Avicenna Journal of Environmental Health Engineering
Volume:8 Issue: 2, Dec 2021

Nowadays, the entry of heavy metals entry into aqueous environments has jeopardized the health of human societies. The experiment was conducted in discontinuous conditions, and the study focused on examining the effect of five parameters including initial concentration, temperature, contact time, pH, and adsorbent dose on the adsorption of Cu heavy metals. In addition, the two-parameter models of Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich were studied and compared to evaluate isothermal absorption. The highest correlation coefficients were obtained for Freundlich (0.969) and Dubinin-Radushkevich (0.9603) models. Finally, thermodynamic parameters such as enthalpy and entropy changes and Gibbs-free energy were calculated as well. The pH parameters, adsorption dose, contact time, temperature, and initial Cu concentrations in the discontinuous system had a statistically significant effect on the adsorption process. The results showed that the maximum efficiency of Cu adsorption by Lignocellulose nanofiber (LCNF) occurred at the pH of 6, contact time of 60 minutes, the ambient temperature of 25°C, and adsorption dose of 0.2 g. In the case of adsorption kinetics, the pseudo-second order model and intra-particle diffusion had more fitness with the experimental data indicating a chemical equilibrium between the adsorbate and the absorbent. Thermodynamic studies demonstrated that the process (negative ΔG) is spontaneous (negative ΔG), endothermic (negative ΔH), and non-random (positive ΔS). Thus, LCNF can be used as an effective adsorbent in the removal of metals by having an extremely high surface area.

This study integrated the rapid impact assessment matrix (RIAM) analysis and the mathematical sustainability modeling to evaluate disposal options so as to find the most appropriate and practical unmitigated option for the main waste disposal site in Tehran, Iran. RIAM analysis was used to assess environmental impacts of five potential disposal options followed by determination of sustainability for each option. RIAM analysis results indicated that option 5 (i.e., composting) had the least negative cumulative impacts on the environmental score value of -481 among the studied options. Incineration of wastes, option 4, was found to be the least favorable option mainly due to the high relevant costs and emission of air pollutants. Option 3, sanitary landfilling, was found to have fewer negative impacts compared to the options 1 (open dumping), 2 (land burial), and 4. It was also found that none of the examined options were sustainable in unmitigated state; however, results indicated that option 5 was the most favorable one in terms of sustainability with an obtained sustainable value of -0.126, which was the lowest value of unsustainability found in the present study. Calculated values of environment for the evaluated options in unmitigated state were not sufficient enough to compensate for the corresponding values of human needs and interests. Finally, option 5 followed by option 3 were suggested as alternative disposal approaches for the current methods in unmitigated state to reduce negative environmental impacts of waste disposal.

Alosa braschnikowi and Vimba persa are commercially important fish species in the southern part of the Caspian Sea. However, little is known about the trace element (TE) concentrations in their muscles. To this end, a total of 82 pieces of V. persa and 74 A. braschnikowi were caught at three different fishing areas (Astara, Anzali, and Kiashahr) around the southwestern shorelines of the Caspian Sea from September 2017 through June 2018. An inductively coupled plasma optical emission spectrometry (ICP-OES) was used to measure the accumulation of 34 traces and macro elements in some tissues of the fish species. Then, comparisons of the element levels in these tissues were made for the three different fishing areas. Overall, in the case of A. braschnikowi, 30, 30, and 28 elements were detected in its skin, gonads, and kidneys, respectively, while in the case of V. persa, 27 and 28 elements were found in its muscle and liver, respectively. The majority of element levels measured in these tissues indicated no significant differences among the sampling areas (P>0.05) except for such elements as copper, lanthanum, and tungsten in skin, lanthanum, rubidium, and vanadium in gonads, as well as molybdenum and zinc in kidney (P<0.05). The capacity of observed elements put human health at risk were examined as well. The TE content in the tissues of A. braschnikowi and in the muscles of V. persa (P<0.05) differed significantly from the international standard levels (P<0.05). In this study, only lead indicated a target hazard quotient (THQ) index above 1. Therefore, high consumption of this fish (360 g per year) may be a matter of concern for the consumer. In the case of other evaluated elements, the THQ value was less than 1.

Fish consumption has been considerably increased in Iran recently. On the other hand, the increase in aquatic ecosystem pollution can cause the accumulation of heavy metals in aquatic animals – the fish, in particular. Therefore, measuring the amount of heavy metals in fish is of great importance for consumers’ health. This study aimed to measure the amount of heavy metals (nickel, chromium, and cobalt) in wild and farmed carps (Cyprinus carpio) by using an ICP device. In this cross-sectional study which was performed in Hamadan province in 2018, 40 carp samples (20 wild carp samples and 20 farmed ones) were randomly collected from Anouch and Shirinsoo dams and from breeding centers of the province and, after completing the digestion phase, the amount of heavy metals in the samples were measured using the ICP device. The study results showed that the amounts of nickel metal in wild and farmed carps were equal to 0.108±0.086 and 0.102±0.108 mg/kg dry weight, respectively; and the amounts of chromium in wild and farmed fish samples were 0.348±0.396 and 0.136±0.074 mg/kg dry weight in muscle tissue, respectively. Cobalt metal was not observed in wild and cultured samples. According to the results from the statistical analysis, no significant difference was detected between wild and farmed fishes regarding contamination with nickel metal. However, a difference was found between wild and farmed fishes (P<0.05) regarding chromium. Taking into account the higher amount of nickel and chromium metals in the wild carp samples compared to the farmed ones, it was recommended that necessary measures be taken to control the sources responsible for polluting the aquatic environment and to prevent the penetration of industrial effluents and other polluting factors into the dams of Hamedan province in order for avoiding the increase in the amount of heavy metals in the province’s water sources.

