Exposure assessment of nitrate and phenol derivatives in Tehran's water distribution system.

The presence of organic and inorganic contaminants in drinking water is a global concern. Nitrate and phenol derivatives are examples of pollutants that could be of anthropogenic origin. They are associated with numerous health risks, underscoring the importance of monitoring their presence in drinking water. This study aimed to measure nitrate and phenol derivatives, including 2,4-Dichlorophenol (2,4-DCP), Pentachlorophenol (PCP), 2,4,5-Trichlorophenol (2,4,5-TCP), 2-Chlorophenol (2-CP), 4-Chlorophenol (4-CP), and phenol, in Tehran's water distribution system (WDS). The pollutants in Tehran's WDS were significantly and positively correlated with precipitation. The Hazard Quotient (HQ) and the Excess Lifetime Cancer Risk (ELCR) of the detected pollutants were estimated. The results showed that the regional mean of nitrate and PCP in Tehran's WDS were 35.58±8.71mg L-1 and 76.14±16.93 ng L-1 lower than the guideline values of 50 mg L-1 and 1000 ng L-1, respectively. Some districts exhibited nitrate concentration exceeding the allowable limit by a factor of 1.2 to 2.3. Consequently, the nitrate intake in some districts constituted approximately 50% of the reference dose. While PCP as a phenol derivative with more health concerns was identified in Tehran's WDS, the likelihood of its health effects was determined to be negligible.

Assessment of burden of disease induced by exposure to heavy metals through drinking water at national and subnational levels in Iran, 2019.

The burden of disease attributable to exposure to heavy metals via drinking water in Iran (2019) was assessed at the national and regional levels. The non-carcinogenic risk, carcinogenic risk, and attributable burden of disease of heavy metals in drinking water were estimated in terms of hazard quotient (HQ), incremental lifetime cancer risk (ILCR), and disability-adjusted life year (DALY), respectively. The average drinking water concentrations of arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), mercury (Hg), and nickel (Ni) in Iran were determined to be 2.3, 0.4, 12.1, 2.5, 0.7, and 19.7 µg/L, respectively, which were much lower than the standard values. The total average HQs of heavy metals in drinking water in the entire country, rural, and urban communities were 0.48, 0.65 and 0.45, respectively. At the national level, the average ILCRs of heavy metal in the entire country were in the following order: 1.06 × 10-4 for As, 5.89 × 10-5 for Cd, 2.05 × 10-5 for Cr, and 3.76 × 10-7 for Pb. The cancer cases, deaths, death rate (per 100,000 people), DALYs, and DALY rate (per 100,000 people) attributed to exposure to heavy metals in drinking water at the national level were estimated to be 213 (95% uncertainty interval: 180 to 254), 87 (73-104), 0.11 (0.09-0.13), 4642 (3793-5489), and 5.81 (4.75-6.87), respectively. The contributions of exposure to As, Cd, Cr, and Pb in the attributable burden of disease were 14.7%, 65.7%, 19.3%, and 0.2%, respectively. The regional distribution of the total attributable DALY rate for all heavy metals was as follows: Region 5> Region 4> Region 1> Region 3> Region 2. The investigation and improvement of relatively high exceedance of As levels in drinking water from the standard value, especially in Regions 5 and 3 as well as biomonitoring of heavy metals throughout the country were recommended.

A systematic review and meta-analysis of human biomonitoring studies on exposure to environmental pollutants in Iran.

