Journal of Advances in Environmental Health Research
Volume:7 Issue: 2, Spring 2019

Approximately 10-20% of the total dyes in the world is consumed in the textile industry. The present study aimed to investigate the photocatalytic activity of zinc oxide nanoparticles (ZnO) immobilized on synthetic activated carbon in the removal of the acid blue 113 dye from aqueous solutions. This experimental study was conducted in a photo-reactor with the useful volume of one liter. The effects of pH (3, 7, and 9), zinc oxide nanoparticle concentrations (0.1-0.4 mmol/l), concentration of activated carbon modified by zinc oxide nanoparticles (20, 40, 60, 80, and 100 mg/l), and the initial concentration of the dye (20, 40, 60, 80, 100, and 200 mg/l) were assessed. In addition, the kinetics of the reaction were investigated. The results indicated that the optimal conditions for the process were the pH of 3, activated carbon modified by zinc oxide nanoparticle concentration of 100 mg/l, ratio of 0.4 millimole of zinc oxide per gram of activated carbon, and acid blue 113 dye concentration of 100 mg/l, which resulted in the maximum efficacy of 96%. Moreover, removal efficiency using zinc oxide was greater in all the stages compared to removal efficiency using activated carbon. The kinetic rate was also determined, demonstrating that the process followed the first-order kinetics. In addition, the findings indicated that the process had outstanding efficiency in the removal of the acid blue 113 dye. The photocatalysis of nanoparticle oxidation on synthetic activated carbon could be used effectively as an advanced oxidation reaction to remove dyes.

The fall velocity of sediment particles plays a key role in sediment transport studies. Researchers have attempted to determine the terminal fall velocity, and most of the studies in this regard have been based on experimental, quasi-experimental, and in-situ measurements. The present study aimed to use a numerical model to estimate the fall velocity of a single sediment particle in distilled and motionless water. We used spherical quartz particles with the diameters of 0.77, 1.09, 2.18, and 4.36 millimeters and density of 2,650 kg/m3. The Flow-3D software was applied to estimate the fall velocity based on the environment of experiment by Ferguson and Church (2004) using the void of flow method. The main objective of this research was to demonstrate the power of the numerical model to simulate the fall velocity of sediment particles. To validate the results of the model, they were compared with the experimental results and 26 well-known publications during 1933-2016 using the root-square-mean and mean-absolute-percentage errors. The results showed good agreement between the experimental and numerical data. Therefore, the proposed numerical model could be used to determine the fall velocity of sediment particles with a wide range of diameters in the proposed environment and particle types.

Limitations in nutrients and physicochemical parameters play a key role in aquatic ecosystems. The present study aimed to determine the influential physicochemical factors in the chlorophyll-a content for wetland management by identifying the restricting factors in primary production. Sampling was conducted during March 2017-February 2018. Factors such as water salinity, temperature, pH, nitrate and phosphate concentrations, biochemical oxygen demand, total dissolved solids, electrical conductivity, total suspended solids, and dissolved oxygen were measured in triplicate at each station. In addition, the trophic state index (TSI) was used to determine the trophic state of the wetland. No significant difference was observed in chlorophyll-a contents in different seasons (P>0.05), with the highest values reported in spring and autumn, and the lowest values reported in summer. The maximum and minimum chlorophyll-a content were observed in stations A and C, respectively. Station A had a significantly higher value compared to the other stations (P<0.05). In addition, no significant differences were observed in the water physicochemical parameters in different seasons (P>0.05). The highest (5.9 mg/l) and lowest water nitrate levels (4.1 mg/l) were observed in spring and autumn, respectively (mean nitrate level: 4.84 mg/l). The highest (2.1 mg/l) and lowest water phosphate levels (0.47 mg/l) were observed in spring and autumn, respectively (mean nitrate level: 1.04 mg/l). Moreover, TSI indicated that the wetland is oligotrophic in spring and winter, while it is mesotrophic in summer and autumn. Overall, the nitrate level in water was the main restricting factor in the management of Choghakhor wetland.

Aflatoxins are fungal toxins with carcinogenic, mutagenic, and teratogenic properties. Aflatoxin M1 (AFM1) is resistant to autoclave, pasteurization temperature, and other food preservation procedures. The present study aimed to measure and compare the levels of AFM1 in 84 raw milk samples collected during six successive months, including 36 samples from a dairy factory and 48 samples from four major local dairy distribution centers. The day of sampling was selected randomly. AFM1 levels were measured using the ELISA assay. In distribution centers number one, two, three, and four, the levels of AFM1 were higher than the permissible limits in 33%, 25%, 8.3%, and 25% of the samples, respectively. Furthermore, the level of AFM1 in 19.44% of the factory samples was higher than the permissible limits in the United States. The mean AFM1 concentration in distribution centers number one, two, three, and four and the dairy factory was 0.0344, 0.243, 0.19, 0.301, and 0.175, respectively. The results of one-way analysis of variance (ANOVA) indicated no significant difference in the mean concentration of AFM1 with (P=0.279). According to the results, it is recommended that more preventive actions be taken in order to control the AFM1 content of livestock feeds and consumed milk in Kurdistan University, Iran.

