Microplastics removal from aquatic environment by coagulation: Selecting the best coagulant based on variables determined from a systematic review.

The present study was carried out in the two phases of systematic review and experimental research. First, for the systematic review phase, Web of Science, Scopus, and PubMed as electronic databases were utilized to find research articles distributed up to March 5, 2021, related to the removal of microplastics by coagulation. In total, 104 publications were found, of which 14 were reviewed for deriving the variables and research design. Then, in the experimental phase, the experiment was carried out based on the variables derived from the systematic phase for three microplastic types (polyethylene, polystyrene, and polyamide) and five coagulants (polyaluminum chloride (PAC), ferric chloride (FeCl3), aluminum chloride (AlCl3), alum (Al(OH)3) and aluminum sulfate (Al2(SO4)3)) in bench scale study. The differences between removal efficiencies in terms of type, shape, concentration, and size of microplastics within the looked into article was analyzed utilizing ANOVA or Kruskal-Wallis test (for parametric or nonparametric analysis, respectively). The results of experimental phase show that the removal efficiency of different microplastics was significantly different, and it was equal to 65, 22, and 12% on average for PA, PS, and PE, respectively. These averages are much lower than the average removal efficiency calculated in the reviewed articles (78 and 52% for PS and PE, respectively). The removal efficiency of microplastics types by coagulants was not significantly different. As a result, a coagulant that has the lowest dose can be selected as the most suitable coagulant, which is Al(OH)3 in this study.

Photocatalytic degradation of chloroform using rGO-CuS nanocomposite under UV/VIS irradiation from gaseous phase.

Environmental pollutants such as organic solvents pose potential hazards to the environment. One of the most commonly used solvents, chloroform, is known to cause heart attacks, respiratory problems, and central nervous system disorders. At the pilot scale, the efficacy of the photocatalytic process for removing chloroform from gas streams using the rGO-CuS nanocomposite was investigated. The results indicated that chloroform degradation at 1.5 L min*1 (74.6%) was more than twice as fast as at 2.0 L min-1 (30%). With increasing relative humidity, the chloroform removal efficiency increased up to 30% and then declined. Therefore, 30% humidity was found to be the optimal humidity for the photocatalyst. As the rGO-CuS ratio increased, the photocatalytic degradation efficiency decreased, and the chloroform oxidation rate increased at higher temperatures. The process efficiency increases with increasing pollutant concentrations until the vacant sites are saturated. After the saturation of these active sites, process efficiency does not change.

Non-Adherence to Preventive Behaviors and the Risk of COVID-19: A Comparative Study.

Background: Transmission routes of COVID-19 have been well identified and documented. Considering the high prevalence of the Covid-19 and its impacts on the population, this study aimed to assess the status of preventive behaviors against coronavirus infection and estimate the odds of its transmission routes among people. Methods: A comparative study was conducted from March to April 2021. A total of 1256 participants were randomly selected, including 262 COVID-19 patients and 994 healthy people from 10 counties in Khuzestan, southwest Iran. A two-part questionnaire was used for data collection that included items on demographic and adherence to preventive behaviors. Statistical analysis was performed using the statistical software SPSS 18.0.0 applying logistic regression. Results: The mean age of participants was 37.60±11.48 years (female: 36.49±11.15 years; male: 38.86±11.74 years). The results showed that having contact with infected patient at home (OR = 4.90, 95%CI = 3.32-7.25), going to the hospital for not-necessary medical reasons (OR = 4.47, 95%CI = 3.05-6.55), leaving home for essential daily services (OR = 2.49, 95% CI = 1.63-3.81), and going to doctors' office (OR = 1.78, 95% CI = 1.20-2.63) could increase the odds of infection. Conclusion: The findings suggest that different factors are responsible for the increased spread of the Covid-19. Indeed, since the intervention for every single factor will have a small contribution to reducing the prevalence of the disease, it seems essential to design comprehensive interventions while emphasizing isolation and contacts tracing. The study provides evidence for multi-level and multi-faceted policy and interventions for promoting adherence to COVID-19 preventive behaviors.

