فصلنامه سلامت و محیط زیست
سال هفتم شماره 2 (پیاپی 24، تابستان 1393)

Pentachlorophenol (PCP) is an organic compound and phenolic derivatives categorized as priority pollutants that have harmful effects on humans، animals، and plants in low concentrations. Therefore، PCP removal from water and wastewater is very important. The aim of this study was to assess the efficiency of A. niger fungus biomass in PCP absorption. This was an experimental study in which different steps of the experiments were performed. A. niger strain was prepared from Persian Type Culture Collection of Iranian Research Organization for Science and Technology (IROST). After activation in potato dextrose agar (PDA) culture plates، fungi were incubated for 7 to 10 days at 25 °C. The prepared A. niger biomass was modified by NaOH and then it was used for PCP absorption assay. The concentration of PCP was measured using high-performance liquid chromatography. The findings of present study showed that contact time is an important and effective factor in the PCP absorption rate. Two hours was selected as the optimum retention time in this experiment and after that the removal percentage did not raise significantly. The results of PCP absorption in different pH demonstrated that the adsorption efficiency decreases by rising pH and initial PCP concentration. The effects of contact time، pH and initial PCP concentration on the absorption process was significant (P-value <0. 001). The results show that absorption efficiency increases by rising retention time under constant conditions. In addition، at low pH the modified A. niger biomass could be a good absorber for PCP.

Dez dam located on Karun River is one of the largest Iranian dams. In a field study, EC, NO3, NH4, PO4, turbidity, TS, alkalinity, coli, temperature, chlorophyll a, DO, BOD5, and Secchi disk (at depths of 0, 2.5, 5, 10, 25, and 50 m)were measured at five sampling points during 2011-2012 water year. Water Quality Index and TSI were calculated for all sampling points and quality zonation was conducted in GIS. It was found that the best water quality index for reservoir water is at second sampling point with amount of 61 situated at the center of reservoir, and the worst index is at entering point to the reservoir with amount of 46 in April. The main reason of changes was turnover of thermal stratification. The laboratory analysis and assessing the quality indices revealed that the Dez reservoir water is suitable for variety of public uses, however, it needs advanced treatment for drinking purpose. Moreover, in the case of continuity of pollutant entrance into the reservoir, the eutrophication risk would threaten the reservoir water quality. Eutrophication occurrence will cause serious limitations in water use applicability, increase turbidity, produce toxic materials, and increase sedimentation regime.

The use of surfactants enhance the bioavailability of nonbiodegradable contaminants such as PAHs. Biosurfactants are more environmental friendly. In this study the ability of removing phenenthrene from soil by biosurfactant was assessed and compared with that of chemical surfactant. A soil sample free of any organic or microbial contamination was artificially spiked with phenanthrene at two concentrations. Then, mineral salt medium at constant concentration of chemical surfactant TritonX-100 and rhamnolipid MR01biosurfactant was added to it in order to have the proportion of 10% w:v (soil:water). A microbial consortium with a potential of phenanthrene biodegradation was inoculated to the soil slurry in two densities (OD=1 and 2) and then it was aerated on a shaker. After eight weeks, the residual concentration of phenanthrene in the soil was extracted by ultrasonic and was analyzed using HPLC. MPN test was used for measuring microbial population. This study was conducted based on the two level full factorial design of experiment. It was found that chemical surfactant exhibited higher PHE removal efficiency than the biosurfactant. Using 120 mg/L of TritonX-100 and rhamnolipid, the PHE removal for the soil contaminated with 50 mg PHE/kg dry soil was 98.5 and 88.7% respectively, while the removal efficieny was decreased to 87 and 76% respectively for the soil contaminated with 300 mg PHE/kg. In the absence of surfactant, the removal efficiency at concentrations of 50 and 300 mg PHE/kg dry soil was achieved 60.76 and 51% respectively. The phenanthrene removal efficiency in OD=2 was more higher than OD=1. In the presence of rhamnolipid, the maximum microbial populations was observed in the second week, while it decreased in the presence of TritonX-100. Use of biosurfactants can be considered as a suitable option in low level pollutant sites. Chemical surfactants as ex-situ has achieved more satisfactory results in high level contaminant sites.

