Sharif Digital Repository

In this study, a laboratory-scale biotrickling filter (BTF) is used to remove Triethylamine (TEA) from gaseous wastes. The BTF is made of stainless steel with a height of 210 cm and an internal diameter of 21 cm packed with lava rocks. TEA elimination pattern was evaluated by changing empty bed residence times (EBRTs). The maximum elimination capacity (EC) has been determined to be 87 g/m3/h. At all EBRTs 52, 31, 20, and 10 s, contaminant transferring from gas phase to liquid was more than the EC. Also, the removal efficiency was 100 % for a mass loading of 100 g/m3/h. While the liquid recirculation velocity of 3.466 m3/m2/h was maintained, the flow rate was adjusted to 60, 100, 156, and 312... 

The aim of this research work is to investigate sorption characteristic of acid treated brown algae Sargassum bevanom (acid treated S. bevanom) for the removal of Cr(VI) ions from aqueous solutions. The acid-treated alga was prepared by transferring the S. bevanom into 0.5. M HCl and then stirring the mixture at 300. rpm for 6. h at room temperature. The sorption of Cr(VI) ions by batch method is carried out. The optimum conditions of biosorption were found to be: a biomass dose of 0.7. g in 100. ml of Cr(VI), contact time of 110. min and pH 3, respectively. In optimum condition, removal efficiency was 89.64%. It was found that temperature has a positive effect on the removal efficiency.... 

The effects of leachate recycling and bed mixing on the removal rate of H 2S from waste gas stream were investigated. The experimental setup consisted of an epoxy-coated three-section biofilter with an ID of 8cm and effective bed height of 120cm. Bed material consisted of municipal solid waste compost and PVC bits with an overall porosity of 54% and dry bulk density of 0.456gcm -3. Leachate recycling had a positive effect of increasing elimination capacity (EC) up to 21gSm -3 bedh -1 at recycling rates of 75mld -1, but in the bed mixing period EC declined to 8g Sm -3bedh -1. Pressure drop had a range of zero to 18mm H 2Om -1 in the course of leachate recycling. Accumulation of sulfur reduced... 

A modelling of the anaerobic digestion process of molasses was conducted in a 70-L multistage anaerobic biofilm reactor or hybrid anaerobic baffled reactor with six compartments at an operating temperature of 26 °C. Five hydraulic retention times (6, 16, 24, 72 and 120 h) were studied at a constant influent COD concentration of 10,000 mg/L. Two different kinetic models (one was based on a dispersion model with first-order kinetics for substrate consumption and the other based on a modification of the Young equation) were evaluated and compared to predict the organic matter removal efficiency or fractional conversion. The first-order kinetic constant obtained with the dispersion model was... 

The objective of this study is the investigation of formaldehyde degradation in a bioreactor with pumice stone as a support. The reactor was tested at different synthetic wastewater concentrations with total COD of 500, 1000 and 1500 mgL, respectively, at 24 h hydraulic retention time. The effect of feed composition was tested by changing the COD TCOD FA ratio in order to analyze the impact of formaldehyde concentration. The average formaldehyde and COD removal efficiencies obtained in the reactor were 97.1% and 88%, respectively. The maximum COD and formaldehyde removal efficiencies occurred at the COD TCOD F of 41 at COD T=1000mgL. The effect of toxic shock on reactor performance was... 

Most of 200 Activated Sludge Plant in Iran are overloaded and as a result, their efficiency is low. In this work, a pilot plant is manufactured and put into operation in one of the wastewater treatment plants in the west of Tehran. Instead of conventional activated sludge, a membrane bioreactor and an upflow anaerobic sludge blanket reactor used as a pretreatment unit in this pilot. For the sake of data accuracy and precision, an enriched municipal wastewater was opted as an influent to the pilot. Based on the attained result, the optimum retention time in this system was 4. h, and the overall COD removal efficiency was 98%. As a whole, the application of this retrofit would increase the... 

