Phosphate Recovery
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ARTICLES ON PHOSPHATE RECYCLING
The list below contains papers published in peer-reviewed journals, with a short summary of their conent.The list is alphabetical by first author.
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F. Abbona* H.E. Lundager Madsen and R. Boistelle
The initial phases of calcium and magnesium phosphate precipitated from solutions of high to medium concentrations.
Journal of crystal growth, vol. 74, pp. 581-590, 1986
The precipitation of calcium and magnesium phosphates was studied by mixing calcium/magnesium solutions with phosphate solutions. The initial phosphate concentration ranged from 0.01-0.5 M and calcium/magnesium were added so as [Ca]+[Mg] = [P]. At the low pH range (2.8-6.8) the first calcium phosphate to precipitate was brushite [CaHPO4* 2H2O] while at higher pH an amorphous calcium phosphate precipitated as the initial phase. From pure magnesium solutions struvite [MgNH4PO4* 6H2O] and newberyite [MgHPO4* 3H2O] were formed, and no amorphous phase detected.
*Dipartimento di Scienze della Terra, Uniuersita di Torino, Via San Massimo 24, l-10123 Torino. Italy
Abbona F.* Lundager Madsen H.E. and Boistelle R.
The final phases of calcium and magnesium phosphates precipitated from solutions of high to medium concentrations.
Journal of crystal growth, vol. 89, pp. 592-602, 1988
The formation of calcium and magnesium phosphates was studied in simple batch systems at 25°C and P concentrations: 0.050 £ [P] £ 0.500M. Initial precipitation was followed, in some cases, by phase transition due to formation of a more stable phase with time. A particular interest was given to these latter phases. Calcium phosphates precipitated were brushite (CaHPO4*2H2O) and monetite (CaHPO4). Newberyite (MgHPO4*3H2O) and struvite (MgNH4PO4*6H2O) were the magnesium phosphates found. A key observation of this study was that the phases precipitating first were not those most supersaturated, but those that nucleated faster.
*Dipartimento di Scienze della Terra, Uniuersita della Calabria, 87030 Castiglione Cosentino Stazione (CS), Italy
Abbona F.* and Franchini-Angela M.
Crystallization of calcium and magnesium phosphates from solutions of low concentration.
Journal of crystal growth, vol. 104, pp. 661-671, 1990
In this paper results are shown of a study into the influence of magnesium on the precipitation of calcium phosphates at low concentration of calcium and phosphates in solution. The first phase to precipitate is amorphous which can transform into a more stable calcium phosphate. The transformation of amorphous calcium phosphate (Ca3(PO4)2*nH2O, ACP) depends on the concentration of magnesium. At low concentrations of magnesium ACP will transform into more stable phases as octa calcium phosphate (Ca4H(PO4)3*2.5H2O) and hydroxylapatite (Ca3(PO4)3OH). At higher concentrations magnesium will inhibit this transformation and ACP will remain.
*Dipartimento di Scienze della Terra, Uniuersita della Calabria, 1-87036 Arcavacata di Rende (CS), Italy
Amjad Z. Koutsoukos P.G. Tomson M.B.* and Nancollas G.H.
The growth of hydroxyapatite from solution. A new constant composition method.
Journal of dental research, vol. 57, pp. 909, 1978
A short explanation of the advantages of using a constant composition method to study the hydroxylapatite growth.
*Department of chemistry, State University of New York at Buffalo, New York
Amjad Z.* Koutsoukos P.G. and Nancollas G.H.
The crystallisation of hydroxyapatite and flourapatite in the presence of magnesium ions.
Journal of colloid and interface science, vol. 101, no. 1, pp. 250-256, 1984
The influence of magnesium on the crystallisation of hydroxyapatite (HAP) and fluorapatite (FAP) was studied using the constant composition method at 37°C. The crystallisation rate of both phases decreases when magnesium is present. The decrease in rate is related to adsorption of magnesium to active sites of both HAP and FAP.
*Department of chemistry, State University of New York at Buffalo, Buffalo, New York, 14214
Barone J.P. Nancollas G.H.* and Tomson M.
The seeded growth of calcium phosphates, the kinetics of growth of dicalcium phosphate dihydrate on hydroxyapatite
Calcif. Tissue. Res., vol 21, pp. 171-182, 1976
The precipitation of dicalcium phosphate dihydrate (DCPD) onto hydroxylapatite (HAP) seeding crystals was studied at a temperature of 37°C and a pH of 4.5-5.0 (pH-stat method). The precipitation of DCPD was determined by the molar ratio of calcium and phosphate disappearing from the solution. The study suggests that crystallisation appears to be controlled by a surface reaction. It was found that nucleation of DCPD onto HAP follows the same kinetics as on DCPD seeds.
*Department of chemistry, State University of New York at Buffalo, Buffalo, New York, 14214
Barone J.P.*
and Nancollas G.H.
The seeded growth of calcium phosphates, the effect of solid/solution ratio controlling the nature of the growth phase
Journal of colloid and interface science, vol. 62, no. 3, pp. 421-431, 1977
The crystal growth of calcium phosphates is studied using a pH-stating method at pH 5.6 and 37°C, and with the use of HAP seeding crystals. The study found that competition between calcium phosphate phases to precipitate is determined by the degree of supersaturation and can be influenced by the concentration of inoculating seeds.
*Department of chemistry, State University of New York at Buffalo, Buffalo, New York, 14214
Adele Ludin Boskey* and Aaron S. Posner
CONVERSION OF AMORPHOUS CALCIUM PHOSPHATE TO MICROCRYSTALLINE HYDROXYAPATITE. A pH-DEPENDENT, SOLUTION-MEDIATED, SOLID-SOLID CONVERSION
A study of the rate of crystallisation of hydroxylapatite from amorphous calcium phosphate, as a function of pH and temperature. At pH 8, there is a sigmoidal function of percentage of crystalline material formed vs time. At constant temperature, the rate of conversion is a function only of the pH of solution.
* Hospital For Special
Surgery, Cornell Unrversity Medrcai College, New York.
Bennett A.C. and Adams F.