In recent years, enterance of oil contaminants especially polycyclic aromatic hydrocarbons (PAHs) to Anzali Wetland, has seriously threatened organisms life. Therefore, the current study was conducted to determine and compare concentration of PAH compounds with multiple sediment quality assessment indice to evaluate the ecological toxicity of surface sediments of Anzali Wetland and present appropriate management strategy. We randomly collected 22 surface sediment samples; each sample was dried and extracted based on the soxhlet method. Then during two-step of column chromatography the PAH compounds were separated and analyzed by gas chromatography equipped with a mass spectrometry detector (GC-MS). Total concentrations of these compounds ranged from 212 to 2674 ng g-1 d.w. with the mean of 907 ng g-1 d.w. The highest concentrations of PAHs was reported from stations (3-1 and 4-1) located in the vicinity of urban areas with shipping activities. In comparison with sediment quality guidelines (SQGs) used in this study, the concentrations of most PAH compounds in the majority of stations situated in low range values of adverse biological effects. Only in a few stations (3-1, 3-2 and 5-3), the concentrations of some of PAH compounds exceeded the low range of adverse biological effects. In comparison with sediment quality guidelines (SQGs) used in this study, the concentrations of most PAH compounds in Anzali Wetland rarely lead to adverse biological effects. However, concentrations of some of these compounds can cause acute toxic effects. Therefore, further studies including toxicity and bioaccumulation tests and survey of benthic community composition, especially in areas exceeded SQGs are essential for proper management.

Cadmium can enter water resources through the industrial wastewater. It could cause intensivly damages to the liver and kidney of humans. Magnetic iron nanoparticles are used to control and eliminate heavy metals from industrial effluents through the mechanisms of adsorption, ion exchange and electrostatic forces. The aim of this study was to evaluate the efficiency of magnetic nanoparticles for adsorption of cadmium. The magnetite nanoparticles were prepared by co-precipitation method through the addition of bivalent and trivalent iron chloride under alkaline conditions. Characteristics of nanoparticles including particles structure, composition and size were determined using analytical devices such as XRD, SEM, and FT-IR. For optimization of adsorption process of cadmium, some parameters such as pH, contact time, initial concentration of cadmium, nanoparticles concentration, and temperature were studied under different conditions. It was found that 95% of cadmium could be removedAt pH ≥ 5.6, 10 mg/L initial cadmium concentration, a dose of 1 mg synthesized magnetite nanoparticles, 10 minutes contact time, and 200 rpm mixing rate at 25 °C. The isotherm of adsorption follows the Langmuir model (R2 < 0.995). Maximum capacity of cadmium adsorption was found to be 20.41 mg/g. Magnetite nanoparticles exhibit high capability for removal of cadmium. The nanoparticles synthesized could be used at industrial scale because of having the magnetic property, which make them easily recovered from aqueous solution through applying a magnetic field.

Perchloroethylene is a chlorinated hydrocarbon used as a solvent in many industries and services activities such as dry cleaning and auto industry as degreasing. We carried out a bioassay using Daphnia Magna in order to determine the ecological effects of wastewater treatment through applying advanced oxidation processes (ultrasonic, ultraviolet irradiation and hydrogen peroxide processes) for removal of perchloroethylene. Due to the sensitivity of Daphnia and reports indicating this species is the most sensitive aquatic invertebrate to a variety of organic compounds, toxicity of perchloroethylene and its intermediate degradation products during applying different processes was tested using Daphnia. Lethal concentration (LC50) and toxic units (TU) were determined. In to determine toxicity of perchloroethylene, its stock solution was prepared at a concentration of 100 mg/L. Then, nine samples each containing 0 (control), 5, 10, 20, 30, 40, 50, 75, and 100% by volume of the primary stock solution were prepared. To determine the toxicity of the intermediate products of perchloroethylene by ultrasonic, photolysis, photolysis with hydrogen peroxide and photosonic processes, an initial concentration of perchloroethylene for each reactor (100 mg/L) was taken. All experiments were carried out at the Laboratory of Microbiology, Faculty of Health, Tehran University of Medical Sciences, Iran. It was found that the 24 h LC50 for perchloroethylene on Daphnia Magna was 35.51 mg /L. The 48 h, 72 h and 96 h LC50 of perchloroethylene were 28.058, 21.033, and 19.27 mg/L respectively. Toxicity of perchloroethylene was decreased after oxidation processes. The toxicity after hybrid processes was lower than the single processes. The toxicity reduction was the same during all time period. Hence, the hypothesis of reducing toxicity of the intermediate products of perchloroethylene degradation after the abovementioned processes is acceptable. It is noteworthy that although there are different intermediate compounds in the effluent of various chemical oxidation processes,, but they are less toxic compared with the original perchloroethylene; this may be due to the partially concentration of intermediate products that will decrease toxicity.

