Chemical Engineering

Secondary structural changes and partitioning process of bovine serum albumin (BSA) in the mixture of (poly-(ethylene glycol 2000) + K 2 HPO 4 + H 2 O) have been studied at 23°C. The effect of varying weight percents of poly(ethylene glycol) and K 2 HPO 4 on the secondary structure of partitioned BSA and the partitioning process of BSA were examined. The equilibrium weight percents of the obtained aqueous two-phase system (ATPS) have been evaluated, and the phase diagrams including the tie lines are presented. It was found that the magnitude of the partition coefficient of BSA and the secondary structures of partitioned BSA depend on the length of obtained tie lines. Occurrences of changes on the secondary structure content of the partitioned BSA were observed by FTIR spectroscopy investigation. The amounts of the secondary structure content of partitioned BSA as R-helix,-sheet,-turn, and unordered structures of BSA were determined and reported.

The removal of copper (II), zinc (II), and chromium (III) from wastewater by carrot residues (CR) was investigated to evaluate cation exchange capacity. The effects of solution pH and coions were studied in batch experiments. Adsorption equilibria were initially rapidly established, and then decreased markedly after 10 min. Column experiments were carried out in a glass column filled with CR to evaluate the metal removal capacity. The influences of the feed concentration and feed rate were also studied in order to compare the dynamic capacity for metal binding in different feed concentrations.

Gas holdup (ε g) and volumetric gas-liquid oxygen transfer coefficient (k L a) in a draft-tube airlift bioreactor (24 × 10 −3 m 3 in volume) were studied using pure kerosene and diesel and their water-in-oil microemulsions, as the model solutions for petroleum biodesulfurization. For comparison, experiments were also done with distilled water. The ε g and the k L a values for kerosene and diesel systems were in most cases significantly higher than the water system. Increase in water-to-oil phase volume ratio (ϕ) of the microemulsion systems resulted in decrease in the values of ε g , which was attributed to a decrease in the coalescence-inhibiting tendency of the petroleum liquids. Increase in the viscosity (v) of the microemulsion systems to around 32 × 10 −6 m 2 /s resulted in the occurrence of the churn turbulent regime with an associated decrease in the value of ε g , which could not be solely accounted for by the increase in ϕ. Furthermore, the k L a values decreased with increase in the viscosity of the petroleum-based liquids. However, when churn turbulent conditions prevailed, increase in viscosity alone could not account for the decrease observed in the k L a values. Empirical correlations were developed that related ε g and k L a to ϕ and ν, respectively, under the bubbly flow regime inside the bioreactor.

In this study one hundred and fifty two bacterial strains were isolated from oil contaminated. Hemolysis was used as a criterion for the primary isolation of biosurfactant producing-bacteria. Fifty five strains had haemolytic activity, among them twelve strains were good biosurfactant producers by measuring surface tension and emulsification activity. Two microorganisms showed the highest biosurfactant production when grown on paraffin and glycerol as sole carbon source. As a result of biosurfactant synthesis the surface tension of the medium were reduced from 73 mN/m to values below 32 mN/m. A rhamnolipid producing bacterium, P.aeruginosa isolate from oil wells in the southern of Iran. Isolated strain was identified by morphological, biochemical, physiological. The identified Pseudomonas aeruginosa confirmed by Persian type culture collection. Glycolipid production by isolated bacterium using different carbon (gasolin, paraffin oil, glycerol, whey) and nitrogen sources (NaNO 3 , (NH 4) 2 SO 4 and CH 4 N 2 O) was studied. Biosurfactant production was quantified by surface tension reduction, critical micelle dilution (CMD), emulsification capacity (EC), and ThinLayerChromatogeraphy. The best result were obtained when using glycerol as a C/N ratio of 55/1 and use of sodium nitrate as nitrogen source resulted in higher production of the rhamnolipid, expressed by rhamnose (4.2 g/l) and by the yield in relation to biomass (Yp/x = 0.65 g/g). Additionally, physicalchemical characteristics of the spent broth with and without cells were studied, providing a low critical micelle concentration of 19 mg/l and surface tension was reduced to 20 mN/m (%).

