Bioremediation of methyl tertiary-butyl ether (MTBE) by three pure bacterial cultures

Background: Bioremediation of groundwater and soil contamination is more economical than physicochemical remediation. The present study focused on the bioremediation capability of two bacterial species (Klebsiella planticola and Enterobacter cloacae) from the family Enterobacteriaceae. These bacteria have been identified as new species with capability of degrading methyl tertiary-butyl ether (MTBE). In order to enhance their degradation capability, selected concentrations and retention time were investigated. Methods: The bacteria were cultured on the nutrient agar (NA) medium at room temperature. pH of the medium was adjusted to 7. The medium was autoclaved at 121°C for 15 minutes and incubated for 24 hours at 35°C. After 24 hours, the mixture was inoculated into 50 mL of Luria Bertani (LB) liquid medium containing 50 and 150 ppm MTBE. The cultures were incubated for 2 and 5 days at 35°C and shacked on a shaker at 150 rpm. Cell concentrations of the bacteria in pure culture were determined from the optical density at 600 nm using a UV–VIS spectrophotometer. Then, the culture was centrifuged at 3800 rpm for 20 minutes. In the next step, the MTBE concentration in the supernatant was measured by gas chromatography/mass spectrometry (GC/MS, Agilent Technologies, 5975, US10304411, 5.02.07). Results: The results showed that both strains are able to grow in the presence of 50 and 150 ppm MTBE. In the best conditions, when cell density was 3×108 CFU/mL during 5 days, the highest rate of MTBE degradation for K. planticola and E. cloacae, was 43% and 40%, respectively. It was also revealed that Escherichia coli can degrade 50 and 150 ppm MTBE about 19.8% and 13.65%, respectively. Conclusion: It seems that E. coli can be a good candidate for MTBE degradation at high concentrations for a time longer than that in the present study. It was also found that the species have high performance at 50 ppm than 150 ppm. So, these bacteria can remove MTBE from the environment. Keywords: Biodegradation, Klebsiella planticola, Enterobacter cloacae, Escherichia coli, methyl tertiarybutyl ethe

Efficiency of wastewater treatment plants in removal of intestinal parasites: A review approach

of the spread and entry of parasitic pathogens into the environment and water resources. Numerous studies have been conducted on the presence of parasitic agents in the entry and effluent of WWTPs in different countries. This study was conducted to review the parasite prevalence in different WWTPs and assess their removal efficiency. Methods: ScienceDirect, Scopus, Web of Science, and PubMed databases and other sites with the ability to receive a full-text related articles, were reviewed. Various keywords such as parasites, wastewater, effluent, treatment efficiency, protozoan cysts, parasitic eggs, and similar keywords were used to search articles published from 2005 to 2019. After screening the titles and abstracts of articles, 26 articles were reviewed in this study. Results: Giardia spp, Cryptosporidium spp, Entamoeba spp, Blastocystis spp, Toxocara spp, Trichostrongylus spp, A. lumbricoides, and Hymenolepis are the most prevalent parasites. Studies show that parasitic egg hatching rates are up to 5%, in aerated lagoons, up to 99.9%, in activated sludge, and up to 5%, in ponds due to high retention time and downstream artificial reefs. Conclusion: Studies show that due to the current state of treatment plants and adverse operating and maintenance conditions, it is not possible to completely remove parasitic pathogens from these systems, therefore, it should be considered by regulatory authorities and the systems need to be improved for better performance of treatment plants and optimizing them, and training of users should also be improved. This review indicated that the types of natural constructed wetland in Kermanshah (Iran) and activated sludge of wastewater treatment processes in Iran and Brazil are most effective in removal of intestinal parasites. Keywords: Waste water, Treatment, Parasites, Efficienc

Evaluation of exposure to phthalate esters through the use of various brands of drinking water bottled in polyethylene terephthalate (PET) containers under different storage conditions

Background: There are many concerns about the migration of phthalates into bottled water. These compounds are hazardous to consumers. In this study, the risk factors of the use of various brands of drinking water bottled in polyethylene terephthalate (PET) containers under different storage conditions were examined. Methods: Phthalate esters were measured and analyzed using air-assisted liquid-liquid microextraction (AALLME) and gas chromatography-mass spectrometry (GC-MS). Subsequently, the risk of exposure to the desired compounds was evaluated by calculating the risk factor and excess cancer risk. Data were statistically analyzed using SPSS version 24 software. Results: The average concentration of phthalate esters (DEHP, DBP, DIBP, DEP, and DMP) after 5 and 15 days of storage at incubator temperature of 42°C, and after 15, 45, and 75 days at incubator temperature of 25°C by increasing the initial level of the conditions was 7.28, 8.99, 1.78, 5.6, 6.45, and 8.55 ppb, respectively. The risk factor of non-carcinogenic effects of phthalates for consumers was low and can be ignored (HQ<1). Also, the risk of additional cancer due to the presence of diethylhexyl phthalate (DEHP) in bottled water is very low (4.8551×10-6). Conclusion: However, due to the increase in the concentration of phthalate esters in bottled water by increasing the storage time and temperature, as well as increasing the ethylene hexyl phthalate content from its established limit, the use of bottled water kept in unsuitable conditions for the society, and especially the sensitive groups, is not appropriate. Keywords: Phthalate esters, Bottled water, Storage conditions, Risk assessment, Various brand

