Particle counting as a tool to predict filterability in membrane bioreactors activated sludge?

2011 ◽  
Vol 64 (1) ◽  
pp. 139-146 ◽  
Author(s):  
M. Lousada-Ferreira ◽  
A. Moreau ◽  
J. B. van Lier ◽  
J. H. J. M. van der Graaf
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Activated Sludge ◽  
Membrane Bioreactors ◽  
Submicron Particles ◽  
Factors Influencing ◽  
Particle Counting ◽  
Large Numbers ◽  
Flux Decline ◽  
Major Factors

Activated sludge quality is one of the major factors influencing flux decline in membrane bioreactors (MBRs). Sludge filterability is a recognized parameter to characterize the physical properties of activated sludge. Decrease in filterability is linked to a higher number of submicron particles. In our present research we studied whether particle counting techniques can be used to indicate deflocculation of the sludge suspended fraction to submicron particles, causing the aforementioned filterability decrease. A total number of 105 activated sludge samples were collected in four full scale municipal MBRs. Samples were tested for filterability and particle counting in the range 2–100 μm. In 88% of the membrane tank samples the filterability varied between good and poor, characterized by the ΔR20, being 0 < ΔR20 < 1. Filterability varied following the season of the year, stability of the MBR operation and recirculation ratio. The membrane tank filterability can be improved by applying low recirculation ratio between MBR tanks. The applied particle counting methodology generated reproducible and reliable results in the range 10–100 μm. Results show that differences in filterability cannot be explained by variations in particle size distribution in the range 10–100 μm. However, measurable deflocculation might be masked by the large numbers of particles present. Therefore, we cannot exclude the suspended particles as a possible source of submicron particles that are subsequently responsible for MBR sludge filterability deterioration.

A comparison of particle breakdown during chewing by guanacos (Lama guanicoe) and sheep

1998 ◽  
Vol 1998 ◽  
pp. 136-136
Author(s):  
M.D. Fraser ◽  
D.H. Baker
Keyword(s):  
Particle Size ◽  
Retention Time ◽  
Microbial Fermentation ◽  
Digestive Efficiency ◽  
Particle Size Reduction ◽  
Lama Guanicoe ◽  
Factors Influencing ◽  
Stomach Motility ◽  
Pass Through ◽  
Major Factors

To date, attempts to account for reported differences in digestive efficiency of camelids and ruminants have focused on factors such as stomach motility and the retention time of feed particles. The physical breakdown of forage into particles small enough to pass through the reticulo-omasal orifice is one of the major factors influencing the rate of passage of digesta from the reticulo-rumen in ruminants. Two of the main processes involved in particle size reduction are chewing (pre- and post-regurgitation) and microbial fermentation. While the characteristic vertical and horizontal jaw movement which occurs during mastication in the camelid is believed to allow for efficient use of the premolars and molars in cutting and grinding fibrous feeds, there have been no comparative studies to verify this, and to assess the contribution of chewing to differences in digestibility coefficients. The aim of this experiment was to directly compare particle breakdown during chewing by guanacos and sheep.

scholarly journals Digital microscopic image application (DMIA), an automatic method for particle size distribution analysis in waste activated sludge

2021 ◽  
Author(s):  
S. Cazares ◽  
J. A. Barrios ◽  
C. Maya ◽  
G. Velásquez ◽  
M. Pérez ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Activated Sludge ◽  
Size Distribution ◽  
Particle Diameter ◽  
Diffraction Method ◽  
Laser Diffraction ◽  
Waste Activated Sludge ◽  
Equivalent Diameter ◽  
Distribution Analysis

Abstract An important physical property in environmental samples is particle size distribution. Several processes exist to measure particle diameter, including change in electrical resistance, blocking of light, the fractionation of field flow and laser diffraction (these being the most commonly used). However, their use requires expensive and complex equipment. Therefore, a Digital Microscopic Imaging Application (DMIA) method was developed adapting the algorithms used in the Helminth Egg Automatic Detector (HEAD) software coupled with a Neural Network (NN) and Bayesian algorithms. This allowed the determination of particle size distribution in samples of waste activated sludge (WAS), recirculated sludge (RCS), and pretreated sludge (PTS). The recirculation and electro-oxidation pre-treatment processes showed an effect in increasing the degree of solubilization (DS), decreasing particle size and breakage factor with ranges between 44.29%, and 31.89%. Together with a final NN calibration process, it was possible to compare results. For example, the 90th percentile of Equivalent Diameter (ED) value obtained by the DMIA with the corresponding result for the laser diffraction method. DMIA values: 228.76 μm (WAS), 111.18 μm (RCS), and 84.45 μm (PTS). DMIA processing has advantages in terms of reducing complexity, cost and time, and offers an alternative to the laser diffraction method.

