Washing of Pulp Fibre Bed

The mechanism of the displacement washing of unbleached kraft pulp was investigated. The flow of the wash liquid through a pulp bed was described by the dispersion model using one dimensionless parameter known as the Peclet number. To characterize the displacement washing, the wash yield, dispersion coefficient, and bed efficiency, as well as time parameters such as the mean residence time of lignin, and space time were evaluated. Results obtained for kraft pulp were compared with those for static bed of glass spheres.

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Long-term Temporal Variation of Mean Residence Time in Spring and Groundwater After Thinning at a Forested Headwater Catchment

10.5194/egusphere-egu2020-6522 ◽

2020 ◽

Author(s):

Isabela Silveira Baptista ◽

Maki Tsujimura ◽

Yuichi Onda

Keyword(s):

Temporal Variation ◽

Residence Time ◽

Mean Residence Time ◽

Flow Model ◽

Dispersion Model ◽

Spring Water ◽

Groundwater Storage ◽

Flow Process ◽

Piston Flow ◽

The Mean

Treatments on plantation forests, such as thinning, have a significant effect on the quality and quantity of water resources in the watersheds in Japan. However, few studies have performed intensive observations regarding the effects of thinning on the groundwater flow process with combined use of tracers, specially over a long period of time.In this study, stable isotope analysis and hydrological observations were applied to investigate the temporal variation of spring water and groundwater mean residence time in a small watershed at Mount Karasawa, Tochigi Prefecture, Japan. We have monitored the research area since 2010, with periodical sampling once a month for 9 years, with a lack of data in some years after the thinning. &#160;We analyzed the date for three different time periods, those are: Before Thinning, from July 2010 to September 2011, Soon After Thinning, from November 2011 to October 2013 and Long After Thinning, from September 2017 to August 2019.The mean residence time of spring water and groundwater were evaluated by using the stable isotopes of hydrogen and oxygen as tracers, then estimating their d-excess variations using two Lumped-Parameter Models, Exponential-Piston Flow Model and Dispersion Model. The SF6 concentrations were used as an Apparent Age analysis for determination of the model&#8217;s parameters. Both models show a tendency of the mean residence time getting older Soon After Thinning and then getting younger again Long After Thinning.According to a selection of the best model for this area, the Exponential-Piston Flow Model shows that the spring water mean residence time was 25 months Before Thinning, 30 months Soon After Thinning and 26 months Long After Thinning; the groundwater at 15m deep mean residence time was 39 months Before Thinning, 46 months Soon After Thinning and 38 months Long After Thinning and the groundwater at 30m deep mean residence time was 38 months Before Thinning, 47 months Soon After Thinning and 45 months Long After Thinning. These results suggest that Soon After Thinning there is a reduction of forest interception and tree evapotranspiration, leading to an increase in infiltration and groundwater storage. Then, Long After Thinning, the forest interception and tree evapotranspiration rise back again with the recovery of the understory vegetation, which leads to a decrease in infiltration and groundwater storage.

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Mass Transfer in Liquid in Apparatus with Mobile Packing. Application of Model of Cascade of Ideal Mixers

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19940336 ◽

1994 ◽

Vol 59 (2) ◽

pp. 336-344

Author(s):

Zdeněk Palatý

Keyword(s):

Mass Transfer ◽

Residence Time ◽

Mean Residence Time ◽

Liquid Velocity ◽

Dispersion Model ◽

Velocity Range ◽

Bed Height ◽

The Mean ◽

Determination Of Parameters

The paper deals with the determination of parameters of a cascade of ideal mixers (i.e. their number and mean residence time of liquid in each member) in modelling the liquid flow on a plate with mobile packing. The number of cascade members has been found practically independent of the gas and liquid velocities and the static bed heights in the gas velocity range from 1.0 to 3.5 m s-1, liquid velocity range from 5.36 . 10-3 to 12.5 . 10-3 m s-1, and the range of static bed height from 21 . 10-3 to 47 . 10-3 m. The mean residence time is increased with increasing static bed height and is decreased with increasing velocities of both gas and liquid. The calculated parameters of the model of flow of liquid and the experimental data on desorption of CO2 from water by a stream of air have been used to calculate the values of mass transfer coefficient in liquid which have been compared with those obtained from the dispersion model. The both approaches have been found to give practically identical results.

