فصلنامه سلامت و محیط زیست
سال هفتم شماره 3 (پیاپی 25، پاییز 1393)

Synthetic dyes are extensively used in various industries such as textile، leather tanning، plastic، pulp and paper. Since dyes are toxic and even carcinogenic، discharging dye-containing wastewater into the environment poses serious environmental and health problems. Therefore، the purpose of this paper was to evaluate the removal of Reactive Red 120 from aqueous solutions using surface modified natural zeolite. The Semnan zeolite was sieved using standard sieves in size of 0. 2 - 0. 3 mm and then was modified by cationic surfactant. Batch adsorption studies carried out to study various parameters included contact time، initial concentration of Reactive Red 120، pH، and adsorbent dosage. The concentration of dye was measured using a UV-vis Spectrophotometer at the wavelength of 537 nm. Freundlich and Langmuir isotherms and Pseudo-first order and pseudo-second order kinetics were used to analyze the isotherm and kinetic data respectively. The adsorption studies indicated that increasing of the contact time، initial concentration of Reactive Red 120، decreasing pH and adsorbent dosage leads to increasing dye adsorption. Equilibration of Reactive Red 120 adsorption was reached at lapse of 90 min. Moreover، it was found that Langmuir isotherm (R2=0. 9814) and pseudo second-order kinetic (R2=0. 9814) are well fitted with our data. The results of the study show that Iranian modified zeolite can be used effectively for removal of Reactive Red 120 in comparison with other parts of the world. Considering the cost، availability and ease of modification، it can be used to remove dye in industrial wastewater.

The presence of natural organic materials (NOM) in water resources affects its quality (i.e. color, odor, and taste). In addition, it leads to the fouling of filters and membranes and reduces water treatment efficiency during flocculation/ coagulation. Moreover, NOM reacts with disinfectants and produces byproducts (DBPs), which are harmful to human health. Magnetic nanoparticles have been reported as effective adsorbents for the removal of pollutants from the aqueous media. In this study, we applied SiO2coating on these nanoparticles in order to enhance their stability and dispersion in aqueous media and investigated their capability in NOM adsorption from water. Iron oxide magnetic nanoparticles were prepared by co-precipitation. Then, we added Tetraethoxysilane (TEOS) to the solution in order to coat it with SiO2. The adsorbent characteristics were determined by SEM and XRD. Then, we carried out the adsorption experiments under different pH(3-12) and contact time (5-240 min)performance conditions. The adsorption kinetic was determined with respect to different Humic acid adsorption times. Later, we determined the effect of different concentrations of adsorbent on different concentrations of Humic acid, and Langmuir and Freundlich coefficients based on the optimum conditions. The morphology investigation of adsorbent showed the average size of Fe3O4/SiO2nanoparticles was 30-130 nm. The pH value of 10.5 and the contact time of 90 min at room temperature were determined as optimum conditions for removal of humic acid using Fe3O4/SiO2 nanoparticles. The maximum adsorption capacity of Fe3O4/SiO2 was192.30. The adsorption isotherm was fitted well by Langmuir model (R2>0.90) and the pseudo-second order model (R2>0.98) could better explain humic acid adsorption. Having high number of active surface sites, magnetic properties, easily separation using magnetic field, and its cost-effectiveness, the Fe3O4/SiO2 nanoparticles could be used as an efficient adsorbent in removal of humic acid from water.

Because of problems dealing with bioremediation including being time consuming, low efficiency and toxicity to biota, application of advanced oxidation processes with higher efficiency and shorter remediation time have been considered for removal of hydrophobic hydrocarbons from contaminated soils. A great interest has been directed to Fenton oxidation because of its simplicity and high oxidation potential. The objective of this study was to determine the Fenton-like oxidation efficiency for pyrene removal from soil using iron nano oxides and Fe2+.

The H2O2/Fe molar ratios of unadjusted with native Fe content of soil, 10, and 20; H2O2 concentrations of 0 – 500 mM; pH 3, 5, and 7; and soil samples containing Fe2+, native iron and iron nano oxides were investigated for removal of 100 mg/kg pyrene according to Taguchi experimental design.

Fe2+, H2O2/Fe molar ratio of 20, pH 3 and H2O2 concentration of 500 mM were determined as optimum conditions. Under optimum conditions, S/N ratio increased to 39.322 and the pyrne removal reached to 86 % for Fe2+ and 83 % for Fe3+ respectively, after 2 hours of reaction time and pH 3.