Membrane technology is a green technology, but it still faces a pressing problem related to the effect of fabrication materials on the environment. The plant Verbascum thapsus L (VTL) was utilized as a biomembrane to reduce chemicals. In this study, VTL was successfully utilized as a membrane for activated sludge separation. The membrane was characterized via scanning electron microscopy (SEM)-EDX, Fourier transform infrared (FTIR), and contact angle measurement. Additionally, the effects of pressures on the fluxes and the rejection ability were studied. The permeability of the bio-based membrane reached 581 L/m2 .h.bar. The VTL membrane was examined for the removal of chemical oxygen demand (COD), protein, and carbohydrate. Accordingly, the maximum COD removal was obtained at a transmembrane pressure of 2.5 bar and reached up to 57%. The protein and carbohydrates rejections raised from 80% and 84% at 0.5 bar to 90% and 98% at 2.5 bar, respectively. The total resistance increased from 87% at a pressure of 0.5 bar to 96% at 2.5 bar. The flux recovery ratio (FRR) for the membrane at working pressures (0.5-2.5 bar) was 96% for 0.5 bar and 70% for 2.5 bar. The physical cleaning showed a flux recovery after three operation cycles. At the end of the filtration experiments, the pressure variation along streamlines over the membrane cross-section was simulated. As a result of this study, the use of a naturally-derived membrane is considered a green technology. The plant-based membrane reduces the use of non-green chemicals. Moreover, VTL has no commercial value and is recognized as an invasive plant species. All of the previous issues made the study worthwhile.

Municipal wastewater is one of the largest volumes of wastewater which contains various organic compounds from proteins and fats to carbohydrates and nucleic acids. Municipal wastewater of Behshahr city (Mazandaran, Iran) was evaluated using aluminum sulfate and iron chloride as chemical coagulants and pectin and sodium alginate as natural ones. Biological oxygen demand was investigated at different temperatures and coagulant concentrations. The fraction of full factorial statistical method and Qualitek-4 software were applied for designing experiments and analyzing the results to determine the optimal conditions for achieving the highest reduction in wastewater organic load and biological oxygen demand. In the case of biological oxygen demand, the optimal condition was achieved at 25°C, using 1, 0.02, 1.5 and 1 g/L of aluminum sulfate, sodium alginate, iron chloride and pectin, respectively. Under the optimal condition, the percentage of biological oxygen demand reduction was equal to 34.5%. Maximum BOD removal of 40.9% was obtained at 25°C using aluminum sulfate, sodium alginate, iron chloride, and pectin at concentrations of 0.6, 0.02, 1.5, and 6 g/L, respectively. The contribution of aluminum sulfate, sodium alginate, iron chloride, and pectin concentration in biological oxygen demand removal of the studied wastewater was 3.8%, 22.4%, 16.3%, and 14.4%, respectively. Coagulation temperature and aluminum sulfate concentration with approximately 42.7% and 3.8% contribution values were determined as the most and the least effective factors in biological oxygen demand reduction.

The current work investigated the optimization of synthetic textile wastewater (STW) containing methyl orange, crystal violet, and neutral red reactive dye degradation on manganese dioxide coated on graphite electrode using the Box-Behnken design (BBD). Carbon coated by manganese oxide (C/ MnO2 ) electrode was prepared by the sol-gel method. Graphite substrates were obtained from spent lithium-ion batteries for recycling and reducing the price of the electrode material in electrochemical processes. C/MnO2 was used as anode and cathode in an electrochemical cell during experiments. In addition, BBD was applied to design the experiments and find the optimal conditions for the degradation of STW. From the proposed model, the rate of the removal efficiency of chemical oxygen demand (COD) reached 83.63% with the optimum conditions (6.989 hours, concentration of 1.5 g/L NaCl, and current density of 50 mA/cm2 ). Based on the obtained optimum values, the specific energy consumption was around 30.359 kWh (kg COD)-1. Furthermore, the C/MnO2 electrode was characterized by Raman spectroscopy, and MnO2 films were prepared from the sol-gel process and deposited on graphite. Thus, using graphite coated with manganese dioxide, indirect anodic oxidation (IAO) can be efficient for the removal of the organic matter from the real textile dye bath.

Several recent studies have focused on leaching pesticides from agricultural soils into surface and groundwater resources during irrigation. As a result, information about herbicide residues in water was necessary for conserving related resources. This study provided an overview of monitoring herbicides in water resources worldwide. In this scoping review, five databases were searched for publications (1990 to April 2021), including Scopus, PubMed/Medline, Cochrane library, Embase, and Web of Science. Among the 394 identified articles, 17 papers were selected for inclusion. Most of these studies have been conducted in regions with low herbicide concentrations, including Spain, Greece, Canada, Brazil, Hungary, Malawi, Portugal, Lesotho, Germany, Serbia, and the USA. The high-level alachlor, metolachlor, atrazine, metribuzin, and simazine herbicides in groundwater were detected in Portugal (0.4-13μg/L). An overview of studies demonstrated that herbicides are widely used in water resources, and surface waters are more contaminated than groundwaters.