Solubility and solubility product of dicalcium phosphate dihydrate in aqueous solutions and soil solutions
Soil science of America journal, vol. 40, pp. 39-42, 1976
The solubility product of dicalcium phosphate dihydrate (CaHPO4*2H2O) was determined experimentally at different ionic strength. pKsp at zero ionic strength was extrapollated from the data and was found to be in the range of 6.56.Soil experiments point out that the presence of dicalcium phosphate dihydrate can be estimated using the ionic acitivity product and the solubility constant.
Borgerding J.
Phosphate deposits in digestion systems
Journal of the water pollution control federation, vol. 44, pp. 813-819, 1972
An investigation into crystalline buildup (struvite, MgNH4PO4*6H2O) in pipes of a wastewater treatment plant was carried out. The in-situ solubility of struvite was determined to be 3.9*10-10 which is much higher than the solubility determined in pure water (2.5*10-13). The causes given for the precipitation are high surface: volume ratio in pipes, roughness of the interior of the pipes, increase in energy by vibration of the sludge screens and a pressure decrease at bends causing CO2 release followed by a rise in pH.
Bohner M. Lemaitre J.* and Ring T.A.
Kinetics of dissolution of beta-tricalcium phosphate
Journal of colloid and interface science, vol. 190, no.1 pp. 37-48, 1997
In this article the rate of dissolution of beta-tricalcium phosphate (TCP) was studied. The dissolution rate was studied as a function of time and at different initial saturation, starting with a saturation of zero. It was concluded that at low saturation the dissolution is controlled by diffusion. At higher saturation the dissolution rate decreased faster than expected, which could be explained either by precipitation of hydroxylapatite on the beta-tricalciumphosphate surface, or by impurities in TCP.
* Powder Technology laboratory (LTP), Swiss Federal Institute of technology (EPFL), MX-ecublens, 1015 Lausanne, Switzerland
Boskey A.L.* and Posner A.S.
Conversion of amorphous calcium phosphate to microcrystalline hydroxyapatite. A pH dependent, solution-mediated, solid-solid conversion
The journal of physical chemistry, vol. 77, no. 19, pp. 2313-2317, 1973
The precipitation of hydroxylapatite (Ca5(PO4)3OH, HAP) is preceded by the precipitation of amorphous calcium phosphate (Ca3(PO4)*xH2O, ACP). This transformation was found to be only a function of pH at constant temperature.
*Hospital for Special Surgery, Cornell University Medical College, New York, New York 10021
Boskey A.L.* and Posner A.S.
Formation of hydroxyapatite at low supersaturation
Journal of physical chemistry, vol. 80, pp. 40-45, 1976
The homogenous nucleation of hydroxylapatite (Ca10(PO4)6(OH)2, HAP) was studied in low supersaturated solutions (degree of supersaturation between 105 to 109) with the pH-stat method. It is found that at these low supersaturated solutions HAP will form directly without being preceded by another calcium phosphate phase. The authors observed that after initial formation, the length of precipitated HAP crystals during the ripening process was a function of time.
*Hospital for Special Surgery, Cornell University Medical College, New York, New York 10021
Brown W.E.* Lehr J.R. Smith J.P. and Frazier A.W.
Crystallography of octacalcium phosphate
Journal of the american chemical society, vol. 79, pp.5318-5319, 1957
Comparison of the x-ray pattern of octa-calcium phosphate with hydroxylapatite. It is concluded that it is highly likely that the formation of hydroxylapatite in tooth and bone may have been preceded by octacalcium phosphate (OCP).
*Division of chemical development, Tennessee Valley Authority, Wilson Dam, Ala.
Brown J.L.*
Calcium phosphate precipitation effects of common and foreign ions on hydroxylapatite crystal growth.
Soil science society of America journal, vol. 45, no.3 pp. 482-486, 1981
In this paper an attempt is made to study the effects of calcium, fluoride, phosphorus, magnesium and carbonate ions together with the effects of hydroxylapatite (HAP) seeding material on calcium phosphates precipitation. The results show that by using a higher amount of seeding material the removal rate of phosphate from solution is higher. A decrease in apatite growth was observed when magnesium or carbonate was present.
* Institute for man and environment, state University of New York, Plattsburgh, NY 12901.
Brown W.E. and Chow L.C.*
Thermodynamics of apatite crystal growth and dissolution
Journal of crystal growth 53, pp. 31-41, 1981
This paper is a discussion of the thermodynamics of dissolution and crystal growth of apatite with emphasis on their relevance to biological processes. It is assumed that dissolution and crystal growth is diffusion controlled in unstirred systems because of the formation of a saturated layer of solution around the surface of the apatite crystals. The authors studied crystal growth in the simple unstirred system (Ca(OH)2-H3PO4-H2O). The effect of other components such as weak acids and a strong electrolyte were investigated.
* American Dental Association Health Foundation research Unit, National bureau of standards, Washington, DC20234, USA.
Budz J.A. and Nancollas G.H.
The mechanism of dissolution of hydroxyapatite and carbonated apatite in acidic solutions.
Journal of crystal growth, vol. 91, pp. 490-496, 1988
Carbonated apatite (CAP) and hydroxylapatite (HAP) were dissolved under constant undersaturation to study the mechanisms of dissolution. Despite the constant undersaturation a decrease in dissolution rates of HAP and CAP was observed. This conforms with a polynuclear mechanism of dissolution.
Chemistry department, State University of New York at Buffalo, Buffalo, New York 14214, USA.
Carliell C.M. and Wheatley A.D.
Metal and phosphate speciation during anaerobic digestion of phosphorus rich sludge.
Water Science and Technology, vol. 36, no.6-7, pp.191-200, 1997
In this paper the results of a study into the speciation of metals and phosphorus during chemical (CPR) or biological P-removal (BPR) are presented. The results showed that phosphorus during CPR is retained as inorganic P in the sludge. During BPR the amount of soluble phosphorus increases. The behaviour of some metals may vary depending on the P-removal method. For example nickel and chromium are more strongly bound to the BPR than CPR sludge.
Water Research Group, Department of Civil and Building Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK.
Carlsson* H. Aspegren H. Lee N. and Hilmer A.
Calcium phosphate precipitation in biological phosphorus removal systems.
Water Research, vol. 31, no. 5, pp. 1047-1055, 1997
The contribution of chemical precipitation in excess biological phosphorus removal (EBPR) process was studied. The results showed that at neutral pH calcium phosphate precipitation takes place when calcium and phosphate concentrations are at least 50 mg/l P and 100 mg/l Ca. Redissolution of the precipitate takes place far above the 1 mg/l limit, making this removal mechanism inefficient.
*Department of water and Environmental engineering, PO Box 118, S-22100, Lund, Sweden.
Choi* E. Oa S.-W. and Lee J.-J.
NIGHTSOIL TREATMENT PLANT CONVERTED INTO A SEQUENCING BATCH REACTOR TO IMPROVE REMOVAL OF POLLUTANTS AND NUTRIENTS
Wat. Sci. Tech. Vol. 35. No. I, pp 233-240, 1997
The paper describes the conversion of an existing two stage aerobic nightsoil treatment plant to a single stage SBR unit with improved nutrient removal. The efficiency of the unit is influenced by pH changes due to nitrification/denitrification. At high pH chemical precipitation of struvite and hydroxyapatite occurs. These phases dissolve at low pH, caused by nitrification under aerobic conditions. P removal occurs 42 % chemically and 36 % biologically.
* Department of Civil
and Environmental Engineering, Korea University, 1 Anamdong,
Seoul 136-701, Korea
Christoffersen J. *
Kinetics of dissolution
of calcium hydroxyapatite.3.Nucleation-controlled dissolution of
a polydisperse
sample of crystals
Journal of crystal growth, vol. 49, pp. 29-44, 1980
In this paper the results
of a study into the dissolution of micro-crystals (particles smaller
than 500nm) are discussed. The
dissolution process can be explained by a polynuclear model. In
this model nuclei (equivalent to small holes when
discribing a dissolution mechanism) spread over the HAP surface
and dissolve the crystals. The dissolution rate is
determined by this surface process.
*Medicinsk-Kemisk Institute, Kobenhavns Universiteit, Raadmansgade 781, DK 2200 N Copenhagen, Denmark.
Christoffersen J.* and Christoffersen M.R.
Kinetics of dissolution of calcium hydroxyapatite.2. Dissolution in non-stoichiometric solution at constant pH
Journal of crystal growth,
Vol. 47, pp. 671-679, 1979
The effect of non-stoichiometric initial aqueous concentrations of calcium and phosphate (initial calcium phosphate ratios were lower as well as higher than the stoichiometric ratio of 1.67) on the dissolution of hydroxylapatite (HAP) was assessed at constant pH in a rotating disc experiment and in a suspension. The dissolution in non-stoichiometric solutions depends upon the calcium as well as the phosphate concentration. Previous suggestions of a two-site dissolution model were shown to be an artifact of the mathematical curve fitting.
*Medicinsk-Kemisk Institute, Kobenhavns Universiteit, Raadmansgade 781, DK 2200 N Copenhagen, Denmark.
Christoffersen J.* and Christoffersen M.R.
Kinetics of dissolution of calcium hydroxyapatite
Faraday discussions, no. 77, pp. 235-242, 1984
In this paper the dissolution
process of hydroxylapatite (Ca10(PO4)6(OH)2)
is described as a surface-controlled reaction.
The rate of the reaction can be assessed using a polynuclear model
described previously (Christoffersen, 1980).
The inhibition of the dissolution process by foreign ions can be
described by a Langmuir isotherm.
*Department of Chemistry, Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark.
Christoffersen J.* and Christoffersen M.R.
Possible mechanisms for the growth of the biomaterial, calcium hydroxyapatite microcrystals
Journal of crystal growth, vol. 121, no. 4, pp. 617-630, 1992
The mechanism by which crystal
growth of hydroxylapatite proceeds was studied. It was concluded
that the growth rate
depends on a surface controlled instead of a transport-controlled
mechanism. Furthermore the rate of growth can be
described by using a spiral or a polynuclear mechanism. Crystal
surface imperfections were found to influence the results.
The authors conclude that it is not possible to distinguish which
of the two mechanisms (spiral or polynuclear) is the one
controlling the dissolution rate.
*Department of Chemistry, Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark.
Christoffersen M.R.* Christoffersen J. and Kibalczyc W.
APPARENT SOLUBILITIES OF TWO AMORPHOUS CALCIUM PHOSPHATES AND OF OCTACALCIUM PHOSPHATE IN THE TEMPERATURE RANGE 30-42" C
Journal of Crystal Growth, vol. 106, pp. 349-354, 1990
The paper investigates the precipitation of calcium phosphate and its transformation into hydroxyapatite, via two stages of formation of an amorphous phase and then OCP.
*Medicinsk-Kemisk Instirut, Panum InMute, University of Copenhagen, Blegdamwej 3, 2200 Copenhagen N, Denmark
Christoffersen J. Christoffersen M.R. and Kjaergaard N.
The kinetics of dissolution of calcium hydroxyapatite in water at constant pH.
Journal of crystal growth 43, pp. 501-511, 1978
The dissolution-rate of synthetic hydroxylapatite was measured in pure water at a temperature of 25C at a constant pH in the range 6.6-7.2, using the pH stat method. On the basis of the results it was suggested that dissolution rate depends on a surface controlled process.
Medicinsk-Kemisk Institute, Kobenhavns Universiteit, Raadmansgade 781, DK 2200 N Copenhagen, Denmark.
Christoffersen M.R. Dohrup J. and Christoffersen J.
Kinetics of growth and
dissolution of calcium hydroxyapatite in suspensions with variable
calcium to
phosphate ratio
Journal of crystal growth, vol. 186, pp. 283-290, 1998
The kinetics of dissolution
and crystal growth of hydroxyapatite were studied at variable Ca/P
ratios (0.1-20) and
explained as being controlled by a polynuclear surface mechanism.The
dissolution rate depends upon the degree of
undersaturation with respect to calcium ([Ca]s
– [Ca]).
The growth rate is explained by two steps, namely calcium ions entering
their crystallographic sites followed by phosphate
ions, which are delayed by a slow production of hydroxyl ions (by
water dissociation) at the surface.
Department of Medical Biochemistry and Genetics, Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
Clark J.S.
