Pre‐treatment and utilization of raw glycerol from sunflower oil biodiesel for growth and 1,3‐propanediol production by Clostridium butyricum

BACKGROUND: The objective of the present work is to report an efficient pre‐treatment process for sunflower oil biodiesel raw glycerol (SOB‐RG) and its fermentation to 1,3‐propanediol. RESULTS: The growth inhibition percentages of Clostridium butyricum DSM 5431 on grade A (pH 4.0) and grade B (pH 5.0) phosphoric acid‐treated SOB‐RG were similar to those of pure glycerol at 20 g glycerol L^?1; i.e., 18.5 ± 0.707% to 20.5 ± 0.7% inhibition. In grade A, growth inhibition was reduced from 85.25 ± 0.35% to 32 ± 1.4% (a 53.25% reduction) at 40 g glycerol L^?1 by washing grade A raw glycerol twice with n‐hexanol (grade A‐2). The kinetic parameters for product formation and substrate consumption in anaerobic batch cultures gave almost similar values at 20 g glycerol L^?1, while at 50 g glycerol L^?1 volumetric productivity (Q_p) and specific rate of 1,3‐propanediol formation (q_p) were improved from 1.13 to 1.85 g L^?1 h^?1 and 1.60 to 2.65 g g^?1 h^?1, respectively, by employing grade A‐2 raw glycerol, while the yields were similar (0.5–0.52 g g^?1). CONCLUSION: The results are important as the pre‐treatment of SOB‐RG is necessary to develop bioprocess technologies for conversion of SOB‐RG to 1,3‐propanediol. Copyright © 2008 Society of Chemical Industry     

Synthesis and photophysical properties of a novel green fluorescent polymer for Fe3+ sensing

BACKGROUND: In recent years, environmental pollution has become a major concern for industrial societies. The design of highly selective and sensitive sensor materials has become a very important scientific goal. RESULTS: A novel 4‐amino‐substituted 1,8‐naphthalimide dye with intense green fluorescence was synthesized. The dye was then copolymerized with methyl methacrylate. The presence of metal cations (Ca²⁺, Mg²⁺, Cr³⁺, Mn²⁺, Fe³⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺) could quench the fluorescence intensity of a tetrahydrofuran solution of the dye and the copolymer at different levels. The effect of Fe³⁺ was much stronger than that of the other cations. There was a good linear correlation between F₀/F (F₀ and F are the fluorescence intensities in the absence and presence of the metal ions, respectively) and the Fe³⁺ concentration in the range 1.33 × 10^?7–4.00 × 10^?4 mol L^?1. The polymeric sensor in a film state exhibited a dynamic response to Fe³⁺ in the concentration range from 3.44 × 10^?6 to 3.04 × 10^?3 mol L^?1 and the average response time was about 20 s. CONCLUSION: In view of the selectivity and rapid responsivity of the polymer sensor studied, it could be used as a new polymeric sensor for water pollution by Fe³⁺ cations. Copyright © 2008 Society of Chemical Industry     

Sewage sludge treatment using microwave‐enhanced advanced oxidation processes with and without ferrous sulfate addition

BACKGROUND: Microwave‐enhanced advanced oxidation processes with and without the addition of ferrous sulfate (MW/H₂O₂/Fe²⁺‐AOP and MW/H₂O₂‐AOP respectively) were studied for reduction of solids and solubilisation of nutrients from secondary sewage sludge. RESULTS: For the MW/H₂O₂/Fe²⁺‐AOP the yields of solubilisation of orthophosphate and ammonia decreased with increasing temperature. The best results (88.1 mg L^?1 for orthophosphate and 22.7 mg L^?1 for ammonia) were obtained at a treatment temperature of 40 °C. In contrast, the MW/H₂O₂‐AOP had an advantage when it was operated at higher temperatures of 60 and 80 °C. The highest yields of solubilisation were obtained at 60 °C for orthophosphate (81.1 mg L^?1) and at 80 °C for both ammonia (35.0 mg L^?1) and soluble chemical oxygen demand (1954 mg L^?1). Over the temperature range used in this study, the MW/H₂O₂‐AOP gave a better performance than the MW/H₂O₂/Fe²⁺‐AOP. CONCLUSION: For sewage sludge treatment the MW/H₂O₂‐AOP is more effective than the MW/H₂O₂/Fe²⁺‐AOP in terms of solid reduction and nutrient solubilisation. It will also be more cost‐effective, as it does not require iron addition in the process. Copyright © 2008 Society of Chemical Industry     