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Precipitation and filtration of zinc, magnesium, copper and aluminium hydroxides

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19823362 ◽

1982 ◽

Vol 47 (12) ◽

pp. 3362-3370

Author(s):

Otakar Söhnel ◽

Eva Matějčková

Keyword(s):

Residence Time ◽

Mean Residence Time ◽

Filtration Resistance ◽

Filtration Pressure ◽

Bed Porosity ◽

The Mean ◽

Filtration Properties

Filtration properties of batchwise precipitated suspensions of Zn(OH)2, Mg(OH)2 and Cu(OH)2 and continuously precipitated Al(OH)3 were studied. For batchwise precipitated suspensions was verified the theoretically predicted dependence of specific filtration resistance on initial supersaturation and for the continuously precipitated Al(OH)3 the relation between the specific filtration resistance and the mean residence time of suspension in the reactor. Dependences were also recorded between the bed porosity and concentration of precipitated solutions, specific filtration resistance and used filtration pressure and the effect of aging of the batchwise precipitated suspension of Mg(OH)2on its filtration properties. The used CST method for determination of filtration characteristics of Zn(OH)2 suspension was also studied.

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Nitrogen use efficiency: does a trade-off exist between the N productivity and the mean residence time within species?

Australian Journal of Botany ◽

10.1071/bt07139 ◽

2008 ◽

Vol 56 (3) ◽

pp. 272 ◽

Cited By ~ 11

Author(s):

Zhi Y. Yuan ◽

Han Y. H. Chen ◽

Ling H. Li

Keyword(s):

Residence Time ◽

Nitrogen Use Efficiency ◽

Mean Residence Time ◽

Negative Relationship ◽

Controlled Experiments ◽

Nitrogen Use ◽

Trade Off ◽

N Supply ◽

Use Efficiency ◽

The Mean

Nitrogen use efficiency (NUE) can be divided into two components, i.e. N productivity (A) and the mean residence time (MRT). Controlled experiments indicate that there is not a trade-off between A and MRT within species, but this theory has not been well tested in field conditions. Here, we studied the A, MRT and NUE of Stipa krylovii Roshev. in a grassland over 4 years of N fertilisation experimentation. The three parameters (A, MRT and NUE) were significantly related to soil N supply and there was a negative relationship between A and MRT within this species (r = –0.775, P < 0.05), i.e. plants with higher A had lower MRT. Our results showed a trade-off between A and MRT within this Stipa species and this observed trade-off was attributed to different responses of A and MRT to soil fertility.

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Roots are key to increasing the mean residence time of organic carbon entering temperate agricultural soils

Global Change Biology ◽

10.1111/gcb.15787 ◽

2021 ◽

Author(s):

Christopher Poeplau ◽

Axel Don ◽

Florian Schneider

Keyword(s):

Organic Carbon ◽

Residence Time ◽

Mean Residence Time ◽

Agricultural Soils ◽

The Mean

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Submarine Groundwater Discharge From Sediments and Sand Boils Quantified by the Mean Residence Time of a Tracer Injection

Frontiers in Earth Science ◽

10.3389/feart.2021.710000 ◽

2021 ◽

Vol 9 ◽

Author(s):

Michael Schlüter ◽

Philipp Maier

Keyword(s):

Residence Time ◽

Mean Residence Time ◽

Submarine Groundwater Discharge ◽

Groundwater Discharge ◽

Tracer Injection ◽

Discharge Rates ◽

Seepage Meter ◽

Submarine Groundwater ◽

Sand Boils ◽

The Mean

To quantify submarine groundwater discharge, we developed an inexpensive automated seepage meter that applies a tracer injection and the computation of the mean residence time. The SGD-MRT is designed to measure a wide range of discharge rates from about 30 to 800 cm³/min and allows minimizing backpressures caused by pipe friction or flow sensors. By modifying the inner volume of the flow-through unit, the range of measurement is adjustable to lower or higher discharge rates. For process control and data acquisition, an Arduino controller board is used. In addition, components like temperature, conductivity, and pressure sensors or pumps extend the scope of the seepage meter. During field tests in the Wadden Sea, covering tidal cycles, discharge rates of more than 700 cm³/min were released from sand boils. Based on the measured discharge rates and numerical integration of the time series data, a water volume of about 400 dm3 with a seawater content of less than 12% was released from the sand boil within 7 h.

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