Evaluation of conventional wastewater treatment plants efficiency to remove microplastics in terms of abundance, size, shape, and type: A systematic review and Meta-analysis.

In the present study Web of Science, Scopus, and PubMed as electronic databases were used to find work published up to October 27, 2020 about microplastics evaluation in conventional wastewater treatment plants. In total, 407 publications were found, of which 77 were eligible for meta-analysis. A comprehensive meta-analysis was undertaken to evaluate the relevant publications regarding microplastics abundance. The average microplastics abundance was within the 1-31,400, 0.2-12,580, 0.002-7863, and 0.003-447 items range per liter wastewater for influent, primary, secondary, and tertiary treatment steps, respectively. The difference between the abundance of microplastics characterization for the different treatment steps was analyzed using ANOVA or Kruskal-Wallis test (depending on the data distribution). According to the pooled data, the average microplastics abundance was 124.04, 20.67, 5.62, and 1.97 (items/l) for influent, primary, secondary, and tertiary treatment. The results of Egger's test (t = 7.49, P ≤ 0.0001) were statistically significant, suggesting the existence of publication bias.

Association between heavy metals and metabolic syndrome in drinking water and surface soil: case-control study in Iran.

Although obesity is a major risk factor for metabolic syndrome (MetS), not all obese people develop MetS that is directly related to obesity. This suggests that the risk of MetS is influenced by other genetic or environmental agents such as heavy metals. The aim of this study was to investigate the relationship between heavy metals in drinking water and surface soil, and its relationship with the incidence of MetS. To determine the sampling points of drinking water and surface soil, from the location of 150 people selected for inclusion in the study, 16 points were selected randomly for heavy metal concentration analysis. Results were indicated that mean concentrations of V, Mn, Ni, As, Cd, and Sr in drinking water of MetS group were higher than control group. The concentration of heavy metals in drinking water, except for Mn and Sr, did not show a significant difference between case and control groups. The results of this study showed that concentration of heavy metals in drinking water and surface soil was positively associated with the incidence of MetS.

Relationship between urinary heavy metals with metabolic syndrome and its components in population from Hoveyzeh cohort study: A case-control study in Iran.

BACKGROUND: The incidence of Metabolic Syndrome (MetS) has been growing rapidly and is rising to pandemic proportions. Although obesity is a primary risk factor for the enhancement of these conditions, not all obese individuals develop metabolic syndrome, indicating that the risk for developing MetS is impacted by other genetic and/or environmental factors such as heavy metals. Therefore, the present study focused on the association between exposures to heavy metal and MetS. METHODS: Urine samples were collected from 150 participants (75 patients with MetS and 75 healthy participants), which were used from Hoveyzeh Cohort center. To make a quantitative comparison between the two groups, Man-Whitney nonparametric test was used. The logistic regression was performed adjusted for age, demographic, lifestyle factor, physical activity, occupational history and urine creatinine. RESULTS: The results of logistic regression showed that OR and 95 % CI for Cd, Pb, Sr, As and Fe concentration were still significant after adjusting for urine creatinine. Moreover, there was a relationship between Cd and Pb levels and waist circumstance (WC). After adjusting for urine creatinine, age, sex, occupation, smoking status, education and place of residence, only Pb concentration was showed a significant association with systolic blood pressure (SBP). The subjects with high urine level of Cd had the high odds (OR: 6.273; 95 % Cl: 1.783-22.070) of MetS and low high-density lipoprotein (HDL-C). The relationship between As concentration and high fasting blood sugars confirmed the previous evidence suggesting that high As level can cause diabetes. CONCLUSION: These results indicated that outbreak of MetS and its component are associated with heavy metal concentrations in urine.

Selection of MSW landfill site by fuzzy-AHP approach combined with GIS: case study in Ahvaz, Iran.

