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Continuous Experiments (continuous + experiment)
Selected AbstractsEnhanced Treatment of Trace Pollutants by a Novel Electrolytic Cell,ENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 6 2006Y. Sakakibara Abstract Continuous experiments were conducted to evaluate the electrolytic performance of a novel 3-dimensional electrolytic cell consisting of granular Pt/Ti electrodes. The electric current efficiency to decompose indigotrisulfonate was approx. 96,%, while energy consumption was one to two orders of magnitude smaller than that for O3 treatment. Furthermore, the cell was successfully applied to treat trace endocrine disrupting chemicals (EDCs) and chlorinated compounds. Energy consumption was in the range of 2 to 10 Wh/m3. From these results, it was concluded that the present electrolytic cell would be a feasible alternative to conventional oxidation processes in water treatment. [source] Removal of toxic metal ions from aqueous systems by biosorptive flotationJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 8 2002Anastasios I Zouboulis Abstract Biosorptive flotation was used as a combined operation for the simultaneous abstraction of nickel, copper and zinc ions from aqueous streams. Laboratory-scale batch experiments, as well as pilot-scale continuous experiments, have been conducted. Grape stalks, a by-product of the winery industry, were used as sorbent material. The experimental procedure consisted of two consecutive stages: (i) biosorption, and (ii) flotation. The possibility of reusing biomass, after appropriate elution, was also examined. The main parameters examined were biomass concentration, particle size of sorbent, surfactant concentration, pH and flocculation. Flotation removals, following laboratory-scale experiments, were found to be in the order of 100, 85 and 70% for copper, zinc and nickel, respectively. In pilot-scale experiments, biomass sorption capacities were determined as 25 for copper, 81 for zinc and 7,µmol,dm,3 for nickel. The order of biomass affinity regarding the studied metals was Cu,>,Zn,>,Ni. Short retention time and high effectiveness suggest that biosorptive flotation is a promising treatment process for the removal of toxic metals from contaminated aqueous solutions. © 2002 Society of Chemical Industry [source] Effect of biodiesel-derived waste glycerol impurities on biomass and 1,3-propanediol production of Clostridium butyricum VPI 1718BIOTECHNOLOGY & BIOENGINEERING, Issue 1 2010Afroditi Chatzifragkou Abstract Aim of the present study was to assess and evaluate the impact of various kinds of impurities of biodiesel-derived raw glycerol feedstock, upon microbial growth and 1,3-propanediol (1,3-PDO) production by Clostridium butyricum. Preliminary trials in 200-mL anaerobic bottles revealed that the presence of NaCl at a concentration of 4.5% (w/w of glycerol) in growth medium imposed an evident inhibitory effect, in contrast with phosphoric salts. However, the application of NaCl at elevated quantities during batch bioreactor experiments [up to 30% (w/w of glycerol)], did neither affect the microbial growth, nor the 1,3-PDO production. Moreover, when oleic acid was added into the growth medium at 2% (w/w of glycerol), a total preclusion of the strain was observed. In order to further investigate whether the nature of oleic acid itself or the presence of the double bond induced the inhibitory phenomenon, stearic acid was added into the medium at the same concentration (2%, w/w, of glycerol). Indeed, no inhibitory effect was observed in the fermentor, suggesting that the presence of the double bond may play a key role in the growth behavior of the microorganism. Finally, methanol effect was tested in batch and continuous bioreactor operations. Interestingly enough, the alcohol addition did not affect the microbial bioconversion of glycerol into 1,3-PDO, even when imposed at relatively high concentrations (10%, w/w, of glycerol) in batch-bioreactor operations. In continuous experiments, methanol was added when steady state had been achieved, and although in one case high concentration was added into the chemostat (5,g/L), the system re-obtained a steady state without indications of negative effect upon biomass production due to the alcohol. Biotechnol. Bioeng. 2010;107: 76,84. © 2010 Wiley Periodicals, Inc. [source] Separation of astaxanthin from cells of Phaffia rhodozyma using colloidal gas aphrons in a flotation columnBIOTECHNOLOGY PROGRESS, Issue 2 2010Maria Dermiki Abstract The aim of this study is to investigate the separation of astaxanthin from the cells of Phaffia rhodozyma using colloidal gas aphrons (CGA), which are surfactant stabilized microbubbles, in a flotation column. It was reported in previous studies that optimum recoveries are achieved at conditions that favor electrostatic interactions. Therefore, in this study, CGA generated from the cationic surfactant hexadecyl trimethyl ammonium bromide (CTAB) were applied to suspensions of cells pretreated with NaOH. The different operation modes (batch or continuous) and the effect of volumetric ratio of CGA to feed, initial concentration of feed, operating height, and flow rate of CGA on the separation of astaxanthin were investigated. The volumetric ratio was found to have a significant effect on the separation of astaxanthin for both batch and continuous experiments. Additionally, the effect of homogenization of the cells on the purity of the recovered fractions was investigated, showing that the homogenization resulted in increased purity. Moreover, different concentrations of surfactant were used for the generation of CGA for the recovery of astaxanthin on batch mode; it was found that recoveries up to 98% could be achieved using CGA generated from a CTAB solution 0.8 mM, which is below the CTAB critical micellar concentration (CMC). These results offer important information for the scale-up of the separation of astaxanthin from the cells of P. rhodozyma using CGA. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] | ||||||||||