Adsorption of chromium VI from aqueous solutions onto nanoparticle sorbent: Chitozan-Fe-Zr

Background and purpose: Various contaminants are released into water resources each year as a results of urbanization and industrialization. Chromium VI is one of the most toxic metals released into the aquatic environments, wastewater, and soil mainly via industrial sewage. The purpose of this study was to evaluate the performance of iron-zirconium/chitosan magnetic nanoparticles composite in removal of hexavalent chromium VI from aquatic environments. Materials and methods: A pilot-study was conducted in laboratory scale. Nancomposites synthesis was done using chemical precipitation and tested by SEM, XRD, and FTIR. Various factors such as contact time (0-720 min), initial pH of the solution (2-12), adsorbent dose (0.4-2 gr), initial concentration of metal (0-10 milligrams per liter), and the system temperature (15-35 �) were studied. The concentration of heavy metal chromium was measured using a spectrophotometer at 540nm. Results: The results showed that the highest removal efficiency of heavy metal chromium was obtained at pH 4.0 (52.99). Moreover, addition of 1 gr composite in the same concentration could boost removing the hexavalent chromium by more than 91. Increasing the concentration levels of heavy metals had little impact on the removal efficiency. Adsorption isotherms fitted the Freundlich isotherm. Conclusion: According to the results, the absorbent showed a high performance in removing chromium VI from aquatic environments. © 2016, Mazandaran University of Medical Sciences. All rights reserved

Biosorption Of Iron From Aqueous Solution By Dried Biomass Of Activated Sludge

This study was conducted to investigate the removal of iron by dried biomass of activated sludge. Dried activated sludge, prepared as a powder, was tested as a sorbent for the removal of iron from aqueous solutions. The effects of various experimental parameters including initial iron concentration, mass of biomass and contact time were examined and optimal experimental conditions were obtained. The equilibrium time for iron adsorption onto biomass was determined as 150 min. The rate of iron removal was directly correlated to biomass amount and contact time. Increasing contact time from 0.5h to 2.5h resulted in 25% improvement in iron removal efficiency. When the weight of the biomass increased from 0.1g to 0.9 g, the iron removal efficiency increased from 62% to 95%. High initial iron concentration had an adverse effect on iron removal efficiency. Increasing initial iron concentration from 2 to 10 (mg/L) caused declining the iron removal efficiency from 70% to 56%. Freundlich, Langmuir, Dubinin-Radushkevich and Temkin isotherm models could describe the adsorption equilibrium of the iron onto the activated sludge. Meanwhile, Freundlich isotherm represented a better correlation compared to other isotherms (R2 < 0.999). Also Elovich kinetic models fits well with experimental data (R2<0.997)

Physico-chemical changes and maturity evaluation of composts from wood residue mixed with sewage sludge and chicken manure

Purpose Using the effective approaches for modifying the recycled wood as a novel bulky agent improves the quality of soil amendment. This study aimed to compare the stability and maturity of the soil amendments produced by the compostation of forest industrial waste and sewage sludge on seed germination. Method Three materials, namely sawdust, sewage sludge, and chicken manure were mixed at different ratios (dry weight basis) to reach the initial bulk density of 0.40 Kg.L-1, the temperature of 30 °C, the C/N ratio of 25, and the moisture content of 60 . A pilot-scale composting process was applied to monitor the aeration rate, temperature, and moisture contents during the process over time. The comparison of physico-chemical, phytotoxicity, and germination indices among the samples was performed in three repetitions. Results The results of this study indicated that the sustainable conditions (i.e., the temperature of 70 °C, aeration rate of 0.30 L.Kg-1DM.min-1, and moisture content of 50-60 ) can have a significant effect on the thermophilic stage for compost curing without any inhibitory repercussion. Increasing the germination index of cress (Lepidium sativum) up to 79 proved that the toxicity of industrial sewage sludge was declined through the elimination of heavy metals. Conclusion This study revealed that the availability of bulky agents such as wood residue can reinforce the microbial activity by continuously decreasing the C/N ratio to the minimum value of 13.2. © 2021, Islamic Azad University. All rights reserved

Treatment of fresh leachate from municipal solid waste landfill using horizontal roughing filter

The roughing filters have effective size of the substrate grain which is greater than 2mm. This study aimed at the examination of the efficiency of horizontal roughing filter in nitrate, turbidity and chemical oxygen demand removal (COD), obtained in the fresh leachate from municipal solid waste landfill. This experimental study was conducted in 2014 in Karaj. Sampling was done in 3 rates 0.5m/h, 1m/h and 1.5 m/h, including simultaneous sampling from input and output filtering, to determine the concentration of nitrate, turbidity and COD. The sampling period lasted from March to August (2015). The average efficiency of COD removal in filtration rates of 0.5 m/h, 1 m/h and 1.5 m/h was equal to 84, 88 and 85 respectively. The average removal efficiency of nitrate in filtration rates of 0.5 m/h, 1 m/h and 1.5 m/h was equal to 88, 88 and 85 respectively. The average removal efficiency of the turbidity in filtration rates of 0.5 m/h, 1 m/h and 1.5 m/h was equal to 72, 86 and 81 respectively. Output values of COD and nitrate were lower than the environmental organization standard (P<0.05). Based on the results of this study, the nitrate removal with a horizontal roughing filter was better than that obtained with COD and turbidity. © 2016, International Journal of Pharmacy and Technology. All rights reserved

Health risk assessment of heavy metals in cosmetic products sold in Iran: the Monte Carlo simulation

Cosmetics can contain harmful compounds such as heavy metals. Several metals have a cumulative effect on the body, especially fatty tissues, and may have different health effects on the human body over the long term. Therefore, the main objective of this study was to assess the health risks of heavy metals in cosmetics in Iran. Also, in this study, Monte Carlo simulation was used to investigate uncertainties. In this study, heavy metals data of cosmetics were extracted from studies carried out at intervals 2010�2018. International and Iranian databases such as Google Scholar, Web of Science, Springer, Science Direct, PubMed, Scopus, Irandoc, Magiran, Scientific Information Database (SID), and Information Institute for Scientific (ISC) were searched for this purpose. In this study, the index of the Margin of Safety was calculated to determine the risk of human contact with metallic impurities in cosmetic products used by humans. In the selected period, 11 studies were conducted on the measurement of heavy metals in cosmetics in Iran. In these studies, cosmetics such as eye shadow, eye pencil, powder, cream, and lipstick were studied. The Margin of Safety (MoS) values calculated for different metals were higher than the established safe standard by WHO. The highest and lowest amount of systemic exposure dosage in all types of cosmetic investigated (lipstick, cream, eye pencil, face powder, and eye shadow) was related to Fe and Hg. The mean hazardous quotient (HQ) for Cd, Cr, Ni, Cu, Mn, Zn, Pb, and Hg was 1.05E-03, 1.03E-01, 7.95E-03, 2.59E-03, 1.05E-03, 4.98E-03, 7.22E-04, 1.85E-01, and 1.35E-05, respectively. The highest HQ (6.10E-01) was found for Pb, which was observed in the cream. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature