Phosphorus retention by granulated apatite: assessing maximum retention capacity, kinetics and retention processes

Abstract Natural apatites have previously shown a great capacity for phosphate retention from wastewater. However, its fine particle size distribution may lead to a premature clogging of the filter. Accordingly, a granulated apatite product was developed and manufactured in order to control the particle size distribution of the media. Experiments were conducted on laboratory columns to assess their phosphorus retention capacity, to identify the processes involved in phosphorus retention and to evaluate their kinetic rates. The results showed phosphorus retention capacities of 10.5 and 12.4 g PO4-P·kg−1 and kinetic rate coefficients in the range of 0.63 and 0.23 h−1 involving lower values than those found for natural apatites in previous studies. Scanning Electron Microscopy images showed that apatite particles in the granules were embedded in the binder and were not readily accessible to act as seeds for calcium phosphate precipitation. The retention processes differ depending on the supersaturation of the solution with respect to calcium phosphate phases: at low calcium concentrations (69.8 ± 3.9 mg·L−1), hydroxyapatite precipitates fill up the porosity of the binder up to a depth of 100–300 μm from the granule surface; at higher calcium concentrations (112.7 ± 7.4 mg·L−1) precipitation occurs at the granule surface, forming successive layers of hydroxyapatite and carbonated calcium phosphates.

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MOISTURE-RETENTION PARAMETERS FOR COARSE-TEXTURED SOILS IN SOUTHERN ALBERTA

Canadian Journal of Soil Science ◽

10.4141/cjss89-027 ◽

1989 ◽

Vol 69 (2) ◽

pp. 263-272 ◽

Cited By ~ 5

Author(s):

D. R. BENNETT ◽

T. ENTZ

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Field Capacity ◽

Soil Series ◽

Moisture Retention ◽

Retention Capacity ◽

Southern Alberta ◽

Laboratory Procedures ◽

Retention Parameters

A combination of field and laboratory procedures was used to estimate moisture-retention parameters of four coarse-textured soil series in southern Alberta. In situ field capacity moisture content was substantially higher than estimates based on conventional laboratory methods, resulting in significant underestimation of total available moisture. Moisture-retention capacity of all four soil series was found to be adequate for irrigation development. Empirical equations were developed to estimate the upper and lower limits of moisture retention on the basis of particle-size distribution, as determined by the Bouyoucos hydrometer method. Five alternative empirical methods were also evaluated for use in predicting moisture-retention parameters of coarse-textured soils. Equations presented by Rawls et al. (1982) were found to have the best relationship with southern Alberta data for both field capacity and wilting point. Key words: Coarse-textured soils, moisture-retention parameters, particle-size distribution, empirical models, irrigation suitability

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PARTICLE SIZE DISTRIBUTION OF ALUMINUM, IRON AND CALCIUM PHOSPHATES IN SOIL PROFILES

Soil Science ◽

10.1097/00010694-196811000-00008 ◽

1968 ◽

Vol 106 (5) ◽

pp. 374-380 ◽

Cited By ~ 6

Author(s):

ANTHONY S. R. JUO ◽

BOYD G. ELLIS

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Calcium Phosphates ◽

Soil Profiles ◽

Aluminum Iron ◽

Iron And Calcium

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Derivation and Verification of the Breakage Rate Coefficient during Flocculation Process Based on Shear Strength

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.779-780.1482 ◽

2013 ◽

Vol 779-780 ◽

pp. 1482-1489 ◽

Cited By ~ 1

Author(s):

Jian Liu ◽

Min Zhou ◽

Jian Hao Zhou ◽

Qi Chao Hu ◽

Jun Guo He

Keyword(s):

Particle Size ◽

Shear Strength ◽

Particle Size Distribution ◽

Size Distribution ◽

Rate Coefficient ◽

Northwest China ◽

Rate Coefficients ◽

Theoretical Derivation ◽

Breakage Rate ◽

Flocculation Process

The dynamics of flocculation is always one of the most interesting and difficult points for water treatment. The applicability of existing breakage rate coefficients was restricted due to the limitations of their theoretical derivation. In order to solve this problem, a breakage rate coefficient of flocculation process was derived based on shear strength. It could be described by the equation "s(m)=E0Fr1.2m1/D". Then it was applied to a flocculation model which described the change of particle size distribution during flocculation. Laboratory scale experiments were carried out to verify the feasibility of the new breakage rate coefficient with the typical surface water in northwest China characterized by low temperature and low turbidity. Results indicated that both the change of particle size distribution with time and the effects of operation variables on the stable particle size distribution could be excellently simulated, agreeing well with the experimental results with the relative error ranged from 3% ~ 17%. It was demonstrated that the breakage rate coefficient based on shear strength could be used to describe the breakage rate of flocs during flocculation.

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Using Different Approaches of Particle Size Analysis for Estimation of Water Retention Capacity of Soils: Example of Keszthely Mountains (Hungary)

Acta Silvatica et Lignaria Hungarica ◽

10.37045/aslh-2021-0003 ◽

2021 ◽

Vol 17 (1) ◽

pp. 37-50

Author(s):

Orsolya Szecsődi ◽

András Makó ◽

Viktória Labancz ◽

Gyöngyi Barna ◽

Borbála Gálos ◽

...

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Soil Properties ◽

Size Distribution ◽

Water Retention ◽

Laser Diffraction ◽

Water Retention Capacity ◽

Retention Capacity ◽

Sedimentation Method ◽

Pre Treatment

PSD (particle size distribution) is a key factor affecting soil hydro-physical properties (e.g. hydraulic conductivity and water retention), which makes its determination essential. Climate change increases the importance of water retention and permeability as extreme weather events can severely impair the water supply of drought-sensitive vegetation. The amount of water in soils is expected to decrease. The modified Thornthwaite model considers soil properties such as root depth, topsoil layer thickness and particle size distribution (silt and clay fraction) of soil particles combined with the most significant soil properties. At the beginning of the research, we developed a laser diffraction method to replace the standard based “pipette” sedimentation method. The theoretical background of laser diffraction measurements is already known, but their practical application for estimating soil water retention capacity is still poorly understood. The pre-sieving of soil aggregates, the pre-treatment (disaggregation and dispersion) of the samples greatly influence the obtained results. In addition to the sedimentation method, laser diffraction measurements (Malvern Mastersizer 3000) were applied with three variants of pre-treatment. For comparison, the results of a Leptosol, a Cambisol, and a Luvisol were prepared for the first modified Thornthwaite water balance model. Significant differences appeared, especially during drought periods, which could be a basis for studying soil drought sensitivity. The development of our method can estimate the water retention capacity of soil, which could support adaptive forest management plans against climatic and pedological transformations.

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