Total Particle Counts

Nowadays filtration processes are still monitored with conventional analyses like turbidity measurements and, in case of flocculation–filtration, with phosphorus analyses. Turbidity measurements have the disadvantage that breakthrough of small flocs cannot be displayed, because of the blindness regarding changes in the mass distributions. Additional particle volume distributions calculated from particle size distributions (PSDs) would provide a better assessment of filtration performance. Lab-scale experiments have been executed on a flocculation–filtration column fed with effluent from WWTP Beverwijk in The Netherlands. Besides particle counting at various sampling points, the effect of sample dilution on the accuracy of PSD measurements has been reflected. It was found that the dilution has a minor effect on PSD of low turbidity samples such as process filtrate. The correlation between total particle counts, total particle volume (TPV) and total particle surface is not high but is at least better for diluted measurements of particles in the range 2–10 μm. Furthermore, possible relations between floc-bound phosphorus and TPV removal had been investigated. A good correlation coefficient is found for TPV removal versus floc-bound phosphorus removal for the experiments with polyaluminiumchloride and the experiments with single denitrifying and blank filtration.

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Évolution du nombre de particules dans l'eau filtrée d'une filière de filtration directe utilisant le polychlorure d'aluminium

Canadian Journal of Civil Engineering ◽

10.1139/l99-039 ◽

1999 ◽

Vol 26 (6) ◽

pp. 771-781

Author(s):

Souleymane Ndiongue ◽

Raymond Desjardins ◽

Michèle Prévost ◽

Chantal Morissette

Keyword(s):

The Other ◽

Raw Water ◽

Polyaluminum Chloride ◽

Direct Filtration ◽

Total Particle ◽

High Turbidity ◽

Particle Counts ◽

St Lawrence River ◽

Do So

This text presents and discusses the performances of direct filtration evaluated by means of particle counts and turbidity of raw water in periods of low and high turbidity. It also deals with the relationships between the removals of particles measuring from 2 to 150 µm (total counts) and those of particles in the other size ranges, which vary from 2 to 5 and from 5 to 15 µm. The tests were carried out on a pilot plant (20 m3/h) that treats waters from the St. Lawrence River (Canada) using the polyaluminum chloride (PACl) coagulation method followed by rapid filtration at 10 m/h. The results show that when the turbidity of the raw water is low, it is not always possible to predict a filter breakthrough based on the turbidity of its effluent, whereas it is possible to do so by observing the evolution of the particle counts. There exist good correlations between the removals of the total particle counts (2-150 µm) and those of the counts of particles in the other size ranges (2-5 and 5-15 µm). Furthermore, the evolution of all these ranges of particle size reveals the same tendencies with respect to the quality of the filtered water.Key words: direct filtration, in-line filtration, filtration, particle counts, turbidity, polyaluminum chloride.

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Microaggregate counts in frozen-preserved erythrocytes: effects of washing in three blood processors and filtration

Blood ◽

10.1182/blood.v50.4.743.bloodjournal504743 ◽

1977 ◽

Vol 50 (4) ◽

pp. 743-748

Author(s):

M Telischi ◽

AR Patel ◽

M Zafar ◽

R Hoiberg

Keyword(s):

Blood Transfusion ◽

Blood System ◽

Pulmonary Insufficiency ◽

Particle Removal ◽

Cell Processing ◽

Total Particle ◽

Particle Counts ◽

Stored Blood

Since microaggregates have been implicated in posttransfusion pulmonary insufficiency, their elimination has become an active concern in blood transfusion. Various types of filters, as well as frozen-preserved erythrocytes, have been used to provide blood relatively low in microaggregates. We have counted particles in frozen-stored blood before deglycerolization, after washing in each of three cell processing systems, and after filtration through a 40-micrometer filter. Washing frozen erythrocytes reduced the total particle counts by an average of 89%. Slight differences were found among the three blood processors with respect to particle removal. Passing washed blood through a 40-micrometer filter did not result in significant further reduction in particle counts. Hence, the use of such filters in a frozen-preserved blood system is not warranted.

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Microaggregate counts in frozen-preserved erythrocytes: effects of washing in three blood processors and filtration

Blood ◽

10.1182/blood.v50.4.743.743 ◽

1977 ◽

Vol 50 (4) ◽

pp. 743-748 ◽

Cited By ~ 1

Author(s):

M Telischi ◽

AR Patel ◽

M Zafar ◽

R Hoiberg

Keyword(s):

Blood Transfusion ◽

Blood System ◽

Pulmonary Insufficiency ◽

Particle Removal ◽

Cell Processing ◽

Total Particle ◽

Particle Counts ◽

Stored Blood

Abstract Since microaggregates have been implicated in posttransfusion pulmonary insufficiency, their elimination has become an active concern in blood transfusion. Various types of filters, as well as frozen-preserved erythrocytes, have been used to provide blood relatively low in microaggregates. We have counted particles in frozen-stored blood before deglycerolization, after washing in each of three cell processing systems, and after filtration through a 40-micrometer filter. Washing frozen erythrocytes reduced the total particle counts by an average of 89%. Slight differences were found among the three blood processors with respect to particle removal. Passing washed blood through a 40-micrometer filter did not result in significant further reduction in particle counts. Hence, the use of such filters in a frozen-preserved blood system is not warranted.

