Enhancement of the catalytic performance of Co-ZIF/WO3 heterostructures for selective catalytic reduction of NOx

Nitrogen oxides (NOx) are one of the growing air pollutants in industrial countries, and their emissions are regulated by stringent legislation. Therefore, the design of the catalyst comprised of metal oxides and ZIFs a potential solution for improving selective catalytic reduction (SCR) of NOx. Here, an efficient strategy was described to fabricate Co-ZIF/WO3 heterostructures for SCR of NOx. First, WO3 nanostructures were fabricated by the solvothermal method, and subsequently epitaxial growth of ZIF-67 on the metal oxide surface to create a new type of semiconductor Co-ZIF/WO3 heterostructures. The obtained heterostructures were systemically characterized by wide-angle XRD, FESEM, UV DRS, FT-IR, AFM, and TEM spectroscopies. The Co-ZIF/WO3 heterostructures shift the temperature corresponding to the maximum conversion around 50 °C towards lower temperatures. The maximum conversion is substantially enhanced from 55% at 400 °C to 78% at 350 °C. The enhanced activity is attributed to better interaction and synergic effect of WO3 incorporated into ZIF-67 and also the electron transfer facility between the WO3 and Co species in Co-ZIF/WO3 heterostructures. Moreover, Co-ZIF/WO3 results in a distinct effect on the production of carbon monoxide (CO) in the product gas stream. The current study highlights some of the challenges in the development of semiconductor-based heterostructures for a decrease in air pollution.

Fabricating modified carbon sesame straw for adsorption of acetaminophen and ibuprofen from aqueous media: isotherm and kinetic models

As acetaminophen (ACT) and ibuprofen (IBP) have serious environmental impacts, despite their widespread use in many countries, the present research examined the effectiveness of activated carbon made from straw and sesame stubble in removing ACT and IBP from water. To that end, the as-synthesized adsorbent was functionalized using zinc chloride. The maximum adsorption capacities were found to be 51.7 mg g-1 for ACT and 63.7 mg g-1 for IBP. The adsorption kinetics and isotherm results showed that the pseudo-second-order (PSO) kinetics and Langmuir isotherm fit the data obtained from this study better than the other experimental models do. Also, the adsorption reached equilibrium within 120 min, and the optimal adsorbent dose and temperature were obtained as 1.0 mg and 25 °C, respectively. The mechanisms involved in the adsorption process would include acid-base, hydrogen bonding, electrostatic forces, and π-π interaction. Reusability studies revealed that the adsorbent still preserved about 89% and 82% of the adsorption performance for ACT and IBP, respectively, after seven repeated adsorption cycles. As the findings indicated, CSS/Zn could be accepted as a hopeful adsorbent to be used in pharmaceutical treatment.

Parametric study and process modeling for metronidazole removal by rhombic dodecahedron ZIF-67 crystals

Metronidazole (MNZ) is an extensively used antibiotic against bacterial infections for humans and farm animals. Prevention of antibiotics discharge is essential to prevent adverse environmental and health impacts. A member of metal-organic frameworks, zeolite imidazole framework-67 with cobalt sulfate precursor (ZIF-67-SO4) and exceptional physio-chemical properties was prepared via room temperature precipitation to adsorb MNZ. The study framework was designed by Box-Behnken Design to evaluate the effect of pH, ZIF-67-SO4 dose, and contact time on adsorption efficiency. The polynomial model fitted the adsorption system indicated the optimal condition for 97% MNZ removal occurs at pH = 7, adsorbent dosage = 1 g/L, and mixing time = 60 min. The model also revealed that the removal increased with contact time and decreased at strong pH. Equilibrium and kinetic study also indicated the adsorption of MNZ followed the intra-particle diffusion model and the Langmuir isotherm model with a qmax = 63.03 mg/g. The insignificant loss in removal efficacy in use-reuse adsorption cycles reflected the practical viability of ZIF-67-SO4.

Molecular Epidemiology and Recycling of Staphylococcus aureus Resistant to Methicillin Among the Staff, Patients, and Surfaces in University Hospital in West Iran, Ilam

BACKGROUND

Staphylococcus aureus is a human pathogen causing nosocomial infections and increased hospitalization and mortality among human communities. Methicillin-resistant S. aureus strains are considered a severe threat in nosocomial infections and cause complications in the remedy process of bacterial infections. In this study, 137 samples were collected from different departments, staff, and patients in Ilam hospital.

