Degradation of 2,4-diclorophenol via coupling zero valent iron and hydrodynamic cavitation for sulfite activation: A turbulence modeling.

The 2,4-dichlorophenol (2,4-DCP) is an important chemical precursor that can affect human endocrine system and induce pathological symptoms. This research reports the degradation of 2,4-DCP using lab-scale hydrodynamic cavitation (HC) approach, which is considered a green and effective method. To promote the degradation efficiency, the zero-valent iron (Fe0) as the catalyst for sulfate radical (SO4•-) generation via activation of sulfite (SO32-) salts was simultaneously used. Degradation efficiency was favorable in acidic pH than the alkaline pH due to higher production of active radicals and was dependent on the dose of Fe0 and SO32-. Under optimal condition, degradation efficiency by Fe0/HC/sulfite (96.67 ± 2.90%) was considerably enhanced compared to HC alone (45.37 ± 2.26%). Quenching experiments suggested that SO4•-, •OH, 1O2, and O2•- radicals were involved in the degradation of 2,4-DCP by Fe0/HC/sulfite process, but the dominant role was related to •OH (70.09% contribution) and SO4•- (29.91% contribution) radicals. From the turbulence model, turbulent pressure at venturi throat decreased from -0.42 MPa to -2.02 MPa by increasing the inlet pressure from 1.0 to 4.0 bar and increase in pressure gradient has intensified bubble collapse due to higher turbulence tension.

Modeling and optimization approach for phytoremediation of formaldehyde from polluted indoor air by Nephrolepis obliterata plant.

This study aimed to model the removal of formaldehyde as an indoor air pollutant by Nephrolepis obliterata (R.Br.) J.Sm. plant using response surface methodology (RSM) and artificial neural network (ANN) models, and optimization of the models by particle swarm optimization algorithm (PSO). The data obtained in pilot-scale experiments under a controlled environment were used in this study. The effects of parameters on the removal efficiency such as formaldehyde concentration, relative humidity, light intensity, and leaf surface area were empirically investigated and considered as model parameters. The results of the RSM model, with power transformation, were in meaningful compromise with the experiments. A multilayer perceptron (MLP) neural network was also designed, and the mean of squared error (MSE), mean absolute error (MAE), and R2 were used to evaluate the network. Several training algorithms were assessed and the best one, the Levenberg Marquardt (LM), was selected. The PSO algorithm proved that the highest removal efficiency of formaldehyde was obtained in the presence of light, maximum leaf surface area and relative humidity, and at the lowest inlet concentration. The empirical system breakthrough occurred at 15 mg/m3 of formaldehyde, and the maximum elimination capacity was about 0.96 mg per m2 of leaves. The findings indicated that the ANN model predicted the removal efficiency more accurately compared to the RSM model.

Investigating the pollution of bottled water by the microplastics (MPs): the effects of mechanical stress, sunlight exposure, and freezing on MPs release.

Bottled water is becoming more popular worldwide and possible contamination's need to be analyzed. Microplastics (MPs) are ubiquitous environmental pollutants and have recently been regarded as an important contaminant in bottled water due to oral intake and possible threats to human health. In the present study, MP amounts in 23 popular Iranian brands of bottled water were determined by filtration and counting under scanning electron microscopy (SEM). The effects of mechanical stress, environmental factors, and freezing on MP release also were investigated. The average amounts of MPs in water samples were 1496.7 ± 1452.2 particles/L (199.8 to 6626.7 particles/L). The amounts of MPs in different brands was significantly different (p < 0.05). As much as 91.3% of detected particles had the size between 1 and 10 µm. The most likely polymers determined by FTIR spectroscopy was polyethylene terephthalate (PET). The freezing of water in the bottles did not show any significant effect on the MPs release, but mechanical stress to the bottles increased MP amounts in the water significantly. Environmental factors including sunlight exposure and the age of bottles showed the most degradative effects on the structure of polymers in the body of PET bottles and release of MPs. Regardless of their type, source and commercial brands, bottled water is contaminated with hundreds to thousands MPs/L. The main portion (above 90%) of these MPs are < 5 µm particles with considerable effects on human health.