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A Simple Method for Total Particle Counts of Trachoma and Inclusion Blennorrhœa Viruses

Nature ◽

10.1038/195923a0 ◽

1962 ◽

Vol 195 (4844) ◽

pp. 923-924 ◽

Cited By ~ 19

Author(s):

PETER REEVE ◽

JANICE TAVERNE

Keyword(s):

Simple Method ◽

Total Particle ◽

Particle Counts

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Evaluation of the rapid filtration system with particle size distribution and Cryptosporidium in different operating conditions

Water Science & Technology Water Supply ◽

10.2166/ws.2006.014 ◽

2006 ◽

Vol 6 (1) ◽

pp. 129-139 ◽

Cited By ~ 1

Author(s):

M.J. Yu ◽

S.K. Ahn ◽

S.H. Chung ◽

S. Noh ◽

J.A. Park ◽

...

Keyword(s):

Water Quality ◽

Performance Evaluation ◽

Operating Conditions ◽

Treatment System ◽

Sand Layer ◽

Sand Filter ◽

Filtration System ◽

Study Results ◽

Total Particle ◽

Particle Counts

The characterization of particle behavior in addition to the measurement of turbidity is becoming more important in performance evaluation as well as in the operation of the water treatment system, in order to provide supporting information on small-sized microorganisms such as Cryptosporidium. Accordingly, the particle counter has been introduced in the evaluation and operation of the treatment system. However, research results on the relation among turbidity, particle counts and/or protozoa have not been concurrent with each other. Therefore, this study investigated the relation to improve performance evaluation of the sand filter so that the risk of protozoan contamination can be reduced. The study results verified that particle counts provide a better insight into the filtration process than turbidity alone. The counts of 4–7 as well as 7–14 μm, instead of total particle counts, can be used to monitor and operate the rapid sand filter effectively, as it has a better relation with Cryptosporidium. Also, the study results showed that the fine single-medium filter is more useful when targeting better water quality despite its low productivity, since it removes small particles more effectively than the dual-media filter. The latter is more useful when targeting better productivity. However, enough depth of sand layer of dual media filter with adequate filtration rate is required to not compromise water quality and productivity, as a shallow sand layer is highly likely to cause an early breakthrough.

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Effects of velocity gradient and mixing time on particle growth in a rapid mixing tank

Water Science & Technology ◽

10.2166/wst.2006.212 ◽

2006 ◽

Vol 53 (7) ◽

pp. 95-102 ◽

Cited By ~ 5

Author(s):

S.M. Park ◽

H.B. Jun ◽

M.S. Jung ◽

H.M. Koo

Keyword(s):

Velocity Gradient ◽

Mixing Time ◽

Maximum Growth ◽

Particle Growth ◽

Small Particles ◽

Turbidity Removal ◽

Rapid Mixing ◽

Total Particle ◽

Particle Counts ◽

G Value

Effects of velocity gradient (G value) and mixing time (t) on the coagulation of particles were investigated by monitoring particle counts in a rapid mixing process. Total particle counts after mixing of 30 s at G value of 200 s−1 were similar to the summation of clay particles and alum precipitates at alum dose of 30 mg L−1. Although small particles (microflocs less than 5 μm) were formed within the mixing time of 30 s, macroflocs larger than 8 μm did not increase significantly until the mixing time of 60 s. However, macroflocs larger than 8 μm started to increase after mixing of 75 s and they reached the maximum counts at 150 s. On the other hand, macroflocs larger than 8 μm decreased after mixing time of 180 s due in breaks of the macroflocs, which resulted in resuspension of small particles. The rapid mixing conditions for the maximum growth of macroflocs were the G value of 200 s−1 and the mixing time of 150 s, which confirmed the best performance of turbidity removal in jar tests. Growth and break of particles and flocs in a rapid mixing step would influence significantly on the sequential flocculation and sedimentation processes for turbidity removal.

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Negative Staining: a Valuable Technique for Studying Subcellular Components

Microscopy and Microanalysis ◽

10.1017/s143192760000859x ◽

1997 ◽

Vol 3 (S2) ◽

pp. 341-342

Author(s):

Sara E. Miller

Keyword(s):

Negative Staining ◽

Cell Organelles ◽

Preparation Time ◽

Nucleic Acid Probes ◽

Virus Identification ◽

High Particle ◽

Thin Sectioning ◽

Particle Counts ◽

Selection Of

Negative staining is the most frequently used procedure for preparing particulate specimens, e.g., cell organelles, macromolecules, and viruses, for electron microscopy (Figs. 1-4). The main advantage is that it is rapid, requiring only minutes of preparation time. Another is that it avoids some of the harsh chemicals, e.g., organic solvents, used in thin sectioning. Also, it does not require advanced technical skill. It is widely used in virology, both in classification of viruses as well as diagnosis of viral diseases. Notwithstanding the necessity for fairly high particle counts, virus identification by negative staining is advantageous in not requiring specific reagents such as antibodies, nucleic acid probes, or protein standards which necessitate prior knowledge of potential pathogens for selection of the proper reagent. Furthermore, it does not require viable virions as does growth in tissue culture. Another procedure that uses negative contrasting is ultrathin cryosectioning (Fig. 5).In 1954 Farrant was the first to publish negatively stained material, ferritin particles.