METHODS

Eighty-eight samples of these strains were examined to test antibiotic resistance and diffusion. MIC (minimum inhibitory concentration) and PCR (polymerase chain reaction) were performed on the samples resistant to oxacillin. 36 (40.9%) strains were MRSA, and 52 (59.1%) isolates were MSSA. 44.4% of MRSA strains with IV SCCmec type.

RESULTS

Fourteen different spa types were found using spa typing, of which the most abundant types were t037, t030, and t701, and three new types, including t15471, t15474, and t17470, were identified among the strains. The molecular analysis by MLST showed that the strains are classified into 11 different sequence types. Sequence type 239 and clonal complexes of 329 and 22 were dominant. ST239- spat037-SCCmec III was also identified as the most frequent clone of MRSA. The most identified clones were MRSA ST239-spa t037-SCCmec III.

CONCLUSION

The results show the spa-type distribution between samples of patients, personnel, and surfaces, demonstrating MRSA circulation between patients and the environment. The results show the need to control environmental health.

Effect of COVID-19 on food security, hunger, and food crisis

COVID-19 affected the world’s socioeconomic and food security more than other infectious diseases. In many countries, food industries’ workers were moderated because of the COVID-19 pandemic, which caused food factories to reduce or slow down their production. Airline closures, national and international restrictions, and lockdowns have severely disrupted the food supply chain. These, along with structural weaknesses in the world food system such as production, distribution, access, and stability in the food chain, have exposed more people to the food crisis and acute hunger in the world. Therefore it is necessary to use proper planning by governmental organizations and charities in the field of food supply in critical situations.

Simultaneous monitoring of SARS-CoV-2, bacteria, and fungi in indoor air of hospital: a study on Hajar Hospital in Shahrekord, Iran

The novel SARS-CoV-2 outbreak was declared as pandemic by the World Health Organization (WHO) on March 11, 2020. Understanding the airborne route of SARS-CoV-2 transmission is essential for infection prevention and control. In this study, a total of 107 indoor air samples (45 SARS-CoV-2, 62 bacteria, and fungi) were collected from different wards of the Hajar Hospital in Shahrekord, Iran. Simultaneously, bacterial and fungal samples were also collected from the ambient air of hospital yard. Overall, 6 positive air samples were detected in the infectious 1 and infectious 2 wards, intensive care unit (ICU), computed tomography (CT) scan, respiratory patients' clinic, and personal protective equipment (PPE) room. Also, airborne bacteria and fungi were simultaneously detected in the various wards of the hospital with concentrations ranging from 14 to 106 CFU m-3 and 18 to 141 CFU m-3, respectively. The highest mean concentrations of bacteria and fungi were observed in respiratory patients' clinics and ICU wards, respectively. Significant correlation (p < 0.05) was found between airborne bacterial concentration and the presence of SARS-CoV-2, while no significant correlation was found between fungi concentration and the virus presence. This study provided an additional evidence about the presence of SARS-CoV-2 in the indoor air of a hospital that admitted COVID-19 patients. Moreover, it was revealed that the monitoring of microbial quality of indoor air in such hospitals is very important, especially during the COVID-19 pandemic, for controlling the nosocomial infections.

Application of health belief model to predict COVID-19-preventive behaviors among a sample of Iranian adult population

BACKGROUND

The novel coronavirus (COVID-19) has infected nearly 9.5 million people in 216 countries, areas, or territories in the world. The fight against the COVID-19 has become a very serious international challenge. The aim of this study was to determine the predictors of COVID-19-preventive behaviors using the health belief model (HBM).

MATERIALS AND METHODS

This cross-sectional study was conducted with the participation of 558 samples from the adult population of Iran. The online convenience sampling was conducted in this research. The online 68-item questionnaire link was published all over Iran through social networks including Telegram and WhatsApp, which are common in Iran. The data were analyzed using SPSS software version 19. Descriptive statistics, bivariate Pearson's correlation test, and multiple linear regression were used to analyze the data.