Reuse of treated wastewater in agriculture is becoming more attractive due to the growing demand for water, particularly in arid and semi-arid regions like Iran.In some areas, industrial wastewaters distribute arsenic in the water and vegetables, among the other plants, are mainly irrigated by municipal and industrial wastewater. This study aimed to evaluate the outcome of radish irrigation using water contaminated with arsenic and zinc and to measure the zinc concentration in the edible parts of radish plant. The experiments were designed in the form of a factorial completely randomized design with three replications in which radishes were planted in pots about five kilograms. Arsenic concentration at four levels (0, 100,300 and 600 μg/l) and zinc concentration at three levels (0, 10, and 50 mg/l) were added to the irrigation water. The pots were equally irrigated once every 3 to 4 days. After harvesting and laboratory operations, zinc concentration was measured using atomic absorption spectroscopy. The study indicated that zinc concentration in radish tubers is correlated with the concentration of zinc in water. The results of the analysis of variance table for the effect of zinc and arsenic-contaminated irrigation water on zinc concentration in radish roots, tubers and leafs show only one treatment (zinc concentration in water) on the property is significant at 5 and 1%. The results of the comparison table revealed that Zn uptake was decreased with increasing arsenic up to 300 μg/l. It was found that zinc concentration in radish roots, tubers, and leafs is correlated with the concentration of zinc in water. Moreover, there was a competition between the absorption of zinc and arsenic in plants. With increasing arsenic in irrigation water, transition of Zn was reduced to aerial part.

The objective of this study was to collect all the conducted studies on nitrate concentration in water resources of Iran. To achieve this purpose, the published papers in ISC and ISI journals as well as conferences and seminars were evaluated. The results of this survey showed that 116 studies have been carried out in 26 provinces of Iran. But,there was no published paper in Ilam, Alborz, South Khorasan, Kohgiluyeh and Boyer-Ahmad, and Lorestan provinces. According to these studies, the largest number of studies was performed in Hamadan province (14 cases), Khuzestan, and Mazandaran provinces (10 cases) and the least number of studies was conducted in Ardabil, Bushehr, Qazvin, Qom, and Kermanshah provinces. In Hamadan province, more than 1435 water samples were collected from water resources of this province, which is representative of large number of studies in this region. Maximum nitrate concentration (318 mg/L) was reported in Isfahan province and then in Zahedan city (295 mg/L), Sistan and Baluchestan Province. Based on the reported results in these studies, the nitrate pollution in water resources of Iran is at medium level. In most of the studies, high nitrate concentrations are due to lack of sewage collection network, discharge of urban and industrial sewage to water resources, and agricultural activities, which use high amounts of manure and fertilizer.

Human environment is surrounded bychemicals that could directly or indirectly endanger human health. Some statistics of WHO is indicative of the fact that four million people are employed in the chemical industry throughout the world and one million people die or become disabled annually due to contact with chemicals. Moreover, 1-4 Millions chemical toxicity occur annually. The purpose of this study was to understand the risks involved in chemicals in the workplace, to assess the task risk, and to propose appropriate control measures in order to eliminate or reduce risk in the petrochemical industry. In this study, the chemicals were identified in Arak Petrochemical and features that are indicative of hazardous materials were identified and using TOPSIS, The hazard rate were determined. Then the job duties of employees and employee exposure rate with chemicals were calculated and finally, a risk rate for exposure to chemicals in job duties was determined. It was found that chemicals do not have too high risk to employees; however, but the high risky chemicals were five chemicals including naphtha, ammonia, acetic acid, chlorine, and methanol for operational staff and two chemicals, i.e. ammonia and chlorine for operation and maintenance staffs. It is better to have an alternative for the materials that their risk rang is high and very high, and their production is suggested to be avoided.