Bio‐oxidation of ferrous ions by Acidithioobacillus ferrooxidans in a monolithic bioreactor

BACKGROUND: The bio‐oxidation of ferrous iron is a potential industrial process in the regeneration of ferric iron and the removal of H₂S in combustible gases. Bio‐oxidation of ferrous iron may be an alternative method of producing ferric sulfate, which is a reagent used for removal of H₂S from biogas, tail gas and in the pulp and paper industry. For practical use of this process, this study evaluated the optimal pH and initial ferric concentration. pH control looks like a key factor as it acts both on growth rate and on solubility of materials in the system. RESULTS: Process variables such as pH and amount of initial ferrous ions on oxidation by A. ferrooxidans and the effects of process variables dilution rate, initial concentrations of ferrous on oxidation of ferrous sulfate in the packed bed bioreactor were investigated. The optimum range of pH for the maximum growth of cells and effective bio‐oxidation of ferrous sulfate varied from 1.4 to 1.8. The maximum bio‐oxidation rate achieved was 0.3 g L^?1 h^?1 in a culture initially containing 19.5 g L^?1 Fe²⁺ in the batch system. A maximum Fe²⁺ oxidation rate of 6.7 g L^?1 h^?1 was achieved at the dilution rate of 2 h^?1, while no obvious precipitate was detected in the bioreactor. All experiments were carried out in shake flasks at 30 °C. CONCLUSION: The monolithic particles investigated in this study were found to be very suitable material for A. ferrooxidans immobilization for ferrous oxidation mainly because of its advantages over other commonly used substrates. In the monolithic bioreactor, the bio‐oxidation rate was 6.7 g L^?1 h^?1 and 7 g L^?1 h^?1 for 3.5 g L^?1 and 6 g L^?1 of initial ferrous concentration, respectively. For higher initial concentrations 16 g L^?1 and 21.3 g L^?1, bio‐oxidation rate were 0.9 g L^?1 h^?1 and 0.55 g L^?1 h^?1, respectively. Copyright © 2008 Society of Chemical Industry     

Comparison of a new immobilized Fe3+ catalyst with homogeneous Fe3+–H2O2 system for degradation of 2,4‐dinitrophenol

BACKGROUND: Heterogeneous Fenton catalysts have been used to treat various organic pollutants in an aqueous environment. The present study has investigated the degradation of 2,4‐dinitrophenol (2,4‐DNP), a priority pollutant generated by such industries as pharmaceuticals, pesticides, pigments and dyes. Degradation of 2,4‐DNP (100 mg L^?1) was studied using Fe³⁺ loaded on Al₂O₃ as a heterogeneous catalyst in the presence of H₂O₂, and the efficiency compared with the homogeneous Fe³⁺/H₂O₂ based Fenton‐like process. The effect of different parameters for both processes, such as catalyst loading, H₂O₂ concentration, initial solution pH, initial substrate concentration and temperature were investigated and the optimum operating conditions determined. RESULTS: Under optimal operating conditions of the homogeneous system ([Fe³⁺] 125 mg L^?1; [H₂O₂] 250 mg L^?1; pH 3; room temperature), 92.5% degradation was achieved in 35 min for an initial 2,4‐DNP concentration of 100 mg L^?1. In the case of immobilized Fe (Fe³⁺–Al₂O₃ catalyst), degradation improved to 98.7% under the condition 10 wt% [Fe³⁺–Al₂O₃] 1 g L^?1 catalyst loading; [H₂O₂] 250 mg L^?1; pH 3; at room temperature for the same duration. CONCLUSIONS: This study demonstrated the stability and reusability of the prepared heterogeneous catalyst. This process is a viable technique for treatment of aqueous solutions containing contaminants. Copyright © 2012 Society of Chemical Industry     