Population exposure to environmental contaminants can be precisely observed through human biomonitoring studies. The present study aimed to systematically review all the biomonitoring studies conducted in Iran on some selected carcinogen environmental pollutants. In this systematic review study, 11 carcinogen agents were selected including arsenic, cadmium, chromium, nickel, lindane, benzene, trichloroethylene (TCE), pentachlorophenol (PCP), radon-222, radium-224, - 226, - 228, and tobacco smoke. The Web of Science, PubMed, and Scopus databases were searched for peer-reviewed articles published in English. After several screening steps, data were extracted from the studies. Meta-analyses (a random-effect model using the DerSimonian-Laired method) were performed only for the biomarkers with more than three eligible articles, including cadmium in blood and breast milk, and arsenic in breast milk. Methodological quality of the studies was assessed using the Newcastle-Ottawa Quality Assessment Scale adapted for cross-sectional studies. Of the 610 articles found in the database search, 30 studies were eligible for qualitative review, and 13 were included in the meta-analysis (cadmium in blood (n = 3), cadmium in breast milk (n = 6), and arsenic in breast milk (n = 4)). The overall pooled average concentrations (95% CI) of cadmium in blood, cadmium in breast milk, and arsenic in breast milk were 0.11 (95% CI: 0.08, 0.14), 5.38 (95% CI: 3.60, 6.96), and 1.42 (95% CI: 1.02, 1.81) µg/L, respectively. These values were compared with the biomarker concentrations in other countries and health-based guideline values. This study showed that there is a need for comprehensive action plans to reduce the exposure of general population to these environmental contaminants.

Tetracycline and ciprofloxacin multiresidues in beef and chicken meat samples using indirect competitive ELISA.

In livestock and poultry, broad-spectrum antibiotics such as tetracyclines and fluoroquinolones are widely used; thus, controlling food productions made from these animals is a necessary task. Meat may contain residues of antibiotics, even in low concentrations, which can cause a selection pressure for antibiotic resistance. Therefore, measurement of amounts of antibiotics in meat is of major importance. A total of 41 beef and 41 chicken meat samples were collected for 1 year. Tetracycline and ciprofloxacin were extracted from samples and tested by an indirect competitive enzyme-linked immunosorbent assay. Overall, 100% of the beef and more than 95% of the chicken meat samples were positive for ciprofloxacin. Only one of the chicken meat samples had concentrations of ciprofloxacin higher than maximum residue limit (MRL). For ciprofloxacin, none of the beef meat samples exceeded the MRL. For tetracycline, 75% of the beef and 58% of the chicken meat samples were positive. All of the samples had concentrations of tetracycline lower than MRL. It was revealed that the chicken meat samples had higher levels of both antibiotics than those of beef samples. The amounts of tested antibiotics were not high in the meat samples, consequently using of beef and chicken meat by consumers in Iran is not resulted in entrance of high amounts of the antibiotics into human body.

Carcinogenic and non-carcinogenic risk assessments of arsenic contamination in drinking water of Ardabil city in the Northwest of Iran.

Based on the environmental health assessment framework of the United State Environmental Protection Agency, a quantitative health risk assessment of arsenic in contaminated drinking water in a city in the northwest of Iran has been carried out. In the exposure assessment step, arsenic concentrations in drinking water were determined during four seasons. In addition, the water ingestion rate for different age groups in this region was determined. The concentration of arsenic in 163 collected samples from different locations during four seasons ranged from 0 to 99 µg L-1. Furthermore, a high percentage of the samples manifested higher levels than the permissible limit of 10 µg L-1. The total daily water intake rates of four age groups 1 to <2 (group 1), 2 to <6 (group 2), 6 to <16 (group 3), and ≥16 years (group 4) were estimated as 0.86, 1.49, 2.00, and 2.33 L day-1, respectively. Calculating the lifetime average daily dose of arsenic indicated that adults (group 4) had the highest and children (group 1) had the lowest daily intake of arsenic in their entire life. The results of risk characteristic showed that the order of excess lifetime cancer risk via arsenic exposure in the four groups was 4 > 3 > 2 > 1. The estimated risks for all age groups were higher than the acceptable range (1E-6 to 1E-4). The hazard quotient values for all of the classified groups were lower than the recommended limit values (<1), but it cannot be concluded that potential non-carcinogenicity risks are non-existent since the possible exposure to arsenic via food and skin may also pose the risk.