Fenton oxidation using iron nano oxides under defined optimum conditions and neutral pH, can be a suitable alternative to conventional Fenton for remediation of soils contaminated with pyrene.

Few investigations on polycyclic aromatic hydrocarbons (PAHs) in surface sediments have reported medium to high petrogenic contamination at the southwest coasts of the Caspian Sea. The aim of this study was to investigate distribution and potential sources of 16 PAH compounds in surface sediments of the southwest coasts of the Caspian Sea (Gillan province). A total of 45 sediment samples from 15 stations at coasts of the Gillan province (from Astara to Lahijan) were collected from 10, 20, and 50 meters depths. Each sample was analyzed using Gas chromatography – Mass spectrometry. Diagnostic ratios were used for source identification. The main PAH compounds in the study area were phenanthrene (87.6±74.6 ng/g), pyrene (43.1±23.5 ng/g), and naphthalene (34.4±40.4 ng/g) respectively. According to the calculated diagnostic ratios such as LMW/HMW (0.25-7.75), Ant/178 (0.02-0.11), Flu/202 (0.20-0.49), and B(a)Ant/228 (0.09-0.54) the main source of PAHs is petrogenic in this study area. According to PAH diagnostic ratios and similarity of dominant PAH compounds in study area with dominant PAH compounds of Azerbaijan oil field, main probable source of PAH compounds in Gillan province coasts is Azerbaijan oil pollution.

Remaining crude oil in storage tanks lead to accumulation of oily sludge at the bottom of the tank, which should be treated and disposed of in a suitable manner. The aim of the present study was to investigate the efficiency of chemical oxidation using H2O2 and Fenton’s reagent in removal of Total Petroleum Hydrocarbons (TPH) from bottom sludge of crude oil storage tanks. In this experimental study, hydrogen peroxide and Fenton’s reagent were added to the sludge in six concentrations including 2, 5, 10, 15, 20, and 30% (w w-1) and TPH was measured for a period of 24 and 48 h of reaction time. The oxidants were added in a single and stepwise addition way, both to the pristine and saturated sludge. The elemental analysis of sludge and TPH measurement were carried out using ICP and TNRCC methods respectively. The mean TPH removal of 2, 5, 10, 15, 20, and 30% oxidant concentrations were 1.55, 9.03, 23.85, 33.97, 41.23, and 53.03%, respectively. The highest removal efficiency was achieved in stepwise addition to the saturated sludge. Increasing oxidation time from 24 to 48 h had a little effect on increase in TPH removal. Moreover, the removal efficiency of H2O2 and Fenton was nearly similar. Mere application of chemical oxidation is not capable of complete treatment of the sludge but it is an effective process as a pre-treatment step for decreasing toxicity and increasing its biodegradability.

In recent decades, progress of telecommunication industry resulted in public availability to cost-effective cellular mobile; hence, boom of base stations of cellular mobile in response to vast public demands. Base stations of cellular mobile are specific source of microwave production in a certain frequency in environment. Antennas are installed on high towers to create proper coverage. General public exposure because of possible health effects resulting from radiofrequency fields has become challenging problem. The purpose of this study was to investigate microwave radiation status in actual exposure in inside buildings vicinity of macro cellular base stations in Zanjan. considering location of base station antenna in city, power density of microwave around 64 base stations in indoor sites such as health care places and residential areas at different distances and different heights was measured. Measurements were performed based on IEEE Std C95.1 standard method using a portable SPECTRAN, HF– 4060 Rev. 3. Analyzing of data was conducted using SPSS Ver. 18 software and statistical tests like Kolmogorov-Smirnov, univariant variance, and multi variant linear regression. It was found that the maximum level of power density was measured at a distance of 20 m from base station about 0.03787mW/m2. With increasing distance from base station, the density of wave power decreased. Minimum measured at a distance of 300 m from tower was 0.00108mW/m2. The positive variation of power density with height increase was shown. The maximum level of power density among total of 252 measurements, in indoor sites was7.320mW/m2. This is about 0.166 % of the Permissible Exposure Limits of the standards for public exposure. We did not consider factors such as building location and interior furniture. Therefore, we suggest such factors be included in the future studies.

