Biomass dewaterability, filterability and settleability in a membrane bioreactor operated with different sludge ages

2007 ◽  
Vol 2 (1) ◽  
Author(s):  
A. Pollice ◽  
G. Laera ◽  
C. Giordano ◽  
D. Saturno ◽  
G. Mininni ◽  
...  
Keyword(s):  
Steady State ◽  
Physical Properties ◽  
Membrane Bioreactors ◽  
Volume Index ◽  
Excess Sludge ◽  
Capillary Suction ◽  
Bench Scale ◽  
Conventional Activated Sludge ◽  
The Relationship

Membrane bioreactors (MBR) are designed to maintain high solid concentrations, thus limiting sludge production and the related operational costs of the process. Sludge physical properties strongly affect the operation of these systems, due to their influence on the filtration process and also on excess sludge handling. This study reports the physical characterization of a bench scale MBR biomass with different sludge ages and with complete sludge retention. The results span over a period of three years when a bench scale MBR was operated under the same conditions except for the sludge retention time (SRT). The main dewatering properties were measured over time and their steady state average values were related to the SRT. The capillary suction time (CST) and the specific resistance to filtration (SRF) showed similar decreasing trends during the transient phase and reached equilibrium values under steady state conditions, except in the case of complete sludge retention. Under all the tested conditions, the average equilibrium values of the CST, the SRF and the compressibility (s) of the MBR sludge were similar to those reported for conventional activated sludge, suggesting the adoption of the same dewatering technologies. In terms of settleability, the relationship between the diluted sludge volume index (DSVI) and the sludge age appeared weak for SRT higher than 20 days. Under the tested conditions, the best performances in terms of physical properties of the MBR excess sludge were obtained for sludge retention times between 40 and 80 days.

Biomechanical and hydrodynamic characterization of the hydrocephalic infant

1985 ◽  
Vol 63 (1) ◽  
pp. 69-75 ◽  
Author(s):  
Kenneth Shapiro ◽  
Arno Fried ◽  
Anthony Marmarou
Keyword(s):  
Steady State ◽  
Ventricular Volume ◽  
Volume Index ◽  
Injection Technique ◽  
Infantile Hydrocephalus ◽  
Content Type ◽  
Two Factors ◽  
The Mean ◽  
Fine Print

✓ The pressure-volume index (PVI) technique of bolus manipulation of cerebrospinal fluid (CSF) was used to measure neural axis volume-buffering capacity and resistance to the absorption of CSF in 16 hydrocephalic infants prior to shunting. The mean steady-state intracranial pressure (ICP) was 11.7 ± 5.7 mm Hg (± standard deviation (SD)), representing a modest elevation of ICP in infants. The mean measured PVI was 28.1 ± 1.5 ml (± standard error of the mean (SEM)) compared to the predicted normal level for these infants of 12.1 ± 2.7 ml (± SD) (p < 0.001). This resulted from an enhanced volume storage capacity in the hydrocephalic infants. The PVI was not related to ventricular size in these hydrocephalic infants. Although absorption of the additional bolus of fluid did not occur at steady-state ICP, it was readily absorbed once ICP was raised above a mean threshold pressure of 16.0 ± 5.0 mm Hg (± SD) in 13 of the 16 infants. Above this pressure, the mean CSF absorption resistance was 7.2 ± 1.3 mm Hg/ml/min (± SEM) which is twice the normal values as measured by the bolus injection technique. The biomechanical profile of infantile hydrocephalus described in this study indicates that two factors are required for progression of ventricular volume. While an absorptive defect may initiate the hydrocephalic process, progressive volume storage requires an alteration in the mechanical properties of the intracranial compartment.

The investigation of the sludge reduction efficiency and mechanisms in oxic–settling–anaerobic (OSA) process

2016 ◽  
Vol 73 (10) ◽  
pp. 2311-2323 ◽  
Author(s):  
Özlem Demir ◽  
Ayşe Filibeli
Keyword(s):  
Control System ◽  
Volume Index ◽  
Endogenous Respiration ◽  
Sludge Reduction ◽  
Capillary Suction ◽  
Term Operation ◽  
Effluent Quality ◽  
Conventional Activated Sludge ◽  
Reduction Mechanisms

This paper aims to provide a full understanding of the sludge reduction mechanisms in the oxic–settling–anaerobic (OSA) process and presents an evaluation of the sludge reduction efficiencies and sludge characteristics in this process compared to the conventional activated sludge process. Fifty-eight percent reduction in observed yield in the OSA process was achieved compared to the control system at the end of the operational period with no deterioration of effluent quality. The settleability of sludge in the OSA process was also found to be better than that of the control system in terms of sludge volume index. In long-term operation, capillary suction time and specific resistance to filtration values confirmed that the OSA process showed good filterability characteristics. The results of batch experiments showed that higher endogenous respiration in the systems might lead to lower sludge production and that energy uncoupling had only a limited impact on sludge reduction.

