Nashrieh Shimi va Mohandesi Shimi Iran
Year:2013 | Volume:32 | Issue:1 (67)|Papers Count:11

In sewages, various pollutants exist. So without refining, they should not return into life cycle. After refining, they result a mass of digested sediments, containing organic materials such as humic acid, fulvic acid and minerals such as heavy metal ions can be washed out by hydrochloric acid 2M. Heavy metal ions are determined, identified, and quantified using the method of potentiometer stripping. In the present research, digested sediments of filter stations and drinking water of some french cities, namely Aix les-bans, Annecy, Montpellier and Chambery were analyzed. Low amounts of heavy metal ions were measured by this technique with higer sensitivity and proper accuracy. Detection limit of Cu+2 was determined 3.2´10-8 M at optimal time of electrolysis 32 minutes. The amount of Cu+2 in digested sediments of filter station of Montpellier city was 5.2 mmol/kg dry materials and its amount in drinking water of this city was estimated as 2.82 ppb. Capacity of cationic exchange of these humic acid containing sediments was determined by method of potentiometer titration in addition to batch method. It was known that the sites of sampling were very different, despite being located in a single region.

Clays and clay minerals specially montmorillonite and bentonite are widely used for environmental pollution control. The heavy metals are important environmental pollutants. In this study the sorption of copper, zinc and nickel ions as heavy metals by bentonite samples was investigated. Sample 1 from Kheir Abad mine, sample 2 from Tange Ghoochan mine and sample 3 from the mine around the Ravari mosque were prepared. The sorption tests of copper, zinc and nickel ions by Kheir Abad Ca-bentonite sample were done. The results showed that the sorption very fast and for doing all tests the appropriate time was obtained 5 minutes. Also the results showed that the reduction of pH causes the reduction of copper, zinc & nickel ions sorption and also appropriate conditions for sorption of each ions were achieved. The sorption tests by other samples in obtained appropriate conditions for sample 1 were done. The results showed that among these samples, sample 2 has the highest percentage of sorption and sample 3 has the lowest percentage of sorption. Also the results showed that the increase of CEC causes the increase of copper, zinc & nickel ions sorption. and sorption of nickel is less than sorption of copper and zinc. Finally these samples can be an excellent and inexpensive sorbent for copper, zinc and nickel ions as heavy metal.

Fluoride is a constituent of natural water. Generally groundwater has been considered as a safe and protected source of drinking water in the rural and developing cities, and little consideration was given to the risks of chemical pollution, particularly to the presence of elevated levels of fluoride, arsenic and nitrate in groundwater. In this study, absorption method of continuous state is used for defluoridation with the bauxite as an absorbent and the graph of equilibrium concentration divided by initial concentration is plotted against the time. This graph helps us to find out the break through the time during the operation of continuous absorption and then optimal data is obtained. Absorption data correlated with Langmuir and Freundlich models but the data fits better to Langmuir’s.

Antibiotic formulation waste water effluents are well known for their hard elimination by traditional bio-treatment methods and their important contribution to environmental pollution due to their fluctuating and recalcitrant nature. In the present study, interactions effect of oxy tetracycline (OTC) with Nano Zero Valent Iron (NZVI) modified by UV-A radiation were investigated using batch experiments with the parameters such as reactant concentration, pH, UV power, nano-iron concentration and time. In this process the UV power was 200 W and after six and half hours, 155 ppm OTC aqueous solutions by 1000 ppm nano-iron powder at pH of 3 were degraded. The removal efficiency of absorption (290 and 348 nm), TOC and COD were 87, 95, 85 and 89 percent, respectively. In the similar process there was no organic compound after 14 hours. The XRD analysis, has detected FeO and FeOOH, as the layer oxides that have formed on the surface of nano zero valent iron particles. The positive effects of this layer on the photocatalytic removal process were studied by blank experiments. The blank experiments were aerated by UV irradiation, and oxidized by iron nano particles in dark conditions that have been compared separately with the results of hybrid process (Iron nano particles in the presence of UV radiation). These experiments have shown superior results for OTC removal in hybrid process.

In this study, effect of ball milling on the structural properties and bleaching performance of the Kerman bentonite sample was investigated. The bentonite sample consisted mainly of montmorillonite and small amount of impurities. The sample was ground with a high energy ball mill and characterized by X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Fourier Transform Infra Red spectrometer (FT-IR) and Scanning Electron Microscopy (SEM). Also particle size distribution and specific surface area of the sample were obtained. The results showed that the crystalline form of the clay was changed by milling with high energy ball mill. With increasing of milling time more fractures and more disorder in structure of sample was happened. In addition, after ball milling the particle size of the bentonite was reduced even to nano metric scale but almost these very small particles re-aggregated. Due to reduction of particle size the specific surface area of the ground sample was increased. The oil bleaching experiment were carried out using the above ground bentonite and acid activated bentonite in a batch process and results showed that both modified bentonite have higher bleaching power. Therefore with bring together experimental conditions the ball milling method is suggested for preparation of bleaching earth.

