Akbar Eslami

Elimination of arsenic contamination from water using chemically modified wheat straw

Abstract Presence of arsenic in natural water resource as a common contaminant has always been a great concern for the scientists. The objective of this study was to explore the possibility of wheat straw modified with sodium bicarbonate (NaHCO3) for removing arsenate from aqueous solution. Adsorption process was accomplished in a laboratory-scale batch with emphasis on the effect of various parameters such as pH, contact time, arsenic concentration, and adsorbent dosage on the adsorption efficiency. In order to understand the adsorption process, sorption kinetics and equilibrium isotherms were also determined. It was found that adsorption of the arsenic is influenced by several parameters such as arsenic initial concentration, adsorbent dosage, and solution pH. Maximum adsorption efficiency was achieved at a pH of 7. The equilibrium adsorbed amount also increased with the initial concentration of the metal ions, as expected. NaHCO3 was used to modify wheat straw and scanning electron microscopy images sh...

Vermicomposting of food waste: assessing the stability and maturity

The vermicompost using earthworms (Eisenia Fetida) was produced from food waste and chemical parameters (EC, pH, carbon to nitrogen contents (C/N)) and germination bioassay was examined in order to assess the stability and maturity indicators during the vermicomposting process. The seed used in the germination bioassay was cress. The ranges of EC, pH, C/N and germination index were 7.5-4.9 mS/cm, 5.6-7.53, 30.13-14.32% and 12.8-58.4%, respectively. The germination index (GI) value revealed that vermicompost rendered as moderate phytotoxic to cress seed. Pearson correlation coefficient was used to evaluate the relationship between the parameters. High statistically significant correlation coefficient was calculated between the GI value and EC in the vermicompost at the 99% confidence level. The C/N value showed that the vermicompost was stable. As a result of these observations, stability test alone, was not able to ensure high vermicompost quality. Therefore, it appears that determining vermicompost quality requires a simultaneous use of maturity and stability tests.

Municipal solid waste landfill leachate treatment by fenton, photo-fenton and fenton-like processes: Effect of some variables

Advanced oxidation processes like Fenton and photo-Fenton have been effectively applied to oxidize the persistent organic compounds in solid waste leachate and convert them to unharmful materials and products. However, there are limited data about application of Fenton-like process in leachate treatment. Therefore, this study was designed with the objective of treating municipal landfill leachate by Fenton, Fenton-like and photo–Fenton processes to determine the effect of different variables, by setting up a pilot system. The used leachate was collected from a municipal unsanitary landfill in Qaem-Shahr in the north of Iran. Fenton and Fenton-like processes were conducted by Jar-test method. Photo-Fenton process was performed in a glass photo-reactor. In all processes, H2O2 was used as the oxidant. FeSO4.7H2O and FeCl3.6H2O were used as reagents. All parameters were measured based on standard methods. The results showed that the optimum concentration of H2O2 was equal to 5 g/L for the Fenton-like process and 3 g/L for the Fenton and photo-Fenton processes. The optimum ratio of H2O2: Fe+2/Fe+3 were equal to 8:1 in all processes. At optimum conditions, the amount of COD removal was 69.6%, 65.9% and 83.2% in Fenton, Fenton-like and photo–Fenton processes, respectively. In addition, optimum pH were 3, 5 and 3 and the optimum contact time were 150, 90 and 120 minutes, for Fenton, Fenton-like and photo–Fenton processes, respectively. After all processes, the biodegradability (BOD5/COD ratio) of the treated leachate was increased compared to that of the raw leachate and the highest increase in BOD5/COD ratio was observed in the photo-Fenton process. The efficiency of the Fenton-like process was overally less than Fenton and photo-Fenton processes, meanwhile the Fenton-like process was at higher pH and did not show problems.

Direct Blue 71 removal by electrocoagulation sludge recycling in photo-Fenton process: response surface modeling and optimization

AbstractFeasibility of RSM-optimized electrocoagulation (EC) sludge recycling was studied in photo-Fenton (PF) process for the removal of Direct Blue 71. By EC process, relatively complete decolorization was obtained in pH 8, 20 min, and 150 mA. The produced sludge, in EC process, was evaluated to be used and recycled in PF process experimental runs for two major targets: (1) Degradation of EC sludge as an environmental, concerning by-product; (2) Application of iron species resulted from anodic dissolution during EC process to play the role of catalyst in PF process. PF process was investigated based on the effects of EC sludge volume (total iron) and hydrogen peroxide concentration on decolorization. Besides, the effect of EC sludge recycling on decolorization and mineralization (TOC decrement) was studied. In optimum conditions of PF process (pH 3, 200 mg/L H2O2, 20 mL EC sludge and 30 min reaction time in the first run), 96.27% decolorization was achieved. In the same conditions, but in 10 min, 67.5% ...

