Iranian Journal of

Background and Objectives: Silica is an inorganic material that found in the nature in various forms. The hazards of crystal of silica or α-quartz (free silica) is greater than other forms. Exposure to dust that contains free silica result to pulmonary injury and result to silicosis and death finally. The present research was conducted in order to evaluate the level of workers exposure to free silica in air of Khaf Iron stone quarries.Materials and methods: The exposure level to total and respiratory dust measured based on personal and environmental sampling methods and concentration of dust determined based on gravimetric method. For determination of amounts of free silica, dust samples analyses based on X-ray diffraction (XRD) method, and results compared with standard levels.Results: The maximum amount of total dust and free silica measured in stone breaking station (800±155mg/m³ and 26.11±6.7 mg/m³) and minimum of them measured in official and safeguarding station (8.28±2.2 mg/m³ and 0.012±0.0019 mg/m³). The maximum amount of respiratory dust and free silica measured in red mound digging number 1 (66.14±13.45 mg/m³ and 1.48±0.39 mg/m³) and minimum of them measured in air hammer machine station (5.26±2.62 mg/m³ and 0.01±0.005 mg/m³).Conclusion: Amount of total dust only in official and safeguarding station was lower than standard levels of Iran. Amount of respiratory dust in all stations was greater than Iran standard levels. Furthermore the level of respiratory free silica only in airy hammer machine station was lower than standard level of Iran. Regarding to this amounts it is so essential to that with applying different methods generation and emission of dust protected.

Background and Objectives: widely use of antibiotics as therapy and uncontrolled discharge of them to receiving waters increased the percentages of antibiotic resistant bacteria in various environments which may cause problems in therapy. The aim of this study was to investigate the antibiotic resistance of E. coli, K. pneumoniae and P. aeruginosa bacteria isolated from urban and hospital wastewaters. Nine antibiotics namely Chloramphenicol, Ciprofloxacin, Trimethoprim Sulfamethoxazol, Gentamycin, Ceftizoxime, Nalidixic Acid, Ceftazidime, Ceftriaxon and Cefalexin were investigated in this study.
Materials and Methods: through a cross-sectional descriptive study the isolation of bacteria from hospital and urban wastewater samples was performed by microbiological identification techniques. The resistance to nine antibiotics was tested by application of the standard disc diffusion technique and zone-size interpretation chart of Kirby-Baeur. Non-parametric Mann-Whitney test was used to assessing two environments differences.
Results: The resistance percentage of E. coli to studied antibiotics was significantly less (ranged from 1.81 to 51.02%) than the resistance percentage of P. aeroginosa (ranged from 3.57 to 61.76) and K. pneumoniae (ranged from 6.45 to 91.83%). the highest resistance to antibiotics studied was for K. pneumonia in comparison with others. E. coli, K. pneumonia and P. aeroginosa bacteria showed the highest resistance to CAZ, SXT and CN, respectively. The study showed the resistance rate in hospital wastewater is more than urban wastewater.
Conclusion: Easy access and uncontrolled usage of antibiotics cause discharge of antibiotics to wastewaters and consequently diminish the drugs' effectiveness. High concentration of antibiotic and diversity in wastewater of hospital in comparison with urban wastewater causes to transfer resistant agents between bacteria and increased the multiple resistances.

Background and Objectives: Wet air oxidation (WAO) is One of the advanced oxidation process which reduce organic matter concentration from industrial wastewater, toxic and non biodegradable substances and, solid waste leachate,etc. In this study the efficiency of wet air oxidation method in leachate treatment generating from Esfahan Composting factory was Evaluated.
Material and Methods: The experiment was carried out by adding 1.5 Lit of pretreated leachate sample the steel reactor with the volume of 3L. The reactor then underwent10 bar pressure at different temperature (100, 200 and 300 °C) and various retention time (30, 60 and 90 min). Leachate sample in 18 stages from composting factory in Isfahan in the volume of 20 Lit was taken and the WAO method, was used for pre-treatments. Removal efficiency of COD, BOD, NH4-N, NO3 and TSS were examined.
Results: The results showed that the removal efficiency was more than 35% for COD, 38% for BOD, and 85% for TSS within one hour of reaction. The Maximum removal efficiency obtained in this study were 53.3% for NH4-N and 73.9 % forNO3-N.
Conclusion: the results indicate that the reaction temperatures are the most important factors affecting degradation of organic matter. COD and BOD5 removal efficiency by WAO process increased as the time of reaction went up. In addition, BOD5/COD ratios of the effluents, which are generally regarded as an important index of biodegradability of leachate sample, were determined and improved grately as it reached to 84%. TheWAO process presented in this paper is considered an efficient process for pretreatment of leachate, as the COD, BOD5 and NO3 reduction observed in leachate samples.

