فصلنامه سلامت و محیط زیست
سال هشتم شماره 2 (پیاپی 28، تابستان 1394)

Phenol and phenol derivatives in industrial wastewater are among the pollutants with priorities. The high cost and low efficiency of some routine treatment processes of industrial wastewater has limited their use. One of the new methods under consideration is، nowadays، adsorption using carbon nanotubes. This study was conducted in order to evaluate the application of alumina-coated multiwall carbon nanotubes in eliminating phenol from synthetic wastewater. This study was performed in laboratory at batch scale. Multi-wall carbon nanotubes were coated with Alumina. The concentration of phenol was determined by spectrophotometer through photometry. The effect of pH changes، dosage of adsorbent، contact time، the initial concentration of phenol، temperature، and the concentrations of different salts on the efficiency of absorption was evaluated. Then، the absorption results were described using the Langmuir and Freundlich isotherms and the synthetics of absorption. It was found that absorption efficiency increased significantly by decreasing the initial concentration of phenol and pH and by increasing the carbon nanotube dosage، temperature، and contact time. On the other hand، the maximum elimination of phenol from the solution (98. 86%) occurred at 4 mg/l phenol concentration، under acidic conditions (pH=3)، at adsorbent dosage of 0. 05 g/l، at temperature of 45°C، and contact time of 10 min. Evaluation of the regressions isotherms showed that the process follows the Langmuir model and second-degree synthetic absorption. The high efficacy (98%) of the adsorption process in this study showed that alumina-coated multiwall carbon nanotubes have a good capability in eliminating phenol and can be used as an appropriate and new method for eliminating phenol and its derivatives from wastewater.

Among the different types of antibiotics, tetracycline antibiotics are the second most common group around the world that their entrance into domestic sewage can result in contamination of water sources. The aim of this study was to investigate the efficacy of the nano-sonocatalytic process on removal of tetracycline antibiotics from aqueous solutions. In this study, the effectiveness of ultrasonic irradiation without and with TiO2 nanoparticles and hydrogen peroxide were studied in tetracycline antibiotics removal. For this purpose, a reactor different concentrations of tetracycline was exposed to two irradiation frequencies of 35 and 130 KHz. Concentration of residual antibiotic was measured using HPLC equipped with a C18 reverse phase column and a UV detector. It was found that the efficacy of ultrasonic irradiation alone in removal of this pollutant was negligible and at the best conditions only 20.3% removal was achieved at the frequency of 35 KHz. Addition of TiO2 nanoparticles improved the removal efficiency; the removal rate increased with the increase in TiO2 concentration until 250 mg/L, after which it remained approximately stable. The best removal efficiency was achieved by adding 100 mg/l hydrogen peroxide to US/TiO2 process at pH 4 in which 94.3% removal was achieved after 60 minute. The results of this study showed that the sonocatalytic process using TiO2 nanoparticles and along with adding H2O2 as an oxidant is very effective and can be used for removal of tetracycline antibiotics from aqueous solutions.

Food borne diseases are one of the common and persistent problems of health system that staff in food preparation and distribution centers play important role in their incident. This study aimed to evaluate the effects of educational courses on changing hygienic knowledge and practice of managers and staff in food preparation and distribution centers in Mashhad in 2012. In this cross-sectional study, knowledge and practice in tree domains of personal, construction and tools hygiene were studied in 513 employees and employers of food preparation and distribution centers in Mashhad. The data was collected through interview, observation, and inspection checklist. 265 subjects (51.6%) passed training course and awarded certificate, while 248 subjects (48.4%) did not participate whatsoever in training courses. Mean scores of knowledge and performance in trained group were 68.1±16.1 and 70.8±10.5% and in untrained group were 62.6±15.4 and 61.8±11.6% respectively, indicating statistically significant difference (p<0.05). Comparing scores of knowledge and practice scores between employers with valid certificate (during last 3 years) with employers without certificate did not show any valuable statistically difference in score reduction. This study showed that hygienic training courses can be effective in improving knowledge and practice of managers and staff in food preparation and distribution centers.

Benzene is one of the main pollutants in air and one of the most extensive chemical compound used in both natural and industrial processes. Benzene exposure leads to the most dangerous adverse health effects, particularly blood cancer. The aim of this study was to evaluate the gas station workers’ exposure to benzene by measuring benzene in breathing air and urinary trans, trans-muconic acid. This cross-sectional study conducted in summer 2014 investigated 40 gas station workers and 40 occupationally non-exposed persons. Spot urine samples were obtained prior to and at the end of the work shift from each subject. The urinary levels of trans, trans-muconic acid was determined by liquid chromatography (HPLC) with diode array detector. At the end of the work shift, the benzene collected on sorbing cartridges was desorbed using carbon disulfide and was analyzed using gas chromatography and mass spectrometry detection. The mean value for exposure to benzene in breathing zone of gas station workers was 5.90 ±1.93 ppm, which was significantly greater than the occupationally non exposed group (1.15±0.744 ppm). The mean urinary concentrations of trans, trans-muconic acid differed significantly between samples of gas station workers (64.75±19.47 μg/L) and occupationally non-exposed persons (47.10±13.67 μg/L). A good correlation (r = 0.581) between the mean values of benzene in breathing zone and the urinary concentration trans, trans-muconic acid was observed. Gas station workers were found to be probably the most exposed groups in this study. Inhalation is presumably the main route of exposure in gas station workers.