Haloacetic acids degradation by an efficient Ferrate/UV process: Byproduct analysis, kinetic study, and application of response surface methodology for modeling and optimization.

Haloacetic acids (HAAs) after trihalomethanes are the second main group of chlorination byproducts. In this study, decomposition of the two most common HAAs in drinking water was studied by an advanced oxidation process using a combination of Ferrate [Fe(VI)] and UV irradiation. The decomposition rate was measured, and the byproducts formed during the process and the mass balances were also analyzed. HAAs were quantified by GC-ECD, and the final products including acetate and chloride ions were measured by ion chromatography (IC). A central composite design was used for the experimental design, and the effect of four variables including the initial HAA concentration, pH, Fe(VI) dosage, and contact time were investigated by response surface methodology (RSM). Dichloroacetic acid decomposed more easily than TCAA. Results show that when TCAA and DCAA were studied individually, the degradation rates were 0.0179 and 0.0632 min-1, respectively. When the HAAs were simultaneously placed in the reactor, the decomposition rates of both TCAA and DCAA decreased dramatically. In this case their decomposition rate constants decreased by 67% and 49%, respectively. In the mixture, the decomposition rate of DCAA was 2.5 times higher than that of TCAA. In summary, Fe(VI)/UV process can be used as a promising treatment option for the decomposition of recalcitrant organic pollutants such as HAAs, and RSM can be used for modeling and optimizing the process.

Statistical analysis of arsenic contamination in drinking water in a city of Iran and its modeling using GIS.

In this research, probable arsenic contamination in drinking water in the city of Ardabil was studied in 163 samples during four seasons. In each season, sampling was carried out randomly in the study area. Results were analyzed statistically applying SPSS 19 software, and the data was also modeled by Arc GIS 10.1 software. The maximum permissible arsenic concentration in drinking water defined by the World Health Organization and Iranian national standard is 10 µg/L. Statistical analysis showed 75, 88, 47, and 69% of samples in autumn, winter, spring, and summer, respectively, had concentrations higher than the national standard. The mean concentrations of arsenic in autumn, winter, spring, and summer were 19.89, 15.9, 10.87, and 14.6 µg/L, respectively, and the overall average in all samples through the year was 15.32 µg/L. Although GIS outputs indicated that the concentration distribution profiles changed in four consecutive seasons, variance analysis of the results showed that statistically there is no significant difference in arsenic levels in four seasons.

Which is better for optimizing the biosorption process of lead - central composite design or the Taguchi technique?

The aim of this study is to evaluate central composite design (CCD) and the Taguchi technique in the adsorption process. Contact time, initial concentration, and pH were selected as the variables, and the removal efficiency of Pb was chosen for the designated response. In addition, face-centered CCD and the L9 orthogonal array were used for the experimental design. The result indicated that, at optimum conditions, the removal efficiency of Pb was 80%. However, the value of R2 was greater than 0.95 for both the CCD and Taguchi techniques, which revealed that both techniques were suitable and in conformity with each other. Moreover, the results of analysis of variance and Prob > F < 0.05 showed the appropriate fit of the designated model with the experimental results. The probability of classifying the contributing variables by giving a percentage of the response quantity (Pb removal) made the Taguchi model an appropriate method for examining the effectiveness of different factors. pH was evaluated as the best input factor as it contributed 66.2% of Pb removal. The Taguchi technique was additionally confirmed by three-dimensional contour plots of CCD. Consequently, the Taguchi method with nine experimental runs and easy interaction plots is an appropriate substitute for CCD for several chemical engineering functions.

Spatial and temporal variability of fluoride concentrations in groundwater resources of Larestan and Gerash regions in Iran from 2003 to 2010.

