrate, respectively.

The PRB technology can be suggested as a reliable and robust system to remediate groundwater containing hydrocarbons based on filling media and hydraulic conditions.

The elimination of methyl tert-butyl ether (MTBE) from water resources remains a main environmental concern. In the present study, photo-assissted process for removal of MTBE was examined in the solutions containing C-N-TiO2 nanoparticles under UV irradiation in the batch mode.

The effects of operational factors such as pH, initial catalyst concentration, and initial MTBE concentration on MTBE removal was investigated.

The optimum degradation condition for MTBE was obtained at pH 7, catalyst load of 100 mg/L, air flow rate = 0.1 L/min and C0 = 5 mg/L with 73 percent degradation of MTBE at 60 min. In addition, Analytical profiles on MTBE removal were based on the first-order kinetics model. However, the removal rate decreased by increasing initial concentration of MTBE.

The findings showed that UV/C-N-TiO2 system is an efficient method for MTBE degradation from aqueous solution.

Population growth and industrial and agricultural activities have increased the consumption of water, leading to clean water scarcity. Wastewater treatment is an important concern as determining proper sites for wastewater treatment plants (WWTP) largely influences proper operation. The present study aimed to determine an optimized site for WWTP in the rural complexes of Zanjanrood catchment in Zanjan province, Iran.

The site priority map was generated using the geographical information system (GIS) and analytical hierarchy process (AHP). Locating of the plants was based on various parameters. After map preparation, the weight of each parameter was determined using the AHP approach, and the conversion of the layers was performed using the GIS. The site priority map for each sub-catchment was determined and optimized.

In the criteria pairwise comparison matrix, the distance from the city had the highest value (16%), while the distance from the oil and gas transmission pipelines had the lowest value (1%). The site was located at the lowest elevation compared to the villages in each complex.

According to the results, the AHP followed by the optimization method could pinpoint the optimal sites for the environmental protection of treatment plant construction in rural areas.

Nowadays, underground water is the main source of drinking water that contamination to organic pollutants such as MTBE is an important issue. One of the suitable methods for these types of pollutants is the advanced oxidation methods. Advanced oxidation processes (AOPs) are involved in the production of highly reactive hydroxyl radicals that oxidize organic matter such as MTBE and even lead to its full mineralization. The use of light in the presence of catalysts is one of the methods of advanced oxidation processes. Photocatalytic methods widely used for a wide range of toxic and none degradable pollutants. Recent advances in the fabrication and characterization of Nano scale materials have extensively developed research into methods for the preparation of highly effective Nano-sized catalysts for the removal of chemical contaminants. This review article discusses the work on the photo catalysis of MTBE in water using different types of photo catalysts.

Natural organic matters (NOMs) have the main role in formation of trihalomethanes. These compounds are in natural water sources due to biological activities. In the presented study, adsorption and separation of humic acid as an index of natural organic matters using multi-walled carbon nanotubes is evaluated.
The experiments were carried out in bath adsorption reactors with different concentrations of humic acid. The effects of pH, adsorbent dose, national concentrations of humic acid and contact time as study variables were tested in separated experiments, as well as, kinetic and isotherm models of the adsorption process were determined.
The results showed that the adsorption follows Freundlich isotherm model and pseudo second-order kinetic equation. The removal percent of humic acid reached to higher than 90% with dosage of 1g/l of nanotube.
Adsorption of humic acid from water by multi-walled carbon nanotubes is an efficient alternative pretreatment method in water treatment plants.

Fluoride is an essential nutrient for the human body. The major routes of fluoride intake include food and drinking water, though the absorption of fluoride from food is much easier. The aim of this study was to evaluate the amount of fluoride in the soil and tomato and onion crops on farms of Zanjan.
Three farms of each crop (tomato and onion) were selected randomly. Each farm was divided into 10 sections, and one sample of soil and crop of each section was taken which means 120 samples in total. Fluoride concentrations in the soil and crops were measured using the Ion Selective Electrode (ISE) and repeated 3 times.
The mean concentration of fluoride in soil samples from studied farms in Zanjan was 0.83 ± 0.17 mg/kg. The mean concentrations of fluoride in tomatoes and onions of Zanjan were observed 2.10 ± 0.80 and 2.23 ± 0.64 mg/kg, respectively.
There was no significant difference between fluoride concentration in tomatoes and onions, although there was a significant difference between the amount of fluoride in the soils of studied farms (Pv