Biofiltration is a commonlypracticed biological technique to remove volatile compounds from waste gas streams. From an industrial view-point, biofilter (BF) operation should be flexible to handle temperatures and inlet load (IL) variations. A compost BF was operated at different temperatures (30-45°C) and at various inlet loading rates (ILR; 8-598gm -3h -1) under intermittent loading conditions. Complete removal of n-hexane was observed at 30 and 35°C at ILRs up to 330gm -3h -1. Besides, 20-75% of the pollutant was removed at 40°C, corresponding to the different ILs applied to the BF. Increasing the temperature to 45°C decreased the removal efficiency (RE) significantly. A feed forward... 

In this study organically modified nanoclay were prepared by exchanging of the cetyltrimethylammonium (CTAB), with inorganic/metal ions/cations in montmorillonite structure. To investigate the influence of the amount of modifier on basal spacing and subsequent removal efficiency of hydrocarbon, different amount of modifier was used. The modified and unmodified nanoclays characterized by XRD, CHN and FTIR techniques. The X-ray diffraction results showed that the interlayer spacing of CTAB-modified clays increased from 12 to 22Å. The effectiveness of the sorbent materials for sorption of a range of products was investigated using crude oil, kerosene, gasoline and toluene. The process... 

In the present work we studied the use of a membrane contactor system for simultaneous absorption of H2S and CO2 from a gas mixture similar to natural gas. MDEA solution and mixtures of MDEA/DEA and MDEA/MEA were used as absorbent liquid. PVDF and PSf hollow fiber membranes were used in the membrane contactor modules. Design of experiments were carried out by Taguchi method in a manner that a systematical investigation of the effect of operational parameters (temperature, pressure, gas and liquid flow rates, absorbent concentration and acid gas content of the feed), in addition to the effect of membrane material and absorbent liquid, was implemented on process performance parameters... 

In this study, the ability of Aspergillus niger and Penicillium simplicissimum to extract heavy metals from a spent refinery catalyst was investigated. For the first step, a spent processing catalyst from one of the oil refineries in Iran was physically and chemically characterized. Aspergillus niger and Penicillium simplicissimum were used to mobilize Al/Co/Mo/Ni from hazardous spent catalysts. The fungi were adapted to the mixture of metals at 100-800 mg L -1 with increments in concentration of 100 mg L -1. Bioleaching experiments were carried out in batch cultures. To investigate the production of organic acids in sucrose medium, analyses of the culture medium by HPLC were performed at... 

This study was carried out for examination of a lab-scale UASB reactor for optimization of organic loading rate and hydraulic retention time. The total volume of the reactor was 5 1 with an effective height of 160 cm and diameter of 5 cm. This reactor was used to treat fortified municipal wastewater at volumetric organic loadings of 3.6, 7.2, 10.8, and 14.4 kg m3 d 1 at temperature 30°C. The result of present work indicated an optimum range for organic loading (7.2 to 10.8 kg m-3 d-1) with COD removal efficiency of about 85%. Moreover, optimum HRT for influent COD concentration of 1200mg/l is shown to be only 4 hours. Furthermore nitrate removal efficiency was about 80% at optimized organic... 

Low cost dispersed supported cobalt oxide nanocatalysts on activated carbon (AC) were prepared by two different methods: (1) combined impregnation and deposition–precipitation (IMP-DP) and (2) heterogeneous deposition–precipitation (HDP). XRD, TEM, FESEM, BET and Boehm techniques were used for the characterization of the support and the catalysts. Characterization analyses indicated the negative effect of the wet impregnation method on the IMP-DP technique for the preparation of catalysts for the total oxidation of cyclohexane in air. The catalysts prepared by HDP and IMP-DP methods were found to have significant differences in oxidation activity, morphology, particle size, and shape of... 