In the present study both the synthetic media composition as well as some process parameters in the anaerobic decolorization of Reactive Black 5 (RB5) by activated sludge were studied and optimized using statistical design of experiments (DOEs). Statistical analysis of the results of Plackett-Burman DOE showed that the addition of Mn or Fe, or increase in concentration of Mg, had a positive effect on the anaerobic decolorization efficiency whereas the effect of increase in concentration of glucose, ammonium chloride, and calcium chloride was negative. The effect of change in the concentration of glucose, mixed liquor suspended solid (MLSS), and RB5 on the anaerobic decolorization efficiency and rate and chemical oxygen demand (COD) removal was studied using central composite design methodology. Statistical analysis of the data showed that all the factors had significant effect on both the dye decolorization efficiency and rate. The interaction of glucose with MLSS and with dye and the interaction of MLSS with glucose and with dye were significant when the response was decolorization efficiency and rate, respectively. When COD removal was the response, the effect of change in glucose and MLSS concentration and the interaction between these two factors had statistically significant effect on the response.

Rhamnolipid has been known as biosurfactant which is produced by Pseudomonas aeruginosa in fermentation process. Several carbon sources such as ethanol, glucose, vegetable oil and hydrocarbon have been used to produce rhamnolipid. In this study, we are trying to use molasses which is a waste product from sugar industry as carbon source to produce rhamnolipid. The bacterium which was previously isolated from Iranian oil over years Glycolipid production by isolated bacterium using sugar beet molasses as a carbon and energy source was investigated. Result from the study showed that the growth of the bacteria using molasses as carbon sources is growth-associated. The specific production rate of rhamnolipid with 2%, 4%, 6%, 8% and 10% of molasses are 0.00065, 4.556, 8.94, 8.85, and 9.09 respectively. The yield of rhamnolipid per biomass with 2%, 4%, 6%, 8% and 10% molasses are 0.003, 0.009, 0.053, 0.041 and 0.213 respectively. The production of rhamnolipid (0.0531 g. rhamnolipid/g biomass) is higher compare to the culture grown in aerobic condition (0.04 g. rhamnolipid/g biomass). These studies indicate that renewable, relatively inexpensive and easily available resources can be used for important biotechnological processes.

Arhamnolipid producing bacterium, Pseudomonas aeruginosa was previously isolated from Iranian oil over years. Isolated strain was identified by morphological, biochemical, physiological and 16 sr RNA (1). Glycolipid production by isolated bacterium using sugar beet molasses as a carbon and energy source was investigated. Biosurfactant production was quantified by surface tension reduction, Critical Micelle Dilution (CMD), Emulsification Capacity (EC), and Thin Layer Chromatogeraphy. biosurfactants during growth on waste Dates as the primary carbon and nitrogen sources, respectively. After 48 h of growth the culture supernatant fluid had a rhamnose concentration of 0.18 g/L and surface tension was reduced to 20 mN/m (%).(reduced the interfacial tension against crude oil from 21 mN/m to 0,47 mN/m) Result from the study showed that the growth of the bacteria using molasses as carbon sources is growthassociated. The specific production rate of rhamnolipid with 2 %, 4 %, 6 %, 8 % and 10 % of molasses are 0.00065; 4.556; 8.94; 8.85; and 9.09. respectively The yield of rhamnolipid per biomass with 2%,4%,6%,8% and 10% molasses are 0.003;0.009;0.053;0.041 and 0.213 respectively. The production of rhamnolipid (0.0531 g rhamnolipid/g biomass) is higher compare to the culture grown in aerobic condition (0.04 g rhamnolipid/g biomass) .The rhamnolipids were able to form stable emulsions with n-alkanes, aromatics, crude oil and olive oil. These studies indicate that renewable, relatively inexpensive and easily available resources can be used for important biotechnological processes.

In this study, the membrane bioreactor (MBR) was utilized to remove styrene from a synthetic wastewater having a chemical oxygen demand (COD) and styrene concentration of 1500 mg/L and 50 mg/L, respectively. At two hydraulic retention times (HRTs) of 24 h and 18 h, the MBR was operated for a period in excess of 100 days. The HRT effects were studied and it was found out that the removal efficiency of COD and styrene for both HRTs was consistently higher than 99%. Unlike conventional activated sludge processes (CASPs), no styrene was detected in the exhaust air, which meant that biodegradation was the major styrene removal mechanism at both HRTs. The transmembrane pressure (TMP) profile during the operation of the MBR showed a fairly low and constant TMP up to day 70, after which, the TMP showed a dramatic rise, as a result of the occurrence of severe membrane fouling. It was thought that an increase in styrene loading rate, when HRT was reduced to 18 h, resulted in the release of extracellular polymeric substance (EPS) from the bacterial cells, which in turn was responsible for the rise in soluble microbial product (SMP) and sludge deflocculation. The severe fouling observed during operation of MBR at HRT of 18 h was attributed to the rise in SMP concentrations and decrease in mean floc size and increase in the proportion of small particles in the activated sludge.