RESULTS

The mean age of the subjects was 33.3 ± 10.01 years. The participants were often female (61.3%), married (57.9%), and resident of the city (81.0%) with university educational level (78.8%). The results showed that the HBM structures predicted 29.3% of the preventive behaviors of COVID-19 in the subjects. The perceived benefits, perceived barriers, and self-efficacy significantly predicted the preventive behaviors, but the perceived susceptibility and perceived severity were not significant in the regression model. The internet and virtual social networks (49.8%), broadcast (33.5%), and healthcare providers (15.8%) were the most important sources of information related with COVID-19. In response to COVID-19-related internal cues to action, 36.6% did not pay attention and 34.7% tried to self-medicate. Only 28.5% of the subjects referred to the hospital, healthcare center, or physician.

CONCLUSION

Self-efficacy, perceived barriers, and perceived benefits were the key determinants of COVID-19-preventive behaviors in the subjects. It can be concluded that the HBM is a good tool to predict COVID-19-preventive behaviors in Iranian population.

The Effects of Personal, Environmental, and Genetic Factors on Epidemic of Coronavirus Disease-19: A Review of the Current Literature

Coronavirus disease (COVID)-19 is a viral disease that broke out in late 2019 in Wuhan, China. The World Health Organization has been forced to declare a public health emergency due to the global outbreak of COVID-19. The concerns about the COVID-19 disease are the rapid increase in the number of patients as well as the number of deaths compared with severe acute respiratory syndrome disease. Given that there is a remarkable variability amongst people for COVID-19 infection, there really is the possibility that there will be genetic and environmental effects, it is a need for their role to be fully clarified as soon as possible. Numerous studies have been performed on the on the stability of COVID-19 virus in different environmental conditions including temperature and humidity. In this study, we aimed to discuss in detail the benefits and effects of these factors on COVID-19. Some studies have confirmed the relationship between environmental conditions and disease transmission and others have rejected. Furthermore, not all COVID-19 exposed people are infected and not all infected patients develop severe respiratory complications. It is quite likely that these disparities are genetically mediated, in part. People who may be occupationally exposed to this virus may be due to different reasons, including lack of health, lack of knowledge and attitude, and working conditions. Reducing human-to-human contact by increasing the level of public health in the community as well as maintaining social distance plays a key role in prevention of COVID-19 disease. However, many aspects of COVID-19 are still unknown and require further and extensive studies.

Assessment of Knowledge, Attitude, and Practice toward COVID-19 among a Sample of Iranian General Population

BACKGROUND: The new coronavirus (COVID-19) pandemic is rapidly spreading around the world. At present (up to July 11, 2020), 255,117 cases and 12,635 deaths due to this disease have been reported in Iran. Following the guidelines recommended for the prevention and control of the disease is the most important approach to combating this global threat. AIM: The aim of this study was to assess the knowledge, attitude, practice, and fear of the Iranian people in relation to COVID-19. METHODS: A cross-sectional study was conducted with the participation of 558 Iranian people who entered the study by convenience sampling method. The knowledge, attitude, practice, and fear of the Iranian general population toward COVID-19 were collected using an online 50-items questionnaire. Descriptive statistics, one-way analysis of variance, independent sample T-test, and bivariate Pearson’s correlation were used to analyze the data. RESULTS: The studied subjects were mostly in urban area (81.0%), female (61.3%), and married (57.9%). The participants’ knowledge about personal hygiene (88.9%), using a facemask (82.2%), and the symptoms of the COVID-19 (76.8%) were adequate. However, their knowledge about contaminated surfaces disinfection procedure (41.8%), and the importance of using a facemask for healthy people (43.7%) was lower. The highest level of the subjects’ attitude was related to the role of social distancing (94.6%), staying at home (94.5%), and personal hygiene (91.2%). The low levels of attitude were also associated with access to personal protective equipment (84.1%) and the psychological effects of COVID-19 (65.3%). Furthermore, the highest levels of practices were related to avoiding hand shaking with others (91.5%) and washing hands frequently (88.8%). The practices such as following a healthy and nutritious diet (45.1%) and wearing gloves (51.4%) were reported to be less common. CONCLUSION: The results showed that about half of the subjects did not have enough knowledge about COVID-19. However, the attitude and practice of most of the participants toward COVID-19 were moderate or good. Nevertheless, the extensive health education interventions are needed to promote knowledge about COVID-19 and also to motivate people to do preventive behaviors.