Background; Enzymes are well known as sensitive catalysts in the laboratory and industrial scale. To improve their properties and for using their significant potential in various reactions as a useful catalyst the stability of enzymes can often require improvement. Enzymes Immobilization on solid supports such as epoxy- functionalized ferric silica nanocomposite can be effective way to improve their characteristics.
Methods; In this study silica coated magnetite nanoparticles were Functionalized with GPTSM as a linker, then immobilization reaction performed by using various amounts of lipase B from Candida Antarctica (CALB), for the next step immobilization effects on thermal stability and optimum pH were investigated in comparison with free CALB.
Results; Results illustrated enzyme was successfully immobilized on nano particles and immobilized derivative retains 100% of its activity by 55°C while free CALB loss its activity at the same condition.
Conclusion; Immobilization of CALB on Fe3O4@SiO2 particles resulted in significant improvements in its characteristics such as thermal stability and methanol tolerance compared to the free CALB.

Various industries produce and discharge wastes containing different heavy metals into the environment. Apart from using living biomass, dead and dried biomasses have been introduced as a new field of biotreatment technology.
The cadmium (Cd) (II) removal characteristics of live (growing), dead (autoclaved), and oven-dried biomasses of Aspergillus versicolor were examined as a function of initial pH, contact time, and initial Cd concentration.
Maximum bioaccumulation of Cd for live biomass [11.63 (mg g−¹)] occurred at an optimal pH of 4 and incubation time of 4 days. Themaximum biosorption of 27.56 (mg g−¹) for dead biomass occurred at 1.5 h and at a pH of 4. The maximum biosorption [18.08 (mg g−¹)] with dried biomass was reached at an equilibrium time of 3 h at a pH of 6.
The present study confirmed that heat treatment promoted the removal capacity of fungi. Cd removal was increased by decreasing the pH in live and dead-mode experiments. Inversely, Cd removal was increased with increasing pH for the dried biomass of A. versicolor. Varying responses to environmental conditions (pH and contact time) clearly proved the different removal mechanisms used by three biomasses of A. versicolor. Higher Cd concentration increased the removal ability of three types of biomasses. The results indicated that all biomasses of A. versicolor used in this study, particularly dead biomass, are a suitable biosorbent for the removal of Cd (II) ions from aqueous solution.

Bio aerosols include airborne micro-organisms such as bacteria, fungi, viruses, etc and their products. Exposure to a bio aerosol is linked with a broad spectrum of health problems, including infectious diseases, acute toxic effects, allergies, and cancer. The aim of this study was to evaluate the quality and quantity of bio aerosols found in the air of different wards in Valiasr Hospital, Zanjan, in summer and fall 2012.
Air samples were collected from six wards including: operating room, infectious, ear, nose, and throat (ENT), surgery, adult intensive care unit (ICU), oncology and administrative with a single-step Anderson sampler. The type and number of colonies were determined in the laboratory, and then the bio aerosol density were calculated in terms of cfu/m3 and compared with the recommended limits.
The most common genera of isolated bacteria and fungi were Staphylococcus and Penicillium, respectively. In the infectious ward bacterial density was higher than the recommended limit of WHO (100cfu/m3) in the visiting times (afternoon). The fungal density in the meeting time (afternoon) in the ICU, ENT, and general surgery, infectious and administrative wards, and in non-visiting times (morning) in the infectious ward was higher than the recommended limit of WHO (50 cfu/m3).
From the findings of this study it can be concluded that the density of fungi and bacteria in the hospital air in some times of working period are higher than recommended levels and therefore, the condition of existing air filtration and ventilation systems should be appropriated according to the international standards of hospitals buildings

Qual2k is a stream water quality model and was used to evaluate the water quality of the Kine-Vars River and assess the response of the river to nutrient management strategies.
For that purpose, 7 sample stations were selected and surface water samples were collected in the winter and summer of 2012 and were analyzed for temperature, dissolved oxygen, biological oxygen demand, ammonia–nitrogen, nitrate–nitrogen, organic nitrogen, organic phosphorus, and inorganic phosphorus.
Results showed that the Kine-Vars River is saturated with N and P and is classified as eutrophic. The simulated data showed that the total nitrogen and total phosphorus loads of the studied river need to be reduced by 76% and 93%, respectively, to reach water quality objectives.
Application of nutrient control strategies can reduce the nutrient loads significantly but is not sufficient to change the river classification from eutrophic to oligotrophic in a short time thus, additional nutrient control measures are necessary.