Solubility criteria for the existence of hydroxyapatite
Canadian journal of chemistry, Vol. 33, pp. 1696-1700, 1955
The solubility of a synthetic
hydroxylapatite was determined through precipitation and dissolution
experiments in a pH-drift,
carbon dioxide free environment. The solubility constant found was
between 114.24 and 116.56. Stable conditions were
established after 24 hr.
Chemistry division, Science Service, Department of Agriculture, Ottawa, Canada.
Clark* T. Stephenson T. and Pearce P.A.
PHOSPHORUS REMOVAL BY CHEMICAL PRECIPITATION IN A BIOLOGICAL AERATED FILTER
Wat. Res., Vol. 31, No 10, pp. 2557-2563, 1997
High levels of phosphorus in aquatic systems have been associated with eutrophication. Phosphorus removal from sewage feed is tested in two pilot-scale columns, an aerated filter packed with seeded expanded shale and an anoxic filter packed with plastic media. Ferrous iron is used for to induce precipitation of phosphate, and was dosed onto the top of the aerated filter at varying ratios of total phosphorus to iron. To meet EC requirements, the most favourable chemical dosing ratio was I: 1.25 (weight ratio P:Fe).
*School of Water Sciences,
Cranfield University, Cranfield, Bedford, MK43 OAL, U.K
Cohen L.H.* and Ribbe P.H.
Magnesium phosphate mineral replacement at mono lake, California
American Mineralogist, vol. 51, 1755-65, 1966
A possible mechanism for the
replacement of struvite (MgNH4PO4*6H2O)
with newberyite (MgHPO4*3H2O)
is discussed.
The paper suggests that newberyite has formed by the decomposition
of struvite in lake sediments, and provides
crystallographic parameters and chemical data for newberyite.
* Department of Geological Sciences, University of California, Riverside California.
Cole C.V. Sterling R. Olsen and Scott C.O.
The nature of phosphate sorption by calcium carbonate
Soil Society of America Proceedings, vol. 17, pp. 352-356, 1953
Phosphate sorption by calcium
carbonate was investigated in batch experiments. At low phosphate
concentrations it was
found that phosphate adsorbes to calcite particles, while at higher
phosphate levels a calcium phosphate precipitated as
dicalcium phosphate (CaHPO4).
Division of Soil and plant relationships B.P.I.S.A.E., U.S. Dept. of Agriculture, Fort Collins, Colo.
Dalas E. and Koutsoukos P.G.*
Crystallisation of hydroxyapatite from aqueous solutions in the presence of cadmium
Journal of the Chemical Society, FaradayTransactions 1, vol 85, pp. 3159-3164, 1989
The influence of cadmium on
the crystallisation of hydroxylapatite (HAP, Ca5(PO4)3OH)
was studied in HAP seeded
experiments at pH 7.4 and 25C using the constant composition method.
It was found that cadmium causes a reduction in
the crystallisation rate. This reduction is a function of the concentration
of cadmium. No cadmium was found incorporated
into the HAP structure. The experimental observations, however,
cannot be fully explained by a simple adsorption
mechanism.
*Department of Chemistry, Physical Chemistry Laboratory and the Research Institute of Chemical Engineering and Chemical Processes at HighTemperatures, P.O. box 1239, University Campus, GR-26110, Patras, Greece.
Danen-Louwerse* H.J. Lijklema L. and Coenraats M.
Coprecipitation of phosphate with calcium carbonate in lake Veluwe
Water Research, vol. 29, pp. 1781-1785, 1995
The co-precipitation of phosphate
with calcite was studied under lab-conditions to model precipitation
of phosphate in lakes.
It was found that co-precipitation only takes place at P concentrations
lower than 0.3 mg/l, a pH higher than 8.5 and the
presence of calcite crystals.
*Agricultural University, Department of Water Quality Management and Aquatic Ecology, P.O. Box 8080, 6700 DD Wageningen, The Netherlands.
T. P. Feenstra* and P. L. de Bruyn
FORMATION OF CALCIUM PHOSPHATES IN MODERATELY SUPERSATURATED SOLUTIONS
The Journal of Physical Chemistry, Vol. 83, No. 4, 1979 475
Calcium phosphate precipitation was achieved under conditions of controlled supersaturation. OCP is the intermediate phase in the apatite formation via heterogeneous nucleation.
* Vanít Hoff Laboratory, Transitorium 3, Padualaan 8. Utrecht, The Netherlands
J.F. Ferguson*, D. Jenkins and J. Eastman
CALCIUM PHOSPHATE PRECIPITATION AT SLIGHTLY ALKALINE pH VALUES
Journal WPCF, p. 620
A low pH calcium phosphate precipitation method is proposed for the removal of P from wastewater. The method is investigated in batch- and continuous-flow reactors, and the effects of variables, such as the concentration of bicarbonate, magnesium, calcium, H+, and residence time are evaluated. The authors propose that the cost of the method is substantially less than that of alternative precipitation techniques using lime, alum or iron salts.
*
J.-C. Heughebaert*, J.F. De Rooij and G.H. Nancollas
THE GROWTH OF DICALCIUM PHOSPHATE DIHYDRATE ON OCTACALCIUM PHOSPHATE AT 25°C
Journal of Crystal Growth, Vol. 77, pp. 192-198, 1986
This paper investigates the crystallisation of calcium phosphates as a function of supersaturation. OCP is used as a seeding material and the experiments are carried out at 25°C and pH 6. At low supersaturation (s<1.02) the phase growing on the seeds is also OCP, whereas at higher supersaturation DCPD is precipitating instead.
*Laboratoire de Physico-Chimie des Solides, , Institut National Polytechnique de Toulouse, 38 Rue des 36 Ponts, F-31400, Toulouse, France.
I. Hirasawa* and Y. Toya
FLUIDIZED-BED PROCESS FOR PHOSPHATE REMOVAL BY CALCIUM PHOSPHATE CRYSTALLIZATION
ACS Symposium Series, Vol.438, pp.355-363, 1990
The paper describes a fluidized bed process for the removal of 2-23 mg/l of P from 1-4 m3/day of waste water. Supersaturation, recirculation ratio and space velocity were identified as the key factors controlling crystallisation rate of phosphate and thus removal efficiency.