Removal of Penicillin G from aqueous solutions by a cationic surfactant modified montmorillonite

Nowadays, antibiotics have been found in the effluents of many pharmaceutical industries and hospitals, sanitary sewage, surface water and groundwater. The purpose of this study was to investigate the possibility of using Hexadecyl Trimethyl Ammonium Bromide modified montmorillonite (HDTMA-Mt) as an inexpensive and suitable adsorbent for the removal of Penicillin G from aqueous solutions. The experiments were conducted in a batch system. The effects of different variables including surfactant loading onto the clay, solution pH, contact time, adsorbate concentration and temperature were investigated on the removal of Penicillin G. Surface properties of the clay were evaluated using X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) techniques. Various isotherms (Langmuir and Freundlich) and kinetics (pseudo-first order, pseudo-second order and intraparticle diffusion models) of adsorption were studied for the data evaluation. The findings indicated that the sorption capacity of the modified clay was found to be 88.5 mg/g over 60 min contact time at pH 9. The pseudo-second kinetic (R2 = 0.999) and Freundlich isotherm (R2 = 0.915) models best fitted the experimental data of Penicillin G by the adsorbent. The negative values of ΔG at higher temperature and positive value of ΔH showed the endothermic and spontaneously sorption of the drug by the clay. It can be concluded that the modified clay can be considered as a cheap and eco-friendly sorbent for the removal of Penicillin G from water and wastewater.

Evaluation of phosphate removal from aqueous solution using metal organic framework; isotherm, kinetic and thermodynamic study

BACKGROUND

Phosphate (PO₄ ^3-) is the main etiological factor of eutrophication in surface waters. Metal organic frameworks (MOFs) are novel hybrid materials with amazing structural properties that make them a prominent material for adsorption.

METHODS

Zeolitic imidazolate framework 67 (ZIF-67), a water stable member of MOFs, with a truncated rhombic dodecahedron crystalline structure was synthesized in aqueous environment at room temperature and then characterized using XRD and SEM. PO₄ ^3- adsorption from synthetic solutions using ZIF-67 in batch mode were evaluated and a polynomial model (R²: 0.99, R² _adj: 0.98, LOF: 0.1433) developed using response surface methodology (RSM).

RESULTS

The highest PO₄ ^3- removal (99.2%) after model optimization obtained when ZIF-67 dose, pH and mixing time adjusted to 6.82, 832.4 mg/L and 39.95 min, respectively. The optimum PO₄ ^3- concentration in which highest PO₄ ^3- removal and lowest adsorbent utilization occurs, observed at 30 mg/L. PO₄ ^3- removal eclipsed significantly in the presence of carbonate. The equilibrium and kinetic models showed that PO₄ ^3- adsorbed in monolayer (q_max: 92.43 mg/g) and the sorption process controlled in the sorption stage. Adsorption was also more favorable at higher PO₄ ^3- concentration, according to the separation factor (K_R) graph. Thermodynamic parameters (minus signs of ∆G°, ∆H° of 0.179 KJ/mol and ∆S° of 44.91 KJ/mol.K) demonstrate the spontaneous, endothermic and physisorption nature of the process.

CONCLUSION

High adsorption capacity and adsorption rates, make ZIF-67 a promising adsorbent for PO₄ ^3- removal from aqueous environment.

Preparation, characterization and Cr(VI) adsorption evaluation of NaOH-activated carbon produced from Date Press Cake; an agro-industrial waste

Date Press Cake (DPC) is an inevitable by-product of date processing industries and may pose environmental problems if not managed properly. In this study, DPC was converted into activated carbon using solid NaOH under various activation conditions. The prepared activated carbon showed high specific surface area (2025.9 m² g^-1) and microporous texture (86.01%). It was successfully applied for the adsorption of Cr(VI) from aqueous solutions with maximum monolayer adsorption capacities as high as 282.8 mg g^-1 (pH = 2) and 198.0 mg g^-1 (pH = 5). The kinetic and isotherm experimental data of Cr(VI) adsorption onto the activated carbon were best described by Elovich and Redlich-Peterson models, respectively. It was found that the Cr(VI) adsorption onto the DPC-derived activated carbon was predominantly a chemisorption process with limited desorption rates (below 50%). Overall, Date Press Cake could be considered as an abundant and renewable agro-industrial precursor for the production of high quality activated carbon.