The combination of coagulation, acid cracking and Fenton-like processes for olive oil mill wastewater treatment: phytotoxicity reduction and biodegradability augmentation

Olive oil mill wastewater (OOMW) is one of the most important industrial wastewaters in the world due to high organic load and phenolic compounds. In this study, an integration of three processes including coagulation, acid cracking and Fenton-like was evaluated to treat OOMW. The performance of alum, ferric chloride and polyaluminum chloride was studied as coagulants. Among coagulants, ferric chloride showed the best results in comparison with the others. Coagulation process with FeCl3 removed 91.2% chemical oxygen demand (COD), 91.3% phenol, 98.9% total suspended solids and 99.2% turbidity at condition of pH = 6 and 3,000 mg/L coagulant dosage. Acid cracking process following the coagulation process with ferric chloride could slightly degrade organic compounds and provided suitable condition for the next process. Fenton-like process with zero valent iron (ZVI) was applied after coagulation and acid cracking. The optimal removal efficiency was achieved by Fenton-like process which was accomplished in condition of 7 g/L ZVI, 1,000 mg/L H2O2 and 180 min reaction time. The biodegradability of final effluent of this integration was improved significantly and biochemical oxygen demand5/COD value increased from 0.14 to 0.83. The results of germination tests revealed that phytotoxicity of the final effluent decreased.

Physicochemical characterization of ambient PM2.5 in Tehran air and its potential cytotoxicity in human lung epithelial cells (A549)

As air pollution is a major problem in Tehran, this study aimed to investigate the physicochemical characterization of the water-soluble and organic contents of ambient PM2.5 in Tehran and determine its in vitro toxicological impact on human lung epithelial cells (A549). A total of 11 sampling stations were selected, including three categories: traffic, urban, and suburban. All sampling was carried out in the spring and summer of 2015. Ion chromatography (IC), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and GC-MS were used to analyze ionic compounds, heavy metals, and polycyclic aromatic hydrocarbons (PAHs), respectively, and an ELISA reader was used for cytotoxicity analysis. The most prevalent ionic species found for all three categories was SO42-. PAH concentrations were 43.45±32.71, 50.51±37.27, and 29.13±33.29ng/m3 for traffic, urban, and suburban stations, respectively. For all sampling stations, Al and Fe had the highest values among the investigated heavy metals. Cell viability measurements, carried out using the MTT assay, showed that all three categories of samples cause cytotoxicity, although the urban station samples showed higher cytotoxicity than those from the other stations (p˂0.05). Based on the results of the present study, organic compounds and insoluble particles could be the main causes of cytotoxicity.

Enhanced sonochemical degradation of tetracycline by sulfate radicals

Tetracyclines (TCs) are widely used antibiotics in human and veterinary medicine and as growth promoters in the world. Sulfate radical-based advanced oxidation processes have been of great interest due to the high oxidizing potential of sulfate radical to degrade refractory organic pollutants in aqueous solution. In this study, the degradation of antibiotic TC in aqueous solution by silver-activated persulfate (Na2S2O8) in the presence of ultrasound irradiation under various conditions has been investigated. The effects of several parameters such as Ag2SO4, Na2S2O8 concentration, temperature, ultrasonic (US) power, initial TC concentration and initial pH on the degradation of TC were investigated. More than 83% of TC removal was achieved within 120 min under optimal conditions. The optimum operational conditions were found to be as follows: Ag2SO4 dosage 3.5 mmol/L, Na2S2O8 concentration 70 mmol/L, reaction temperature 25 °C, US power 120 W, initial TC concentration 50 mg/L, pH 3.0 and contact time 120 min. The degradation of TC in the persulfate/Ag(+)/US process followed the pseudo-first-order kinetics.

Assessment of annual effective dose due to natural gamma radiation in Zanjan (Iran)

The outdoor and indoor measurement of natural gamma radiation in Zanjan province (Iran) was made using a Geiger-Muller dosemeter. The average outdoor and indoor dose rates were determined as 127 +/- 20 and 135 +/- 23 nSv h(-1), respectively. The average annual effective dose was calculated as 0.82 mSv, which is more than the same value worldwide.

Natural radioactivity levels of 226Ra and 40K in soil of Zanjan province, Iran

Radioactivity concentration of naturally occurring radionuclides, (226)Ra and (40)K, in soil samples of Zanjan province, in north-west of Iran and from 21 geographical areas was measured by gamma spectrometry. The activity concentration of (226)Ra ranged from 58.4 + or - 1.8 to 132 + or - 3.1 Bq kg(-1) with the mean value of 88.5 + or - 22.9 Bq kg(-1). The activity concentration of (40)K ranged from 267 + or - 5.9 to 791 + or - 8.1 Bq kg(-1) with the mean value of 497.4 + or - 162.6 Bq kg(-1). The mean values for absorbed dose rate in air and annual effective dose were determined as 62.6 + or - 16.5 nGy h(-1) and 0.076 + or - 0.02 mSv, respectively.

Health risk assessment of heavy metals on PM 2.5 in Tehran air, Iran

The general goal of this study was to measure the concentration of heavy metals on suspended particles and evaluate the health-risk assessment of these metals on human health. In this study, the concentration of heavy metals adsorbed on suspended particles less than 2.5 μm was determined. For determining of health-risk assessment, the developed method of USEPA was used. The health-risk assessment of carcinogen and non- carcinogen of suspended particles were evaluated in three main paths include oral ingestion, inhalation, and dermal contact. The average annual concentrations of Al, Fe, As, Cd, Cr, Cu, Mn, Ni, Pb, V, and Zn were 1.77, 1.14, 0.03, 0.02, 0.07, 0.15, 0.06, 0.03, 0.1, 0.04, and 0.14 μg/m3, respectively. Between different stations, the order for the heavy metals was followed as urban>traffic>suburban. The average risk of carcinogenic at urban stations in the spring for As, Cd, and Cr was 2.25*10−9, 2.09*10–12, and 2.05*10–11, respectively.