There is discrepancy about intervals of fluoride monitoring in groundwater resources by Iranian authorities. Spatial and temporal variability of fluoride in groundwater resources of Larestan and Gerash regions in Iran were analyzed from 2003 to 2010 using a geospatial information system and the Mann-Kendall trend test. The mean concentrations of fluoride for the 8-year period in the eight cities and 31 villages were 1.6 and 2.0 mg/l, respectively; the maximum values were 2.4 and 3.8 mg/l, respectively. Spatial, temporal, and spatiotemporal variability of fluoride in overall groundwater resources were relatively constant over the years. However, results of the Mann-Kendall trend test revealed a monotonic trend in the time series of one city and 11 villages for the 8-year period. Specifically, one city and three villages showed positive significant Kendall's Tau values, suggesting an upward trend in fluoride concentrations over the 8-year period. In contrast, seven villages displayed negative significant Kendall's Tau values, arguing for a downward trend in fluoride concentrations over the years. From 2003 to 2010, approximately 52 % of the Larestan and Gerash areas have had fluoride concentrations above the maximum permissible Iranian drinking water standard fluoride level (1.4 mg/l), and about 116,000 people were exposed to such excess amounts. Therefore, our study supports for a close monitoring of fluoride concentrations from health authorities in monthly intervals, especially in villages and cities that showed positive trend in fluoride concentrations. Moreover, we recommend simultaneous implementation of cost-effective protective measures or interventions until a standard fluoride level is achieved.

Exposure assessment of metal(loids) in indoor air and biomonitoring in six urban residential areas in Iran.

Exposure to metal(loid)s can cause adverse health effects. This study evaluated the concentrations of aluminum, arsenic, cadmium, chromium, mercury, nickel, and lead in particulate matter <10 µm (PM10) and in the urine of 100 participants from urban residential areas in Iran. A total of 100 residential buildings (one adult from each household) in six cities across Iran were recruited for this study. The levels of metal(loid)s in PM10 and the urine of participants were measured using acid digestion followed by inductively coupled plasma mass spectrometry (ICP-MS). The average (±SE) PM10 concentration in the buildings was 51.7 ± 3.46 µg/m3. Aluminum and cadmium had the highest and lowest concentrations among the metal(loid)s, averaging 3.74 ± 1.26 µg/m3 and 0.01 ± 0.001 µg/m3, respectively. In 85 % of the samples, the concentration of metal(loid)s in indoor air exceeded WHO air quality standards. Cadmium and lead had the highest and lowest numbers of indoor air samples exceeding the recommended standards, respectively. A significant correlation was found between the concentration of metal(loid)s in urine samples and indoor PM10 levels, as well as the wealth index of participants. There was also a significant direct relationship between the concentrations of nickel, arsenic, lead, and mercury in urine and the age of participants. Factors such as building location, type of cooling systems, use of printers at home, and natural ventilation influenced the concentration and types of metal(loid)s in the indoor air.

Survey of hazardous organic compounds in the groundwater, air and wastewater effluents near the Tehran automobile industry.

Potential of wastewater treatment in car industry and groundwater contamination by volatile organic compounds include perchloroethylene (PCE), trichloroethylene (TCE) and dichloromethane (DCM) near car industry was conducted in this study. Samples were collected in September through December 2011 from automobile industry. Head-space Gas chromatography with FID detector is used for analysis. Mean PCE levels in groundwater ranged from 0 to 63.56 µg L(-1) with maximum level of 89.1 µg L(-1). Mean TCE from 0 to 76.63 µg L(-1) with maximum level of 112 µg L(-1). Due to the data obtained from pre treatment of car staining site and conventional wastewater treatment in car factory, the most of TCE, PCE and DCM removed by pre aeration. Therefor this materials entry from liquid phase to air phase and by precipitation leak out to the groundwater. As a consequence these pollutants have a many negative health effect on the workers by air and groundwater.

Human biomonitoring and reference values of urinary 1-hydroxypyrene among Iranian adults population.