Cationic Surfactant-modified Clay as an Adsorbent for the Removal of Synthetic Dyes from Aqueous Solutions

In this study, the potential of hexadecyl trimethyl ammonium bromide modified montmorillonite (HDTMA-Mt) to remove the synthetic dyes Alizarin Red S (ARS) and Bromocresol Green (BCG) from aqueous media was assessed. The effect of different factors including surfactant loading rate onto the clay, contact time, pH, adsorbent dosage and dye concentrations, on the removal of ARS and BCG in batch systems were investigated. The adsorbent was characterized by means of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometry (XRD). The equilibrium time for ARS and BCG was reached at 40 and 20 min, respectively, under optimized conditions (i.e. pH = 3, adsorbent dosage=1 g/L, surfactant loading rate onto the clay 70% of the cation exchange capacity (CEC) for ARS and 120% of the CEC for BCG, ARS concentration 50 mg/L and BCG concentration 500 mg/L). The adsorption rate of both dyes fitted the pseudo-second-order kinetic model and the equilibrium data was described by the Freundlich isotherm equation. The maximum monolayer adsorption capacities were equal to 666.6 and 1250 mg/g for ARS and BCG, respectively. Therefore, the HDTMA-Mt can be considered as an effective adsorbent for the removal of ARS and BCG from aqueous solutions.

Food Safety Knowledge and Practices of Male Adolescents in West of Iran

BACKGROUND:

Every year many people around the world become infected with food-borne infections. Insufficient knowledge and skills related to food safety and hygiene are among the factors affecting the incidence of food-borne diseases, especially in adolescents.

AIM:

The purpose of this study was to determine the knowledge and practices associated with food safety and hygiene in Ilam city male adolescents.

MATERIAL AND METHODS:

Three hundred and eighty of male adolescents aged 13 to 19 were selected randomly and entered the cross-sectional study. Data were collected using a researcher-made questionnaire From December 2016 to February 2017. Descriptive statistics, Pearson correlation, independent t-test and one-way ANOVA were used to analyse the data in SPSS software (version 19.0).

RESULTS:

The findings of the study showed a positive and significant relationship between knowledge and practices related to food safety and hygiene (r = 0.122; p = 0.018). Also, the findings showed that food safety knowledge and practice of adolescents were significantly affected by the level of their education, parental education level, parental employment status and household economic conditions, (p < 0.005). Also, the results showed that the participants generally obtained 57.74% of the knowledge score and 57.63% of practices score. The subjects had the most knowledge about food supply and storage (60%), and the highest practice was related to personal and environmental hygiene, (61.73%).

CONCLUSION:

The inadequacy of knowledge and performance of adolescents about food safety and hygiene shows the need for implementation of health education interventions in this area.

A time series analysis of environmental and metrological factors impact on cutaneous leishmaniasis incidence in an endemic area of Dehloran, Iran

The aim of this study was to investigate the relationship between the environmental and metrological variables and cutaneous leishmaniasis (CL) transmission and its prediction in a region susceptible to this disease prevalence using a time series model. The accurate locations of 4437 CL diagnosed from 2011 to 2015 were obtained to be used in the time series model. Temperature, number of days with temperature over 30 °C, and number of earthquake were related to CL incidence using the Seasonal Auto-correlated Integrated Moving Average (SARIMA) model according to the Box-Jenkins method. In addition, the relationship between land use and surface soil type in 500- and 1000-m radius around the CL patients were investigated. The SARIMA models showed significant associations between environmental and meteorological variables and CL incidence adjusted for seasonality and auto-correlation. The result indicated that there are need more robust preventive programs in earthquake-prone areas with high temperature and inceptisol soil type than other areas. In addition, the region with these characteristics should be considered as high-risk areas for CL prevalence.