Application of Taguchi’s experimental design method for optimization of Acid Red 18 removal by electrochemical oxidation process

Background: Electro-oxidation is developed as an electrochemical method to overcome the problems of the conventional decolorization technologies and is an appropriate alternative for the treatment of colored wastewater from various industries. The purpose of this study was to evaluate the efficiency of the electrochemical oxidation process in removal of chemical oxygen demand (COD) and Acid Red 18 (AR18) dye from aqueous solutions. Methods: In this research, a laboratory scale of electro-coagulation reactor for the treatment of synthetic wastewater was made and studied. The effects of different variables including pH, current density, dye concentration, and electrolysis time were investigated. The experiment steps were designed by Design- Expert 10 software using the selected variables. Finally, the dye and COD analysis was performed by spectrophotometer. The optimization was performed using Taguchi fractional factorial design during the removal of dye and COD. Results: Maximum removal of dye (89%) and COD (72.2%) were obtained at pH=3, current density=20 mA/cm2, initial dye concentration=100 mg/L, and reaction time=45 min. ANOVA test showed a significant relationship between statistical model and test data. Also, the results indicate that the distribution of the residues of the model was normal. Conclusion: By designing experiments through Taguchi method, the removal process will be optimized and by decreasing the number of experiments, the optimal conditions for pollutant removal will be prepared. The results suggest that the Electro-oxidation system is a very suitable technique for the enhancement of wastewater treatment. Keywords: Electrolysis, Wastewater, Azo compounds, Models, Statistical, Analysis of varianc

Evaluation of the presence of coliform in bottled drinking water, released in Sari in 2016

Background: Today, bottled water is used in many countries of the world due to its relatively low cost, better taste, ease of access and low levels of impurities. In unfavorable conditions, the maintenance of microorganisms due to hydrophobicity and adherence to bottles and as a result of increased lipolytic activity can lead to undesirable changes in color, taste and odor, and in cases of more severe load, microbial contamination may cause unhealthy water and flooding. In this study, the presence or absence of coliform in a number of bottled water brands was examined. Methods: The microbial quality of 10 markers of bottled water present in the market of Sari that was randomly selected from each mark and three samples was examined. The samples were analyzed using the coliform - presence/absence (P-A) test. The results were compared with national standards and the World Health Organization (WHO) guidelines. Data were analyzed using SPSS version 24 and EXCEL. Results: Samples showed no microbial contamination Also, coliform and fecal coliforms were not observed in any of the samples. Finally, it was revealed that all cases were in accordance with national standards and WHO guidelines. Conclusion: Increasing the health indexes of places, food supply and distribution centers, and maintaining health conditions and measures that have been considered especially in the recent years on the health of bottled water, have greatly reduced the problems. Keywords: Taste, Drinking water, Bacteria, World Health Organization, Bottled wate

Calcium and Magnesium in Ilam Drinking Water Sources during 2009-2013 using Geographic Information System (GIS)

Physicochemical quality of water from the acceptability point of view is essential for consumers; protecting the health of consumers and maintenance of water supply systems. The aim of this study is to determine temporal and spatial variations of Calcium and Magnesium in Ilam drinking water sources using the GIS system. This cross-sectional study was conducted on 20 drinking water sources in Ilam city and the 5 years results by water and wastewater company archive GIS software version 3.9 were analyzed via SPSS version 16 as well as one-way variance analysis. Water and wastewater sampling and measurement were conducted in order to verify the data by researchers according to standard methods. Based on interpolation map, the maximum calcium and magnesium contents are related to western and central regions. ANOVA test showed that there no a significant difference between the mean calcium variable verification test in summer during 2009-2013 and at 95% level. (P=0.760>0.05). The one-way analysis of variance showed that there is a significant difference between the average magnesium variable in summer during 2013-2009 years and the verification test at 95% level. (P=0.01

Slaughterhouse wastewater treatment by combined anaerobic baffled reactor and anaerobic filter: study of OLR and HRT optimization in ABR/AF reactors