Effect of centrifugation on the removal of extracellular polymers and physical properties of activated sludge

1994 ◽  
Vol 30 (8) ◽  
pp. 117-127 ◽  
Author(s):  
F. Dilek Sanin ◽  
P. Aarne Vesilind
Keyword(s):  
Activated Sludge ◽  
Physical Properties ◽  
Inorganic Materials ◽  
Extracellular Polymers ◽  
Capillary Suction ◽  
The Past ◽  
Main Components ◽  
The Relationship ◽  
Flocculated Suspension ◽  
Extracellular Polymer

Activated sludge is a flocculated suspension of living and dead microorganisms enmeshed together in a polymer matrix along with some organic and inorganic materials. Extracellular polymers, main components of which are the polysaccharides, proteins, and nucleic acids, act as a protective barrier to the living microbial community, and give the floc its integrity and rigidity. These polymers have been found to affect the dewatering and settling characteristics of activated sludge. Even though they were studied considerably in the past there is not a complete understanding of the relationship between the amount of polymer and changes in the physical properties of sludge. The purpose of this research is to observe the effects of centrifugal force on the extraction of the extracellular polymers from an activated sludge and to correlate the amount of polymer extracted to the subsequent physical properties of the sludge. Centrifugal forces of 2000, 5000, 8000, 11,000, 14,000, and 16,500 G were tested for their effects on the amount of extracellular polymer collected, as well as the final properties of sludge like viscosity, filterability, compactability and supernatant turbidity. Results were evaluated in comparison to those of an uncentrifuged control waste activated sludge. Removal of extracellular polymers seems to affect the viscosity of activated sludge. Filterability, as measured by the capillary suction time instrument, was affected by the extraction of polymers to a great degree. Results of the independent tests correlated well with each other and with the amount of polymers extracted. Results of this study have important implications on sludge pumping and dewatering.

Receptor-mediated endocytosis: a model and its implications for experimental analysis

1984 ◽  
Vol 247 (5) ◽  
pp. R768-R779 ◽  
Author(s):  
M. Gex-Fabry ◽  
C. DeLisi
Keyword(s):  
Steady State ◽  
Tumor Promoters ◽  
Coated Pits ◽  
Quantitative Characterization ◽  
Receptor Mediated Endocytosis ◽  
Receptor Complexes ◽  
Binding Data ◽  
Receptor Number ◽  
The Relationship

We present a mathematical model for analyzing, simulating, and quantitating the dynamic and steady-state characteristics of receptor-mediated endocytosis. The basic processes considered by the model are ligand-receptor binding, diffusion of receptors and ligand-receptor complexes in the plane of the membrane toward and away from coated pits, binding of ligand-receptor complexes to coated pit proteins, endocytosis of coated pit contents, degradation of ligand, and recycling of undegraded receptors. The model accounts quantitatively for a wide variety of kinetic data and makes new predictions about steady-state characteristics. We show that for homogeneous receptors the slope of the Scatchard plot is not necessarily constant but can have a positive or negative derivative, depending on the concentration of coated pit proteins and their reactivity. This finding suggests that binding data, which show linear and concave curves, might be explainable be a simple coated pit-related mechanism. Similarly the relationship between the x-intercept and the number of receptors is also affected by kinetic parameters controlling endocytosis. We briefly discuss these results in terms of possible mechanisms for the action of tumor promoters, the large variations in receptor number and affinity in the literature, and methods for quantitative characterization of parameters.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Microstructural Characterization of Au-Ge-Ni based ohmic contacts to GaAs/AlGaAs modfet device

1987 ◽  
Vol 45 ◽  
pp. 326-327
Author(s):  
A.K. Rai ◽  
A.K. Petford-Long ◽  
A. Ezis ◽  
D.W. Langer
Keyword(s):  
Contact Resistance ◽  
Ohmic Contact ◽  
Ohmic Contacts ◽  
Microstructural Characterization ◽  
Almost Everywhere ◽  
Spacer Layer ◽  
Good Contact ◽  
The Relationship ◽  
Lower Contact

Considerable amount of work has been done in studying the relationship between the contact resistance and the microstructure of the Au-Ge-Ni based ohmic contacts to n-GaAs. It has been found that the lower contact resistivity is due to the presence of Ge rich and Au free regions (good contact area) in contact with GaAs. Thus in order to obtain an ohmic contact with lower contact resistance one should obtain a uniformly alloyed region of good contact areas almost everywhere. This can possibly be accomplished by utilizing various alloying schemes. In this work microstructural characterization, employing TEM techniques, of the sequentially deposited Au-Ge-Ni based ohmic contact to the MODFET device is presented.The substrate used in the present work consists of 1 μm thick buffer layer of GaAs grown on a semi-insulating GaAs substrate followed by a 25 Å spacer layer of undoped AlGaAs.

The Basic Study on the Relationship between the Physical Properties of Coating Pigment and the Coated Paper Quality

2011 ◽  
Vol 65 (12) ◽  
pp. 1293-1297
Author(s):  
Keiko Hashiguchi ◽  
Takehiro Yoshimatsu ◽  
Masanori Kawashima
Keyword(s):  
Physical Properties ◽  
Coated Paper ◽  
Basic Study ◽  
The Relationship ◽  
Paper Quality
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