In this paper, retrofit and optimization of the cold-end section of 6th Olefin plant of BIPC is investigated. Having considered the importance of a simultaneous design through the elements (distillation columns, heat exchanger network and refrigeration cycles), three levels of modifications are suggested. The best operating column parameters along with available refrigeration cycles, a modification of refrigeration levels along with the same core process and heat exchanger network and finally a comprehensive and simultaneous retrofit scheme are evaluated for this case study. Having compared the results, one can conclude that simultaneous optimization of operating column parameters, refrigeration cycles and the associated heat exchanger network leads to higher efficiency showing 23.9% of energy saving with an investment payback of 3 months.

Rhamnolipids are among the best known biosurfactants and have been proven to be very promising in enhanced oil recovery, cosmetics, food and pharmaceutics. In this research, rhamnolipid production by Pseudomonas aeruginosa NP2 in a bioreactorhas been investigated. This study shows that the Pseudomonas aeruginosa NP2 is able to produce high quantities of rhamnolipid during 2.5 L batch bioreactor cultivations with sunflower oil as sole carbon source. The results showed that the maximum rhamnolipid concentration obtained was 13.5 g/L after 80 h of cultivation. The results also showed that the rhamnolipid production started at exponential growth phase and continued during the stationary phase. Two rhamnolipids, RL1 and RL3, produced by the microorganism, were confirmed by TLC and HPLC analysis. Finally, the produced rhamnolipid showed good surface activity because it is able to reduce the surface tension from 68 mN/m to 26 mN/m. Thus, Pseudomonas aeruginosa NP2 could be an appropriate model for rhamnolipid production in pilot plant bioreactor systems.

In this study, microbial enhanced oil recovery was investigated by rhamnolipid biosurfactants. Surface tension reduction, the ability to emulsify oil, ecological acceptability, high biodegradability, stability at salinities and temperature are among the main characteristics of these biosurfactants. In this research, the ability of Pseudomonas aeruginosa NP2 to produce rhamnolipid was shown and the production of rhamnoilipd was confirmed by TLC and HPLC analysis. The rhamnolipid production started at exponential growth phase and continued during the stationary phase.During investigation of rhamnolipid production on sunflower oil as sole carbon, the results showed that the maximum rhamnolipid was reached about 0.8 g/L. Finally, the ability in recovering the oil was also demonstrated using the rhamnolipid at CMC concentration. For core flooding tests, first the brine (1% by weight) was injected at the rate of 10 mL/h until no more oil was produced in the effluent, then injection of rhamnolipid instead of water was done. The recovery value of oil after water flooding was obtained 61.68 % of original oil in place, whereas nearly 68.56 % of original oil in place was recovered using rhamnolipd after water flooding or in other words about 6.76% enhanced oil recovery was obtained by rhamnolipid injection in core.

Toxic and heavy metals in various chemical and physical forms areas environmental pollution. Nowadays, the methods of physical, chemical, and biological diversity were used to remove contaminants from the environment. In this study, nickel and zinc ions uptake by brown algae packed-bed reactor were studied. Experiments using Fourier Transform Infra Red spectroscopy (FT-IR) showed that carboxyl groups surface alginate, have key role biosorption. These groups are located in the walls of the algae. Langmuir equation was used to calculate biosorption by algae demonstrated that maximum adsorption of Ni and Zn, respectively, 0.71 and 0.95 g mol was calculated. The kinetics of ion adsorption equilibrium time of about 340 minutes in distilled water and tap water were calculated.

Nowadays, due to the exhaustion of high-grade mining resources and environmental considerations, the processing of mining wastes or low-grade ores to extract metals values using microorganisms has been attracted attention in industry. In this study, the ability of Pseudomonas aeruginosa (ATTC 9027) bacteria to leach zinc from low-grade zinc oxide ores of Zanjan Angoran mine has been investigated. In culture media contains glucose, this bacteria produces organic acids which dissolve zinc from its ore. Ore sample contains 14% zinc that occurred in Smithsonite (ZnCO3) mineral. Pseudomonas aeruginosa bacteria have been inoculated in culture media that contained glucose then optimum conditions have been determined. The solid/liquid ratio1/100, glucose in culture media 6% and leaching time 5 days were optimum condition and effective parameters on ore sample bioleaching and 41% of zinc content has been dissolved in these conditions. After this step using sequential cultivation technique bacteria was adapted to high concentrations of zinc ion present in this environment and the final test using adapted bacteria and in offer mentioned optimum conditions was performed and the zinc extraction was reached to 62%. Conditions have been controlled by pH measurement and zinc extraction determination at the same intervals.