scholarly journals Performance Analysis for the Anaerobic Membrane Bioreactor Combined with the Forward Osmosis Membrane Bioreactor: Process Conditions Optimization, Wastewater Treatment and Sludge Characteristics

Water ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2958
Author(s):  
Yi Ding ◽  
Zhansheng Guo ◽  
Xuguang Hou ◽  
Junxue Mei ◽  
Zhenlin Liang ◽  
...  
Keyword(s):  
Particle Size ◽  
Wastewater Treatment ◽  
Activated Sludge ◽  
Membrane Bioreactor ◽  
Forward Osmosis ◽  
Membrane Bioreactors ◽  
Capillary Water ◽  
Absorption Time ◽  
Capillary Water Absorption ◽  
Sludge Flocs

The anaerobic membrane bioreactors (AnMBR) were operated at 35 °C (H-AnMBR) and 25 °C (L-AnMBR) for long-term wastewater treatment. Two aerobic forward osmosis membrane bioreactors (FOMBRs) were utilized to treat the effluents of H-AnMBR and L-AnMBR, respectively. During the 180 days of operation, it is worth noting that the combined system was feasible, and the pollutant removal efficiency was higher. Though the permeate chemical oxygen demand (COD) of H-AnMBR (18.94 mg/L) was obviously lower than that of L-AnMBR (51.09 mg/L), the permeate CODs of the FOMBRs were almost the same with the average concentrations of 7.57 and 7.58 mg/L for the H-FOMBR and L-FOMBR, respectively. It was interesting that for both the AnMBRs, the permeate total nitrogen (TN) concentration was higher than that in bulk phase. However, the TN concentrations in the effluent remained stable with the values of 20.12 and 15.22 mg/L in the H-FOMBR and L-FOMBR effluents, respectively. For the two systems, the characteristics of activated sludge flocs were different for H-AnMBR-FOMBR sludge and L-AnMBR-FOMBR sludge. The viscosity of L-AnMBR-activated sludge (2.09 Pa·s) was higher compared to that of H-AnMBR (1.31 Pa·s), while the viscosity of activated sludge in L-FOMBR (1.44 Pa·s) was a little lower than that in H-FOMBR (1.48 Pa·s). The capillary water absorption time of L-AnMBR-activated sludge (69.6 s) was higher compared to that of H-AnMBR (49.5 s), while the capillary water absorption time of activated sludge in L-FOMBR (14.6 s) was little lower than that in H-FOMBR (15.6 s). The particle size of H-AnMBR-activated sludge (119.62 nm) was larger than that of L-AnMBR-activated sludge (84.92 nm), but the particle size of H-FOMBR-activated sludge (143.81 nm) was significantly smaller than that of L-FOMBR-activated sludge (293.38 nm). The observations of flocs indicated that the flocs of activated sludge in H-AnMBR were relatively loose, while the flocs of L-AnMBR were relatively tight. The fine sludge floc was less present in the L-FOMBR than in the H-FOMBR. Therefore, in the process of sewage treatment, the influent of each unit in the AnMBR-FOMBR system should have suitable organic content to maintain the particle sizes of sludge flocs.

scholarly journals Factors influencing particle size distributions in finely ground forage

1994 ◽  
Vol 74 (2) ◽  
pp. 383-385 ◽  
Author(s):  
R. Soofi-Siawash ◽  
G. W. Mathison
Keyword(s):  
Particle Size ◽  
Moisture Content ◽  
Particle Size Distribution ◽  
Key Words ◽  
Size Distribution ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Routine Procedure ◽  
Factors Influencing

Two studies were conducted to assess the possibility of using particle size distribution following grinding as a routine procedure of forage evaluation. It was concluded that although differences in particle size distribution could be detected when different feeds were ground, it would be difficult to standardize the technique since particle size distributions were influenced by type of mill used for grinding, particle size of forage before grinding, and moisture content of the forage. Key words: Forages, grinding, particle size, moisture, mill

scholarly journals Acid precipitation of kraft lignin from aqueous solutions: the influence of anionic specificity and concentration level of the salt