The study was aimed to use fuzzy multi-criteria decision making integrated with GIS to select the optimum location for municipal solid waste (MSW) landfill sites that comply with standard landfill guidelines and environmental and socio-economic criteria. Fuzzy logic and, in particular, fuzzy sets were applied to create the criteria layers in GIS and to weigh and integrate these layers in GIS. Analytical Hierarchy Process (AHP) was also used to determine the land suitability for landfill. The method was used as a case study to determine the location of landfills in the suburbs of Ahvaz, Iran. According to the results, transportation networks and residential and commercial areas were the most influential factors on the placement of landfills, with a final weight of 0.163 and 0.131, respectively. Areas near roads and transportation networks but far from the sensitive environmental zones were most suitable for landfill. Finally, 11 sites that met the defined requirements were selected as suitable locations for MSW landfill. This technique and its results can provide a proper guideline to help decision makers choose the optimal landfill site in the future. Depending on their importance in each region, the methodology can incorporate other factors and criteria.

Application of surface response method (RSM) to optimize ammonia nitrogen removal from fresh leachate using combination of ultrasound and ultraviolet.

Ammonia nitrogen levels are very high in leachate. This study was conducted to optimize the removal of ammonia nitrogen from fresh landfill leachate using a combination of ultrasound waves and ultraviolet irradiation. A sample of fresh landfill leachate was obtained from a municipal landfill site, located in Shahroud (Semnan, Iran) and its ammonia nitrogen was measured by spectrophotometric method. Ultrasound and ultraviolet irradiation were simultaneously used to remove ammonia nitrogen. Box-Behnken design (BBD) based on response surface method (RSM) was applied to analyze and optimize ammonia nitrogen removal by different variables, including pH, contact time, ultrasound frequency and UV intensity. Based on this method, 29 samples with three replications were tested. The analysis of variance indicated quadratic model was significant for removal of ammonia nitrogen from leachate. According to the model, 99.7% removal efficiency (%) of ammonia nitrogen was obtained in the optimal conditions (pH at 9.7, contact time of 59.1 min, ultrasound frequency of 54 kHz and UV intensity of 40 W). The removal efficiency of ammonia nitrogen was obtained 98.6% from the laboratory experiment in these conditions, which agrees well with the predicted response value.

Qualitative and health-related evaluation of point-of-use water treatment equipment performance in three cities of Iran.

BACKGROUND: Application of the point-of-use water treatment (POU-WT) systems has consistently increased during the last decade in Iran. In this study, the qualitative performances of reverse osmosis-based POU devices in selected cities of Iran were investigated. METHODS: This applied- descriptive study was conducted in three cities of Tehran, Rasht, and Ahvaz in 2016 (selected based on the level of POU devices sale index in three phases). After choosing the most popular five brands of six stages POU devices, 360 water sampling zones and POU consumer households of the selected cities were measured. Also, the awareness of the consumers about POU-WT systems selection and performance was investigated through a designed questionnaire. RESULTS: The qualitative parameters in the three cities were acceptable (p < 0.05) for tap water (except for EC in Ahvaz), the output water were as follows: pH = 6.05-7.5, EC = 49.8-58.2 µs/cm, TOC = 0.01-0.23 mg/L and Nitrate = 0.52-4.5 mg/LNO3 (lower or within the range of regulatory limits), Total Hardness = 33-41.5 mg/L and Fluoride = 0.01-0.23 mg/L (which were lower than the admissible limit, with p < 0.05), HPC values were in the range of 543-676 CFU/mL, which exceeded the regulatory level. Results of ANOVA analysis showed significant differences between the selected cities. The results of the questionnaire survey showed that the dissatisfaction of tap water quality and health-related concerns were the two main reasons for household POU-WT systems; awareness levels of 64% of these households about the performances of their POU systems were weak. Also, social media were mostly used by POU-WT users for brand selected. CONCLUSION: Based on the results of the tap-water quality application of POU-WT systems are not recommended in Tehran and Rasht, and regarding the outputs of these systems, side effects of softened water, lack of Fluoride and a remarkable increase of the number of bacteria should be considered. In Ahvaz, application of POU-WT systems can decrease the health-related problems and it is necessary to increase the access to read POU-WT efficiency information for the consumers.

