scholarly journals The sensitivity of SDI and MFI to a change in particle concentration and properties under saline conditions

2012 ◽  
Vol 2 (3) ◽  
pp. 140-148
Author(s):  
N. Prihasto ◽  
Seung-Hyun Kim
Keyword(s):  
Particle Size ◽  
Ionic Strength ◽  
Particle Concentration ◽  
Relative Proportion ◽  
Saline Condition ◽  
Particle Properties ◽  
Silica Suspension ◽  
Density Index ◽  
Modified Fouling Index ◽  
Silt Density Index

The sensitivity of existing fouling indices of SDI (silt density index) and MFI (modified fouling index) to a change in particle concentration and properties was evaluated in this study. The MFI formula predicts an increased fouling tendency when the particle concentration increases and the particle size and density decrease. Consequently, concentration, size and density were selected as parameters to examine. For this purpose, silica particles and Aldrich humic acid (HA) were selected as target foulants because of the substantial difference in their size and density. According to this study, both SDI and MFI were sensitive to a change in particle properties of size and density, while MFI was more sensitive to a change in particle concentration than SDI. It is also found that the fouling tendency could be represented better by separate evaluation of T0 and T15 than SDI, at which the ratio of T0 and T15 is evaluated. T15 is found to be as sensitive as the MFI for both silica suspension and HA solution. The saline condition increased the fouling index. MFI and T15 were sensitive to a change in ionic strength. When inorganic and organic foulants were mixed, their relative proportion determined the fouling index values.

Silt Density Index and Modified Fouling Index relation, and effect of pressure, temperature and membrane resistance

Desalination ◽  
2011 ◽  
Vol 273 (1) ◽  
pp. 48-56 ◽  
Author(s):  
A. Alhadidi ◽  
A.J.B Kemperman ◽  
B. Blankert ◽  
J.C. Schippers ◽  
M. Wessling ◽  
...  
Keyword(s):  
Membrane Resistance ◽  
Effect Of Pressure ◽  
Density Index ◽  
Modified Fouling Index ◽  
Silt Density Index

New insights into silt density index and modified fouling index measurements

2008 ◽  
Vol 8 (4) ◽  
pp. 401-411 ◽  
Author(s):  
A. Nahrstedt ◽  
J. Camargo-Schmale
Keyword(s):  
Boundary Conditions ◽  
Membrane Area ◽  
Filter Holder ◽  
Feed Pressure ◽  
Exact Boundary ◽  
Density Index ◽  
Different Types ◽  
Robust Parameter ◽  
Modified Fouling Index ◽  
Silt Density Index

In order to investigate the accuracy and reproducibility of the parameters SDI (silt density index) and MFI (modified fouling index), tests in diverse conditions were performed: with three different types of filter holder, two microfilter pore sizes, with and without permeate spacer and with two foulants (alginate as organic foulant and silica flour as the particulate). Additionally the effect of pressure on fouling indices was analysed. It was concluded, that there is a need to define more boundary conditions in the ASTM standard (exact type of filter holder, exact type of membrane, start conditions) for the SDI to achieve a parameter with reliable and comparable values. But in comparison to MFI, SDI seems to be a more robust parameter for a use in practice pertaining to the influence of a feed pressure level and the effective membrane area. The MFI gives more insights in acting mechanisms and offers advantages for research. It shows a correlation to a concentration of particulate or organic foulants. Like the SDI, it is necessary to define and standardize exact boundary conditions for the MFI tests (classified by the use of MF, UF or NF filter media).

A theory of aerosol deposition in the human respiratory tract

1975 ◽  
Vol 38 (1) ◽  
pp. 77-85 ◽  
Author(s):  
D. B. Taulbee ◽  
C. P. Yu
Keyword(s):  
Particle Size ◽  
Respiratory Tract ◽  
Particle Deposition ◽  
Particle Concentration ◽  
Diffusion Mechanism ◽  
Aerosol Deposition ◽  
Lung Model ◽  
Brownian Diffusion ◽  
Human Respiratory Tract ◽  
Apparent Diffusion

The deposition of inhaled aerosol particles in the human respiratory tract is due to the mechanisms of inertia impaction, Brownian diffusion, and gravitational settling. A theory is developed to predict the particle deposition and its distribution in human respiratory tract for any breathing condition. A convection-diffusion equation for the particle concentration with a loss term is used to describe the transport and deposition of particles. In this equation, an apparent diffusion coefficient due to the velocity dispersion in the lung is present and found to be the dominant diffusion mechanism for the cases considered here. Expressions for deposition by various mechanisms are also derived. The governing equation is solved numerically with Weibel's lung model A. The particle concentration at the mouth is calculated during washin and washout and compared favorably with experimental recordings for 0.5-mum diameter di(2-ethylhexyl) sebacate particles. The total deposition in the lung for particle size ranging from 0.05 to 5 mum is also computed for a 500-cm-3 tidal volume and 15 breaths/min. The results in general agree with recent measurements of Heyder et al. However, a particle size of minimum deposition is found to exist theoretically near 0.3 mum.