What competencies do environmental health graduates need to manage social determinants of health?

BACKGROUND: Graduates of environmental health engineering should be able to manage Social Determinants of Health (SDH) and acquire the essential competencies during their studies at university. This study was performed to determine the expected competencies of environmental health graduates in a way to be able to manage environmental and Social Determinants of Health according to their job description. METHODS: This descriptive cross-sectional study was performed using Delphi technique. First, the literature review was done and the Delphi technique was performed in three rounds. The purposeful sampling was used and 50 people were selected among the specialists in the field of environmental health engineering and SDH. Participants answered an open-ended question, for the first round. Then, a questionnaire with 8 areas was designed based on the results of the first round and distributed for the second round. Data analysis was performed using descriptive statistics. The third round was done to reach the agreement on final items. RESULTS: The agreement on the items of the third round of Delphi was more than 70%. The final results showed eight competency areas under which 29 competencies were defined. Competency areas included expert knowledge, reasoning and planning, advocacy, system-based practice, professionalism, instructional expertise, social and personal skills and, research and self-development. The first three priorities of the required competency areas were expert knowledge (4.46 ± 0.55), professionalism (4.42 ± 0.64), and advocacy (4.32 ± 0.77). CONCLUSIONS: It is necessary that environmental health engineers achieve necessary competencies regarding managing SDH, upon their graduation. It is suggested to integrate these competencies into the curriculum of environmental and health engineering in Iran universities.

Artificial neural network and logistic regression modelling to characterize COVID-19 infected patients in local areas of Iran.

BACKGROUND: COVID-19 is an infectious disease that started spreading globally at the end of 2019. Due to differences in patient characteristics and symptoms in different regions, in this research, a comparative study was performed on COVID-19 patients in 6 provinces of Iran. Also, multilayer perceptron (MLP) neural network and Logistic Regression (LR) models were applied for the diagnosis of COVID-19. METHODS: A total of 1043 patients with suspected COVID-19 infection in Iran participated in this study. 29 characteristics, symptoms and underlying disease were obtained from hospitalized patients. Afterwards, we compared the obtained data between confirmed cases. Furthermore, the data was applied for building the ANN and LR models to diagnosis the infected patients by COVID-19. RESULTS: In 750 confirmed patients, Common symptoms were: fever (%) >37.5 °C, cough, shortness of breath, fatigue, chills and headache. The most common underlying diseases were: hypertension, diabetes, chronic obstructive pulmonary disease and coronary heart disease. Finally, the accuracy of the ANN model to the diagnosis of COVID-19 infection was higher than the LR model. CONCLUSION: The prevalent symptoms and underlying diseases of COVID-19 patients were similar in different provinces, but the incidence of symptoms was significantly different from each other. Also, the study demonstrated that ANN and LR models have a high ability in the diagnosis of COVID-19 infection.

Association between prenatal phthalate exposure and anthropometric measures of newborns in a sample of Iranian population.