Absorption is a common technology used for water and wastewater treatment since it is often fast and efficient, while costly at the same time. Therefore, the development of low-cost and efficient adsorbents has led to the rapid growth of research interest in this regard. Chitosan is a natural polyaminosaccharide with effective adsorption properties, which is applied to remove various pollutants. However, it has low efficiency in the adsorption of some pollutants, and its separation from aqueous solutions is difficult as well. Therefore, modification of chitosan has been recommended to address this issue. The present study aimed to synthesize nanosized chitosan-magnetic iron particles and determine their properties. Magnetic iron nanoparticles were fabricated using the chemical precipitation method, and magnetic chitosan was prepared. Several methods were applied to assess the properties of the synthesized adsorbent, including scanning electron microscopy, X-ray diffraction, atomic force microscopy, Fourier-transform infrared spectroscopy, dynamic light scattering, and zeta potential. Chitosan-magnetic iron nanoparticles had higher surface roughness and irregular pores, and the magnetic iron nanoparticles were successfully embedded in chitosan. Due to the surface charge of the chitosan-magnetic iron nanoparticles, it could be used as an effective adsorbent for the removal of contaminants with negative charge and their complete separation from aqueous solutions using magnets.

Adsorption is a chemical method for water purification. In the present study, native and impregnated active carbon was used for adsorption to evaluate the efficacy of the process in manganese removal from aqueous solutions. Impregnation reaction was performed using the precipitate colloids of manganese oxides onto the carbon surface. X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy confirmed that the process was appropriate for carbon impregnation. The experiments indicated that the highest adsorption of Mn2+ ions by impregnated active carbon occurred at the pH of 9 (Mn2+ removal: 67.19%). In addition, the reaction time, mixing rate, and adsorbent dosage affected the efficacy of adsorption, and optimal results were obtained at the reaction time of 100 minutes, mixing rate of 100 rpm, and adsorbent dosage of 4 mg/l. In all the test conditions, impregnated active carbon had better performance in Mn2+ removal from aqueous solutions compared to native active carbon (99% confidence level). The Langmuir and Freundlich isotherm models were also applied to evaluate the adsorption process. Accordingly, RL was 0.07 and 0.027 for raw active carbon and impregnated active carbon, respectively. RL magnitude confirmed the suitability of the Langmuir model for Mn2+ adsorption using impregnated active carbon. According to the results, impregnated active carbon exhibited the maximum adsorption capacity (qmax) of 20.53 mg/g, while this value was estimated at 6.62 mg/g in raw active carbon. On the other hand, the adsorption kinetic analysis indicated that the pseudo-second order mode and intra-particle diffusion model could be used for this process.

Cement dust deposition on soil has been implicated in the heavy metal (HM) contamination of soil, leading to adverse effects on plants and humans. This study assessed the impact of cement dust deposition on the HM content of the soil samples in the vicinity of a cement factory and its implication on the public health of the host community. Topsoil samples were collected at varying distances and directions in the vicinity of the cement factory and a remote area to the factory (control). The Pb, Cu, Mn, Fe, Cd, Se, Cr, Zn, and As content of the soil samples were determined by atomic absorption spectrophotometry. The HM content of the soil samples in the studied locations were within the safe limits, except for Zn, which was higher in the samples closest to the factory. The levels of Mn, Fe, Zn, Pb, Cu, and Cr were significantly higher in the samples closest to the factory compared to the other locations (P<0.05). Moderate contamination with Cu and Pb and considerable contamination with Cr were observed in the samples closest to the factory. The HM content of the soil samples of all the locations demonstrated minimal enrichment (EF<2) and average pollution index (1<IPI≤2). Cement production is associated with the exacerbation of the HM contamination of the surrounding soil, with the degree of contamination depending on the distance from the factory. Moderate soil contamination with HM poses potential risk of deleterious public health effects if appropriate remediation strategies are not implemented.

The recycling and separation of waste from the source could reduce the amount of unusable waste. Workers in this sector are exposed to severe health complications. The present study aimed to assess the health status of waste recycling workshops in Jouybar and Ghaemshahr, Iran in 2018. In this descriptive, cross-sectional study, data were collected using a researcher-made questionnaire, the reliability of which has been confirmed. Among 400 workshops in the mentioned cities, 90 were selected via cluster sampling, and the questionnaires were completed. Data analysis was performed in SPSS version 24 and Excel software using the analysis of variance (ANOVA). The results indicated that 58% of the floors of the workshops, 71% of the walls of the workshops, and 70% of the ceilings of the non-sanitary waste collection workshops were preserved in accordance with the relevant regulations. However, 31% of wastewater contaminated the environment and agricultural lands in the vicinity of the workshops. Only 6% of the employees reported to have taken periodic examinations, and the majority of the workers used no work clothes and gloves. In addition, only 2.2% of the workers were vaccinated. Most of the studied workshops only performed a breakdown without making specific changes in the waste materials. According to the results, the health status of the waste recycling workshops and its workers was unfavorable. Therefore, I is recommended that regulators and policymakers be aware of the needs and vulnerabilities of these workers and identify the effective interventions for their health protection.