Due to the importance of Sanandaj Gheshlagh Reservoir (SGR) in the region and proven mercury pollution in SGR water, a research project was carried out to determine the amount of mercury concentration and bioaccumulation and its behavior through a food route in SGR food chain (i.e., water, sediments, fish, and human).This was done, because it has been reported that mercury concentration and its toxicity could increase during mercury exchange between trophic levels. During April to December 2012, 24 water, sediment, and fish samples (Capoetta trutta) (4 samples per month) from SGR and 24 human hair samples from Sarab Ghamish village settlers (the major Capoetta trutta consumers in the region) were collected. Total mercury mean concentration in water, sediment, Capoeta trutta, and human hair were 0.0028±0.000128, 0.110±0.0057, 0.296±0.0119, 2.059±0.1704 ppm respectively. Calculated bioconcentration factors were 4 × 10 and 1 × 102 in SGR sediment and fish, and related biomagnifications factors were 40 and 5 respectively. Due to the high bioaccumulation, biomagnifications factors and mercury concentration recorded in edible parts of SGR fish, local consumers should not eat more than 1182 gram of this fish weekly without accounting for other potential sources of total mercury in their food basket.

Petroleum hydrocarbons are a bunch of pollutants hazardous to the environment. Nowadays, biodegradation of petroleum contaminants is considered as one of the most efficient and most cost effective methods of removing oil contamination from the environment. The main objective of this study is to investigate the potential of cyanobacterium Schizothrix vaginata ISC108 in the biodegradation of crude oil and to evaluate oil effects on growth rates, dry weight, and chlorophyll content. In this experimental study, the cyanobacterium Schizothrix vaginata ISC108 was obtained from the algal culture collection of Research Institute of Applied Science, ACECR, Tehran, Iran. First, purification of the cyanobacterium was performed using agar plate method on solid medium of BG11. Growth rate, chlorophyll content and dry weight of cyanobacteriaum was measured using spectrophotometry method. The biodegradation rate of crude oil was calculated using gas chromatography (GC) analysis. Measuring the growth rate of cyanobacterium Schizothrix vaginata at 1% treatment of crude oil and control samples showed that the growth of cyanobacterium in the presence of crude oil as the sole carbon source increases at the same rate as the control sample. Moreover, it was found that increasing the concentration of crude oil will result in increasing dry weight of Schizothrix vaginata; however, and the chlorophyll content reduced in various crude oil treatments. The average biodegradation of petroleum hydrocarbon after 14 and 28 days of treatment was 54.78 and 93.98% respectively. It was found that cyanobacterium Schizothrix vaginata ISC108 has great potential in biodegradation of crude oil. Therefore, since oil is a product toxic to biological systems and is one of the main pollutants of bioecosystem, it has a great potential to be used as an indicator to eliminate pollution in contaminated areas.

Bakery’s yeast industry wastewater contains various pollutants and is generally characterized with high chemical oxygen demand (COD), dark color, high-nitrogen and sulfate and non-biodegradable organic pollutants. Having persistent soluble colored compounds (called melanoidins), effluent from yeast industry is a major source of water and soil pollution. The aim of this study was to evaluate advanced oxidation efficiency using Fenton process for COD and color removal from bakery’s yeast wastewater. This was an experimental- laboratory scale study. In this study, the effect of time and Fenton concentrations were tested for COD and color removal from bakery’s yeast wastewater. The sample used for this study was yeast effluent from Separator 2 with initial concentrations of COD and color of 5300 mg/L and 6950 pt-co respectively. In order to obtain the optimum operating conditions of the process, Taguchi analysis method was used. Experiments were carried out in five stages of the time in the range of 15, 30, 45, 60 and 75 min with various concentrations of hydrogen peroxide (e.g., 0.02, 0.04, 0.06, 0.08, and 0.1 molar) and concentrations of Fe 2+ (e.g., 0.01, 0.02, 0.03, 0.04, and 0.05 molar) at pH = 3. Jar test method was used to determine the best operating conditions including: reaction time, dosages of hydrogen peroxide and Fe 2+. According to Taguchi method and SN-ratio analysis, the best H2O2/Fe 2+ dosages were 0.08/0.04 molar at pH 3 and in reaction time of 30 min for removal of COD and color. For these conditions, the maximum COD and color removal efficiencies were 63 and 69 percent respectively. Based on the results, with increasing reaction time, there was no perceptible change in the removal efficiency. It can be concluded that Fenton’s oxidation method can be used successfully, as an alternative option to the design and choice of color and COD removal from strength industrial wastewaters e.g., bakery’s yeast industry.