Phthalates or phthalic acid esters (PAEs) are a group of compounds which they can be entered into the human body through the various pathways. The aim of this study was to examine associations between prenatal phthalates exposure with anthropometric measures of neonates. Urine samples were obtained from 121 Iranian pregnant women at their first trimester of pregnancy, and the levels of monobutyl phthalate (MBP), mono-benzyl phthalate (MBzP), mono-2-ethylhexyl phthalate (MEHP), and mono (2-ethyl-5hydroxyhexyl) phthalate (MEHHP) metabolites were determined by gas chromatography mass spectrometry (GC/MS). The correlations between the maternal urinary concentrations of phthalate metabolites with anthropometric measures of neonates as well as with the socio-demographic factors of participants (maternal education, age, family income, pre-pregnancy body mass index), their lifestyle variables (smoking habit, food pattern, and physical activity), and use of cleaning products (cosmetic and household cleaning products) were investigated. MBzP, MBP, MEHP, and MEHHP were detected in 100% of the participants with the concentration ranged 120 to 860 µg/g creatinine. Significant correlations were observed between the urinary levels of maternal MBzP (adjusted ß = 0.3 (0.001), p = 0.03) and MEHHP (adjusted ß = 0.3 (0.001), p = 0.04) with the birth weight of female neonates. MBP (adjusted ß = -0.3 (0.02), p = 0.04) and MBzP (adjusted ß = -0.3 (0.001), p = 0.02) had negative associations with the head circumference in male and female newborns, respectively. Furthermore, plastic packaging for pickle and passive smoking during pregnancy were identified to be significantly associated with low birth weight (p value < 0.05). Iranian pregnant women had higher concentrations of urinary phthalates compared to the other countries. Based on the findings, the higher prenatal exposure to phthalates could adversely impact the health status of newborns.

Association of maternal urinary concentration of parabens and neonatal anthropometric indices.

PURPOSE: Parabens are used as preservatives in a wide range of products. Although parabens are generally known as safe, but recent evidences indicate that these compounds could lead to potential adverse effects on fetal growth. Thus, this study aimed to investigate the association between maternal parabens level in a sample of Iranian pregnant women with neonatal anthropometric measures. METHODS: This cross-sectional study was conducted in 2018-2019 in Isfahan city, Iran. Early morning urine samples were collected from 117 pregnant women who were in their first trimester of pregnancy. The urinary concentrations of four parabens including methylparaben (MeP), ethylparaben (EtP), propylparaben (PrP), and butylparaben (BuP) were measured by gas chromatography-mass spectrometry. To compensate for variation in urine dilution, the paraben concentrations were adjusted by the creatinine levels. Associations between maternal parabens level and neonatal anthropometric indices were evaluated. RESULTS: The MeP, EtP, PrP, and BuP were detected in %92, %36, %65, and %89 of the urine samples, respectively. No significant association was observed between maternal parabens level and birth length (p-value>0.05). In adjusted model, the BuP concentration in first trimester urine samples showed significantly negative association with head circumference in female neonates [ß = -0.013, 95% CI: -0.024, -0.003], while positive significant association with that index in male neonates [ß = 0.019, 95% CI: 0.001, 0.038]. In subgroup analysis by sex, in crude and adjusted analyses BuP was found to be only associated with higher birth weight in female neonates. PrP also showed significant positive association with head circumference and birth weight of male neonates in crude analysis. CONCLUSION: Findings of this study on the association of urinary parabens of pregnant mothers with birth weight and head circumference suggest that maternal exposure to parabens might impact the fetal growth, However, these findings are based on cross-sectional data, thus the results should be interpreted with caution. The current findings underscore the necessity of providing more strict regulations in industries for limiting parabens use in their products, and the importance of public education for women of reproductive age for using paraben-free compounds.

In situ treatment of metalworking wastewater by chemical addition-dissolved air flotation coupled with UV, H2O2 & ZnO.