Polycyclic aromatic hydrocarbons (PAHs) are one of the most important environmental pollutants. Urinary concentrations of 1-hydropyren metabolites of PAHs have been used as biomarkers of these chemicals' exposure in humans. This cross-sectional study was conducted on 468 healthy Iranian adults over 25 years old and non-smokers in six provinces who were selected based on the clustering method. Fasting urine sampling and body composition and demographic measurements were performed. Urine samples were analyzed by GC-MS. The analysis included descriptive statistics and analytical statistics using multiple linear regression by Python software. 1-Hydroxypyrene was found in 100% of samples, and the mean (Reference Value 95%) concentration of 1-hydroxypyrene was 6.12 (RV 95%: 20) µg/L and 5.95 (21) µg/gcrt. There was a direct relationship between the amount of body composition (body fat, visceral fat), BMI, and age with the urinary concentrations of 1-hydropyren metabolites, and this relationship was significant for BMI with urinary concentrations of 1-hydropyren metabolites (P = 0.045). The amount of 1-hydroxypyrene in healthy Iranian adults has been higher than in similar studies in other countries. These results provide helpful information regarding the exposure of Iranian adults to 1-hydroxypyrene, and these data can be used to supplement the national reference values of human biomonitoring for the interpretation of biomonitoring results.

In Commemoration of Dr. Bijan Sadrizadeh, a Prominent Physician and Expert in the Field of Public Health in Iran and Around the World.

In line with the commemoration of the scientists who played a significant role in advancing knowledge and providing services to the country, it is imperative to publish their biographies so that their lives and achievements are recorded in the history of the country and serve as an example for future generations. Dr. Bijan Sadrizadeh, a physician and a public health specialist, undertook many valuable activities, particularly in the field of public health in Iran and the world during more than 60 years of great services, including the promotion of public health in the Islamic Republic of Iran, the development of I.R. Iran's international collaborations in the field of public health, and the development of research programs in the field of neglected tropical diseases and the eradication of polio in the world. He served the country in many high-level executive capacities, including three periods as deputy Minister of Health. In addition to several years of full-time employment in the World Health Organization (WHO), Dr. Sadrizadeh also served on the WHO Executive Board and was a member of numerous scientific and advisory committees. In reviewing his life, great determination, devotion, believing in primary health care and universal health coverage and a deep sense of responsibility are visible and can be an inspiration and a model for all.

Simultaneous Removal of Nitrate and Natural Organic Matter from Drinking Water Using a Hybrid Heterotrophic/Autotrophic/Biological Activated Carbon Bioreactor.

Simultaneous removal of nitrate ([Formula: see text]) and natural organic matter (NOM) from drinking water using a hybrid heterotrophic/autotrophic/BAC bioreactor (HHABB) was studied in continuous mode. The HHABB consisted of three compartments: ethanol heterotrophic part, sulfur autotrophic part, and biological activated carbon (BAC)-part (including anoxic and aerobic sections). Experiments were performed with [Formula: see text] concentration 30 mg N/L, [Formula: see text] loading rate 0.72 kg N/m(3)/d, C : N ratio 0.53, and three concentrations of NOM (0.6, 2.6, and 5.7 mg C/L). Overall denitrification rate and efficiency of the HHABB were not affected by NOM concentration and were in the suitable ranges of 0.69-0.70 kg N/m(3)/d and 96.0%-97.7%, respectively. NOM removal at concentration 0.6 mg C/L was not efficient because of organic carbon replacement as soluble microbial products. At higher NOM concentrations, total NOM removal efficiencies were 55%-65%, 55%-70%, and 55%-65% for dissolved organic carbon, trihalomethane formation potential, and UV absorbance at 254 nm (UV(254)), respectively. The more efficient compartments of the HHABB for the removal of NOM were the ethanol heterotrophic phase and aerobic BAC-phase. The efficiency of the HHABB in the removal of NOM was considerable, and the effluent dissolved organic carbon and trihalomethane formation potential concentrations were relatively low. This study indicated that the HHABB without the anoxic BAC-phase could be a feasible alternative for simultaneous removal of [Formula: see text] and NOM from drinking water at full scale.