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Assessing reinforcing versus aversive consequences in a real-time secondhand smoke intervention

Translational Behavioral Medicine ◽

10.1093/tbm/ibab004 ◽

2021 ◽

Author(s):

Vincent Berardi ◽

John Bellettiere ◽

Benjamin Nguyen ◽

Neil E Klepeis ◽

Suzanne C Hughes ◽

...

Keyword(s):

Real Time ◽

Real World ◽

Secondhand Smoke ◽

Relative Effectiveness ◽

Feedback System ◽

Control Group ◽

Sensing Technology ◽

Control Versus ◽

Particle Counts ◽

Post Hoc

Abstract Few studies have examined the relative effectiveness of reinforcing versus aversive consequences at changing behavior in real-world environments. Real-time sensing devices makes it easier to investigate such questions, offering the potential to improve both intervention outcomes and theory. This research aims to describe the development of a real-time, operant theory-based secondhand smoke (SHS) intervention and compare the efficacy of aversive versus aversive plus reinforcement contingency systems. Indoor air particle monitors were placed in the households of 253 smokers for approximately three months. Participants were assigned to a measurement-only control group (N = 129) or one of the following groups: 1.) aversive only (AO, N = 71), with aversive audio/visual consequences triggered by the detection of elevated air particle measurements, or 2.) aversive plus reinforcement (AP, N = 53), with reinforcing consequences contingent on the absence of SHS added to the AO intervention. Residualized change ANCOVA analysis compared particle concentrations over time and across groups. Post-hoc pairwise comparisons were also performed. After controlling for Baseline, Post-Baseline daily particle counts (F = 6.42, p = 0.002), % of time >15,000 counts (F = 7.72, p < 0.001), and daily particle events (F = 4.04, p = 0.02) significantly differed by study group. Nearly all control versus AO/AP pair-wise comparisons were statistically significant. No significant differences were found for AO versus AP groups. The aversive feedback system reduced SHS, but adding reinforcing consequences did not further improve outcomes. The complexity of real-world environments requires the nuances of these two contingency systems continue to be explored, with this study demonstrating that real-time sensing technology can serve as a platform for such research.

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Simultaneous Monitoring of Particle-Bound PAHs Inside a Low-Energy School Building and Outdoors over Two Weeks in France

Atmosphere ◽

10.3390/atmos12010108 ◽

2021 ◽

Vol 12 (1) ◽

pp. 108

Author(s):

Céline Liaud ◽

Sarah Chouvenc ◽

Stéphane Le Calvé

Keyword(s):

Particle Size ◽

Air Quality ◽

High Performance ◽

Sampling Period ◽

Temporal Variations ◽

Ventilation Rate ◽

Low Energy ◽

Total Particle ◽

Polycyclic Aromatic ◽

Individual Pahs

The emergence of new super-insulated buildings to reduce energy consumption can lead to a degradation of the indoor air quality. While some studies were carried out to assess the air quality in these super-insulated buildings, they were usually focused on the measurement of gas phase pollutants such as carbon dioxide and volatile organic compounds. This work reports the first measurements of Polycyclic Aromatic Hydrocarbons (PAHs) associated with particles as a function of time and particle size in a low-energy building. The airborne particles were collected indoors and outdoors over three to four days of sampling using two three-stage cascade impactors allowing to sample simultaneously particles with aerodynamic diameter Dae > 10 µm, 2.5 µm < Dae < 10 µm, 1 µm < Dae < 2.5 µm, and Dae < 1 µm. The 16 US-EPA priority PAHs were then extracted and quantified by high-performance liquid chromatography (HPLC) coupled to fluorescence detection. The resulting total particle concentrations were low, in the ranges 3.73 to 9.66 and 0.60 to 8.83 µg m-3 for indoors and outdoors, respectively. Thirteen PAHs were always detected in all the samples. The total PAH concentrations varied between 290 and 415 pg m−3 depending on the particle size, the environment (indoors or outdoors) and the sampling period considered. More interestingly, the temporal variations of individual PAHs highlighted that high molecular weight PAHs were mainly associated to the finest particles and some of them exhibited similar temporal behaviors, suggesting a common emission source. The indoor-to-outdoor concentration ratios of individual PAH were usually found close to or less than 1, except during the event combining rainy conditions and limited indoor ventilation rate.

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