Improved xylitol production in media containing phenolic aldehydes: application of response surface methodology for optimization and modeling of bioprocess

BACKGROUND: The combined effects of vanillin and syringaldehyde on xylitol production by Candida guilliermondii using response surface methodology (RSM) have been studied. A 2² full‐factorial central composite design was employed for experimental design and analysis of the results. RESULTS: Maximum xylitol productivities (Q_P = 0.74 g L^?1h^?1) and yields (Y_P/S = 0.81 g g^?1) can be attained by adding only vanillin at 2.0 g L^?1 to the fermentation medium. These data were closely correlated with the experimental results obtained (0.69 ± 0.04 g L^?1 h^?1 and 0.77 ± 0.01 g g^?1) indicating a good agreement with the predicted value. C. guilliermondii was able to convert vanillin completely after 24 h of fermentation with 94% yield of vanillyl alcohol. CONCLUSIONS: The bioconversion of xylose into xylitol by C. guilliermondii is strongly dependent on the combination of aldehydes and phenolics in the fermentation medium. Vanillin is a source of phenolic compound able to improve xylitol production by yeast. The conversion of vanillin to alcohol vanilyl reveals the potential of this yeast for medium detoxification. Copyright © 2009 Society of Chemical Industry     

Purification and characterization of solvent‐tolerant,thermostable, alkaline metalloprotease from alkalophilic Pseudomonas aeruginosa MTCC 7926

BACKGROUND: Microbial proteases are becoming imperative for commercial applications. The protease secreted by Pseudomonas aeruginosa MTCC 7926, isolated from solvent‐contaminated habitat was purified and characterized for activity at various edaphic conditions. The purified alkaline protease was investigated for dehairing of animal skin, anti‐staphylococcal activity and processing of X‐ray film. RESULTS: The protease was 24‐fold purified by ammonium sulfate fractionation, sephadex G‐100 gel filtration and DEAE‐cellulose, with 36% recovery. K_M and V_max, using casein were 2.94 mg mL^?1 and 1.27 µmole min^?1, respectively. The apparent molecular mass by SDS‐PAGE was 35 kDa. Alkaline protease was active at pH 6–11 and temperature 25–65 °C. Its activity was (a) 86.8% in 100 mmol L^?1 NaCl, (b) >95% in metal ions (Mn²⁺, Ca²⁺, Mg²⁺, Fe²⁺) for 1 h, (c) >90% in bleaching agents and chemical surfactants, (d) 135.4 ± 2.0% and 119.9 ± 6.2% with rhamnolipid and cyclodextrin, respectively, (e) stable in solvents for 5–30 days at 27 °C, and (f) inhibited by EDTA, indicating metalloprotein. CONCLUSION: This work showed that purified protease retained its activity in surfactants, solvents, metals, and bleaching agents. The enzyme is an alternative for detergent formulations, dehairing of animal skin, X‐ray film processing, treatment of staphylococcal infections and possibly non‐aqueous enzymatic peptide synthesis. Copyright © 2009 Society of Chemical Industry     

2,4,6‐Trichlorophenol and phenol removal in methanogenic and partially‐aerated methanogenic conditions in a fluidized bed bioreactor