Background: Slaughterhouse wastewater (SWW) is hardly treated due to the large amount of organic matter, nutrients and suspended solids. These materials are naturally decomposed through biological processes, and then environmental pollution, transmission of pathogens and problems become smelled. Conventional purification methods require high investment costs, high energy consumption and expert workforce. Therefore, the efficient and sufficient treatment of SWW with low cost, efficient construction and operation is important. Methods: A combined anaerobic system consisting of three pilot-scale anaerobic baffled reactors (ABRs) in the first stage and three anaerobic filters (AFs) were used to treat SWW. The ABR reactors arranged at three hydraulic retention times (HRTs) of 12, 18 and 24 hours and organic loading rates (OLRs) of 4, 7 and 10 kg/m3/d. The OLR applied for ABR reactors, was 0.5 to 1.55 kg COD/m3/d. Results: Evaluation of the ABR reactor indicated that this reactor at OLR of 7 and 10 kg COD/m3/d and HRT of 18 hours, had removal efficiency of 83.29% and 85.79%, respectively. AF reactor, at OLR of 0.981, 0.576 and 0.561 kg COD/m3/d and HRT of 36 hours, had removal efficiency of 79.39%, 74.09% and 63.14%, respectively. Conclusion: The optimum HRT and OLR were 24 hours and 7 kg COD/m3/d and 36 hours and 1 kg COD/m3/d in ABR and AF reactor, respectively. Keywords: Waste water, Slaughterhouse, Anaerobic treatmen

Measurement of BTEX (benzene, toluene, ethylbenzene and xylene) concentration at gas stations

Background: Fuel stations are one of the major sources of air pollution with volatile organic compounds, especially the four main petrol compounds benzene, toluene, ethylbenzene, and xylene (BTEX). BTEX in gasoline enters the air of gas stations due to high evaporation of gasoline. Therefore, determining the concentration of these compounds in gas stations in crowded and busy cities is one of the important priorities of environmental health, which is doubly important in terms of its negative effects on health. Methods: In this descriptive cross-sectional study, a total of 39 samples were collected from 13 gas stations. Sampling was performed in autumn 2018 in three working shifts (morning, noon, and night). The method NIOSH-1501 (i.e., using charcoal sorbent tubes and SKC pump with a flow rate of 0.2 L/min) was used for sampling the BTEX compounds. The mean difference and correlation of BTEX compounds based on meteorological parameters and the number of nozzles in gas stations were assessed using one-way ANOVA and correlation tests. Results: The mean and standard deviation of benzene, toluene, ethylbenzene, and xylene concentrations in the air of fuel stations were 2.784 ± 1.461, 3.495 ± 1.390, 2.091 ± 0.811, and 1.140 ± 0.419 mg/m3, respectively. The relationship between BTEX compounds and meteorological parameters such as humidity and exposure time is very important. There is a strong correlation between the concentrations of BTEX compounds. The highest correlation was observed between benzene and toluene and the lowest one was observed between benzene and xylene. In this study, no significant relationship was observed between air temperature and concentration of BTEX compounds, but there was a relationship between relative humidity and the concentration of BTEX compounds. Conclusion: The average benzene concentration in the air at the fuel stations was about 5.5 times the standard limit. Authorities should improve fuel quality and reduce its evaporation through engineering measures to overcome the issue. Keywords: BTEX, Gas stations, Ira

Global burden of 87 risk factors in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019