* Ebara Research Company, Ltd., 4-2-l Honfujisawa Fujisawa, Kanagawa 251, Japan
M.J.J.M. Van Kemenade* and P.L. de Bruyn
A KINETIC STUDY OF PRECIPITATION FROM SUPERSATURATED CALCIUM PHOSPHATE SOLUTIONS
J. of Colloid and Interface Sci., vol. 118, pp.564-585, 1987
A study of calcium phosphate (DCPD, OCP, HAP, amorphous) formation as a function of pH and supersaturation. Homogeneous crystallisation of HAP is not observed; instead HAP is always preceded by one of the other phases acting as a precursor. The extent of heterogeneous nucleation of HAP on OCP surfaces increases as a function of supersaturation.
* Van Hoff Laboratory, Transitorium 3, Padualaan 8, 3584 CH Utrecht, The Netherlands
W. Kibalczyc*, J. Christoffersen, M.R. Christoffersen, A. Zielenkiewicz and W. Zielenkiewicz
THE EFFECT OF MAGNESIUM IONS ON THE PRECIPITATION OF CALCIUM PHOSPHATES
Journal of Crystal Growth 106, 355-366, 1990
The presence of magnesium
ions in solution were found to inhibit the formation of amorphous
calcium phosphate and the growth of OCP, although no incorporation
of the Mg ion in the calcium phosphate lattice was observed.
*Institute of Physics, Technical University of Lodz, Wolczanska 219, 93-005 Lodz, Poland
Y. Liang*, D.R. Baer, J.M., McCoy, J.E. Amonette, and J.P. LaFemina
DISSOLUTION KINETICS AT THE CALCITE-WATER INTERFACE
Geochimica et Cosmochimica Acta, vol. 60, pp. 4883-4887, 1996
The dissolution kinetics of calcite (1014) surface is investigated using Atomic Force Microscopy, a terrace-edge-kink model and kinetic Monte Carlo simulations. The paper assesses elementary rates and activation energies for dissolution at specific kink sites on the calcite surface.
* Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 993 52, USA
D. Marant*, A.C. Di Pinto, R. Ramadori and M.C. Tomei
PHOSPHATE REMOVAL FROM MUNICIPAL WASTEWATER WITH LOW LIME DOSAGE
Environmental Technology, vol. 18, pp. 225-230, 1997
The paper discusses the potential of liming as a pre-treatment of municipal wastewater, prior to biological processing. A model was calibrated with results from lime addition tests to sewage. The model assumes phosphate and carbonate solubility controlled by a metastable phosphate [Ca4H(PO4)3] and amorphous calcium carbonate respectively. It is predicted that lime addition up to pH 9 can cause efficient P removal and prevent carbonate precipitation even at high pH.
* Water Research Institute, Via Reno 1, 00198 Rome, Italy
J.L McCoy, L.J. Sikora, and R.R. Weil*
PLANT AVAILABILITY OF PHOSPHORUS IN SEWAGE SLUDGE COMPOST
Jour. Environ. Qual., 15:404-409, 1986
Aerobically digested sewage sludge clarified with ferric chloride steel Industry by-products was composted to produce a stable product in which contained 12 to 14% total P, of which 52% to 84% was dithinonite citrate bicarbonate extractable (that is associated with iron). This material not an effective P fertilizer for maize in a P-deficient soil, even when rates of total P applied exceeded 1000 kg/ha.
* University of Maryland, College Park, MD 20742, USA
F.S. Payer and R.R. Weil*
PHOSPHORUS RENOVATION OF WASTEWATER BY OVERLAND FLOW LAND APPLICATION
J. Environ, Qual., 16:391-397, 1987
An overland flow waste water renovation system removed an average of 66% of the total P in the incoming wastewater. Most of the removed P was in the suspended form. Uptake of P by reed canary grass grown on the site accounted for some 17 kg/ha of P removed.
* University of Maryland, College Park, MD 20742, USA
M.H. Salimi *, J.C. Heughebaert and G.H. Nancollas
CRYSTAL GROWTH OF CALCIUM PHOSPHATES IN THE PRESENCE OF MAGNESIUM IONS
Langmuir, Vol.1, No.1, pp.119-122, 1985
Magnesium ions retard the rate of octacalcium phosphate growth, but have no detectable effect on the growth of dicalcium phosphate dihydrate, at constant supersaturation. The crystallisation of the thermodynamically more stable hydroxyapatite is even more strongly inhibited.
* Chemistry Department, State University of New York at Buffalo, Buffalo, New York 14214, USA
Van Dijk* J. C. and H. Braakensiek
PHOSPHATE REMOVAL BY CRYSTALLIZATION IN A FLUIDIZED BED
Wat. Sci. Tech., Vol. 17, Amsterdam, 133-142, 1984
Phosphate removal from sewage
treatment plant is achieved via the crystallisation of calcium phosphate
in a fluidised bed
reactor. The process produces pellets that have the potential to
be reused. Plans for building the first demonstration plant
are in place; costings are discussed.
* DHV Consulting Engineers, P.O. Box 85, 3800 AB Amersfoort, The Netherlands
A.G. Walton* W.J. Bodin H. Furedi and A. Schwartz
NUCLEATION OF CALCIUM PHOSPHATE FROM SOLUTION
Canadian Journal of Chemistry, Vol. 45, p. 2695, 1967
The paper describes a method of determining the stoichiometry of metastable phases from their nucleation characteristics. The method is applied to the precipitation of calcium phosphate at pH 7.0-9.1 and [Ca]/[P] ratio of 1.49. The precipitate is an amorphous metastable material rather than the expected hydroxyapatite.
* Dept. of Chemistry, Case Institute of Technology, Cleveland, Ohio, USA
D. Zhao* and A. K. Sengupta
SELECTIVE REMOVAL AND RECOVERY OF PHOSPHATE IN A NOVEL FIXED-BED PROCESS
Wat. Sci. Tech., Vol. 33, No. 10-11, pp. 139-147, 1996
This study shows that a polymeric ligand exchanger (PLE) can selectively remove phosphate from wastewater. Phosphate may be recovered and the PLE can be reused.