A fluidized bed bioreactor (FBBR) was operated for more than 575 days to remove 2,4,6‐trichlorophenol (TCP) and phenol (Phe) from a synthetic toxic wastewater containing 80 mg L^?1 of TCP and 20 mg L^?1 of Phe under two regimes: Methanogenic (M) and Partially‐Aerated Methanogenic (PAM). The mesophilic, laboratory‐scale FBBR consisted of a glass column (3 L capacity) loaded with 1 L of 1 mm diameter granular activated carbon colonized by an anaerobic consortium. Sucrose (1 g COD L^?1) was used as co‐substrate in the two conditions. The hydraulic residence time was kept constant at 1 day. Both conditions showed similar TCP and Phe removal (99.9 + %); nevertheless, in the Methanogenic regime, the accumulation of 4‐chlorophenol (4CP) up to 16 mg L^?1 and phenol up to 4 mg L^?1 was observed, whereas in PAM conditions 4CP and other intermediates were not detected. The specific methanogenic activity of biomass decreased from 1.01 ± 0.14 in M conditions to 0.19 ± 0.06 mmolCH₄ h^?1 gTKN^?1 in PAM conditions whereas the specific oxygen uptake rate increased from 0.039 ± 0.008 in M conditions to 0.054 ± 0.012 mmolO₂ h^?1 gTKN^?1, which suggested the co‐existence of both methanogenic archaea and aerobic bacteria in the undefined consortium. The advantage of the PAM condition over the M regime is that it provides for the thorough removal of less‐substituted chlorophenols produced by the reductive dehalogenation of TCP rather than the removal of the parent compound itself. Copyright © 2005 Society of Chemical Industry     

Synthesis,solution properties and scale‐inhibiting behaviour of a diallylammonium/sulfur dioxide cyclocopolymer bearing phospho‐ and sulfopropyl pendents

Zwitterion (Z) monomer 3‐[diallyl{3‐(diethoxyphosphoryl)propyl}ammonio]propane‐1‐sulfonate underwent cyclocopolymerization with sulfur dioxide to give a new alternating copolymer poly(Z‐alt‐SO₂) in excellent yield (ca 90%). The polyzwitterion (±) (PZ) (i.e. poly(Z‐alt‐SO₂), bearing a diethylphosphonate as well as a sulfonate functionality in each repeat unit, upon ester hydrolysis gave its corresponding pH‐responsive polyzwitterionic acid (±) (PZA). The pH‐induced equilibrations (+) cationic polyelectrolyte ? (±) PZA ? polyzwitterion/anion (± ?) (PZAN) ? polyzwitterion/dianion (± =) (PZDAN) permitted us to examine the effects of charge types and their densities on the interesting solubility and viscosity behaviours. The apparent protonation constants of the basic functionalities &tbond;N^±PO₃^2? in (± =) PZDAN and &tbond;N^±PO₃H^1? in (± ?) PZAN in salt‐free water and 0.1 mol L^?1 NaCl were determined using potentiometric titrations. (±) PZA at a meagre concentration of 20 ppm was found to be an effective antiscalant to inhibit the precipitation of CaSO₄ from its supersaturated solution: after 500 and 800 min, the respective scale inhibitions of 86 and 98% indicated its potential use as an effective antiscalant in reverse osmosis plant. © 2014 Society of Chemical Industry     

Batch treatment of saline wastewater by Halanaerobium lacusrosei in an anaerobic packed bed reactor