Characterization of ionic composition of TSP and PM10 during the Middle Eastern Dust (MED) storms in Ahvaz, Iran.

Because of the recent frequent observations of major dust storms in southwestern cities in Iran such as Ahvaz, and the importance of the ionic composition of particulate matters regarding their health effects, source apportionment, etc., the present work was conducted aiming at characterizing the ionic composition of total suspended particles (TSP) and particles on the order of ∼10 µm or less (PM(10)) during dust storms in Ahvaz in April-September 2010. TSP and PM(10) samples were collected and their ionic compositions were determined using an ion chromatography. Mean concentrations of TSP and PM(10) were 1,481.5 and 1,072.9 µg/m(3), respectively. Particle concentrations during the Middle Eastern Dust (MED) days were up to four times higher than those in normal days. Ionic components contributed to only 9.5% and 11.3% of the total mass of TSP and PM(10), respectively. Crustal ions were most abundant during dust days, while secondary ions were dominant during non-dust days. Ca(2+)/Na(+) and Cl(-)/Na(+) ratios can be considered as the indicators for identification of the MED occurrence. It was found that possible chemical forms of NaCl, (NH(4))(2)SO(4), KCl, K(2)SO(4), CaCl(2), Ca(NO(3))(2), and CaSO(4) may exist in TSP. Correlation between the anionic and cationic components suggests slight anion and cation deficiencies in TSP and PM(10) samples, though the deficiencies were negligible.

Butyltin compounds in fish commonly sold in north of Iran.

Levels of tributyltin (TBT) and its degradation products, mono (MBT) and dibutyltin (DBT), were monitored in fish commonly consumed in Iran. Samples were purchased from fish markets at seasonal intervals in 2010 along the North coast of Iran. Concentration of MBT, DBT and TBT in the muscle of these fish were in the range of n.d. -1.01 ± 0.84, n.d. -0.33 ± 0.26 and n.d. -4.31 ± 0.95 ngg(-1) (wet weight), respectively. Residue levels of butyltins were found lower than the tolerable average residue level of 100 ngg(-1) (wet weight).

Fluoride removal from aqueous solution via environmentally friendly adsorbent derived from seashell.

Nowadays, the presence of excessive ions in water resources is of utmost concern and has attracted increasing attention; therefore, excessive amounts of these ions such as fluoride should be removed from drinking water. Conventional water treatment processes are shown to be incapable of the complete removal of redundant fluoride from aqueous water bodies, whereas adsorption is a promising, effective, cost-benefit, and simple method for this purpose. This study aimed to synthesize effective adsorbents from bivalve shells and evaluate the adsorption function of bivalve shells in removing fluoride from aqueous solutions. In this study, the oyster shell was collected from the Persian Gulf's seaside and were crushed by manual mortar and blender, and graded with standard sieves with 70 mesh size. The prepared bivalve shell was characterized by SEM and FTIR. To investigate and optimize various variables on fluoride removal percentage a response surface methodology based on central composite design (RSM-CCD) was used. Under optimal conditions (pH: 5.5, adsorbent dose: 0.3 g/L, contact time: 85 min and fluoride concentration: 3 mg/L) the maximum removal efficiency was 97.26%. Results showed that the adsorption equilibrium and kinetic data were matched with the isotherm Langmuir Model (R2 = 0.98) with qmax = 27.31 mg/g and pseudo-second-order reaction (R2 = 0.99). Also, a thermodynamic study exhibited that the adsorption process of fluoride into bivalve shells was an exothermic reaction and could not be a spontaneous adsorption process. Based on the results, the bivalve shell was found as an appropriate adsorbent to remove fluoride from aqueous solutions.

Comparison of the Toxic Effects of Pristine and Photocatalytically Used TiO2 Nanoparticles in Mice.