* Dept. of Civil & Environmental Engineering, 13 E. Packer Avenue, Lehigh University, Bethlehem, PA 18015, USA
D. Zhao* and A. K. Sengupta
ULTIMATE REMOVAL OF PHOSPHATE FROM WASTEWATER USING A NEW CLASS OF POLYMERIC ION EXCHANGERS
Wat. Res., Vol. 32, No. 5, pp. 1613-1625, 1998
A new class of sorbents, referred to as polymeric ligand exchangers (PLE) are shown to selectively remove phosphorus in laboratory studies. The method is based on anion exchange accompanied by Lewis acid-base interaction. PLEs are amenable to regeneration.
* Dept. of Civil & Environmental Engineering, 13 E. Packer Avenue, Lehigh University, Bethlehem, PA 18015, USA
ARTICLES ON PHOSPHATE RECYCLING
The list below contains papers published in peer-reviewed journals, with a short summary of their conent.The list is alphabetical by first author.
Please
submit your abstracted papers for the list
A,
B,
F, S, Z
F. Abbona* H.E. Lundager Madsen and R. Boistelle
The initial phases of calcium and magnesium phosphate precipitated from solutions of high to medium concentrations.
Journal of crystal growth, vol. 74, pp. 581-590, 1986
The precipitation of calcium and magnesium phosphates was studied by mixing calcium/magnesium solutions with phosphate solutions. The initial phosphate concentration ranged from 0.01-0.5 M and calcium/magnesium were added so as [Ca]+[Mg] = [P]. At the low pH range (2.8-6.8) the first calcium phosphate to precipitate was brushite [CaHPO4* 2H2O] while at higher pH an amorphous calcium phosphate precipitated as the initial phase. From pure magnesium solutions struvite [MgNH4PO4* 6H2O] and newberyite [MgHPO4* 3H2O] were formed, and no amorphous phase detected.
*Dipartimento di Scienze della Terra, Uniuersita di Torino, Via San Massimo 24, l-10123 Torino. Italy
Abbona F.* Lundager Madsen H.E. and Boistelle R.
The final phases of calcium and magnesium phosphates precipitated from solutions of high to medium concentrations.
Journal of crystal growth, vol. 89, pp. 592-602, 1988
The formation of calcium and magnesium phosphates was studied in simple batch systems at 25°C and P concentrations: 0.050 £ [P] £ 0.500M. Initial precipitation was followed, in some cases, by phase transition due to formation of a more stable phase with time. A particular interest was given to these latter phases. Calcium phosphates precipitated were brushite (CaHPO4*2H2O) and monetite (CaHPO4). Newberyite (MgHPO4*3H2O) and struvite (MgNH4PO4*6H2O) were the magnesium phosphates found. A key observation of this study was that the phases precipitating first were not those most supersaturated, but those that nucleated faster.
*Dipartimento di Scienze della Terra, Uniuersita della Calabria, 87030 Castiglione Cosentino Stazione (CS), Italy
Abbona F.* and Franchini-Angela M.
Crystallization of calcium and magnesium phosphates from solutions of low concentration.
Journal of crystal growth, vol. 104, pp. 661-671, 1990
In this paper results are shown of a study into the influence of magnesium on the precipitation of calcium phosphates at low concentration of calcium and phosphates in solution. The first phase to precipitate is amorphous which can transform into a more stable calcium phosphate. The transformation of amorphous calcium phosphate (Ca3(PO4)2*nH2O, ACP) depends on the concentration of magnesium. At low concentrations of magnesium ACP will transform into more stable phases as octa calcium phosphate (Ca4H(PO4)3*2.5H2O) and hydroxylapatite (Ca3(PO4)3OH). At higher concentrations magnesium will inhibit this transformation and ACP will remain.
*Dipartimento di Scienze della Terra, Uniuersita della Calabria, 1-87036 Arcavacata di Rende (CS), Italy
Amjad Z. Koutsoukos P.G. Tomson M.B.* and Nancollas G.H.
The growth of hydroxyapatite from solution. A new constant composition method.
Journal of dental research, vol. 57, pp. 909, 1978
A short explanation of the advantages of using a constant composition method to study the hydroxylapatite growth.
*Department of chemistry, State University of New York at Buffalo, New York
Amjad Z.* Koutsoukos P.G. and Nancollas G.H.
The crystallisation of hydroxyapatite and flourapatite in the presence of magnesium ions.
Journal of colloid and interface science, vol. 101, no. 1, pp. 250-256, 1984
The influence of magnesium on the crystallisation of hydroxyapatite (HAP) and fluorapatite (FAP) was studied using the constant composition method at 37°C. The crystallisation rate of both phases decreases when magnesium is present. The decrease in rate is related to adsorption of magnesium to active sites of both HAP and FAP.
*Department of chemistry, State University of New York at Buffalo, Buffalo, New York, 14214
Barone J.P. Nancollas G.H.* and Tomson M.
The seeded growth of calcium phosphates, the kinetics of growth of dicalcium phosphate dihydrate on hydroxyapatite
Calcif. Tissue. Res., vol 21, pp. 171-182, 1976
The precipitation of dicalcium phosphate dihydrate (DCPD) onto hydroxylapatite (HAP) seeding crystals was studied at a temperature of 37°C and a pH of 4.5-5.0 (pH-stat method). The precipitation of DCPD was determined by the molar ratio of calcium and phosphate disappearing from the solution. The study suggests that crystallisation appears to be controlled by a surface reaction. It was found that nucleation of DCPD onto HAP follows the same kinetics as on DCPD seeds.
*Department of chemistry, State University of New York at Buffalo, Buffalo, New York, 14214
Barone J.P.*
and Nancollas G.H.
The seeded growth of calcium phosphates, the effect of solid/solution ratio controlling the nature of the growth phase
Journal of colloid and interface science, vol. 62, no. 3, pp. 421-431, 1977
The crystal growth of calcium phosphates is studied using a pH-stating method at pH 5.6 and 37°C, and with the use of HAP seeding crystals. The study found that competition between calcium phosphate phases to precipitate is determined by the degree of supersaturation and can be influenced by the concentration of inoculating seeds.
