مجله سلامت و بهداشت
سال چهارم شماره 1 (پیاپی 12، بهار 1392)

Investigating performance of naturally operated treatment plants may be due to the fact that they cannot be operated as desired or should be modified to achieve good performance e،g for nutrients removal. The advantage of the kinetic coefficients determination is that the model can be adjusted to fit data and then used for analyzing alternatives to improve the process. This study investigates the efficiency of subsurface artificial wetland and determines its kinetic coefficients for nutrient removal. Present study investigated the kinetics of biological reactions occurred in subsurface wetland to remove wastewater nutrient. Samples were taken from 3 points of wetlands for 6 months. The nutrient content was determined through measuring TKN، ammonium، nitrate، and phosphate values. Average levels for TKN، ammonium، nitrate، and phosphate in effluent of control wetland and wetland with reed were41. 15، 23. 59، 1. 735 and 6. 43 mg/l and 28. 91، 19. 99، 1. 49 and 5. 63 mg/l، respectively. First order، second order، and Stover-Keane Canon models were applied and statistical parameters obtained from the models (i. e. µmax،kB) were analyzed. The nutrients removal at Yazd wastewater treatment plant was remarkable and presence of reed beds has not a significant effect on system performance improvement. Other more efficient plants are suggested to be evaluated in the system. Stover-Keane Canon model provided predictions having the most significant relationship with actual data obtained from the field.

Objective & Phenol and its derivatives are common organic pollutants existing in wastewater of many industries such as oil refineries، coal processing، coking operations، and petrochemical، resin، and plastic manufacturing industries. Phenol is very toxic for human and environment. Adsorption is one of the processes used to remove phenol from aqueous solution. At present، one of the most interested absorbents is agricultural wastes. Thus، the aim of this study was application of carbonized service bark (CSB) and modified-carbonized services bark by ZnO nanoparticles (ZnO/CSB) due to the abundance of these wastes in the area studied. This Applied fundamental study was performed in Batch system. The adsorbent was carbonized at 500 °C for 2 hours and soaking method was applied for their modification by ZnO nanoparticles. Required concentrations of phenol were prepared by dissolving crystalline phenol in double distilled water. All experiments were performed in 100 ml Erlenmeyer flasks on shaker and the effect of different parameters such as pH، contact time، adsorbent dosage، initial phenol concentration and mixing speeds were investigated. Phenol was measured by 4-aminoantipyrine colorimetric method according to standard methods for the examination of water and wastewater. Data were analyzed using Excel software. Maximum removal of phenol was observed at pH 2 for both adsorbents. The best condition for both adsorbents obtained in initial phenol concentration of 50 mg/l، adsorbent dose of 1 g/l and mixing speed of 200 rpm. The results indicated that established ZnO on CSB may increase adsorption capacity and it can be used as an effective adsorbent for phenol removal.

Fluoride is an essential element for human health and prevents tooth decay at standard levels. If fluoride concentration in drinking water exceeds standard levels، it may lead to various diseases such as Alzheimer''s syndrome، brittle bones، infertility، and thyroid disorder. Therefore، this work aimed to investigate efficiency of natural and modified pumice to remove fluoride from aqueous solution. In this work، natural and modified pumice were used for removal of fluoride from aqueous solution. Several experimental parameters including pH (2-10)، temperature (20-60oC)، adsorbent mass (2-10 g/L)، initial fluoride concentration (5-20 mg/L) and contact time were studied. All experiments were conducted in batch system with varying one experimental parameter whilest others remaining constant. Results showed that removal efficiency was increased with increase in contact time، initial fluoride concentration، and adsorbent dosage. In addiiton، removal efficiency was decreased with increases in solution temperature. The highest removal efficiency was observed at pH 6. At pH=6، adsorbent doseof 10 g/L، fluoride concentration of 20 mg/L، and contact timeof 210 minutes، the final fluoride concentration reached to 1. 76 and 1. 23 mg/L by natural and modified pumice، respectively. The results of present work demonstrated that pumice especially modified one،as inexpensive adsorbents،can be effectively used to remove fluoride.

Present study was conducted to survey the role of conscientiousness on job satisfaction and job stress considering mediating effect of perceived control. The statistical population of this study consisted all of Imam Reza hospital staff in Urmia، including nurses، GPs، specialists، and administrative staff. A sample of 248 individuals was chosen using stratified random sampling method. Data were gathered through standard questionnaires of; Costa and Mc Crae’s conscientiousness، Brayfield & Roth’s job satisfaction، House and Rizzo’s Job Stress، and Tetrick & Larocco’s perceived control. Structural Equation Modeling was applied to evaluate relations between latent and measured variables in a conceptual model. The results showed significant positive relationships between personality trait of conscientiousness and stress and Job Satisfaction. The results also showed that the relationship between personality traits of conscientiousness and Job Satisfaction and job Stress is mediated through perceived control. All regression weights were statistically significant in the concerned model. The results emphasize on necessity of reassessing the mediating role of perceived control on surveying the causal relation among personality traits of conscientiousness and its consequences.