TiO2 nanoparticles used in the photocatalytic degradation of pollutants in water treatment processes undergo physiochemical changes; therefore, their toxicological effects may be potentially different from those of the pristine nanoparticles. This study compared the toxic effects of exposure to pristine and photocatalytically used TiO2 nanoparticles in mice. To obtain used TiO2, the nanoparticles were used for photocatalytic degradation of a model pollutant under UV irradiation several times. Two groups of mice were exposed to pristine (PT group) and photocatalytically used TiO2 (UT group) at three different concentrations (5-20 mg/m3) using whole-body exposure chambers (2 h/day, 5 days/weeks, 4 weeks). Exposure to both pristine and used TiO2 increased the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphate (ALP), lactate dehydrogenase (LDH), C-reactive protein (CRP), and creatine kinase (CK-MB) significantly. Both exposed groups showed higher levels of WBC, lymphocytes, platelets, hematocrits, hemoglobin, and mean corpuscular volume (MCV) and lower levels of RBC and mean corpuscular hemoglobin concentration (MCHC) in a concentration-dependent manner. In all analyses, there were small non-significant differences between the PT and UT groups. More pathological changes were observed in the lung, kidney, and brain of the UT group, while the PT group showed more pathological effects in the liver and heart. The histological observations indicated that damage was mostly in the form of vascular endothelial injury. These two types of TiO2 may activate different pathways to promote adverse effects. Further studies are required to evaluate and distinguish the mechanisms through which pristine and used TiO2 induce toxicity.

Effect of dilution factor on the isolation of Helicobacter pylori from municipal wastewater using culture technique.

Background and Objectives: Isolating Helicobacter pylori (H. pylori) from wastewater and culturing it using a conventional method has always been a controversial issue because the bacterium converts into a coccoid form when exposed to an unfavourable environment like wastewater. To clarify the cultivability behaviour of the bacterium in fresh wastewater samples, the effect of municipal wastewater dilation on the cultivation of the bacterium using a conventional method was examined. Materials and Methods: Several dilutions of wastewater samples were inoculated with fresh H. pylori suspension (with McFarland's dilution 0.5) to examine the dilution effect of wastewater on the bacterium isolation. Results: The H. pylori growth was found to be possible for a dilution factor from 1/106 to 1/107 of raw wastewater. In higher dilution factors the growth of fungi was dominant and could prevent the isolation of the bacterium. Conclusion: The optimized technique could be applied in future studies for increasing the chance of H. pylori isolation from fresh wastewater environments.

Photocatalytic degradation of bisphenol a from aqueous solution using bismuth ferric magnetic nanoparticle: synthesis, characterization and response surface methodology-central composite design modeling.

Purpose: Bisphenol A (BPA), as endocrine-disrupting compound (EDC), is extensively used as an important chemical in the synthesis of polycarbonate polymers and epoxy resins. BPA absorption into the body can result in the development of metabolic disorders such as low sex-specific neurodevelopment, immune toxicity, neurotoxicity and interference of cellular pathway. Therefore, the presence of BPA in the body and the environment can create hazards that must reach standards before being discharged into the environment. Methods: In this study, bismuth ferric nanomagnetic (BFO NMPs) were successfully synthesized via sol-gel method and developed as photocatalysts for BPA removal under visible light irradiation. FE-SEM, TEM, PL, XRD, UV-Vis DRS, VSM, EDX, and FTIR were used to characterize the BFO NMPs. Results: RSM model (R2 = 0.9745) showed a good correlation between experimental and predicted removal efficiency of BPA. The investigation of four independent variables indicated that pH had the most significant positive effect on the degradation of BPA. Under optimal conditions (pH = 4.042, catalyst dose = 7.617 mg, contact time = 122.742 min and BPA concentration = 15.065 mg/L), maximum degradation was calculated to be 98.7%. After five recycles, the removal of BPA remained >82%, which indicated the proper ability to reuse the catalyst. Conclusion: In conclusion, it can be stated like BPA, the prepared BFO NMPs is a promising photocatalyst for practical application in organic pollutant decomposition.