Kinetic studies on the removal of phenol by MBBR from saline wastewater.

BACKGROUND: Phenols are chemical compounds which are included in the high priority of pollutants by environmental protection agency (USEPA). The presence of high concentrations of phenols in wastewaters like oil refineries, petrochemical plants, olive oil, pesticide production and oil field operations contain high soluble solids (TDS) and in an olive oil plant, wastewater is acidic, high salty and phenol concentrations are in the range of 0.1- 1%. METHODS: Kinetic parameters were calculated according to Monod, Modified Stover- Kincannon, Hamoda and Haldane models. The influence of different initial phenol concentrations on the biodegradation rate was performed. The concentrations of phenol varied from 0 to 500 mg/l. RESULTS: The value of Ki in saline phenolic wastewater in attached growth systems was higher than suspended growth systems that represented a higher phenol inhibition in suspended growth systems. It was obvious that the best model fitting the obtained data are Hamoda model and the Modified Stover-Kincannon model, having highest R2 values of 0.991 and 1, respectively. The value of Ki in saline phenolic wastewater in attached growth system was higher than suspended growth systems which represented a higher phenol inhibition in suspended growth systems. CONCLUSIONS: Hamoda model and the Modified Stover-Kincannon model having highest R2 value of 0.991 and 1, respectively, and also predicting reasonable kinetic coefficient values.

The influence of ZnO-SnO2 nanoparticles and activated carbon on the photocatalytic degradation of toluene using continuous flow mode.

The present study examined the gas-phase photocatalytic degradation of toluene using ZnO-SnO2 nanocomposite supported on activated carbon in a photocatalytic reactor. Toluene was selected as a model pollutant from volatile organic compounds to determine the pathway of photocatalytic degradation and the factors influencing this degradation. The ZnO-SnO2 nanocomposite was synthesized through co-precipitation method in a ratio of 2:1 and then supported on activated carbon. The immobilization of ZnO-SnO2 nanocomposite on activated carbon was determined by the surface area and scanning electron micrograph technique proposed by Brunauer, Emmett, and Teller. The laboratory findings showed that the highest efficiency was 40% for photocatalytic degradation of toluene. The results also indicated that ZnO-SnO2 nano-oxides immobilization on activated carbon had a synergic effect on photocatalytic degradation of toluene. Use of a hybrid photocatalytic system (ZnO/SnO2 nano coupled oxide) and application of absorbent (activated carbon) may be efficient and effective technique for refinement of toluene from air flow.

Factorial experimental design application in modification of volcanic ash as a natural adsorbent with Fenton process for arsenic removal.

This paper describes an experimental design technique for the modification of volcanic ash with Fenton reagent (FMVA) to be used as a natural adsorbent in the removal of As(III) and As(V) from aqueous solution. The influence of pH, contact time and Fe(2+)/H2O2 on arsenic removal by the modified volcanic ash was investigated. It was observed that the arsenic removal efficiency was influenced by two of these parameters. The Fe(2+)/H2O2 ratio is an important factor that affects both As(III) and As(V) adsorption (P = 0.000). The pH affects As(V) adsorption (P = 0.003) more significantly than As (III) adsorption (P = 0.02). It was observed that the maximum As(III) adsorption by the FMVA was obtained at pH 2, Fe(+2)/H2O2 = 0.06 and 30 min of contact time (39 microg As(III) per mg FMVA), whereas the maximum As(V) adsorption was obtained under the conditions of pH 5, Fe(+2)/H2O2 = 0.06 and 30 min of contact time (41 microg As(V) per mg FMVA).