Electrocoagulation (EC) as an electrochemical method was developed to overcome the drawbacks of conventional decolorization technologies and is an attractive alternative for the treatment of textile dyes. This study was aimed at the optimization of the EC process for decolorization and COD removal of a real textile wastewater using response surface methodology (RSM). RSM is an important branch of experimental design and a critical technology in developing new processes, optimizing their performance, and improving design and formulation of a new products. In this study, a bench scale EC reactor was designed, constructed, and studied for treatment of a textile wastewater. The main operational variables were current intensity, residence time, initial pH, and electrode materials as independent variables; color and COD removal were considered as dependent variables. The experimental runs were designed using selected variables using Design Expert 7.0 software and the process was optimized for decolorization and COD removal using the response surface method. The optimal operational conditions in the EC process for attaining the maximum decolorization and COD removal were current density of 0.97 A, initial pH of 4.04, residence time of 48 min, and Fe electrode. The desirability factor for Fe electrode was 1, while decolorization and COD removal were predicted 76.3 and 75.6% respectively, which was confirmed by the experimental results. The experimental results indicated that the EC process is an efficient and promising process for the decolorization and COD removal of textile effluents. Under the optimized conditions, the experimental values had a good correlation with the predicted ones, indicating suitability of the model and the success of the RSM in optimizing the conditions of EC process in treating the textile wastewater with maximum removals of color and COD under selected conditions of independent variables.

Electrochemical methods as one of the advanced oxidation processes (AOPs), have been applied effectively to degrade recalcitrant organics in aqueous solutions. In the present work, the performance of electro-Fenton (EF) method using iron electrodes on the degradation of phenol was studied. In this study, a lab-scale EF batch reactor equipped with four electrodes and a DC power supply was used for removing phenol. The effect of operating parameters such as pH, voltage, H2O2 and initial phenol concentration and operating time were evaluated. We added H2O2 manually to the reactor while iron anode electrode was applied as a ferrous ion source. It was found that initial pH of the solution, initial H2O2 concentration, applied voltages were highly effective on the phenol removal efficiency in this process, so that 87% of phenol after 15 min of reaction at pH=3.0, voltage 26 V and H2O2 100 mg/L was removed. Phenol removal efficiency decreased with increasing pH, so that at pH 10, after 15 min, efficiency was 11%. To remove 99.99% phenol at pH 3, 100 mg/L concentration of H2O2 and voltage 26 V for 60 min was required. Electro-Fenton process using iron electrodes for phenol degradation and remediation of wastewater could be a promising process.

Phenol presence in water and wastewater is interesting because of its stability in environment and health problems. Therefore, it must be removed for water pollution prevention. The aim of this study was to evaluate phenol adsorption from aqueous solutions using walnut green hull. This was an experimental study in which walnut green hull was used as biosorbent with a range of mesh 40. In this study, stock solution of phenol was prepared and effects of effective parameters such as pH (4,6,8, and10), contact time (3-60 min), adsorbent dosage (0.25-5 g/L), and initial phenol concentration (10,20,40, and 50 mg/L) on adsorption process were evaluated. Moreover results were evaluated using Langmuir and Freundlich isotherms and first order and pseudo-second order kinetics. All experiments were conducted in double and the mean adsorption rate was reported. The maximum adsorption capacity of 30.30 mg/g corresponded with Langmuir model. Kinetic evaluation indicated that the adsorption of phenol by the walnut green hull clearly followed the pseudo-second order reaction. It was found that increasing contact time and adsorbent dosage would lead to increasing of adsorption of phenol and increasing pH and initial phenol concentration lead to decreasing of phenol adsorption. Maximum phenol removal was achieved at pH 4, with more than 99.9 % efficiency. The results of this study show that the walnut green hull can be used effectively in phenol removal, because walnut green hull is agriculture waste and is produced annual in high volume; hence, it can be used as adsorbent in phenol removal from wastewater.