BACKGROUND: This study considers batch treatment of saline wastewater in an upflow anaerobic packed bed reactor by salt tolerant anaerobic organisms Halanaerobium lacusrosei . RESULTS: The effects of initial chemical oxygen demand (COD) concentration (COD₀ = 1880–9570 mg L^?1), salt concentration ([NaCl] = 30–100 g L^?1) and liquid upflow velocity (V_up = 1.0–8.5 m h^?1) on COD removal from salt (NaCl)‐containing synthetic wastewater were investigated. The results indicated that initial COD concentration significantly affects the effluent COD concentration and removal efficiency. COD removal was around 87% at about COD₀ = 1880 mg L^?1, and efficiency decreased to 43% on increasing COD₀ to 9570 mg L^?1 at 20 g L^?1 salt concentration. COD removal was in the range 50–60% for [NaCl] = 30–60 g L^?1 at COD₀ = 5200 ± .100 mg L^?1. However, removal efficiency dropped to 10% when salt concentration was increased to 100 g L^?1. Increasing liquid upflow velocity from V_up = 1.0 m h^?1 to 8.5 m h^?1 provided a substantial improvement in COD removal. COD concentration decreased from 4343 mg L^?1 to 321 mg L^?1 at V_up = 8.5 m h^?1, resulting in over 92% COD removal at 30 g L^?1 salt‐containing synthetic wastewater. CONCLUSION: The experimental results showed that anaerobic treatment of saline wastewater is possible and could result in efficient COD removal by the utilization of halophilic anaerobic bacteria. Copyright © 2008 Society of Chemical Industry     

Photo-fenton and UV photo degradation of naphthalene with zero- and two-valent iron in the presence of persulfate

An initial set of 12 kinetic experiments was carried out to remove naphthalene from an aqueous effluent by photo-Fenton involving Fe⁰ and Fe²⁺ at two different concentrations of H₂O₂ (150 and 300?mg?L^?1) and three different pHs (3, 5, and 7) (2²×3¹ experiments). The rate constants (k) for the reaction of naphthalene degradation by involving Fe²⁺ as reactant were in general higher than those with Fe⁰, but the use of Fe²⁺ increased the concentration of naphthalene at equilibrium (C_e) when compared with the same response obtained with Fe⁰ at analogous conditions. A second set of twelve kinetic experiments of photo-Fenton degradation was also performed with persulfate as additive at the conditions already reported, but at a constant concentration of H₂O₂ of 150?mg?L^?1 (2¹×3¹ experiments with NaCl +2¹×3¹ experiments without NaCl). In almost all the runs in which only the source of iron was varied, k from the kinetic data involving Fe²⁺ was higher than that involving Fe⁰, but no difference was observed in terms of C_e that was always zero. The addition of persulfate to treat the effluent either containing or not containing salt enhanced the chemical kinetics, and shifted the equilibrium toward the full removal of naphthalene. A final set of nine experiments of UV photo degradation of naphthalene by involving persulfate without iron, with Fe⁰ and Fe²⁺ in the pH range from 3 to 7 (3² experiments) mainly showed that the use of H₂O₂ may be avoided to remove rapidly and completely naphthalene from wastewater.     

Removal of high concentrations of H2S from simulated natural gas by Acidithiobacillus ferrooxidans immobilized on polyurethane foam

A chemo‐biochemical process for desulfurization of simulated natural gas containing hydrogen sulfide (H₂S) was investigated. The results showed that using polyurethane foam as a support for immobilization of Acidithiobacillus ferrooxidans obtained good biological oxidation performance and the maximum oxidation rate of ferrous iron was 4.12 kg m^?3 h^?1. Moreover, a semi‐empirical formula was set up for calculating theoretical ferrous oxidation rate as a function of influent Fe²⁺ and Fe²⁺ concentration in the bioreactor. The integrated chemical and biological process achieved removal efficiencies of about 80% when treating high concentrations of H₂S (15 000 ± 100 ppmv). © 2012 Society of Chemical Industry     

Effects of electrolytes on the reduction of 2,4‐dinitrotoluene by zero‐valent iron