The hybrid treatment techniques have been proven that could be a proper solution to the metalworking fluid (MWF) wastewaters disposal challenge. Hence, this investigation was conducted aim to the assessment of chemical addition-dissolved air floatation (CA-DAF) unit followed with a heterogeneous photocatalytic (PC) process as UV/H2O2/ZnO to treat MWF wastewater produced in one of the central industrial estates in the Middle East. The CA-DAF unit was implemented as trial and errors and had an appropriate efficiency. However, the environmental discharge standards were not achieved only by this unit, so that, a PC process considered for this purpose in a pilot-scale reactor. And also, Chemical oxygen demand (COD), total petroleum hydrocarbons (TPHs) were considered as physicochemical parameters to analyze the applied photochemical reaction throughout the concentrations of ZnO and H2O2, and pH value as variables of the study. The ideal and optimized conditions were observed at pH 10, 600 mg l-1 of ZnO, and 13.11 g l-1 of H2O2 via 99.87% and 97.9% reduction rates in total COD and TPH, respectively. These removal rates were obtained for this integrated strategy under the optimized reaction. By evaluating the synergistic effect, it was found that UV/ZnO could be a predominant reaction in this process. The organic and intermediates analysis appeared 78.46% reduction for all detected organic matters. Besides, PC generation of bis phthalate, mono phthalate, benzene, and benzoic acid to 2,6-bis (1,1-dimethylethyl)-4-mthyl phenol was the reason of the residual phenolic compound concentration in the reaction solution with low removal rate. The kinetic study showed that this reaction could be well fitted with the pseudo-first-order kinetic model by R 2 equal with 0.973 and 0.988 in turn for COD and TPH. The expenditures to treat 1 m3 of the CA-DAF was estimated at 5.335 us$ via cost analysis. Finally, the collected findings indicate that CA-DAF integrated with UV/H2O2/ZnO can be an efficient approach in the MWF wastes disposal or treatment for reuse.

Biohydrogen production from alkaline wastewater: The stoichiometric reactions, modeling, and electron equivalent.

Hydrogen gas (H2) is the cleanest energy carrier with 142 kJ/g energy content and without toxic byproducts release during combustion. There is interest to H2 production by biological process from sustainable resources including municipal and industrial wastewater and also solid waste. Here, we describe the biohydrogen production that involves first survey the effect of alkalinity on biohydrogen production based on stoichiometric reaction, followed by the electron equivalent balances determination and examination of prediction capability of Gamperts model for biohydrogen production. •The method uses a dark fermentation biological process for H2 production from wastewater.•As the influent alkalinity increased, the hydrogen production increased and then promptly descended.•The predicted gas volume, based on Gamperts model confirmed good agreement with experimental value.

Method for quantitative and qualitative evaluation of hazardous waste in laboratories of Isfahan University of Medical Sciences, Iran.

Hazardous wastes (HWs) is waste that has substantial or potential threats to public health or the environment. The aim this study is evaluation of quantitative and qualitative of hazardous waste in laboratories of Isfahan University of Medical Sciences (IUMS), Isfahan, Iran. In this data research, four out of ten faculties of IUMS that produce the highest amount of HWs were selected for collection of required data. The required information collected by using interview with laboratory staffs, completion of questionnaire, and refer to the available documents. The 33 laboratories (including 18 and 15 chemical and biological laboratories, respectively) and one clinic were selected. The obtained data showed that annually 2609.9 kg HWs generated in IUMS. The dentistry, public health, medical, and pharmacy faculties were produced 104, 266.6, 793.9, and 1445.4 kg of HW per year, respectively that they were including 4%, 10%, 31%, and 55% in the total amount of generated HW. According to the acquired result, to protect the health of the environment, IUMS must establish a comprehensive solid waste management programs for prevention and reduction, higher rates of recycling, and managing HWs in all faculties.

Monitoring of urinary phthalate metabolites among pregnant women in Isfahan, Iran: the PERSIAN birth cohort.