Backgrounds and Objectives: Wet air oxidation (WAO) is one of the advanced oxidation process which is mostly used to reduce organic matter concentration from industrial wastewater, toxic and non biodegradable substance and solid waste leachate.The objective of this paper is comparisons of three advance oxidation in organic matter removal in different conditions from Esfahan composing factory leachate
Material and Methods: The experiment was carried out by adding 1.5 Lit pretreated leachate sample to 3Lit autoclave reactor and adding 10 bar pressure at temperature of 100, 200 and 300 °C and pressure (10 bars) with retention time of 30, 60 and 90 min. leachate sample in 18 stages from composting factory in Isfahan in the volume of 20 lit was taken and the three methodsWAO, WPO, and a combination of WAO/GAC were used for pre-treatments. Pure oxygen and 30% hydrogen peroxide was used as oxidation agent.
Results: The result shows significant improvement on the removal rate of COD (7.8-33.3%), BOD5 (14.7-50.6%)by WAO process.The removal efficiency of 4.6-34% COD, 24-50% BOD, was observed in the reactor.Adding theGACto the reactor improved removal efficiency of all parameters.Combination Process (WAO/GAC) removed 48% of COD, 31-43.6% of BOD.Combination process demonstrated higher efficiency than two other previous methods as BOD5/COD ratio of 90% achieved.
Conclusion: The WAO process presented in this paper is efficient for pretreatment of leachate, And the modified WPO process remove organic materials and ammonia moreover WAO/GAC can be considered as an excellent alternative treatment for removing reluctant organic matter (COD, BOD5) and organic nitrogen compounds, which found in leachate.

Background and Objectives: Wastewater contains various pathogens including viruses, bacteria, fungi, etc. These microorganisms can easily become airborne during normal operations of wastewater treatment plant and contaminate the neighborhood environment. The aim of this study was to investigate the type and density of bioaerosols in a petrochemical wastewater treatment plant in Iran.
Materials and Methods: In this cross sectional study, bioaerosols density was measured in different units of a petrochemical wastewater treatment plant according to the NIOSH 0800 method and the values measured were compared with background level (control area). For this purpose, air samples were collected on blood agar and dextro agar in Andersen single-stage sampler with air flow of 28.3 l/min for 10 minutes. Samples collected were shipped to the laboratory immediately and were incubated for 48 hours. Then, incubated samples were counted for colonies concentration.
 Results: Average concentration of bacteria and fungi bioaerosols measured were 731.70±185.49 and 28.43±10.58 (M±SD) CFU/m3 respectively throughout the wastewater treatment plant units. These values were 35 and 1.45 times higher than background level (Control area). The differences between average concentrations of bacteria in all units of wastewater treatment plant with control area were statistically significant.
Conclusions: Generally, it was found that the density of bioaerosols, especially bacteria was much higher than the background level. The maximum density was measured at aeration chamber, where the emission of bioaerosols could be reduced through replacing nozzle diffused aeration system.

Backgrounds and Objectives: Nowadays, global concerns about nitrate in groundwater and its adverse impact on health have increased. This study aims to evaluate the efficiency of nitrate reduction from aqueous solution through modified Fenton process using Nano scale zero-valent iron. Material and Methods: This research was an experimental study and performed at laboratory scale. Nitrate reduction was conducted by advanced oxidation process of Fe°/FeІІ/FeШ/H₂O₂ at pH 2-10, contact time 10-90 min, nitrate concentrations of 50-300 mg/L, and the molar ratio of [H₂O₂]/[Fe] 0.5-5. The effect of adding H2O2, molar ratio of reagents, contact time, and pH on nitrate removal was examined and optimal conditions for each of these parameters were determined. Spectrophotometer Dr/5000 was used to measure nitrate in the effluent. Results: We found that the optimal parameters in our studywere pH 3, the molar ratio [H₂O₂]/[Fe°] of 0.5, and the contact time 15 min. By applying these conditions, nitrate removal efficiency at the retention time 15 min, initial nitrate concentration of 100 mg/L, iron concentration of 10 mg/L, and pH 4 for FeШ، FeІІ، Fe°، FeІІ/Fe°/H₂O₂ and FeШ/Fe°/H₂O₂ was 10.5, 27.6, 36.5, 62.3, and 74% respectively. Conclusion: According to the experimental results, it was determined that modified Fenton process using zero iron nano-particles can reduce nitrate under optimal conditions and this method can be used for the removal of similar compounds.

Background and Objectives: 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. Materials and Methods: Water Quality Index and TSI were calculated for all sampling points and quality zonation was conducted in GIS. Results: 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. Conclusion: 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.

Background and Objectives: 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. Methods: 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. Results: It was found that 95% of cadmium could be removedAt pH &ge 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. Conclusion: 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.

Background and Objectives: 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. Materials and Methods: 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. Results: 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. Conclusion: 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.