Reactive dyestuff causes difficulties including toxicity، carcinogenesis، and mutagenesis in the environment. Traditional physical and chemical treatment methods such as coagulation، flocculation، and adsorption can’t destroy these compounds and cause secondary environmental pollution. Advanced oxidation processes like Fenton oxidation are one of the most efficient processes for dyestuff pollutants removal from aqueous solution. In this study، the ability of Remazol Black- B (RB-B) removal from aqueous medium by Fenton oxidation process was investigated. This experimental-intervention study was carried out in laboratory scale. In order to determine the effect of Fenton oxidation on decolorization of RB-B، optimum levels of variables such as pH، FeSO4 and H2O2 and reaction time was measured in a 1 L batch reactor. The results of the experiments showed that for 100 mg/L of dyestuff the respective optimum concentrations of FeSO4 and H2O2were10 and50 mg/L. For 200 and 500 mg/L of dyestuff they were50 and300 mg/L، respectively. Under the optimal condition، pH=3 and 15 min of reaction time، up to 95% decolorization efficiency was achieved for all three concentrations of dyestuff. Based on the results of this study، the Fenton process is an effective method for the treatment of different concentrations of RB-B dyestuff in wastewater. The selection of proper concentration of Fenton is important to reduce treatment costs، environmental problems، and sludge produced.

Phosphorus as a main nutrient for plants is responsible for eutrophication of surface water. In this research، efficiency of orthophosphate removal through chemical precipitation process using lime and Bentonite clay was investigated in west wastewater treatment plant of Ahvaz. This bench scale study was conducted on influent of secondary clarifier. The effect of pH and coagulant dose on orthophosphate removal efficiency was investigated using jar test. Orthophosphate removal efficiency increases by increasing coagulant dose and pH. Comparing with bentonit، lime displayed higher efficiency in orthophosphate removal from wastewater at normal pH range. Lime reduced orthophosphate concentration to 0. 404 mg/l at a dose of 80 mg/l and pH=7. Comparing with bentonit، lime may be used as appropriate and economic coagulant to remove orthophosphate from effluent of wastewater treatment plant، since it has high efficiency and there is also no need to modify PH to an optimum level، resulting in reduced chemical cost.

Pollution of water resources to organic matters and their associated problems including taste، odor، and formation of disinfectant by-products require evaluating removal methods for these materials from drinking water. This study aimed to evaluate performance of organic matter removal from water using deaerating system. A PVC pilot deaerator tower (diameter=15، height=140 cm) was designed، constructed، and used for this study. The system was loaded in flow rates of 0. 6، 0. 8، 1، 1. 2، and 1. 5 l/min. Absorption of samples were measured at wavelength of 253. 7 nm and COD was determined for all samples. COD levels and absorption rates of samples decreased with time for flow rates of. 6، 0. 8، 1، and 1. 2 l/min. However، absorption rates and CODs increased with increasing flow rate (except for flow rate of 1. 5 l/min). Deaeration tower system has capability to remove organic matters from water and the highest efficiency was observed at low flow rates. In addition، significant relationships (R2>0. 95) was observed between COD and absorption rates (except for flow rate of 1. 5 l/min)، and that COD may be measured through determination of absorption rate at UV wave length.

Millions of people around the world are at the risk of Rabies due to animal bites annually. Rates of animal bites in Ardabil and Golestan provinces are higher than other parts of the country. This study aimed to determine the impact of health education methods combined with executive interventions on incidence of animal bites and awareness on rabies and preventive behaviors in selected villages of Ardabil city. In this quasi-experimental study، 500 participants from selected villages were trained using direct and indirect education methods. Executive interventions were applied by Ardebil district health center in2010. Data were collected using a researcher made questionnaire prior and 2-4 months after training program. Animal bites statistics were taken from Ardabil district health center. Data were analyzed by SPSS software. 70 percent of participants were male and 30% were female. Health education significantly increased knowledge on nature of the rabies and preventive behaviors among target group (p<0. 05). Number of animal bites occurring in 2010-2011 was lower than the average number recorded for the years 2006-2009. Integrating health education with executive control interventions may raise subjects'' awareness and behavioral pattern and decrease incidence of animal bites and consequently the risk of Rabies in selected area.