Recently, increasing evidences have shown that the exposure to phthalates can adversely affect health status of pregnant women and their newborns. However, only a limited number of studies have investigated the concentrations of these compounds in the body fluids of pregnant women. In the present study, we aimed to evaluate the concentrations of phthalate metabolites in urinary samples of pregnant women in correlation with the population characteristics and different lifestyle factors. The study was conducted in 2018-2019 and urinary samples were taken from 121 pregnant women during their first pregnancy trimester who lived in Isfahan, Iran. The concentrations of monobutyl phthalate (MBP), mono-benzyl phthalate (MBzP), mono-2-ethylhexyl phthalate (MEHP), and mono (2-ethyl-5hydroxyhexyl) phthalate (MEHHP) metabolites in urinary samples were determined by gas chromatography mass spectrometry (GC/MS). The socio-demographic profile of the participants (maternal education, age, family income, pre-pregnancy BMI), their lifestyle information (smoking habit, food pattern, and physical activity), cleaning products use data (cosmetic and household cleaning products) were collected by the use of PERSIAN birth cohort questionnaire. MBzP, MBP, MEHP, and MEHHP were detected in 100% of participated pregnant women with the mean concentration of 342.5 ± 193.8, 308.5 ± 229.4, 126.5 ± 118.3, and 866.5 ± 307.6 µg/g creatinine, respectively. Significant correlations were observed between the mean concentration of urinary phthalate metabolites with the following variables: using plastic packaging (for bread, lemon juice, pickle, leftover, and water), lower physical activity, passive smoking exposure during pregnancy (p value<0.05). Furthermore, the pre-pregnancy BMI (r = 0.27, r = 0.3, r = 0.26, and r = 0.26), use of the household cleaning products (r = 0.2, r = 0.22, r = 0.3, and r = 0.26), utilize of the cosmetic products (r = 0.46, r = 0.48, r = 0.49, and r = 0.54), and passive smoking status (r = 0.5, r = 0.44, r = 0.44, and r = 0.26) directly correlated with the urinary concentrations of MBP, MBzP, MEHP, and MEHHP, respectively. No significant association was seen between the concentration of urinary phthalate metabolites with the maternal education level and family income. According to our findings, higher amounts of phthalate metabolites were detected in urinary samples of pregnant women who were passive smokers, or had higher pre-pregnancy BMI and lower physical activity, as well as those women who used higher amounts of cosmetic and household cleaning products, or used plastic packaging for food and non-food products.

Removal of atenolol from aqueous solutions by multiwalled carbon nanotubes modified with ozone: kinetic and equilibrium study.

The aim of study is removal of atenolol from aqueous solutions by multiwalled carbon nanotubes modified with ozone. The design of the experiment was adopted across four levels with the L16 matrix arrangement. The factors influencing atenolol adsorption include changes in the pH value, contact time, the dose of the modified multiwall carbon nanotube, and the initial concentration of atenolol in the solution; these factors were evaluated along with the extent of their influence on removal efficiency. Data analyses were performed by the Design Expert 6 software. The results indicated that the pH, contact time, adsorbent dose, and the initial concentration were 7, 20 min, 0.15 g/L and 1 mg/L, respectively. In this state, the removal efficiency was calculated to be 75.79%. The maximum adsorption capacity was obtained as 5.05 mg/g under optimal conditions. The data were analyzed using adsorption models obtained from the isotherm fitting tool software. The results suggested that the data had a greater congruence with the Freundlich model (corrected Akaike information criterion = 2.58). Furthermore, the kinetics of the reactions followed pseudo second order kinetics (R2 = 0.95). Based on this study, it can be concluded that modified multiwall carbon nanotubes enjoy high potential and efficiency as adsorbents for the removal of atenolol from aqueous solutions.

Association of polycyclic aromatic hydrocarbons with cardiometabolic risk factors and obesity in children.