Background and Objective: 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. Materials and Methods: 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. Results: 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. Conclusion: 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.

Background & Objectives: Entering LAS through the wastewater plant’s effluent to water resources causes taste and odor changes, aquatics death, oxygen transfer limitation, and disorders in water treatment processes. Therefore, the study objective was to determine optimum conditions for fenton oxidation process to remove linear alkyl benzene sulfonate from aqueous environments using taguchi method and its requirement evaluation for additional treatment of Biolac effluent. Materials &Methods: LAS removal using Fenton oxidation was evaluated in a 500 mL laboratory-scale batch reactor. In order to save the costs, to determine the optimum conditions of the Fenton oxidation, 25 runs were computed using Taghuchi method by Minitab 16 software. Sampling and required tests were performed based on standard methods examination for water and wastewater. For evaluation of Biolac process sufficiency in LAS removal, biolac efficiency in Urmia Wastewater Treatment Plant was studied in 2012. Results: Based on the LAS removal and chemicals required, Minitab software (Ver. 16) recommended the optimum conditions of Fenton oxidation at 900 mg/L H2O2, 170 mg/L Ferrous ion, pH of 4, and reaction time of 20 minutes. It was found that the Fenton oxidation for LAS removal had 86.5% efficiency under optimum condithions and it was second order reaction with the rate coefficient of 0.0152 L/mg.min. Biolac process does not need any additional treatment due to meeting LAS standard in municipal wastewater treatment. Thus, this process decreased annually mean LAS from 5.28 mg/L to 0.734 mg/L in municipal wastewater. Conclusion: Although the Fenton oxidation appears as a chemical process with high efficiency in the removal of LAS, the low efficiency of COD corresponding to the LAS indicated partial decomposition of linear alkyl benzene sulfonate by Fenton oxidation.

Background and Objective: Collection and disposal of waste has an important role in public health. Isolation and separation procedures at the origin is considered as one of the most important and least costly methods of isolation and separation of waste. This study was aimed to culture and educate those involved in recycling and waste reduction in the Kalaeh City using two educational methods. .

Materials and Methods:  This semi-experimental study was conducted in Kalaleh City. In the social and cultural context,   Kalaleh was divided into six regions. Using cluster sampling, regions were selected randomly. In each area, 120 samples were used. The first group was face-to-face trained and the second group received training through the training package. Waste collection period was 60 days. After this time, the questionnaires were again filled up  and the impact of teaching methods were investigated.

Results: Face-to-face training resulted in increasing waste separation from 70.8 (before training) to 95%. Whereas, this figure in the group receiving training package increased from 57.5 (before training) to 86.7%. Waste recycling rate was between 0.6 to 1 Kg per person per week. These wastes included paper, glass, plastic, and metal containers. On average, the waste recycled in face-to-face training group and training package group was  91 and 83 Kg per week.

Conclusion: Knowledge, attitude and cooperation in waste separation increased after training in both groups. However, in the face-to-face training group, the knowledge and participation in waste separation was more compared with training package group. Continuous training and organizing waste separators could be helpful to re-use waste. It causes less pollution of the environment, reduce the transmission of diseases associated with non-systematic disposal of solid waste, reduce costs and increase awareness about the problems and issues of solid waste, and reduce the solid waste volume.

Background and Objectives: In recent years, anthropogenic and natural activities have caused high levels of metal contamination into the aquatic ecosystem. These pollutants can accumulate in the food chain. The present study examined the amount of metals such as nickel, zinc, and vanadium in the muscle tissue of Sander and Alosa because of their importance in the southeast of the Caspian Sea.            

Method and materials:  After bioassay, the samples of Sander and Alosa were prepared through acid digestion method and the amount of metals was measured using atomic absorption device (Scientific Equipment GBS).

Results:  Statistical tests showed that there was no significant difference between the amount of zinc in two species of the Sander and Alosa (p>0.05) while the amount of nickel and vanadium in Alosa was significantly higher than Sander (P> 0.05). Statistical analysis of differences in the accumulation of metals in Sander was: Zn>Ni ~ V and of Alosa was Zn>Ni ~ V. There was a correlation between nickel and vanadium of Sander and between zinc and vanadium of Alosa (p>0.05). The amount of nickel metal in both species and vanadium in Alosa were higher than the WHO guideline. The maximum and minimum THQ for Alosa were vanadium (0.059) and zinc (0.017) respectively. Whereas, for Sander, these values were zinc (0.016) and vanadium (0.004) respectively.  In general, the TQM measured in this study was <1, indicating no food risk in present consumption rate (21 g/day) of these fish.

Conclusion:  Food risk assessment of case study species indicates that the consumption of Sander and Alosa with the current consumption rate causes no danger to consumers from the viewpoint of zinc, nickle, and vanadium.