BACKGROUND: Dinitrotoluenes (DNTs) are environmentally persistent, making the remediation of contaminated streams and groundwater difficult. Zero‐valent iron (Fe⁰) can be used as an electron source for the reduction of recalcitrant DNTs in waste‐water and thus enhance their biodegradability. However, little is known about the qualitative effects of major anions and cations present in waste‐water on the reduction of DNTs by Fe⁰. RESULTS: The presence of Na₂SO₄ and NaCl at levels between 0.25 and 2 mmol L^?1 was observed to enhance the reactivity of Fe⁰ towards 2,4‐DNT. The positive effect of K₂SO₄ is stronger than that of Na₂SO₄ at the same level (1 mmol L^?1). Varying (NH₄)₂SO₄ from 0.1 to 1.0 mmol L^?1 improved the efficiency of 2,4‐DNT degradation by Fe⁰. The effects of varying NaNO₃ and NaNO₂ from 0 mmol L^?1 to 4.7 mmol L^?1 and 0 mmol L^?1 to 5.8 mmol L^?1, respectively, were also investigated. Both NaNO₃ and NaNO₂ at low concentration improved the efficiency of 2,4‐DNT degradation by Fe⁰, however, at high concentration, inhibiting effects appeared. CONCLUSION: SO₄^2?, Cl^?, Na⁺, K⁺ and NH₄⁺ notably enhanced 2,4‐DNT reduction by Fe⁰ at the tested concentrations. The positive effect of K⁺, Cl^? was relatively stronger than that of Na⁺ and sulfate (SO₄^2?). However, the effect of NH₄⁺ was relatively weaker at concentrations greater than 1.0 mmol L^?1. The presence of low concentrations of NO₃^? and NO₂^? promoted 2,4‐DNT reduction by Fe⁰ and inhibited the reaction. The results suggest that 2,4‐DNT reduction by Fe⁰ can be controlled by the ions composition of the waste‐water. Copyright © 2010 Society of Chemical Industry     

Effect of sonication assisted by titanium dioxide and ferrous ions on polyaromatic hydrocarbons (PAHs) and toxicity removals from a petrochemical industry wastewater in Turkey

BACKGROUND: In Izmir (Turkey) polyaromatic hydracarbon (PAH) removal efficiencies are low in petrochemical industry aerobic biological wastewater treatment plants because bacteria are not able to overcome the inhibition of these toxic and refractory organics. In order to increase PAHs removal, sonication process was chosen among other advanced treatment processes include sonication processes. The effects of ambient conditions, increasing sonication time, sonication temperature, TiO₂ and Fe⁺² concentrations on sonication at a petrochemical industry wastewater treatment plant in Izmir (Turkey) was investigated in a 650 W sonicator, at a frequency of 35 kHz and a 500 mL glass reactor. RESULTS: Increasing the temperature improved PAH removal after 150 min sonication at 30 °C and 60 °C. The maximum total PAH removal efficiencies were the same in a reactor containing 20 mg L^?1 TiO₂ and in a TiO₂‐free reactor at 30 °C and 60 °C after 150 min sonication. Maximum 91% and 97% total PAH removals were obtained in a control reactor and a reactor containing 20 mg L^?1 Fe⁺² at 30 °C and 60 °C, respectively, after 150 min sonication. The PAH concentration was toxic to Daphnia magna, so that the EC₅₀ value decreased significantly from 342.56 ng mL^?1 to EC₅₀ = 9.88 ng mL^?1 and to EC₅₀ = 3.35 ng mL^?1, at the lowest TiO₂ (0.1 mg L^?1) and Fe⁺² (2 mg L^?1) concentrations, respectively, after 150 min sonication at 30 °C. CONCLUSION: PAHs and the acute toxicity in a petrochemical industry wastewater were removed efficiently through sonication. Copyright © 2010 Society of Chemical Industry     

Kinetic study on ethanol production using Saccharomyces cerevisiae ITV‐01 yeast isolated from sugar cane molasses