A limited body of evidence exists on the association of exposure to polycyclic aromatic hydrocarbons (PAHs) with cardiometabolic risk factors and obesity in children. No study has evaluated these associations in subgroups of children with and without excess weight, and those with and without cardiometabolic risk factors. We aimed to investigate the association between PAH exposure and cardiometabolic risk factors in children independent of their weight status. The secondary aim was to evaluate the obesogen properties of PAHs in children independent of their cardiometabolic risk factors. This study was based on a representative sample of 186 children (aged 6-18 years) living in Isfahan, Iran (2014-2016). We enrolled four groups of participants with and without excess weight and with and without cardiometabolic risk factor. Urinary levels of monohydroxy PAHs (OH-PAHs) were measured twice, six months apart. Logistic regression models were developed to estimate the associations of tertiles of urinary OH-PAH concentrations with cardiometabolic risk factors and excess weight, adjusted for the relevant covariates. The findings in all participants combined showed that increased risk of cardiometabolic risk factors and excess weight was associated with exposure to most of evaluated PAHs. Exposure to 1-hydroxypyrene was associated with higher risk of cardiometabolic risk factors in participants with excess weight. Exposure to 2-Naphtol was also associated with higher risk of cardiometabolic risk factors in both groups, but the associations were not significant (p < 0.1). For participants without cardiometabolic risk factors, exposure to 2-naphtol, 9-phenanthrol, and ∑ OH-PAH was associated with increased risk of obesity. For participants with cardiometabolic risk factors, we observed similar pattern of associations for 2-naphtol and ∑ OH-PAH, but the associations were not statistically significant (p < 0.1). We found that exposure to PAHs could possibly explain, in part, the cardiometabolic risk factors in children with excess weight as well as obesity in children with normal cardiometabolic profile.

Electrochemical degradation of diclofenac using three-dimensional electrode reactor with multi-walled carbon nanotubes.

The electro-oxidation treatment of aqueous solution containing diclofenac (DCF) on a Ti/RuO2-TiO2 electrode in the presence of multi-walled carbon nanotubes (MWCNTs) was studied in a three-dimensional electrochemical (3DE) reactor. The response surface methodology (RSM) based on central composite design (CCD) was utilized to determine the influence of different factors. The results revealed that the obtained polynomial experimental model had a high coefficient of determination (R2 = 0.9762) based on analysis of variance. The optimum condition for the removal of DCF by the 3DE process was obtained with the initial pH of 3.8, the initial DCF concentration of 4 mg/L, the current density of 20 mA/cm2, the particle electrode concentration of 70 mg/L, and the electrolysis time of 85 min. The quadratic model developed for DCF removal and subsequently the analysis of the F value illustrated that the initial pH was the most important factor in the removal of DCF. The comparative experiments between electrochemical processes showed the high electrocatalytic activity and removal efficiency of the 3DE reactor with the MWCNT particle electrode. The results also showed that the Ti/RuO2-TiO2 electrode, in addition to its high stability, had a very good electrocatalytic activity in the 3D reactor. The stability and reusability test proved that MWCNTs, as a particle electrode, had a potential to improve the long-term electrocatalytic degradation of DCF in the aqueous solutions. Based on the identified intermediate compounds along with the results of other studies, a possible pathway for the electrochemical oxidation of DCF by the 3DE process catalyzed with MWCNTs was proposed.

Comparison of Acetate-butyrate and Acetate-ethanol Metabolic Pathway in Biohydrogen Production.

BACKGROUND: Hydrogen gas is the cleanest energy carrier and could be produced by biological process. Dark fermentation is one of the biohydrogen production methods that carried out just on organic wastes conversion. METHODS: In this study, the batch tests were conducted to compare the biohydrogen production and glucose fermentation via acetate-butyrate and acetate-ethanol metabolic pathway induced by NaOH and KOH (10 M) pretreatment. In batch test, the glucose concentration in the feed was varied from 3.75 to 15 g/L under mesophilic conditions (37°C ± 1°C). In order to sludge pretreatment, NaOH and KOH (as an alkaline agent) was used. RESULTS: Batch tests showed that maximum biohydrogen production under NaOH (2.7 ± 0.5 L) and KOH (2.2 ± 0.7 L) pretreatment was achieved at 15 g/L of influent glucose. In the batch test, with increasing influent glucose concentration, the lower yields of hydrogen were observed. The biohydrogen reactions had good electron closure (5.2%-13.5%) for various glucose concentrations and pretreatments. For NaOH and KOH pretreatment, the biohydrogen yield decreased from 2.49 to 1.63 and from 2.22 to 1.2 mol H2/mol glucose, respectively, when glucose concentration increased from 3.75 to 15 g/L. CONCLUSIONS: By applying alkaline sludge pretreatment by NaOH and KOH, the glucose fermentation was followed with acetate-butyrate and acetate-ethanol metabolic pathway, respectively. The lower biohydrogen yields were observed under acetate-ethanol metabolic pathway and related to metabolically unfavorable for biohydrogen production.