Natural organic matters (NOMs) are a mixture of chemically complex polyelectrolytes with varying molecular weights, produced mainly from the decomposition of plants and animal residues. Various purification methods are used for removal of NOMs from water. The objective of this study was to remove NOMs from aqueous solution using reformed continuous carbon nanotubes column. The removal of NOMs from aqueous solution using reformed continuous carbon nanotubes column was studied. Effect of several variables such as zero point of pH (pHZPC), pH, influent concentration of natural organic matters were studied and different isotherms were assessed. Investigation of pH effect showed that the adsorbability of NOMs increased with decreasing of pH. The experiments indicated that carbon nanotubes (CNT) samples exhibit pHZPC around 6. Results from Freundlich, Langmuir, and BET isotherm experiments revealed that the correlation coefficient R2 in Freundlich model was higher than that of Langmuir. In addition, experiments of continuous flow in different initial concentrations of NOMs showed that the adsorption capacities of CNT were 53.46, 30.40, and 24.75 mg/g for NOMs initial concentrations of 10, 5, and 3 mg/L, respectively. The present study shows that CNTs have high potential for adsorption of NOMs from aqueous solution.

Natural organic matters (NOM) are known as precursors to disinfection byproducts. As conventional treatment processes cannot get disinfection by-product standards, novel methods have been increasingly applied for the removal of disinfection by-products precursors. The UV/ZnO process is one of the advanced oxidation processes using photocatalytic technology. The present study aims to investigate the effect of UV/ZnO photocatalytic technology on the NOM removal from aqueous solution. This study was conducted in a lab-scale batch photocatalytic reactor. The volume of reactor was 1liter and covered with UV lamps. Peristaltic pump was used for complete mixing. Humic acid is a key component of natural organic matter and it was used in this study. Each of the samples taken from the UV/ZnO process and other processes were analyzed for their UV absorbance at 254 nm by spectrophotometric. Initial concentration of Humic acid, contact time, pH, and UV irradiation were investigated. The highest efficiency of the UV/ZnO photocatalytic process for removal of Humic acid from aqueous solution was achieved at initial concentration = 2 mg/L, contact time = 120 min, UV irradiation = 3950 μw/cm2, and pH=3. In this process, the removal efficiency for 2 mg/L humic acid was 100 % at 2h retention time. The research showed that performance of system was increased by increasing contact time and UV irradiation and was decreased by increasing HA initial concentration and pH and UV radiation with ZnO agent could not remove NOM lonely. Photocatalytic system using zinc oxide immobilized on glass have high performance to remove humic acid from aqueous solution. The UV/ZnO process was efficient and environmental friendly for natural organic matter removal.

Over the past few decades, the entry of pollutants, especially PAHs compounds in natural ecosystems such as lakes and open water for aquatic organisms has created potential environmental hazards. This study aimed to investigate the extent and pattern of bioaccumulation of pyrene oil pollution in muscle, gill, and liver of common carp (Cyprinus carpio) cultured in vitro. thirty fishes with mean weight of 140±10g were exposed to 10, 50, and 100 μg/l pyrene. At the end of the 35 days trial period, fish were sampled in order to study the pyrene accumulation in different tissues. Preparing process of samples include soaping, extracting, and two-phase chromatography and finally injecting samples to the gas chromatography-mass spectrometry. Comparison between bioaccumulation of pyrene in muscle, gill, and liver tissues of cyprinus carpio in 10, 50, and 100 μg/l doses showed significant differences. Maximum average accumulation was in liver (dose100) with 685.67 ± 78.5 and the minimum was in muscle in dose 10 with 0.52 ±. 0.13 pyrene’s accumulation trend was the same in all studied doses: liver>gill>muscle. In the present study, pyrene accumulated in fatty tissue, especially liver-acceptor of all of the oil pollutants- was far more than of gills and muscle.

PAHs are main components of urban air pollution and are mutagenic for human being. Seasonal variations have effects on the amount of exposure to PAHs. The objectives of this research were to determine the amount of newsagent’s exposure to PAHs found in the urban atmosphere of Tehran City during warm and cold periods and comparing exposure levels in two periods. The assessment of personal exposure was performed based on NIOSH method 5515 and was analyzed by gas chromatography–mass spectrometry (GC/MS). Mann- Whitney test was used to determine the effects of seasonal variation on the amount of newsagent’s exposure to PAHs. The mean levels of newsagent’s exposure to benzo[a]pyrene in the south area of Tehran City were 0.148±0.010 and 0.417±0.041 μg/m3 in summer and autumn seasons respectively. The amount was higher than the mean levels of newsagent’s exposure in other geographic areas of city. The levels of newsagent’s exposure to all PAHs (p<0.001) were significantly higher in autumn compared with summer. The levels of exposure to PAHs during autumn were 2 to 3 fold higher than the levels of exposure during summer. Newsagents in the south area of Tehran City were experiencing higher levels of exposures to PAHs.