*Department of chemistry, State University of New York at Buffalo, Buffalo, New York, 14214
Adele Ludin Boskey* and Aaron S. Posner
CONVERSION OF AMORPHOUS CALCIUM PHOSPHATE TO MICROCRYSTALLINE HYDROXYAPATITE. A pH-DEPENDENT, SOLUTION-MEDIATED, SOLID-SOLID CONVERSION
A study of the rate of crystallisation of hydroxylapatite from amorphous calcium phosphate, as a function of pH and temperature. At pH 8, there is a sigmoidal function of percentage of crystalline material formed vs time. At constant temperature, the rate of conversion is a function only of the pH of solution.
* Hospital For Special
Surgery, Cornell Unrversity Medrcai College, New York.
Bennett A.C. and Adams F.
Solubility and solubility product of dicalcium phosphate dihydrate in aqueous solutions and soil solutions
Soil science of America journal, vol. 40, pp. 39-42, 1976
The solubility product of dicalcium phosphate dihydrate (CaHPO4*2H2O) was determined experimentally at different ionic strength. pKsp at zero ionic strength was extrapollated from the data and was found to be in the range of 6.56.Soil experiments point out that the presence of dicalcium phosphate dihydrate can be estimated using the ionic acitivity product and the solubility constant.
Borgerding J.
Phosphate deposits in digestion systems
Journal of the water pollution control federation, vol. 44, pp. 813-819, 1972
An investigation into crystalline buildup (struvite, MgNH4PO4*6H2O) in pipes of a wastewater treatment plant was carried out. The in-situ solubility of struvite was determined to be 3.9*10-10 which is much higher than the solubility determined in pure water (2.5*10-13). The causes given for the precipitation are high surface: volume ratio in pipes, roughness of the interior of the pipes, increase in energy by vibration of the sludge screens and a pressure decrease at bends causing CO2 release followed by a rise in pH.
Bohner M. Lemaitre J.* and Ring T.A.
Kinetics of dissolution of beta-tricalcium phosphate
Journal of colloid and interface science, vol. 190, no.1 pp. 37-48, 1997
In this article the rate of dissolution of beta-tricalcium phosphate (TCP) was studied. The dissolution rate was studied as a function of time and at different initial saturation, starting with a saturation of zero. It was concluded that at low saturation the dissolution is controlled by diffusion. At higher saturation the dissolution rate decreased faster than expected, which could be explained either by precipitation of hydroxylapatite on the beta-tricalciumphosphate surface, or by impurities in TCP.
* Powder Technology laboratory (LTP), Swiss Federal Institute of technology (EPFL), MX-ecublens, 1015 Lausanne, Switzerland
Boskey A.L.* and Posner A.S.
Conversion of amorphous calcium phosphate to microcrystalline hydroxyapatite. A pH dependent, solution-mediated, solid-solid conversion
The journal of physical chemistry, vol. 77, no. 19, pp. 2313-2317, 1973
The precipitation of hydroxylapatite (Ca5(PO4)3OH, HAP) is preceded by the precipitation of amorphous calcium phosphate (Ca3(PO4)*xH2O, ACP). This transformation was found to be only a function of pH at constant temperature.
*Hospital for Special Surgery, Cornell University Medical College, New York, New York 10021
Boskey A.L.* and Posner A.S.
Formation of hydroxyapatite at low supersaturation
Journal of physical chemistry, vol. 80, pp. 40-45, 1976
The homogenous nucleation of hydroxylapatite (Ca10(PO4)6(OH)2, HAP) was studied in low supersaturated solutions (degree of supersaturation between 105 to 109) with the pH-stat method. It is found that at these low supersaturated solutions HAP will form directly without being preceded by another calcium phosphate phase. The authors observed that after initial formation, the length of precipitated HAP crystals during the ripening process was a function of time.
*Hospital for Special Surgery, Cornell University Medical College, New York, New York 10021
Brown W.E.* Lehr J.R. Smith J.P. and Frazier A.W.
Crystallography of octacalcium phosphate
Journal of the american chemical society, vol. 79, pp.5318-5319, 1957
Comparison of the x-ray pattern of octa-calcium phosphate with hydroxylapatite. It is concluded that it is highly likely that the formation of hydroxylapatite in tooth and bone may have been preceded by octacalcium phosphate (OCP).
*Division of chemical development, Tennessee Valley Authority, Wilson Dam, Ala.
Brown J.L.*
Calcium phosphate precipitation effects of common and foreign ions on hydroxylapatite crystal growth.
Soil science society of America journal, vol. 45, no.3 pp. 482-486, 1981
In this paper an attempt is made to study the effects of calcium, fluoride, phosphorus, magnesium and carbonate ions together with the effects of hydroxylapatite (HAP) seeding material on calcium phosphates precipitation. The results show that by using a higher amount of seeding material the removal rate of phosphate from solution is higher. A decrease in apatite growth was observed when magnesium or carbonate was present.
* Institute for man and environment, state University of New York, Plattsburgh, NY 12901.
Brown W.E. and Chow L.C.*
Thermodynamics of apatite crystal growth and dissolution
Journal of crystal growth 53, pp. 31-41, 1981
This paper is a discussion of the thermodynamics of dissolution and crystal growth of apatite with emphasis on their relevance to biological processes. It is assumed that dissolution and crystal growth is diffusion controlled in unstirred systems because of the formation of a saturated layer of solution around the surface of the apatite crystals. The authors studied crystal growth in the simple unstirred system (Ca(OH)2-H3PO4-H2O). The effect of other components such as weak acids and a strong electrolyte were investigated.
* American Dental Association Health Foundation research Unit, National bureau of standards, Washington, DC20234, USA.
Budz J.A. and Nancollas G.H.
The mechanism of dissolution of hydroxyapatite and carbonated apatite in acidic solutions.
Journal of crystal growth, vol. 91, pp. 490-496, 1988
Carbonated apatite (CAP) and hydroxylapatite (HAP) were dissolved under constant undersaturation to study the mechanisms of dissolution. Despite the constant undersaturation a decrease in dissolution rates of HAP and CAP was observed. This conforms with a polynuclear mechanism of dissolution.
Chemistry department, State University of New York at Buffalo, Buffalo, New York 14214, USA.
Carliell C.M. and Wheatley A.D.
Metal and phosphate speciation during anaerobic digestion of phosphorus rich sludge.