scholarly journals On microphysical processes of noctilucent clouds (NLC): observations and modeling of mean and width of the particle size-distribution

2010 ◽  
Vol 10 (2) ◽  
pp. 3605-3625
Author(s):  
G. Baumgarten ◽  
J. Fiedler ◽  
M. Rapp
Keyword(s):  
Particle Size ◽  
Linear Relationship ◽  
Size Distribution ◽  
Eddy Diffusion ◽  
Particle Sizes ◽  
Noctilucent Clouds ◽  
Atmospheric Variability ◽  
Distribution Width ◽  
Particle Properties ◽  
Microphysical Processes

Abstract. Noctilucent clouds (NLC) in the polar summer mesopause region have been observed in Norway (69° N, 16° E) between 1998 and 2009 by 3-color lidar technique. Assuming a mono-modal Gaussian size distribution we deduce mean and width of the particle sizes throughout the clouds. We observe a quasi linear relationship between distribution width and mean of the particle size at the top of the clouds and a deviation from this behavior for particle sizes larger than 40 nm, most often in the lower part of the layer. The vertically integrated particle properties show that 65% of the data follows the linear relationship with a slope of 0.42±0.02. For the vertically resolved particle properties (Δz=0.15 km) the slope is smaller and only 0.39±0.03. We compare our observations to microphysical modeling of noctilucent clouds and find that the distribution width depends on turbulence, the time that turbulence can act (cloud age), and the sampling volume/time (atmospheric variability). The model results nicely reproduce the measurements and show that the observed slope can be explained by eddy diffusion profiles as observed from rocket measurements.

scholarly journals A review of biomass burning emissions, part II: Intensive physical properties of biomass burning particles

2004 ◽  
Vol 4 (5) ◽  
pp. 5135-5200 ◽  
Author(s):  
J. S. Reid ◽  
R. Koppmann ◽  
T. F. Eck ◽  
D. P. Eleuterio
Keyword(s):  
Particle Size ◽  
Biomass Burning ◽  
Measurement Techniques ◽  
Emission Factors ◽  
Future Research ◽  
Data Set ◽  
Particle Properties ◽  
In Situ Experiments ◽  
Literature Base ◽  
Biomass Burning Particles

Abstract. The last decade has seen tremendous advances in atmospheric aerosol particle research that is often performed in the context of climate and global change science. Biomass burning, one of the largest sources of accumulation mode particles globally, has been closely studied for its radiative, geochemical, and dynamic impacts. These studies have taken many forms including laboratory burns, in situ experiments, remote sensing, and modeling. While the differing perspectives of these studies have ultimately improved our qualitative understanding of biomass burning issues, the varied nature of the work make inter-comparisons and resolutions of some specific issues difficult. In short, the literature base has become a milieu of small pieces of the biomass-burning puzzle. This manuscript, the second part of four, examines the properties of biomass-burning particle emissions. Here we review and discuss the literature concerning the measurement of smoke particle size, chemistry, thermodynamic properties, and emission factors. Where appropriate, critiques of measurement techniques are presented. We show that very large differences in measured particle properties have appeared in the literature, in particular with regards to particle carbon budgets. We investigate emissions uncertainties using scale analyses, which shows that while emission factors for grass and brush are relatively well known, very large uncertainties still exist in emission factors of boreal, temperate and some tropical forests. Based on an uncertainty analysis of the community data set of biomass burning measurements, we present simplified models for particle size and emission factors. We close this review paper with a discussion of the community experimental data, point to lapses in the data set, and prioritize future research topics.

scholarly journals Influence of Particle and Grain Size on Sand Filtration: Effect on Head Loss and Turbidity

2020 ◽  
Vol 8 (2) ◽  
pp. 36
Author(s):  
Racha Medjda Bouchenak Khelladi ◽  
Abdelghani Chiboub Fellah ◽  
Maxime Pontié ◽  
Fatima Zohra Guellil
Keyword(s):  
Particle Size ◽  
Flow Rate ◽  
Granular Media ◽  
Particle Concentration ◽  
Head Loss ◽  
Sand Filtration ◽  
Circular Column ◽  
Filter Performance ◽  
Filter Operation ◽  
Suspended Matters

Sand filtration is an eco-friendly method to treat either drinking water or wastewater ; it requires only natural granular media. It is also easy to use and to maintain ; the only problem they face is clogging that affects filter performance, that can be detected when head loss or turbidity increase. The purpose of this work is to see what are the factors that influence the performance of filter operation, for this, we used a pilot consisting on a circular column filled with sand (from South Algeria), where various parameters were tested; pressure, flow rate, sand granulometry, suspended matters and particle concentration of the water which is filtered. After eighteen weeks of operation, we have found that head loss increases by decreasing granulometry and increasing flow rate, pressure, particle size, and concentration. However, turbidity increases by decreasing particle size and increasing granulometry and particle concentration. Turbidity and head loss have different behaviour towards the same parameter; that is why it is necessary to take them into account in order to find a compromise between acceptable head loss / turbidity for a good functioning of the filter.

