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Selected AbstractsEffect of a chemical synthesis-based pharmaceutical wastewater on performance, acetoclastic methanogenic activity and microbial population in an upflow anaerobic filterJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2002B Kasapgil Ince Abstract The performance of an upflow anaerobic filter (UAF) treating a chemical synthesis-based pharmaceutical wastewater was evaluated under various operating conditions. During start-up, the UAF was initially fed by glucose till an organic loading rate (OLR) of approximately 7.5,kg COD m,3 day,1 with a hydraulic retention time of 2.3 days. A soluble COD removal efficiency of 98% was achieved before the addition of the wastewater. Initially, the filter inertia was acclimatized to the wastewater by sequential feeding of 10% (w/v), 30% (w/v) and 70% (w/v) of the pre-aerated wastewater mixed with glucose followed by a 100% (w/v) pre-aerated wastewater. During the operation, the COD removal efficiency and methane yield decreased to 75% and 0.30,m3 CH4,kg,1 CODremoved respectively. As the UAF became accustomed to the pre-aerated wastewater, raw wastewater was fed in increasing ratios of 20% (w/v), 60% (w/v) and 80% (w/v) with the pre-aerated wastewater as the remaining part. During this stage of the operation, a COD removal efficiency in a range of 77,86% was achieved and the methane yield decreased to 0.24,m3 CH4,kg,1 CODremoved. Finally, 100% (w/v) raw wastewater was fed and a COD removal efficiency of 65% was achieved with a methane yield of 0.20,m3 CH4,kg,1 CODremoved. At the end of the operation, acetoclastic methanogenic activity was only measured in the bottom section of the UAF, this showed a 90% reduction in comparison with activity of inoculation sludge. Microscopic examinations revealed that rod-shaped methanogens remained as the dominant species whereas Methanosarcina -like species and filaments were present only in insignificant numbers along the UAF. © 2002 Society of Chemical Industry [source] Effect of compressibility on performance of hydraulic wash columnsAICHE JOURNAL, Issue 7 2002L. van Oord-Knol In a hydraulic wash column the solid crystals are separated from the mother liquor by filtration in the top section of the column. Remaining impurities are removed via countercurrent washing of the crystals in the bottom section. Since compressibility limits the capacity of a wash column, this phenomenon needs to be quantified and modeled rigorously. The compressibility of the bed was determined from the porosity profile and the liquid-pressure profile inside the wash column. The porosity of the bed decreases from 0.65 to 0.3 during transport of the bed. This is associated with a decrease in local bed permeability by a factor of 10. The compressibility of the bed, therefore, partly explains the large ratio between the average permeability above and below the wash front. Compressibility coefficients make it possible to relate the compressive stress to the porosity and permeability in the top section of the bed. These coefficients are, therefore, incorporated in a model to successfully predict the capacity of a wash column with a compressible bed. [source] Neurochemistry of Olivocochlear Neurons in the HamsterTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 4 2009Stefan Reuss Pseudocolored frontal sections of the Phodopus sungorus brainstem, showing the location of the superior olivary nuclei in Nissl-stained sections, from rostral (top section) to candal (bottom section). See Reuss, et al., on page 461, in this issue.Anatomical Record 292:461,471. [source] Axial Distribution of Oxygen Concentration in Different Airlift Bioreactor Scales: Mathematical Modeling and SimulationCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 9 2006H. Znad Abstract Steady and unsteady state oxygen concentration distributions in the liquid and gas phases along the axial direction of different airlift bioreactor scales have been simulated for various gas flow rates and oxygen consumption rates by applying the axial dispersion model to the riser and the downcomer, and a complete mixing model for the top (separator) and the bottom sections of the bioreactor. The results show that the dissolved oxygen concentration is very low at the lower part of the downcomer when the rate of oxygen consumption by microorganisms is very high. Furthermore, the shorter (small) bioreactor shows relatively more uniform axial dissolved oxygen concentrations than the longer (large) bioreactor, due to the effect of the hydrostatic pressure along the bioreactor. One of the most important geometric factors for mass transfer is the reactor height, which dominates the mean pressure and thus influences the saturation concentration and mass transfer driving force. The presented model can be applied for modeling and scale-up of practical airlift bioreactors. [source] | ||||||||||