Chemical spillage of equipment is possible in petrochemical processes. Occurrence of such event can result in firing and explosion and consequently would bring about some risks to the environment affected. The aim of this study was to assess environmental risks in Olefin Plant, Arya Sasol Petrochemical Company in order to identify environmental risks at producing source. The basic data was gathered through using the results of monitoring and measurement of ambient air pollutants and stack exhaust gases, safety review method and field observation. For determination the effects of hydrocarbons leakage from equipment on the environment, measuring BTEX in ambient air was performed as per EPA0030 Standard method with using Gas Chromatography at 4 stations of the complex and a portable Testo 350 XL device was used for monitoring stack exhaust gases, from 9 stacks from May 2011 to April 2012. Assessment and risk management tool used in this study was the fault tree analysis method. The main part of the risk assessment in fault tree method is selecting a top event. According to the statistics of accidents and environmental aspects of ethane cracking operations, hydrocarbon leakage is detected as top event and then composition and relationship between risk factors is determined in the form of terminal event, intermediate event and the gate “and” and “or”. With qualitative and quantitative analysis of fault tree of this accident, the main causes of the accident and the likelihood of the top event was calculated for a year. Comparing with other stations, it was found that benzene with concentration of 0.37 mg/m3 in autumn, toluene with concentration of 0.13 mg/m3 in spring, and ethyl benzene with concentration of 0.09 mg/m3 in autumn, and xylene with the concentration of 1.01 mg/m3 in autumn season had the highest concentration. The fault tree developed had 16 events (including final, intermediate, and initial), which were connected to each other with seven logic gates. The maximum error percentage in the terminal events was attributed to the hardware failures such as malfunction in equipment with 55.55 percent followed by human and administrative errors in the next ranking. The highest percentage (22.2%) of the terminal events was related to the gasket unsuitable material; the main reason is due to the economic sanctions and the lack of effort to provide high quality products. Most likely occurrence of the final event was related to the gasket unsuitable material (2×10-2). Control action to prevent the occurrence of leakage could be supplying high quality gaskets and the failure is classified in the hardware failure category.

Phenol is one of priority pollutants produced through leather, paint, resin, and pharmaceutical industries and it can contaminate groundwater after entering to the environment. Hence, it is necessary to use a suitable method for its removal. The aim of this study was synthesize and efficiency evaluation of magnetic nanocomposite of activated carbon powder-zero valent iron/silver (PAC-Feo/Ag) in the removal of phenol from aqueous solution. Reduction method was used for converting bivalent iron to zero valent iron and co-precipitation method for depositing of iron on activated carbon. For coating silver on nano zero valent iron, rapid mixing at high temperature was used. The adsorbent was characterized using SEM, TEM, and XRD techniques. Then, the impact of pH, contact time, agitation speed, temperature, adsorbent, and initial phenol concentration were evaluated and optimized by one factor at the time method. Reaction kinetics and isotherms were also determined. It was found that PAC-Feo/Ag has cubic and intertwined structure and has a diameter in the range from 40 to 100 nm. The optimum conditions for phenol removal by PAC-Feo/Ag were as pH=3, 90 min contact time, 200 rpm agitating speed and adsorbent concentration equal to 1 g/l. Isotherm and kinetic equations showed that the experimental data of phenol adsorption onto PAC-Feo/Ag are correlated to the Langmuir (R2>0.969) and pseudo-second order (R2<0.965) models, respectively. Under optimum conditions, modified adsorbent by zero valent iron and silver with maximum efficiency of 97% has quickly and effectively ability in removal of phenol and it can be easily separated from the solution sample by magnet because of its magnetic properties.

Present study aimed to investigate response of metallothionein (MT) in oyster Crassostrea sp. to the experimental concentrations of Hg and Cd in order to assess the possibility of MT usage as a biomarker of Hg and Cd contamination in this mollusk. Oysters were collected from docks of Imam Khomeini Port. After seven days acclimation period in laboratory, they were exposed with Hg at concentrations of 15 and 75 μg.L-1 and Cd at concentrations of 15 and 150 μg.L-1 for 14 days. MT levels were measured through spectrophotometric method after extraction and precipitation. After preparation and acid digestion, the concentration of heavy metals was quantified by atomic absorption. The amounts of MT in oysters exposed with Hg and Cd were significantly increased compared with control samples (P<0.05). The highest value of MT biosynthesis in oysters exposed with concentrations of Hg and Cd were 137.2±7.6 and 312.4±17.9 μg.g-1 w.w respectively. Exposing the oysters with Cd induced biosynthesis of MT more than three times compared with control samples. Among Hg and Cd, there was only significant correlation between biosynthesis of MT and Cd bioaccumulation in oysters (P<0.01). MT protein in oyster Crassostrea sp. can be considered as a suitable biomarker of Cd contamination in body and environment. Hence, it could be used for assessing and monitoring ecosystems.