Copper and cobalt oxides supported on almond shell derived activated carbon (AC) with different loadings were synthesized by sequential and co-deposition-precipitation methods leading to Cu(shell)/Co(core)/AC, Co(shell)/Cu(core)/AC and Cu-Co(mixed)/AC catalysts that were subsequently used for catalytic oxidation of gaseous mixtures of toluene and cyclohexane in air in a tubular flow reactor. The catalysts and the support were characterized by Boehm test, Brunauer-Emmett-Teller (BET) surface area, X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy... 

In this investigation, a spent processing catalyst from one of the oil refineries in Iran was initially characterized physically and chemically. Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans were used to mobilize aluminum, cobalt, molybdenum and nickel from hazardous spent catalysts. Bioleaching experiments were performed in batch cultures. The growth characteristics of the bacteria (pH, Eh, cell concentration and ferrous and ferric iron concentration) were determined during bioleaching along with the concentration of metal values extracted from the catalyst. The results obtained from Inductive coupled plasma-optical emission spectrometry (ICP-OES) showed that after the... 

The effect of temperature and impeller speed on the performance of induced gas flotation (IGF) systems for the removal of oil from produced water in different ranges (5-300 g/L) of total dissolved solids (TDS) was investigated in a pilot plant study. Furthermore, it was evaluated whether the IGF pilot plant effluent could reach the 15 mg/L outlet oil content as required by Article VI of the Kuwait Convention for Persian Gulf region, before being discharged to the sea. The results showed that oil removal efficiencies up to 90% could be reached at high temperature (80°C) in just one single flotation cell without adding any chemicals. Flotation unit, however, should be followed by at least one... 

In this study, degradation of trichloroethylene (TCE), a chlorinated hydrocarbon, using starch supported Fe/Ni nanoparticles was investigated. The scanning electron microscope images showed applying water soluble starch as a stabilizer for the Fe/Ni nanoparticles tended to reduce agglomeration and discrete particle. Also the mean particle diameter reduced from about 70 nm (unsupported Fe/Ni nanoparticle) to about 30 nm. Effects of three key independent operating parameters including initial TCE concentration (10.0-300.0 mg L-1), initial pH (4.00-10.00) and Fe0 dosage (0.10-2.00) g L-1 on TCE dechlorination efficiency in 1 hour were analysed by employing response surface methodology (RSM).... 

This study investigated the diesel and COD removal from oily wastewater by electrocoagulation. Experiments were conducted in a 2-l reactor using aluminum and iron electrodes. Effects of different parameters including pH (3–11), time (10–60 min), voltage (4.5–10.5 V), supporting electrolyte (NaCl concentration), electrode material and initial diesel concentration (3500–11,000 mg/L) were studied in order to evaluate the efficiency of electrocoagulation. Furthermore, the consumption of energy and the amount of sludge produced by this method were evaluated. The highest removal efficiency (COD removal of 99.1 ± 0.2 % and diesel removal of 98.8 ± 0.2 %) was observed under the following conditions:... 

Porous nanocomposite hydrogels were prepared using CaCO3 particles as solid porogens. The hydrogels were prepared by polymerization and grafting of acrylamide and 2-acrylamido-2-methylpropane sulfonic acid onto the starch in the presence of CaCO3 and graphene oxide. CaCO3 solid porogens were then removed by washing with acid and porous structures were obtained. The prepared hydrogels were used as adsorbents for methylene blue as a model cationic dye; and a very high adsorption capacity, up to 714.29 mg g-1, was obtained. Kinetics and isotherms of adsorption and the effect of porosity of hydrogel as well as other experimental conditions were also investigated. The prepared adsorbents were... 

In this study, maleic anhydride grafted polypropylene microporous flat-sheet membranes were prepared via a thermally induced phase separation method with a mixture of dibutyl phthalate and dioctyl phthalate as a diluent. The effects of the polymer composition and coagulation bath temperature on the morphology and performance of the fabricated membranes were investigated. The hydrophilicity results of the membranes demonstrated that membrane modification reduced the water contact angle by about 45°, whereas the pure water flux was enhanced about four times. The antifouling behavior of the fabricated membranes was also investigated in a membrane bioreactor. The results show that the pure water...