BACKGROUND: Bio‐ethanol production from renewable sources, such as sugar cane, makes it a biofuel that is both renewable and environmentally friendly. One of the strategies to reduce production costs and to make ethanol fuel economically competitive with fossil fuels could be the use of wild yeast with osmotolerance, ethanol resistance and low nutritional requirements. The aim of this work was to investigate the kinetics of ethanol fermentation using Saccharomyces cerevisiae ITV‐01 yeast strain in a batch system at different glucose and ethanol concentrations, pH values and temperature in order to determine the optimum fermentation conditions. RESULTS: This strain showed osmotolerance (its specific growth rate (µ_max) remained unchanged at glucose concentrations between 100 and 200 g L^?1) as well as ethanol resistance (it was able to grow at 10% v/v ethanol). Activation energy (Ea) and Q₁₀ values calculated at temperatures between 27 and 39 °C, pH 3.5, was 15.6 kcal mol^?1 (with a pre‐exponential factor of 3.8 × 10¹² h^?1 (R² = 0.94)) and 3.93 respectively, indicating that this system is biologically limited. CONCLUSIONS: The optimal conditions for ethanol production were pH 3.5, 30 °C and initial glucose concentration 150 g L^?1. In this case, a maximum ethanol concentration of 58.4 g L^?1, ethanol productivity of 1.8 g L^?1 h^?1 and ethanol yield of 0.41 g g^?1 were obtained. Copyright © 2010 Society of Chemical Industry     

Kinetics of glucoamylase hydrolysis of corn starch

Corn starch was hydrolysed by glucoamylase (EC 3.2.1.3, 1,4‐a‐D ‐glucan glucohydrolase) in a chemostat; 106 g L^?1 reducing sugar was produced at 40 °C after 46 h, whereas only 42 g L^?1 was produced at 30 °C. When corn starch concentration was increased from 64.6 g L^?1 to 161.5 g L^?1, the amount of reducing sugar produced increased with the initial substrate concentration. The studies show that there is a product concentration (p₀) above which product inhibition becomes apparent. A new model for starch hydrolysis considering the product inhibition point is presented. Copyright © 2006 Society of Chemical Industry     

Production of L‐lactic acid with very high gravity distillery wastewater from ethanol fermentation by a newly isolated Enterococcus hawaiiensis

BACKGROUND: A great amount of wastewater with high contents of chemical oxygen demand (COD) are produced by ethanol production. It would be useful to utilize distillery wastewater to produce L‐lactic acid, which could be a high additional value byproduct of ethanol production. The fermentation process of L‐lactic acid production by a newly isolated Enterococcus hawaiiensis CICIM‐CU B0114 is reported for the first time. RESULTS: The strain produced 56 g L^?1 of L‐lactic acid after cultivation for 48 h in optimized medium consisting of (g L^?1) 80 glucose, 10 peptone, 10 yeast extract, 1.5 Na₂HPO₄ and 0.2 MgSO₄. E. hawaiiensis CICIM‐CU B0114 was isolated and purified by subculture for growing and producing L‐lactic acid in distillery wastewater of very high gravity (VHG) from ethanol fermentation. L‐lactic acid fermentation was further studied with distillery wastewater substrate in 7 L and 15 L fermentors. The results showed that L‐lactic acid concentrations of 52 g L^?1 and 68 g L^?1 was achieved in 7 L and 15 L fermentors with the initial sugar concentrations of 67 g L^?1 and 87 g L^?1, respectively. CONCLUSION: The production of L‐lactic acid by the newly isolated E. hawaiiensis CICIM‐CU B0114 was carried out and the fermentation medium was optimized by orthogonal experimental design. This new strain holds the promise of L‐lactic acid production utilizing distillery wastewater from VHG ethanol fermentation. Copyright © 2010 Society of Chemical Industry     

Profiles of xylose reductase,xylitol dehydrogenase and xylitol production under different oxygen transfer volumetric coefficient values