Trihalomethanes have been known as carcinogen material for human by IARC. Considering the Zanjanś drinking water is supplied from the dam in 2008 and water disinfection with chlorine is performed, this study was carried out to determine THM concentrations in drinking water of Zanjan city.
In this descriptive-cross-sectional research, 32 samples were taken from storage tanks, effluent treatment plant and different points of drinking water distribution system after the city map meshing so that covers all parts of the system in winter and summer seasons in 2013. The reason for these two seasons been variations in the concentration of organic substances in water resources and consequently the concentration of THMs precursors produced and the effect of temperature on the formation of THMs. Gas chromatography technic was used in purge and trap method with electron capture detector for analyzing THM’s samples for each of four components including Chloroform, Bromodichloromethane, Dibromocholoromethane and Bromoform.
The average concentration of THMs in winter for Chloroform, Bromodichloromethane, Dibromocholoromethane and Bromoform, were 4.7±1.44, 4.72±1.25, 3.08±0.43 and 1.98±0.14 µg/Lit and in summer were 4.21±1.83, 4.71±1.8, 3.65±0.81 and 2.22±0.14 µg/Lit, respectively. The average of total THMs in winter equal to 14.19±3.09 µg/Lit and in summer equal to 14.81±4.4 µg/Lit.
Concentration of trihalomethanes and total trihalomethanes in Zanjan drinking water distribution system is lower than the national and international standards and the drinking water consumers arenot at risk of exposure to trihalomethanes.

Backgrounds and The base structure of total petroleum hydrocarbons (TPH) is made of hydrogen and carbon. Widespread use, improper disposal and accidental spills of this compounds lead to long term remaining of contaminations such as organic solvents and poly aromatic hydrocarbons (PAHs) in the soil and groundwater resources, resulting in critical environmental issues. In this study, an oil-contaminated soil was washed using Tween 80 surfactant and the application of photo-Fenton process (UV/Fe2+/H2O2) for treatment of the produced wastewater was evaluated. Tween 80 is a yellow liquid with high viscosity and soluble in water. In order to determine of the photo-Fenton process efficiency, we studied effective variables including Fe concentration, pH, H2O2 concentration, and irradiation time. The UV irradiation source was a medium-pressure mercury vapor lamp (400 w) vertically immersed in the solution within 2L volume glass cylindrical reactor. The results showed that efficiency of COD removal depends on the initial Fe concentration, pH, H2O2 concentration and irradiation time. Under optimum conditions, (Fe: 0.1mM, H2O2: 0.43 mM, pH: 3 and UV light irradiation time: 2 hours) the removal efficiency of COD was 67.3%. pH plays a crucial role in the photo-Fenton process such that the removal efficiency increased with decreasing of pH. According to the results of this study, under acidic condition, this process is an efficient method for COD removal from the wastewater studied.

 In the present investigation, the methyl tertiary-butyl ether (MTBE) removal efficiency from the synthetic solutions by the means of advanced oxidation process of UV/O 3 was studied. 

 To study the efficiency of process, the following variables were studied: ozone concentration, pH, MTBE initial concentration, and radiation duration. As The radiation source, a Mercury vapor UV lamp with moderate pressure (400W) was used which was immersed vertically in the solution containing MTBE, in a glass reactor (Volume: 2 L). 

 The results showed that the efficiency of UV radiation and ozone alone in 50 mg/L concentration and pH: 7 on MTBE removal was 4 and 53%, respectively. The UV/O 3 compound process removal efficiency in 60 minutes was 63%. The pH played a significant role in the process, as with the increase in pH, the removal rate increased as well. The removal rates for the initial concentrations of 10, 20, 50, and 100 mg/L of MTBE were 98, 81.5, 72.8, and 63.8%, respectively. 

 The results of the present survey indicated that the efficiency of the UV/O 3 combination process was more than ultraviolet (UV) and Ozone alone. In the UV/O 3 combination process, the MTBE removal efficiency increased as the O 3 concentration and pH increased, while the efficiency decreased as the MTBE concentration decreased.