Environmental Health Engineering and Management Journal

1-5

Authors: Ali Asghar Najafpoor, Ghorban Soleimani, Mohammad Hasan Ehrampoush, Mohammad Taghi Ghaneian, Elham Rahmanpour Salmani , Maryam Dolatabadi Takabi

Background: The presence of heavy metals in the environment especially in water supplies have caused many concerns because of their toxicity and non-degradability. Hexavalent Chromium (Cr) is one of the most toxic metals which is used in many industries, so it is essential to remove it from industrial wastewater. In this study, we made a comparison between different adsorption isotherms in the chromium (VI) removal process using carbon nano tubes from aqueous solutions. Methods: This experimental study used atomic absorption spectrophotometry. To determine the adsorption isotherms, a synthetic sample with defined concentration of Cr (VI) was prepared and different doses of adsorbent were added to it. The effect of initial Cr concentration, pH, adsorbent dose, and reaction time on removal of Cr was investigated. Temperature and mix rate were steady during a defined time. At the end, Cr (VI) concentration measured and adsorbents equality capacities were calculated via formulas and graphs. Data analysis were performed using descriptive statistics. Results: Adsorption capacities (qe) increased with increasing of initial Cr concentration, and reaction time decreased with increasing adsorbent dose and pH. Correlation coefficients for Langmuir, and Freundlich isotherms in oxidized Multi-Walled Carbon Nano Tubes (MWCNTs) were 0.93, 0.874, and 0.714 and in oxidized Single-Walled Carbon Nano Tubes (SWCNTs) were 0.904, 0.868, and 0.711 respectively. Conclusion: Chromium ions adsorption in carbon nano tubes is accordant to Langmuir isotherm model, and MWCNTs have more cc than SWCNTs. Carbon nano tubes are effective adsorbents in removal of Cr (VI) from aqueous solutions.

13-18

Authors: Zabihollah Yousefi , Ramazan Motallebi , Afshin Takdastan

Background: Reverse Osmosis (RO) is an increasingly common method of desalination. A full scale water desalination system by membrane technology (RO) evaluated in a southern city (Jask) in Iran. Methods: First, data collection on water supply and network were performed. Analysis on most of the water quality parameters (Turbidity, pH, EC, Cl-, Na+, Alkalinity, Ca, Na, K, No3, No2, Fe, Mg, Mn, NH4, Po4, HCo3-, So42- etc.) was performed as standard methods. The membranes of the RO in the desalination system were Poly-Amid (CSM type). Results: The efficiency of the RO water desalination system was 94.16, 84.12, 92.00, and 96.17% respectively for Turbidity, Na+, Mg2+, So42-. The result shows a significant difference between influent and effluent water of the RO system. The produced water is in agreement with national standard of drinking water. Furthermore, water exited from the RO system for TDS, Ca+2, and Mg2+ was less than minimum limit of the guideline. Conclusion: The quality parameters of the water resource (EC, TDS, Cl-, Na+ etc.) were higher than Iranian drinking water standards. The RO technology modified the quality of the water parameters.

25-28

Authors: Mohammad Miri, Reza Ali Fallahzadeh, Mohammad Hassan Ehrampoush , Mohammad Hossien Salmani

Background: Solvents, which are widely used in industry, are able to dissolve another substance for creating a solution. Solvents have various effects on human health based on their type and chemical composition. Methods: This was a cross-sectional study to investigate the harmful effects of solvents on wood painters in Yazd city. To achieve information, a census questionnaire was prepared and distributed among wood painters. The studied parameters include the mean score of knowledge, attitude, and practice of wood painters about harmful effects of dyes and solvents on body according to age, work experience, education, hours worked per day, and smoking. The data of survey were analyzed by Chi-square test and T-test in SPSS. Results: The average age and work experience of wood painters were 29 and 7.5 years, and the age of 25 years and work experience of 5 years had the highest frequency among them. Analysis of data indicated that 71.8% of people had middle school and lower education level, 68.3% was married, 31.7% was single, and 37.5% was smoking. Average working hours were 8 hours in day. Conclusion: Results show that attitudes had significant correlation with education level and different age groups. None of the studied parameters were not significant correlation with performance. Also, there was significant correlation between knowledge with experience.

37-44

Authors: Shidvash Dowlatshahi, Ahmad Reza Haratinezhad Torbati , Mahshid Loloei

Background: Industrial development has caused the release of various pollutants including heavy metals into the environment. These toxic compounds are extremely dangerous to living beings and the environment due to their non-biodegradability, severe toxicity, carcinogenicity, the ability to be accumulated in nature and the ability to contaminate groundwater and surface water. The aim of the present research was to provide an appropriate and cost-effective adsorbent to remove heavy metals from aqueous solutions. Methods: The activated carbon was produced from the dried. Batch experiments were performed on real and synthetic samples at room temperature. The effect of pH, adsorbent dose, initial concentration, and contact time were studied, and the adsorption isotherms of heavy metals were determined. The removal efficiency was evaluated on real wastewater. Results: The maximum removal efficiency of heavy metals (copper, cadmium and lead) by activated carbon adsorbent prepared from saffron leaves was obtained in pH 7. The optimum amount of adsorbent was 0.6 g, and the optimum contact times were 45 min for copper and cadmium ions and 90 min for lead ion, respectively. In these optimum conditions the removal efficiencies were 76.36%, 91.25% and 97.5%, respectively. The removal efficiencies of heavy metals from actual samples (copper industry and the battery industry) in the optimum conditions were 82.25%, 69.95% and 91.23%, respectively. The results obtained showed the highest correlation with Langmuir isotherm model. Conclusion: Based on the results obtained, the activated carbon produced from saffron leaves has a good capability in removal of the metal ions from the aqueous solutions. Considering the availability of saffron leaves in Khorasan, its cost-effectiveness, and high uptake capacity, it can be applied as a proper absorbent to remove the heavy metals from industrial wastewater.