Events are the second leading cause of disability and one of the problems that can cause physical and psychological disorders, and in more severe cases lead to death. Therefore, at the first, the risks must be identified, so that one can offer how to confront and eliminate risk. Thus, this study aimed to determine the frequency and type of events among nomads. This cross-sectional study was performed on 534 nomad in Chaharmahal- Bakhtiari Province during first half of 2014. The data collection was through interviews based on a predetermined checklist and finally the data gathered were analyzed using SPSS (Ver.19) software and descriptive statistics. It was found that out of 534 nomads, 144 were female (26.97%) and 390 male (73.03%) and age average of them was 26.32±24.12. These people are often faced with 18 types of events in their location or during their shifting; the most frequent one is caused by sinking of thorns and sharp rock aggregates in their organs during labor activities (62.46%) and the least frequent one was hurt caused by lightning (0.19%) and electric shock by electrical tower (0.19%). The results showed that there was a significant relationship between sex, season of the year, the summer location, and accident rate (P ≤0.002) but there was no significant relationship between the nomads and clans of the study and event rate. Like many diseases, events are preventable, and this requires the development of knowledge about the principles of safety during migration and housing. Therefore, it seems that for the preserving nomadic population and reducing lost caused by these events, the national event management centers and emergency medical centers should have better planning in this field.

Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants in aquatic environments. These contaminants are generated through oil spills, manufactory processes, and industrial wastes or naturally through the incomplete combustion of coal, oil, gas, and wood waste. Most of these compounds are noted as carcinogenic and mutagenic. Therefore, detection of these pollutants by a sensitive and inexpensive method is very important. In this study, an electrochemical DNA biosensor was used to detect PAHs due to its sensitivity, ability, and high response rate. For this purpose, the bovine thymus double-stranded DNA was fixed on a screen-printed electrode. Then, the electrodes electrochemical behavior was investigated. This electrochemical DNA biosensor works upon the difference between the electrochemical response of guanine bases in DNA structure in the presence and absence of PAH compounds. To evaluate the biosensors performance, the response of biosensor to real samples was compared with conventional pollutant determination methods like liquid-liquid chromatography. Optimum conditions were examined for biosensor response including effect of activation potential and time on electrode pretreatment, applied potential for DNA immobilization, and detection potential. Under optimal conditions, the pretreatment of the electrode obtained in 1.6 V for 350s, then the DNA was immobilized on the electrode surface by applying a potential of -0.5 V to detect different PAHs in real samples in the range of micro molar. Electrochemical DNA biosensors are capable of detecting the sum of PAHs in water samples with high accuracy, sensitivity, and low cost compared with chromatographic methods.

Polycyclic aromatic hydrocarbons (PAHs) are considered as important organic contaminants due to their high toxicity and carcinogenic properties. Among PAHs, phenanthrene is found in most contaminated sites. Sorption and desorption of phenanthrene in soil affect the fate of the contaminant in soil-water system. Presence of organic matter (OM) in the soil matrix can also affect sorption and desorption of phenantherene. In this research, effect of soil organic matter on sorption of phenanthrene in kaolin soil was studied. The sorption of sorption of phenanthrene in kaolin clay was assessed in the presence and absence of organic matter. These two soil types were used in batch sorption experiments of Phenanthrene to determine the sorption properties. It was found that organic matter increases the cation exchange capacity, water content, and pH of the soil. Sorption of phenantherene in both kaolin and OM-added kaolin was better fitted with Freundlich linear model. Moreover. soil organic matter increased phenanthrene sorption in soil. It was observed that with 41.04% increase in OM, distribution coefficient of phenanthrene sorption in soil increased by 36.69%.

Significant increase in population and as a result, the production of excessive waste has recently made attention to municipal solid waste management a necessary issue. The objective of this study was to use matrix-based EIA process in order to determine best waste management option in Birjand City and to suggest appropriate solutions to managers and planners of this city. Assessing the environmental impacts of waste management options was done using Iranian Leopold Matrix. Through this method, the environmental impacts of waste management options were determined in the Birjand City. The options were Open dumping, Recycling, Composting, and Sanitary damping. The results indicated that Open dumping with a final score of -3.06 had the highest environmental impact and was introduced as the fourth preference. In addition, composting with final score of -2.34 has the lowest environmental impact compared with other options. About 76.95% of the composition of municipal solid waste of Birjand City is household waste; therefore, putrescible organic materials are the predominant waste. Thus, according to the results of the Iranian Leopold matrix method, composting option was introduced as the first priority and the most logical option for waste management in the Birjand City.