In this study different strategies were employed for adapting Acidithiobacillus ferrooxidans cells to both Zn 2+ ions and high grade sphalerite concentrate. The serial subculturing was found to be a very efficient strategy for adapting A. ferrooxidans cells to higher Zn 2+ concentrations, as well as high grade sphalerite concentrate, provided that a suitable protocol was employed. Adaptation of A. ferrooxidans cells to 30 g/L Zn 2+ significantly enhanced the rate of bioleaching of Zn 2+ from high grade sphalerite concentrate. Preadaptation to Zn 2+ ion also shortened the time required to adapt the cells to the concentrate. A. ferrooxidans PTCC 1642, exhibited a higher rate of Zn 2+ bioleaching from high grade sphalerite concentrate compared to A. ferrooxidans DSMZ 583; however, due to the adaptation protocol employed the difference in performance of the two strains was not very great. Based on the results obtained in this study suggestions were given for the mechanisms during the adaptation of A. ferrooxidans cells to high grade sphalerite concentrate.

Central composite design (CCD) technique was used to develop an empirical model for the treatment of olive oil mill wastewater (OMW) by loofa-immobilized Phanerochaete chrysosporium. The concentration of OMW (A) (i.e., 20%, 30% and 40%), concentration of ammonium sulfate as a source of nitrogen (B) (i.e., 0.25, 0.5 and 0.75 g/l) and glucose as a carbon source (C) (i.e., 3, 5 and 7 g/l), both of which used for the fungus growth, were considered as independent variables. The influence of these three regressors on the four dependent variables, i.e., chemical oxygen demand (COD), total phenols (TP), color and aromaticity removals was evaluated using second-order polynomial multiple regression model. Analysis of variance (ANOVA) showed a high coefficient of determination (R 2) value of 0.912-0.982, thus ensuring a satisfactory adjustment of the regression model with the experimental data. The positive sign for the coefficient of OMW concentration in the model, indicated that the COD, color and aromaticity removals increased with increased levels of this factor. While TP removal decreased with the increased concentration of OMW. The negative effect of nitrogen source concentration on the COD and color removals indicated that the response levels decreased as B increased. The positive sign for the coefficient of the interaction between two factors A and B on the removal of TP and color, indicated that a simultaneous increase in the OMW and the nitrogen source concentrations led to an increase in those responses. Although simultaneous increase in the concentrations of nitrogen source and glucose, decreased COD removal. Quadratic models were predicted for the response variables, i.e., pollutant removals, and the maximum values predicted were 64%, 88%, 48% and 39% for COD, TP, color and aromaticity, respectively. Optimum conditions for this wastewater treatment were obtained based on the performance of the loofa-immobilized P. chrysosporium in the experiment where OMW concentration was at the high level and variables B and C were each at their midrange value.

Olive oil mill wastewater (OMW) has a high organic load, and this is a serious concern of the olive industry. Conventional biological wastewater treatments, despite their simplicity and suitable performance are ineffective for OMW treatment since phenolics possess antimicrobial activity. In order to carry out a proper treatment of OMW, use of a microorganism able to degrade the phenolics is thus necessary. In this study the ability of Phanerochaete chrysosporium to degrade the phenolic compounds of OMW and to decrease the chemical oxygen demand (COD) using cells immobilized on loofah was examined. The basal mineral salt solution along with glucose, ammonium sulfate and yeast extract was used to dilute the OMW appropriately. The fungus did not grow on the concentrated OMW. The extent of removal in this bio-treatment, of total phenols (TP) and the COD were 90 and 50%, respectively, while the color and aromaticity decreased by 60 and 95%, respectively. The kinetic behavior of the loofah-immobilized fungus was found to follow the Monod equation. The maximum growth rate l max was 0.045 h)1 while the Monod constant based on the consumed TP and COD were (mg/l) 370 and 6900, respectively.