Phytoremediation of VOCs from indoor air by ornamental potted plants: A pilot study using a palm species under the controlled environment.

Volatile organic compounds (VOCs) in indoor air have recently raised public concern due to their adverse health effects. One of hazardous VOC is Formaldehyde which can cause sensory irritation and induce nasopharyngeal cancer. The aim of this study was to investigate potted plant-soil system ability in formaldehyde removal from indoor air. We applied one of common interior plant from the palm species, Chamaedorea elegans, inside a chamber under the controlled environment. Entire plant, growing media and roots contribution in formaldehyde were evaluated by continuously introduction of different concentrations of formaldehyde into the chamber (0.66-16.4 mg m-3) each over a 48-h period. Our findings showed that the plant efficiently removed formaldehyde from polluted air by 65-100%, depending on the inlet concentrations, for a long time exposure. A maximum elimination capacity of 1.47 mg/m2. h was achieved with an inlet formaldehyde concentration of 14.6 mg m-3. The removal ratio of areal part to pot soil and roots was 2.45:1 (71%: 29%). The plants could remove more formaldehyde in light rather than dark environment. Concentrations up to 16.4 mg m-3 were not high enough to affect the plants growth. However, a trivial decrease in chlorophyll content, carotenoid and water content of the treated plants was observed compared to the control plants. Thus, the palm species tested here showed high tolerance and good potential of formaldehyde removal from interior environments. Therefore, phytoremediation of VOCs from indoor air by the ornamental potted plants is an effective method which can be economically applicable in homes and offices.

Biohydrogen production under hyper salinity stress by an anaerobic sequencing batch reactor with mixed culture.

BACKGROUND: This study investigated the effect of organic loading rate (OLR) and NaCl concentration on biohydrogen production by preheated anaerobic sludge in a lab scale anaerobic sequencing batch reactor (ASBR) fed with glucose during long time operation. METHODS: During ASBR operation, the OLR was increased in steps from 0.5 to 5 g glucose/L.d and NaCl addition started at an OLR of 5 g glucose/L.d, to obtain NaCl concentrations in the reactor in the range of 0.5-30 g/L. RESULTS: With an increasing OLR from 0.5 to 5 g glucose/L.d, the biohydrogen yield increased and reached 0.8 ± 0.4 mol H2/mol glucose at an OLR of 5 g glucose/L.d. A NaCl concentration of 0.5 g/L resulted in a higher yield of biohydrogen (1.1 ± 0.2 mol H2/mol glucose). Concentrations above 0.5 g/L NaCl led to decreasing biohydrogen yield and the lowest yield (0.3 ± 0.1 mol H2/mol glucose) was obtained at 30 g/L of NaCl. The mass balance errors for C, H, and O in all constructed stoichiometric reactions were below 5%. CONCLUSIONS: The modified Monod model indicated that r (H2)max and Ccrit values were 23.3 mL H2/g VSS/h and 119.9 g/L, respectively. Additionally, ASBR operation at high concentrations of NaCl shifted the metabolic pathway from acidogenic toward solventogenic.

Hybrid coagulation-UF processes for spent filter backwash water treatment: a comparison studies for PAFCl and FeCl3 as a pre-treatment.

