Sharif Digital Repository

Owing to wide-ranging searches (there are various alignments between two points) as well as complex and nonlinear cost functions and a variety of geometric constraints, the problem of optimal railway alignment is classified as a complex problem. Thus, choosing an alignment between two points is usually done based on a limited number of alignments designed by experts. In recent years, the study of railway alignment optimization has shown the importance of optimization and the introduction of various algorithms and their usefulness in solving different problems. It is expected that applying meta-heuristic optimization algorithms such as methods based on swarm intelligence can lead to better... 

Organic loading rate (OLR) is an important parameter significantly affecting microbial ecology and characteristics of UASB systems. In this study, UASB performance was evaluated in a 1000 1 reactor receiving feed from a traditional medium-size slaughterhouse. The initial seed for granules formed earlier was from a mesophilic municipal anaerobic digester sludge with a VSS content of 29gl-1. The temperature of influent was adjusted by an inline thermostat around 33°C. The reactor was started with an OLR of 5kg SCODm-3d-1 with gradual increase to 10kg SCOD m -3d-1 over a 2-week period. Examination of VSS data showed that on the average 89.3±11.3% of bioparticle mass was present at the lower 30%... 

The performance of a rotating biological contactor (RBC) for posttreatment of the slaughterhouse effluent from an upflow anaerobic sludge blanket (UASB) reactor was investigated in this study. The 280-L, six-stage RBC pilot plant was operated at different organic loading rates (OLRs) and biodisk speeds. The overall removal efficiencies for soluble biochemical oxygen demand (SBOD), total biochemical oxygen demand (TBOD), and total chemical oxygen demand (TCOD) decreased with increasing OLRs. Disk rotational speed did not have a significant effect on performance in the range studied. The results showed that satisfactory posttreatment to meet regulatory requirements for agricultural purposes... 

Catalytic ozonation has recently been used as a new means of contaminant removal from water and wastewater. In this study, bone charcoal (BC), a new catalyst prepared under laboratory conditions, was used to catalyze the ozonation of humic substances (HS) in aqueous solutions. The catalytic effect of bone charcoal and the relevant parameters of this ozonation process (solution pH, temperature, scavenger effect, humic acids concentration and BC dosage) were investigated. In the catalytic ozonation experiments, the degradation kinetics was investigated. The reaction rate and the rate constant were determined. The results showed that using a BC catalyst in the ozonation of HS produced a 1.43-... 

Using two techniques of thermogravimetry and differential scanning calorimetry under O2 gas atmosphere from 25 to 600°C, the thermal behavior of laboratory-produced compound lead(IV) oxide α-PbO2 was investigated. The identity of products at different stages were confirmed by XRD technique. Both techniques produced similar results supporting the same decomposition stages for the compound. Three distinct energy changes were observed, namely, two endothermic and one exothermic in DSC. The amount of ΔH for each peak is also reported. © 2008 Springer Science+Business Media, LLC  

The compound, alkaline lead acetate, Pb(CH3COO)2·PbO·H2O (ALA), was purchased from the Fluka Company. The X-ray diffraction film and SEM electron microgaph of this compound were obtained and reported in this paper for the first time. The thermal behavior of alkaline lead acetate (ALA) was studied using thermogravimetery (TGA) and Differential Scanning Calorimetery (DSC) techniques under an O2 gas atmosphere from 25 to 600°C. Four distinct energy changes associated with weight changes were observed, all of them being exothermic in the DSC results. The amount of ΔH for each peak is reported. © Sharif University of Technology  

The compound, lead hydroxide Pb6O4(OH)4, was prepared by a method used for the first time in the authors laboratory. The compound was identified by XRD and it's purity was determined by analytical methods (100%). The thermal characteristics of this compound were investigated by using a thermogravimetry (TGA). This compound was found to be stable at room temperature and at 160°C will decompose completely to produce lead (II) oxide. © Sharif University of Technology, April 2007  

The present study was conducted to investigate the impacts of retrofitted CNG vehicles on air pollutant emissions in Tehran over a 20 years period using available statistical data, precise automobile tests, data analysis, and LEAP Software. The obtained results revealed an increase in air pollutant emissions including CO (equal to 1030.77 thousand tons), NOx (equal to 1030.77 thousand tons), THC (269.02 thousand tons) and CO2 (equal to 38.43 thousand tons) resulting from utilizing retrofitted CNG vehicles within the studied period. Considering the obtained results, if the current trend of producing retrofitted CNG vehicles continues, a total cost of 435 million USD will impose on the... 

