Displacement washing of soda rapeseed pulp

2015 ◽  
Vol 69 (8) ◽  
Author(s):  
František Potůček ◽  
Kateřina Hájková
Keyword(s):  
Residence Time ◽  
Mean Residence Time ◽  
Average Length ◽  
Plug Flow ◽  
Breakthrough Curves ◽  
Step Function ◽  
Rapeseed Straw ◽  
Soda Pulping ◽  
Pulp Fibres ◽  
Displacement Washing

AbstractThe paper deals with the displacement washing of unbleached pulp cooked from rapeseed straw by soda pulping under laboratory conditions. Pulp fibres were characterised by their average length, as well as by effective specific volume and surface. Using the step function input change method, the washing breakthrough curves measured for alkali lignin as a tracer were described by the dispersed plug flow model containing a dimensionless criterion, the Péclet number. Besides the wash yield, the dispersion coefficient as well as the mean residence time and space time were evaluated. Preliminary results obtained for soda rapeseed pulp were compared with those for kraft hardwood (beech) and softwood (spruce, pine) pulps published earlier. The wash yield measured for soda pulp was found to be lower than that for hardwood and softwood pulps which manifested lower hydraulic resistance. The presence of silique valves in rapeseed straw resulted in lower mean residence time of lignin removed from the pulp bed in comparison with pulp manufactured from stalks only.

Washing of Pulp Fibre Bed

1997 ◽  
Vol 62 (4) ◽  
pp. 626-644 ◽  
Author(s):  
František Potůček
Keyword(s):  
Residence Time ◽  
Mean Residence Time ◽  
Kraft Pulp ◽  
Dimensionless Parameter ◽  
Dispersion Coefficient ◽  
Dispersion Model ◽  
Glass Spheres ◽  
Displacement Washing ◽  
Time Parameters ◽  
The Mean

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.

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

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.

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

2008 ◽  
Vol 56 (3) ◽  
pp. 272 ◽  
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.

scholarly journals Struvite recovery from solution containing phosphate(V) and sulphate(VI) ions

2015 ◽  
Vol 13 (1) ◽  
Author(s):  
Nina Hutnik ◽  
Anna Kozik ◽  
Krzysztof Piotrowski ◽  
Andrzej Matynia
Keyword(s):  
Product Quality ◽  
Constant Temperature ◽  
Residence Time ◽  
Mean Residence Time ◽  
Crystallization Process ◽  
Magnesium Ions ◽  
Ammonium Ions ◽  
Internal Circulation ◽  
Mean Size ◽  
Type Crystallizer

AbstractThe research results concerning the application of magnesium and ammonium ions for continuous removal of phosphate(V) ions from solution containing 1.0 or 0.20 mass% of PO43– and from 0.10 to 0.50 mass% of SO42– are presented. A continuous struvite MgNH4PO4 × 6H2O reaction crystallization process was carried out both under stoichiometric conditions and using 20% excess of magnesium ions. The research was conducted in a DT MSMPR type crystallizer with internal circulation of suspension driven by a propeller stirrer, in constant temperature 298 K. The pH varied from 9 to 11 and mean residence time of suspension in a crystallizer τ varied from 900 to 3600 s. It was concluded, that sulphate(VI) ions influenced product quality disadvantageously. Depending on process parameter combinations struvite crystals of mean size from ca. 18 to ca. 44 μm and of moderate homogeneity: CV 7–95% were produced. Presence of sulphate(VI) ions favored crystallization of struvite as prismatic crystals, but tubular forms were also identified. The best shaped struvite crystals were produced at relatively low concentration of sulphate(VI) ions, pH 9 and for mean residence time of suspension in a crystallizer elongated up to 3600 s.

Mean Residence Time of a Liquid in a Trickling Filter

1959 ◽  
Vol 85 (6) ◽  
pp. 51-78 ◽  
Author(s):  
Morton D. Sinkoff ◽  
Ralph Porges ◽  
James H. McDermott
Keyword(s):  
Residence Time ◽  
Mean Residence Time ◽  
Trickling Filter

Mean residence time of the shelf water in the East China and the Yellow Seas determined by228Ra/226Ra measurements

1989 ◽  
Vol 16 (11) ◽  
pp. 1297-1300 ◽  
Author(s):  
Yoshiyuki Nozaki ◽  
Vimonrut Kasemsupaya ◽  
Hiroyuki Tsubota
Keyword(s):  
Residence Time ◽  
Mean Residence Time ◽  
East China ◽  
Shelf Water

scholarly journals Reactivation of nutrient cycling in an urban tropical dry forest after abandonment of agricultural activities

2021 ◽  
Vol 27 (3) ◽  
pp. 355-365
Author(s):  
Juan D. León-Peláez ◽  
◽  
William Caicedo-Ruiz ◽  
Jeiner Castellanos-Barliza ◽  
◽  
...  
Keyword(s):  
Organic Matter ◽  
Leaf Litter ◽  
Residence Time ◽  
Mean Residence Time ◽  
Dry Forest ◽  
Agricultural Activities ◽  
Forest Fragment ◽  
Leaf Litterfall ◽  
Passive Restoration ◽  
Standing Litter

Introduction: Standing leaf litter represent an essential source of organic matter and nutrients to dynamize biogeochemical processes at the ecosystem level. Objectives: To characterize the accumulation and decomposition of organic materials and flow of nutrients from standing litter in an urban dry tropical forest in a successional stage, after 10 years of abandonment of agricultural activities, and to determine the potential use of three species in future active restoration activities. Materials and methods: Standing litter samples were collected from a forest fragment in Santa Marta, Colombia, separating leaves, reproductive material, woody material and other residues. Additionally, leaves of three species of interest for ecological restoration (Albizia niopoides Spruce ex Benth., Cordia alba [Jacq.] Roem. & Schult. and Machaerium milleflorum Dugand G. A.) were separated and Ca, Mg, K, N and P concentrations were determined. Results and discussion: Total standing litter was 8.3 Mg∙ha-1 with a mean residence time of two years. The leaves represented 20% of the standing litter, with a mean residence time of 1.4 years. Based on the decomposition constant (kj = 0.73) and the rate of leaf litterfall, organic matter returns accounted for 3.4 Mg∙ha-1∙year-1. Leaf decomposition rate decreased in the following order C. alba > M. milleflorum > A. niopoides. P represented the greatest limitation with low release rates (0.1 to 1.2 kg∙ha-1∙year-1). Conclusions: The passive restoration strategy allowed reactivation of biogeochemical cycle via fine leaf litter. Cordia alba showed potential for inclusion in restoration activities, with lower values for leaf N/P ratio, and higher rates for leaf litterfall, litter decomposition and nutrient release.

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