Background: Rigorous analysis of levels and trends in exposure to leading risk factors and quantification of their effect on human health are important to identify where public health is making progress and in which cases current efforts are inadequate. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 provides a standardised and comprehensive assessment of the magnitude of risk factor exposure, relative risk, and attributable burden of disease. Methods: GBD 2019 estimated attributable mortality, years of life lost (YLLs), years of life lived with disability (YLDs), and disability-adjusted life-years (DALYs) for 87 risk factors and combinations of risk factors, at the global level, regionally, and for 204 countries and territories. GBD uses a hierarchical list of risk factors so that specific risk factors (eg, sodium intake), and related aggregates (eg, diet quality), are both evaluated. This method has six analytical steps. (1) We included 560 risk–outcome pairs that met criteria for convincing or probable evidence on the basis of research studies. 12 risk–outcome pairs included in GBD 2017 no longer met inclusion criteria and 47 risk–outcome pairs for risks already included in GBD 2017 were added based on new evidence. (2) Relative risks were estimated as a function of exposure based on published systematic reviews, 81 systematic reviews done for GBD 2019, and meta-regression. (3) Levels of exposure in each age-sex-location-year included in the study were estimated based on all available data sources using spatiotemporal Gaussian process regression, DisMod-MR 2.1, a Bayesian meta-regression method, or alternative methods. (4) We determined, from published trials or cohort studies, the level of exposure associated with minimum risk, called the theoretical minimum risk exposure level. (5) Attributable deaths, YLLs, YLDs, and DALYs were computed by multiplying population attributable fractions (PAFs) by the relevant outcome quantity for each age-sex-location-year. (6) PAFs and attributable burden for combinations of risk factors were estimated taking into account mediation of different risk factors through other risk factors. Across all six analytical steps, 30 652 distinct data sources were used in the analysis. Uncertainty in each step of the analysis was propagated into the final estimates of attributable burden. Exposure levels for dichotomous, polytomous, and continuous risk factors were summarised with use of the summary exposure value to facilitate comparisons over time, across location, and across risks. Because the entire time series from 1990 to 2019 has been re-estimated with use of consistent data and methods, these results supersede previously published GBD estimates of attributable burden. Findings: The largest declines in risk exposure from 2010 to 2019 were among a set of risks that are strongly linked to social and economic development, including household air pollution; unsafe water, sanitation, and handwashing; and child growth failure. Global declines also occurred for tobacco smoking and lead exposure. The largest increases in risk exposure were for ambient particulate matter pollution, drug use, high fasting plasma glucose, and high body-mass index. In 2019, the leading Level 2 risk factor globally for attributable deaths was high systolic blood pressure, which accounted for 10·8 million (95% uncertainty interval [UI] 9·51–12·1) deaths (19·2% [16·9–21·3] of all deaths in 2019), followed by tobacco (smoked, second-hand, and chewing), which accounted for 8·71 million (8·12–9·31) deaths (15·4% [14·6–16·2] of all deaths in 2019). The leading Level 2 risk factor for attributable DALYs globally in 2019 was child and maternal malnutrition, which largely affects health in the youngest age groups and accounted for 295 million (253–350) DALYs (11·6% [10·3–13·1] of all global DALYs that year). The risk factor burden varied considerably in 2019 between age groups and locations. Among children aged 0–9 years, the three leading detailed risk factors for attributable DALYs were all related to malnutrition. Iron deficiency was the leading risk factor for those aged 10–24 years, alcohol use for those aged 25–49 years, and high systolic blood pressure for those aged 50–74 years and 75 years and older. Interpretation: Overall, the record for reducing exposure to harmful risks over the past three decades is poor. Success with reducing smoking and lead exposure through regulatory policy might point the way for a stronger role for public policy on other risks in addition to continued efforts to provide information on risk factor harm to the general public

The global burden of adolescent and young adult cancer in 2019 : a systematic analysis for the Global Burden of Disease Study 2019

Background In estimating the global burden of cancer, adolescents and young adults with cancer are often overlooked, despite being a distinct subgroup with unique epidemiology, clinical care needs, and societal impact. Comprehensive estimates of the global cancer burden in adolescents and young adults (aged 15-39 years) are lacking. To address this gap, we analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019, with a focus on the outcome of disability-adjusted life-years (DALYs), to inform global cancer control measures in adolescents and young adults. Methods Using the GBD 2019 methodology, international mortality data were collected from vital registration systems, verbal autopsies, and population-based cancer registry inputs modelled with mortality-to-incidence ratios (MIRs). Incidence was computed with mortality estimates and corresponding MIRs. Prevalence estimates were calculated using modelled survival and multiplied by disability weights to obtain years lived with disability (YLDs). Years of life lost (YLLs) were calculated as age-specific cancer deaths multiplied by the standard life expectancy at the age of death. The main outcome was DALYs (the sum of YLLs and YLDs). Estimates were presented globally and by Socio-demographic Index (SDI) quintiles (countries ranked and divided into five equal SDI groups), and all estimates were presented with corresponding 95% uncertainty intervals (UIs). For this analysis, we used the age range of 15-39 years to define adolescents and young adults. Findings There were 1.19 million (95% UI 1.11-1.28) incident cancer cases and 396 000 (370 000-425 000) deaths due to cancer among people aged 15-39 years worldwide in 2019. The highest age-standardised incidence rates occurred in high SDI (59.6 [54.5-65.7] per 100 000 person-years) and high-middle SDI countries (53.2 [48.8-57.9] per 100 000 person-years), while the highest age-standardised mortality rates were in low-middle SDI (14.2 [12.9-15.6] per 100 000 person-years) and middle SDI (13.6 [12.6-14.8] per 100 000 person-years) countries. In 2019, adolescent and young adult cancers contributed 23.5 million (21.9-25.2) DALYs to the global burden of disease, of which 2.7% (1.9-3.6) came from YLDs and 97.3% (96.4-98.1) from YLLs. Cancer was the fourth leading cause of death and tenth leading cause of DALYs in adolescents and young adults globally. Interpretation Adolescent and young adult cancers contributed substantially to the overall adolescent and young adult disease burden globally in 2019. These results provide new insights into the distribution and magnitude of the adolescent and young adult cancer burden around the world. With notable differences observed across SDI settings, these estimates can inform global and country-level cancer control efforts. Copyright (C) 2021 The Author(s). Published by Elsevier Ltd.Peer reviewe