One of the main factors affecting membrane fouling in MBRs is operational conditions. In this study the influence of aeration rate, filtration mode, and SRT on hollow fiber membrane fouling was investigated using a triple fouling layers perspective. The sludge microbial population distribution was also determined by PCR method. Through various applied operational scenarios the optimal conditions were: aeration rate of 15 LPM; relaxation mode with 40s duration and 8 min. interval; and SRT of 30 days. The similarity between SMP variations in triple fouling layers with its corresponding hydraulic resistance confirmed the effect of SMP on membrane fouling. Among three fouling fractions, the... 

The feasibility of a mesophilic anaerobic treatment of an alcohol distillery wastewater (beet molasses stillage) was studied in a 1300 I Upflow Anaerobic Sludge Blanket (UASB) reactor for a period of 180 days. The system was seeded with 600 L of mesophilic anaerobic sludge harvested from the bottom of a dairy anaerobic lagoon. Nutrients were added to acidified effluent and after adjusting the pH in an equalization tank, the system was fed with a diluted effluent containing COD in the range of 1000-11000 mg/L at 30°C. Initially, the system had an OLR of 1 kg COD m-3 d-1 and upflow velocity was maintained at 0.6 m/h (HRT= 6 h) throughout the study. A gradual increase in OLR, through increased... 

Site visits of selected factories and mines show large amounts of coal were collected as spoil and waste outside these locations due to un-efficiency of coal exploiting technology from mined material. The coal content of these waste materials is about 60%. In this work, we propose a method to be used for complete consumption of these materials in industry. In some samples, volume and weight of spoils could be decreased by half. This review also shows that aluminum oxide in industrial and minerals spoils are high, in some samples up to 25%. We suggest some remedies, e.g. we can use ashes produced by complete combustion of coal for production of aluminum hydroxide thus making it economical.... 

Direct discharge of high-strength industrial effluent often upsets municipal wastewater treatment plant processes. This pilot study was undertaken to evaluate the performance of a UASB system in pre-treating effluent from a medium-size traditional slaughterhouse. Experiments were conducted in a continuous flow 500-1 pilot plant initially inoculated with 200 1 municipal anaerobic digested sludge. With an influent COD concentration of 3000-5000 mg/l, the system was started with a loading of 1.8 kg COD/m3.d (F/M of 0.24 kg COD/kg VSS.d) at 25°C. The granules formed after 4 months of operation were dark brownish with a diameter of 1-4 mm and a settling velocity of 20 m/hr. Once granules were... 

Laboratory scale experiments were conducted in order to investigate the photolysis of Reactive Blue 19 (RB 19) dye using UV as the irradiation source in alkaline solution. The effects of operating parameters such as, pH, initial dye concentration, UV dosage, hydrogen peroxide and oxygen have been evaluated. The results indicate that the UV photolysis process in alkaline solution is ideal for decolorizing of RB 19 and it can be taken as a starting step to establish the economical feasibility of the method for the decolorization of wastewater from textile industries  

Adsorption of violet B azo dye from aqueous solutions was studied by different cellulose agricultural waste materials (almond shell (AS), pistachio shell (PS), walnut shell (WS), Tea waste (TW) and orange peel (OP)). Cellulose agriculturalwaste sorbents characterized by FTIR and SEM methods. The effects of different parameters such as contact time, pH, adsorbent dosage and initial dye concentration were studied. Maximum removal of dye was obtained at contact time of 90 min and pH 11. The adsorption of violet B was fitted by pseudo-second-order kinetic model. The Langmuir isotherm model was better fitted than Freundlichmodel. The results showed that the adsorption efficiency of violet B by... 

The present study shows the approach developed and employed to wastewater treatment utilizing the vermifiltration technique in a region with a population of approx. 280 people. The domestic sewage from the residential area accumulated in the septic tank was fed into the system designed based on the combination of the sand filter and the vermifilter with the optimum loading rate of 2m2 per day for 45 days. The pH, electrical conductivity, chemical oxygen demand, turbidity and nitrate concentration of wastewater were measured before and after vermitreatment for the mentioned period. The results demonstrated that the unique combination of the vermifiltration system with the sand filter was able...