In this study, the reclamation of clean water from spent filter backwash water (SFBW) was investigated through pilot-scale experiments. The pilot plant consisted of pre-sedimentation, coagulation, flocculation, clarification, and ultrafiltration (UF). Two coagulants of PAFCl and FeCl3 were investigated with respect to their performance on treated SFBW quality and UF membrane fouling. At the optimum dose of PAFCl and FeCl3 turbidity removal of 99.6 and 99.4% was attained, respectively. PAFCl resulted in an optimum UV254, TOC, and DOC removal of 80, 83.6, and 72.7%, respectively, and FeCl3 caused the removal of those parameters by 76.7, 80.9, and 65.9%, respectively. PAFCl removed hydrophilic and transphilic constituent better than FeCl3, but FeCl3 had, to some extent, higher affinities to a hydrophobic fraction. It was concluded that PAFCl showed a better coagulation performance in most cases and caused a lower membrane fouling rate compared to FeCl3. Finally, the treated SFBW with both coagulant-UF systems met the drinking water standards.

Association of atmospheric concentrations of polycyclic aromatic hydrocarbons with their urinary metabolites in children and adolescents.

This study aims to determine the atmospheric concentrations of particulate matter 2.5 (PM2.5)-bounded polycyclic aromatic hydrocarbons (PAHs) and their association with their urinary metabolites in children and adolescents. This study was conducted from October 2014 to March 2016 in Isfahan, Iran. We measured 16 species of PAHs bounded to PM2.5 by gas chromatography mass spectrometry (GC/MS) from 7 parts of the city. Moreover, PAH urinary metabolites were measured in 186 children and adolescents, randomly selected from households. Urinary metabolites consisted of 1-hydroxy naphthalene (1-naphthol), 2-hydroxy naphthalene (2-naphthol), 9-hydroxy phenanthrene (9-phenanthrol), and 1-hydroxy pyrene using GC/MS. Considering the short half-lives of PAHs, we measured the metabolites twice with 4 to 6 months of time interval. We found that the ambient concentrations of PAHs were significantly associated with their urinary metabolites. 1-hydroxy naphthalene and 2-hydroxy naphthalene concentrations showed an increase of 1.049 (95% CI: 1.030, 1.069) and 1.047 (95% CI: 1.025, 1.066) for each unit increase (1 ng/m3) in ambient naphthalene. Similarly, 1-hydroxy pyrene showed an increase of 1.009 (95% CI: 1.006-1.011) for each unit increase (1 ng/m3) in ambient pyrene concentration after adjustment for body mass index, physical activity level, urinary creatinine, age, and sex. The association of urinary 9-hydroxyphenanthrene and ambient phenantherene was significant in the crude model; however after adjustment for the abovementioned covariates, it was no more significant. We found significant correlations between exposure to ambient PM2.5-bounded PAHs and their urinary excretion. Considering the adverse health effects of PAHs in the pediatric age group, biomonitoring of PAHs should be underscored; preventive measures need to be intensified.

A Systematic Review on the Effects of Polycyclic Aromatic Hydrocarbons on Cardiometabolic Impairment.

BACKGROUND: Various epidemiological studies have shown that exposure to environmental pollutants including polycyclic aromatic hydrocarbons (PAHs) might increase the risk of cardiovascular diseases (CVDs) and their risk factors. This study aims to systematically review the association of PAH exposure with metabolic impairment. METHODS: Data were collected by searching for relevant studies in international databases using the following keywords: "polycyclic aromatic hydrocarbon" + "cardiovascular disease," PAH + CVD, polycyclic aromatic hydrocarbon and "air pollutant" + "CVD," and the desired data were extracted and included in the study according to the systematic review process. RESULTS: From the 14 articles included in the present systematic review, eight articles were conducted on the relationship between PAH and CVDs, four articles were conducted to examine the association of PAH exposure with blood pressure (BP), and two articles investigated the link between PAH and obesity. CONCLUSIONS: Most studies included in this systematic review reported a significant positive association of PAH exposure with increased risk of CVDs and its major risk factors including elevated BP and obesity. These findings should be confirmed by longitudinal studies with long-term follow-up.