Holzforschung ◽  
2019 ◽  
Vol 73 (10) ◽  
pp. 937-945 ◽  
Author(s):  
Tor Sewring ◽  
Hans Theliander
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Concentration Level ◽  
Acid Precipitation ◽  
Kraft Lignin ◽  
Low Ph ◽  
Ion Concentration ◽  
Submicron Particles ◽  
Salting Out

Abstract In this study, the formation of particles and evolution of the particle size distribution in the micron range were monitored in situ during acid precipitation of kraft lignin. The objective of this work was to study the influence of anionic specificity and the ion concentration level. The concentrations of ions in the solution were altered both in terms of the concentration of Na+ and the type of anion in the salt added ( ${\rm{SO}}_4^{2 - }$ and Cl−). The results indicate that a salting-out phenomenon occurred as NaCl was added (Na+ ≥2 mol kg−1 water) to the kraft lignin solution at high pH, but not when Na2SO4 was added. However, the onset pH of the formation of particles (≥1 μm), triggered by acidification, showed to be virtually non-specific to the anion but strongly dependent on the Na+ concentration. As the pH decreased further to below the onset pH of the formation of particles ≥1 μm, the chord length distributions (particle-size related) indicated that most of the volume of the precipitated kraft lignin (and thus possibly also the mass) may be found among the micron-sized particles, despite the fact that a relatively large number of submicron particles may also be present. The volume-based distributions tended to be wide at relatively low pH and high Na+ concentrations (e.g. pH 9.4 and 2.0 mol kg−1 water).

Particle size analysis and sedimentation properties of activated sludge flocs

1997 ◽  
Vol 36 (4) ◽  
pp. 167-175 ◽  
Author(s):  
Dieter Hilligardt ◽  
Erhard Hoffmann
Keyword(s):  
Particle Size ◽  
Activated Sludge ◽  
Shape Analysis ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Organic Loading ◽  
Sludge Characteristics ◽  
Sludge Flocs ◽  
Factors Influencing ◽  
Differential Sedimentation

Activated sludge is one of the best investigated and understood suspensions. But up to now we still lack the factors influencing the sedimentation velocities concerning the main sludge characteristics/properties to describe the settleability of different sludges. Different in terms of SVI, organic loading, sludge retention time, composition, content of polymers, iron or aluminium, density, porosity and particle size distribution. But for the design of clarifiers most of these parameters are disregarded, of none importance or neglectable. With the help of PSD and particle shape analysis we can improve our knowledge of the settleability of activated sludge flocs. The measurements, done with the CIS show the influence of the differential sedimentation in comparison to the effluent of the secondary clarifiers under different conditions. Calculating the sedimentation velocities, the behaviour of activated and precipitated sludge could be explained and conclusions can be drawn to optimize the solid flux in secondary clarifiers.

A comparison of particle breakdown during chewing by guanacos (Lama guanicoe) and sheep

1998 ◽  
Vol 1998 ◽  
pp. 136-136 ◽  
Author(s):  
M.D. Fraser ◽  
D.H. Baker
Keyword(s):  
Particle Size ◽  
Retention Time ◽  
Microbial Fermentation ◽  
Digestive Efficiency ◽  
Particle Size Reduction ◽  
Lama Guanicoe ◽  
Factors Influencing ◽  
Stomach Motility ◽  
Pass Through ◽  
Major Factors

To date, attempts to account for reported differences in digestive efficiency of camelids and ruminants have focused on factors such as stomach motility and the retention time of feed particles. The physical breakdown of forage into particles small enough to pass through the reticulo-omasal orifice is one of the major factors influencing the rate of passage of digesta from the reticulo-rumen in ruminants. Two of the main processes involved in particle size reduction are chewing (pre- and post-regurgitation) and microbial fermentation. While the characteristic vertical and horizontal jaw movement which occurs during mastication in the camelid is believed to allow for efficient use of the premolars and molars in cutting and grinding fibrous feeds, there have been no comparative studies to verify this, and to assess the contribution of chewing to differences in digestibility coefficients. The aim of this experiment was to directly compare particle breakdown during chewing by guanacos and sheep.

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