Environmental Health Engineering and Management Journal
Volume:1 Issue: 1, Autumn 2014

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. 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. 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. 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.

Yazd waste stabilization pond facilities consist of three stabilization pond systems, module 1, module 2 and module 3 that AWSP module 1 has started its operation. The existing facilities have had several problems in their operation. The objectives of this research were to evaluate the performance of stabilization ponds in wastewater treatment of the city of Yazd, due to several problems in their operation, and to prepare a scheme of its upgrading, if necessary. During the period from December to June 2010, data analysis were carried out for both raw and treated wastewater. Results of these investigations showed that the average effluent concentrations of Biochemical Oxygen Demand 5 (BOD5), Chemical Oxygen Demand (COD) and Suspended Solid (SS) taken from anaerobic pond and secondary facultative ponds of module 1 were 306.9, 135.18, 139.75 and 136.75, 69.025, 136.5 mg/L, respectively. These results indicated that the effluent of the anaerobic pond of module 1 was complied with the Iranian treated wastewater standards for agricultural reuse in terms of BOD5 and COD concentrations; hence the secondary facultative ponds could be changed to other primary facultative ponds in order to increase the capacity of wastewater treatment plant.

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. 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). 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. 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.

This study aimed at determining the appropriate method for dewatering and drying biomass and selecting a suitable organic solvent for lipid extraction. Nannochloropsis Oculata was cultured in Gillard F/2 medium and after reaching the end of the stationary growth phase, algal biomass was separated from aqueous by centrifuge and dried through three Oven, Air-dried and Lyophilized. Soxhlet apparatus achieved lipid extraction of all samples: diethyl ether, n-hexane and n-pentane using three solvents. At each stage, the quantity and quality of the extracted lipids were determined by Gas Chromatography. In all three drying methods, palmitic acid and palmitoleic acid, and most significantly fatty acid composition of microalgae were extracted. The fatty acid composition of palmitic acid extracted by Diethyl ether was significantly more than the other two solvents. Maximum production of triglyceride was observed in Lyophilized and air-dried microalgae where lipid extraction was performed with diethyl ether solvents and are 75.03% and 76.72% of fatty acid. The use of Lyophilized method for dewatering and drying of biomass and Diethyl ether as solvent for the extraction of lipids from biomass, studied in this paper, as compared to other methods, had higher yields and researches proved that the production of biodiesel from microalgae’s lipid was more efficient.

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. 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. 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. 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.

Iran is located in the seventh rank in terms of CO2 emissions resulting from the fuel combustion in the world. Gas compressor booster stations, due to the several sources of contaminants, are causing the release of large amounts of CO2 and CH4, which will cause climate change; therefore, estimating the emissions of the gases from oil and gas, different processing units are necessary. In this study, the emissions factor method, provided by various organizations, was used for determining emissions of CO2 and CH4 from different sources. According to the results obtained, the total amount of CO2 emissions in selected units is from the selected unit and is a significant contribution to the CH4 emissions, so that the whole amount of CO2 emissions is equal to 7739.027 tons per day and the total amount of CH4 emissions is 4 tons per day. Burner has the highest amount of CO2 emissions among the sources of pollutants in the fixed combustion sources; and, the highest emissions of CH4, among the exit gas sources, belong to the process of removing water. Among the exit gas sources-compressors maintenance activities the highest emissions belong to CH4. The amount of CO2 emissions from indirect sources, including electrical equipment in the studied units, are from natural gas fuel which are much more than those from fuel oils for burning. CH4 gas from volatile sources in the gas compressors have the highest emissions compared to other sources.

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. 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. 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. 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.

In large cities, the share of vehicles in air pollutants emissions is nearly 70% that is mainly due to use of fossil fuels. Environmental simulation has many advantages such as accuracy and speed of modeling. Present study was conducted to create a model of air pollution [Carbon Monoxide (CO) and Nitrogen Oxides (NOx)] from vehicles in fifty following years, in Mashhad. According to the collected data from license plate, traffic and transportation organizations, modeling of CO and NOx was performed by STELLA software. Hence, five strategies, including reduction in the number of imported vehicles and the proportion of distance traveled by vehicles, increase in the number of junked vehicles, application of Euro 4 standards instead of Euro 3 and a combination of their application, were applied in the model. In the current condition, CO and NOx concentrations are 27,894 and 2,121, and after 50 years they would be 26,227,930 and 2,070,011 ton/year, respectively. Applying the aforementioned strategies, their concentrations were declined approximately (35% and 35%), (50% and 50%), (16% and 16%), (7% and 47%) and (75% and 85%), correspondingly. Developed model showed that if the present condition remains stable, air quality will be more and more undesirable in the 50 following years. However, application of the second method, reduction of the distance traveled, was the most effective strategy in reducing the amounts of ones, so it will be better that this strategy is considered in the administrative policies. Nevertheless, as far as possible all of them ought to be taken advantage of.