The mineral Kissiris, which is formed from the thickened foam of volcanic lava, was tested to approximate its mineral composition using energydispersive X-ray (EDX) analysis. The solid mineral contains silicon dioxide at about 16 (w/w). The considerable surface roughness of Kissiris along with its extensive porosity made this natural solid cell support an attractive candidate for manganese peroxidase (MnP) production for synthetic dye decolourization, at low cost. The white rot fungus Phanerochaete chrysosporium immobilized on the mineral Kissiris was grown in both stationary and agitated cultures (rotary shaker, 100 rev/min) using either carbon-or nitrogenlimited growth medium to study the ability of the fungus to degrade the synthetic dye methylene blue (MB). The value of residual dye for MB used at 60 ppm was 6% within 8 days of the incubation of the nitrogen-limited culture under the shaken conditions. Production of (MnP) occurred simultaneously in nitrogen-limited culture medium with the added MnSO 4 at 100 ppm. The MnP activity was at relatively high level (170 U/l).

In this study the effect of NaCl, normally found in dye bath wastewaters employing reactive azo dyes, on the performance of sequential anaerobiceaerobic processes for treatment of Reactive Black 5 (RB5) containing media, with concentration in the range 100e500 mg L À1 , was investigated. Three possible scenarios of the sequential anaerobiceaerobic process, namely two stage process and one stage processes employing either anaerobic or activated sludge, were considered. The results showed a statistically significant enhancement of the anaerobic decolourisation efficiency as a result of the addition of 30 g L À1 NaCl to the RB5 containing media for two stage processes and one stage processes employing anaerobic sludge. NaCl at 30 g L À1 concentration also inhibited aerobic colour formation during two stage processes whereas it prevented aerobic decolourisation during one stage processes. HPLC and UV Vis analysis indicated that during anaerobic phase/stage the majority of azo bonds in RB5 molecules cleave whereas the hydrophobicity/MW of the resulting dye reduction metabolites decreases. The same analysis revealed partial mineralisation of RB5 reduction metabolites under aerobic conditions. The results of the present work also showed that the effect of salt on anaerobic decolourisation efficiency, TVFA and methane production was dependent on the exposure history of anaerobic sludge.

The effects of important design and operating parameters on the hydrodynamics and oxygen transfer characteristics of draft-tube airlift bioreactors (DTABs) were investigated. A water-in-kerosene microemulsion system was used inside the DTAB to simulate the physicochemical properties of the fermentation broths used in petroleum biodesulfurization (BDS) processes. For this system, the churn-turbulent regime occurred at higher air flow rates compared to those of water-based systems. An increase in draft-tube surface area was found to be a more effective means for enhancement of both mixing and oxygen transfer than an increase in top-section surface area expansion. An increase in the draft-tube height and liquid level had a similar effect on the performance of DTABs containing the microemulsion or water-based media. Correlations were developed that predicted overall and local gas holdups, liquid velocity, mixing time, and overall volumetric oxygen transfer coefficient as a function of aeration rate, bioreactor geometry, and liquid level inside the DTAB containing water-in-oil microemulsion for all experimental conditions examined.

A rhamnolipid producing bacterium, P.aeruginosa MM1011, was previously over years isolated from crude oil. Isolated strain was identified by morphological, biochemical, physiological, and 16srRNA. 1 The identified Pseudomonas aeruginosa was confirmed by Persian Type Culture Collection (PTCC idendification confirmation report No. 1011). Glycolipid production by isolated bacterium using sugar beet molasses as a carbon and energy source, was investigated. MM1011 was used for the development of a continuous process for biosurfactant production. The active compounds were identified as rhamnolipids. A final medium for production was designed in continuous culture by means of medium shifts, since the formation of surface-active compounds was decisively influenced by the composition and concentration of the medium components. In the presence of yeast extract, biosurfactant production was poor. For the nitrogen-source nitrate, which was superior to ammonium, an optimum carbon-to-nitrogen ratio of ca. 18 existed. The iron concentration needed to be minimized to 27.5 mg of FeSO 4 • 7H 2 0 per g of glucose. A carbon-to-phosphate mass ratio, z c/p = 20, obtained the maximum production of rhamnolipids. The final productivity dilution rate diagram indicated that biosurfactant production was correlated to low growth rates (dilution rate below 0.18 h-1). With a medium containing 24.2 g l-1 of glucose, a biosurfactant mass concentration (expressed as rhamnolipids) of up to 1.1 g l-1 was obtained in the cell-free culture liquid. The rhamnolipid mass concentration was 7.5 mg ml-1 and surface tension was reduced to 20 mN m-1. 2,3