Adsorption of Congo Red Dye from Aqueous Solutions by Montmorillonite as a Low-cost Adsorbent

In this study, the sorption of Congo red (CR), as a toxic dye, from aqueous media was investigated using montmorillonite (MMT) as a low-cost adsorbent. The influence of several factors such as contact time, pH, adsorbent dosage, dye content, and ionic strength was investigated on the dye removal. MMT was characterized by Fourier transformed infrared (FTIR) spectroscopy and X-ray diffractometer (XRD). Different kinetic and isotherm models including pseudo-first and pseudo-second order kinetic and Langmuir and Freundlich were applied to analyze experimental data, respectively. The results showed that the data were well fitted by pseudo-second-order kinetic and Freundlich isotherm models. The optimum conditions for the sorption of CR were achieved over 40 min and at pH=2. According to the results of the present study, MMT can be used as a low-cost, eco-friendly and effective option for the adsorption of CR from aqueous solutions.

Experimental Study and Mathematical Modeling of Propane-SCR-NOx Using Group Method of Data Handling and Artificial Neural Network

In this study, the catalytic behavior of protonated clinoptilolite in propane-SCR-NOx was investigated. The experiments were carried out in the temperature range of 200–500 °C as a function of zeolite mesh size 20, 35 and 70 at different weights of zeolite (0.45–1 g) and flow rates (300–600 ml/min) and consequently at various gas hourly space velocities (GHSV). Group method of data handling (GMDH) and artificial neural network (ANN) system were applied for mathematical modeling of NOx conversion to N2 in propane-SCR-NOx. The operating temperature (T), volumetric flow rate (F) and the weight of clinoptilolite zeolite (W) and the conversion of NOx to N2 (X) were considered as the inputs and output, respectively. In order to evaluate the models performance, conversions of NOx obtained from the GMDH and ANN systems were compared with those obtained from the experimental method. It is concluded that the ANN could successively estimate the conversion and the results were in a good agreement with the experimental data.

The Effect of Dust Storm on the Microbial Quality of Ambient Air in Sanandaj: A City Located in the West of Iran

Background and Aims:

The presence of pathogenic microorganisms in the dust storm can cause diseases such as Asthma, Pneumonia, and respiratory infections. The aim of this study was to determine the relationship between air-borne particles with airborne microorganisms in normal and dusty days in Sanandaj, a city located in the west of Iran.

Materials and Methods:

Air sampling was conducted during the normal and dusty days through Andersen single-stage impactor (28.3 L/min) for 2.5 min. Air particles concentration (PM₁₀) was measured daily and microbial sampling was also conducted on every six days and on the dusty days. Finally, the data was analyzed by SPSS-16 (ANOVA and paired T-tests).

Results:

The concentration of airborne microorganisms (bacteria and fungi) was increased by an increase of the airborne particles. Particles concentration in May, June and July (twice per month) was more than of the standard value. The predominant species of bacteria and fungi during the occurrence of Dust storm was Bacillus spp. (56.2% of total bacteria) and Mycosporium spp. (28.6% of total fungi), respectively.

Discussion and Conclusion:

The results showed that the number of airborne microorganisms (bacteria and fungi) increased during the dust storm. Therefore, the microorganisms in the dust storm can cause biological harmful effects on human health.

Investigation on the lung function of general population in Ilam, west of Iran, as a city exposed to dust storm

BACKGROUND

Dust storm is one of the most important natural sources of air pollution in the Middle East that has caused a major concern in recent years. The aim of this study was to evaluate the respiratory tract function of people living in Ilam city (Iran) during dust storm.

METHODS

A sample size of 250 people was selected and the cluster sampling was randomly used from 13 health centers in Ilam city. Pulmonary function test (PFT) was determined via a standard spirometry apparatus. Vital capacity (VC), Forced Vital capacity (FVC), FVC in first second (FEV1), FEV1/VC, FEV1/FVC, peek expiratory flow (PEF), forced expiratory flow (FEF25-75%), forced expiratory flow (FEF25-75%), forced expiratory flow (FEF75-85%), forced mid flow time (FMFT) and maximum voluntary ventilation (MVV) were measured.

RESULTS

Mean values of respiratory capacities measured in all participants excluding FEV1/VC and FMFT were less than predicted mean values by ECCS reference. 21.6% of the population suffered from obstructive lesions. This value among males (24.1%) was more than females (19.6%). This could be related to more exposure (outdoor jobs) of males with dust storms.