BACKGROUND: Xylitol is a sugar alcohol (polyalcohol) with many interesting properties for pharmaceutical and food products. It is currently produced by a chemical process, which has some disadvantages such as high energy requirement. Therefore microbiological production of xylitol has been studied as an alternative, but its viability is dependent on optimisation of the fermentation variables. Among these, aeration is fundamental, because xylitol is produced only under adequate oxygen availability. In most experiments with xylitol‐producing yeasts, low oxygen transfer volumetric coefficient (K_La) values are used to maintain microaerobic conditions. However, in the present study the use of relatively high K_La values resulted in high xylitol production. The effect of aeration was also evaluated via the profiles of xylose reductase (XR) and xylitol dehydrogenase (XD) activities during the experiments. RESULTS: The highest XR specific activity (1.45 ± 0.21 U mg_protein^?1) was achieved during the experiment with the lowest K_La value (12 h^?1), while the highest XD specific activity (0.19 ± 0.03 U mg_protein^?1) was observed with a K_La value of 25 h^?1. Xylitol production was enhanced when K_La was increased from 12 to 50 h^?1, which resulted in the best condition observed, corresponding to a xylitol volumetric productivity of 1.50 ± 0.08 g_xylitol L^?1 h^?1 and an efficiency of 71 ± 6.0%. CONCLUSION: The results showed that the enzyme activities during xylitol bioproduction depend greatly on the initial K_La value (oxygen availability). This finding supplies important information for further studies in molecular biology and genetic engineering aimed at improving xylitol bioproduction. Copyright © 2008 Society of Chemical Industry     

Effect of loading rate on TOC consumption efficiency in a sulfate reducing process: sulfide effect in batch culture

BACKGROUND: The sulfate reducing process (SRP) was analyzed in order to identify factors that diminish the effectiveness of the SRP during wastewater treatment. The effect of different sulfate loading rates (SLR, 290 to 981 mg SO₄‐S L^?1d^?1) and lactate at a stoichiometric C/S ratio of 0.75 on SRP was studied in an upflow anaerobic sludge blanket (UASB) reactor. The effect of sulfide concentration (0 to 200 mg sulfide‐S L^?1) on SRP in batch culture was evaluated. RESULTS: When the SLR was increased, the total organic carbon (TOC) and sulfate consumption efficiencies decreased from 93% ± 3 to 66% ± 2 and 60% ± 5 to 45% ± 4, respectively. Acetate and propionate were accumulated. Microbial analysis showed the presence of microorganisms related with the SRP, fermentation and methanogenesis. In batch culture, when lactate and sulfate were present, SRP and fermentation were observed. When sulfide was added only SRP was observed. At concentrations higher than 150 mg sulfide‐S L^?1 the efficiencies, yields and specific consumption rates (q) decreased. CONCLUSION: Based on the sulfide‐S/volatile suspended solid ratio, it was found that the decrease in efficiency and accumulation of acetate and propionate in the UASB reactor was not related to sulfide inhibition but to the q of acetate and propionate, which were up to 11 times lower than lactate. Copyright © 2008 Society of Chemical Industry     

Magnetic molecularly imprinted polymer nanoparticles coupled with high performance liquid chromatography for solid‐phase extraction of carvedilol in serum samples

Herein, we report a magnetic molecularly imprinted polymers (m‐MIPs) using Fe₃O₄ as a magnetic component, carvedilol as a template molecule for the solid‐phase extraction (MISPE) as the sample clean‐up technique combined with high‐performance liquid chromatography (HPLC) and for the controlled release of carvedilol at different pH values of 1.0 (simulated gastric fluid), 6.8 (simulated intestinal fluid), and 7.4 (simulated biological fluid). The adsorption kinetics was modeled with the pseudo‐first‐order and pseudo‐second‐order kinetics, and the adsorption isotherms were fitted with Langmuir and Freundlich models. The performance of the m‐MIPs for the controlled release of carvedilol was assessed and results indicated that the magnetic MIPs also have potential applications in controlled drug release. Furthermore, the m‐MIPs were applied to the extraction of carvedilol from human blood plasma samples. Carvedilol can be quantified by this method in the 2–350 μg L^?1 concentration range. The limit of detection and limit of quantification in plasma samples are 0.13 and 0.45 μg L^?1. The results from HPLC showed good precision (3.5% for 50.0 μg L^?1) and recoveries (between 85 and 93) using m‐MIP from human plasma samples. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41209.