Adsorption of cadmium by biochar produced from pyrolysis of corn stalk in aqueous solution

2016 ◽  
Vol 74 (6) ◽  
pp. 1335-1345 ◽  
Author(s):  
Fengfeng Ma ◽  
Baowei Zhao ◽  
Jingru Diao
Keyword(s):  
Aqueous Solution ◽  
Particle Size ◽  
Ionic Strength ◽  
Ph Value ◽  
Batch Adsorption ◽  
Order Kinetic ◽  
Corn Stalk ◽  
Adsorbent Dosage ◽  
Initial Ph ◽  
Adsorbent Particle

The purpose of this work is to investigate adsorption characteristic of corn stalk (CS) biochar for removal of cadmium ions (Cd2+) from aqueous solution. Batch adsorption experiments were carried out to evaluate the effects of pH value of solution, adsorbent particle size, adsorbent dosage, and ionic strength of solution on the adsorption of Cd2+ onto biochar that was pyrolytically produced from CS at 300 °C. The results showed that the initial pH value of solution played an important role in adsorption. The adsorptive amount of Cd2+ onto the biochar decreased with increasing the adsorbent dosage, adsorbent particle size, and ionic strength, while it increased with increasing the initial pH value of solution and temperature. Cd2+ was removed efficiently and quickly from aqueous solutions by the biochar with a maximum capacity of 33.94 mg/g. The adsorption process was well described by the pseudo-second-order kinetic model with the correlation coefficients greater than 0.986. The adsorption isotherm could be well fitted by the Langmuir model. The thermodynamic studies showed that the adsorption of Cd2+ onto the biochar was a spontaneous and exothermic process. The results indicate that CS biochar can be considered as an efficient adsorbent.

scholarly journals Wildfire Smoke Particle Properties and Evolution, From Space-Based Multi-Angle Imaging II: The Williams Flats Fire during the FIREX-AQ Campaign

2020 ◽  
Vol 12 (22) ◽  
pp. 3823
Author(s):  
Katherine T. Junghenn Noyes ◽  
Ralph A. Kahn ◽  
James A. Limbacher ◽  
Zhanqing Li ◽  
Marta A. Fenn ◽  
...  
Keyword(s):  
Particle Size ◽  
Biomass Burning ◽  
In Situ Measurements ◽  
Statistical Characterization ◽  
Smoke Particle ◽  
Particle Properties ◽  
In Situ Data ◽  
Particle Property ◽  
Aircraft Data

Although the characteristics of biomass burning events and the ambient ecosystem determine emitted smoke composition, the conditions that modulate the partitioning of black carbon (BC) and brown carbon (BrC) formation are not well understood, nor are the spatial or temporal frequency of factors driving smoke particle evolution, such as hydration, coagulation, and oxidation, all of which impact smoke radiative forcing. In situ data from surface observation sites and aircraft field campaigns offer deep insight into the optical, chemical, and microphysical traits of biomass burning (BB) smoke aerosols, such as single scattering albedo (SSA) and size distribution, but cannot by themselves provide robust statistical characterization of both emitted and evolved particles. Data from the NASA Earth Observing System’s Multi-Angle Imaging SpectroRadiometer (MISR) instrument can provide at least a partial picture of BB particle properties and their evolution downwind, once properly validated. Here we use in situ data from the joint NOAA/NASA 2019 Fire Influence on Regional to Global Environments Experiment-Air Quality (FIREX-AQ) field campaign to assess the strengths and limitations of MISR-derived constraints on particle size, shape, light-absorption, and its spectral slope, as well as plume height and associated wind vectors. Based on the satellite observations, we also offer inferences about aging mechanisms effecting downwind particle evolution, such as gravitational settling, oxidation, secondary particle formation, and the combination of particle aggregation and condensational growth. This work builds upon our previous study, adding confidence to our interpretation of the remote-sensing data based on an expanded suite of in situ measurements for validation. The satellite and in situ measurements offer similar characterizations of particle property evolution as a function of smoke age for the 06 August Williams Flats Fire, and most of the key differences in particle size and absorption can be attributed to differences in sampling and changes in the plume geometry between sampling times. Whereas the aircraft data provide validation for the MISR retrievals, the satellite data offer a spatially continuous mapping of particle properties over the plume, which helps identify trends in particle property downwind evolution that are ambiguous in the sparsely sampled aircraft transects. The MISR data record is more than two decades long, offering future opportunities to study regional wildfire plume behavior statistically, where aircraft data are limited or entirely lacking.

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