CONCLUSION

The results also showed a negative significant relationship between duration of inhabitance in Ilam city and all respiratory capacities. Further studies are needed for confident confirmation of whether reduction of respiratory capacities among Ilamian people is only related to dust storms.

Investigation on the trophic status of Ekbatan reservoir: a drinking water supply reservoir in Iran

BACKGROUND

Eutrophication is one of the detrimental environmental problems in water reservoirs dye to the irregular introducing nutrients (phosphorus and nitrogen). This study aimed to explore the eutrophication state of Ekbatan Reservoir, Hamadan, western Iran.

METHODS

Monthly sampling was conducted during April 2010 to March 2011. Seven sampling stations were selected in the various locations of the reservoir and the samples were collected in the depth of 50 cm. The grab sampling of water for nitrogen, phosphorous and chlorophyll-a was carried out at all localities by Hatch sampler. The trophic state of the dam was determined by Carlson's Trophic State Index (TSI) and Chapra's classification.

RESULTS

The highest concentrations of phosphorus and chlorophyll-a were measured in August and the lowest concentration for both of the parameters was determined in February. The TSI index according phosphorus concentration showed that the reservoir was in eutrophic status during May to November and was in mesotrophic status over November to May.

CONCLUSIONS

It seems that the eutrophication process in the lake was resulted from the rural wastewaters and agricultural fertilizers. Therefore, using long term management methods including prevent of uncontrolled discharge of agricultural wastewaters is recommended in order to reduce the eutrophication in the reservoir. Decrease of phosphorus concentration in the dam by 50% can convert the eutrophic state to mesotrophic state.

Application of Glycyrrhiza glabra root as a novel adsorbent in the removal of toluene vapors: equilibrium, kinetic, and thermodynamic study

The aim of this paper is to investigate the removal of toluene from gaseous solution through Glycyrrhiza glabra root (GGR) as a waste material. The batch adsorption experiments were conducted at various conditions including contact time, adsorbate concentration, humidity, and temperature. The adsorption capacity was increased by raising the sorbent humidity up to 50 percent. The adsorption of toluene was also increased over contact time by 12 h when the sorbent was saturated. The pseudo-second-order kinetic model and Freundlich model fitted the adsorption data better than other kinetic and isotherm models, respectively. The Dubinin-Radushkevich (D-R) isotherm also showed that the sorption by GGR was physical in nature. The results of the thermodynamic analysis illustrated that the adsorption process is exothermic. GGR as a novel adsorbent has not previously been used for the adsorption of pollutants.

Ultraviolet irradiation: An effective inactivation method of Aspergillus spp. in water for the control of waterborne nosocomial aspergillosis

Invasive aspergillosis is the second most common cause of nosocomial fungal infections and occurring mainly by Aspergillus fumigatus, Aspergillus flavus, and Aspergillus niger. There is evidence that nosocomial aspergillosis may be waterborne. This study was conducted to evaluate the ultraviolet (UV) irradiation efficiency in terms of inactivating the most important Aspergillus species in water since these are potential sources for nosocomial aspergillosis. A continuous flow UV reactor which could be used as a point-of-use (POU) system was used to survey Aspergillus inactivation by UV irradiation. The inactivation efficiency of UV fluence (4.15-25 mJ/cm(2)) was measured by determination of fungal density in water before and after radiation. Because turbidity and iron concentration are two major water quality factors impacting UV disinfection effectiveness, the potential influence of these factors on UV inactivation of Aspergillus spp. was also measured. The 4 log inactivation for A. fumigatus, A. niger and A. flavus at a density of 1000 cfu/ml was achieved at UV fluences of 12.45 mJ/cm(2), 16.6 mJ/cm(2) and 20.75 mJ/cm(2), respectively. The inactivation efficiency for lower density (100 cfu/ml) was the same as for the higher density except for A. flavus. The removal efficiency of Aspergillus spp. was decreased by increasing the turbidity and iron concentration. UV disinfection could effectively inactivate Aspergillus spores from water and eliminate potential exposure of high-risk patients to fungal aerosols by installation of POU UV systems.