Water Science and Technology, vol. 36, no.6-7, pp.191-200, 1997
In this paper the results of a study into the speciation of metals and phosphorus during chemical (CPR) or biological P-removal (BPR) are presented. The results showed that phosphorus during CPR is retained as inorganic P in the sludge. During BPR the amount of soluble phosphorus increases. The behaviour of some metals may vary depending on the P-removal method. For example nickel and chromium are more strongly bound to the BPR than CPR sludge.
Water Research Group, Department of Civil and Building Engineering, Loughborough University, Loughborough, Leicestershire, LE11 3TU, UK.
Carlsson* H. Aspegren H. Lee N. and Hilmer A.
Calcium phosphate precipitation in biological phosphorus removal systems.
Water Research, vol. 31, no. 5, pp. 1047-1055, 1997
The contribution of chemical precipitation in excess biological phosphorus removal (EBPR) process was studied. The results showed that at neutral pH calcium phosphate precipitation takes place when calcium and phosphate concentrations are at least 50 mg/l P and 100 mg/l Ca. Redissolution of the precipitate takes place far above the 1 mg/l limit, making this removal mechanism inefficient.
*Department of water and Environmental engineering, PO Box 118, S-22100, Lund, Sweden.
Choi* E. Oa S.-W. and Lee J.-J.
NIGHTSOIL TREATMENT PLANT CONVERTED INTO A SEQUENCING BATCH REACTOR TO IMPROVE REMOVAL OF POLLUTANTS AND NUTRIENTS
Wat. Sci. Tech. Vol. 35. No. I, pp 233-240, 1997
The paper describes the conversion of an existing two stage aerobic nightsoil treatment plant to a single stage SBR unit with improved nutrient removal. The efficiency of the unit is influenced by pH changes due to nitrification/denitrification. At high pH chemical precipitation of struvite and hydroxyapatite occurs. These phases dissolve at low pH, caused by nitrification under aerobic conditions. P removal occurs 42 % chemically and 36 % biologically.
* Department of Civil
and Environmental Engineering, Korea University, 1 Anamdong,
Seoul 136-701, Korea
Christoffersen J. *
Kinetics of dissolution
of calcium hydroxyapatite.3.Nucleation-controlled dissolution of
a polydisperse
sample of crystals
Journal of crystal growth, vol. 49, pp. 29-44, 1980
In this paper the results
of a study into the dissolution of micro-crystals (particles smaller
than 500nm) are discussed. The
dissolution process can be explained by a polynuclear model. In
this model nuclei (equivalent to small holes when
discribing a dissolution mechanism) spread over the HAP surface
and dissolve the crystals. The dissolution rate is
determined by this surface process.
*Medicinsk-Kemisk Institute, Kobenhavns Universiteit, Raadmansgade 781, DK 2200 N Copenhagen, Denmark.
Christoffersen J.* and Christoffersen M.R.
Kinetics of dissolution of calcium hydroxyapatite.2. Dissolution in non-stoichiometric solution at constant pH
Journal of crystal growth,
Vol. 47, pp. 671-679, 1979
The effect of non-stoichiometric initial aqueous concentrations of calcium and phosphate (initial calcium phosphate ratios were lower as well as higher than the stoichiometric ratio of 1.67) on the dissolution of hydroxylapatite (HAP) was assessed at constant pH in a rotating disc experiment and in a suspension. The dissolution in non-stoichiometric solutions depends upon the calcium as well as the phosphate concentration. Previous suggestions of a two-site dissolution model were shown to be an artifact of the mathematical curve fitting.
*Medicinsk-Kemisk Institute, Kobenhavns Universiteit, Raadmansgade 781, DK 2200 N Copenhagen, Denmark.
Christoffersen J.* and Christoffersen M.R.
Kinetics of dissolution of calcium hydroxyapatite
Faraday discussions, no. 77, pp. 235-242, 1984
In this paper the dissolution
process of hydroxylapatite (Ca10(PO4)6(OH)2)
is described as a surface-controlled reaction.
The rate of the reaction can be assessed using a polynuclear model
described previously (Christoffersen, 1980).
The inhibition of the dissolution process by foreign ions can be
described by a Langmuir isotherm.
*Department of Chemistry, Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark.
Christoffersen J.* and Christoffersen M.R.
Possible mechanisms for the growth of the biomaterial, calcium hydroxyapatite microcrystals
Journal of crystal growth, vol. 121, no. 4, pp. 617-630, 1992
The mechanism by which crystal
growth of hydroxylapatite proceeds was studied. It was concluded
that the growth rate
depends on a surface controlled instead of a transport-controlled
mechanism. Furthermore the rate of growth can be
described by using a spiral or a polynuclear mechanism. Crystal
surface imperfections were found to influence the results.
The authors conclude that it is not possible to distinguish which
of the two mechanisms (spiral or polynuclear) is the one
controlling the dissolution rate.
*Department of Chemistry, Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark.
Christoffersen M.R.* Christoffersen J. and Kibalczyc W.
APPARENT SOLUBILITIES OF TWO AMORPHOUS CALCIUM PHOSPHATES AND OF OCTACALCIUM PHOSPHATE IN THE TEMPERATURE RANGE 30-42" C
Journal of Crystal Growth, vol. 106, pp. 349-354, 1990
The paper investigates the precipitation of calcium phosphate and its transformation into hydroxyapatite, via two stages of formation of an amorphous phase and then OCP.
*Medicinsk-Kemisk Instirut, Panum InMute, University of Copenhagen, Blegdamwej 3, 2200 Copenhagen N, Denmark
Christoffersen J. Christoffersen M.R. and Kjaergaard N.
The kinetics of dissolution of calcium hydroxyapatite in water at constant pH.
Journal of crystal growth 43, pp. 501-511, 1978
The dissolution-rate of synthetic hydroxylapatite was measured in pure water at a temperature of 25C at a constant pH in the range 6.6-7.2, using the pH stat method. On the basis of the results it was suggested that dissolution rate depends on a surface controlled process.
Medicinsk-Kemisk Institute, Kobenhavns Universiteit, Raadmansgade 781, DK 2200 N Copenhagen, Denmark.
Christoffersen M.R. Dohrup J. and Christoffersen J.
Kinetics of growth and
dissolution of calcium hydroxyapatite in suspensions with variable
calcium to
phosphate ratio
Journal of crystal growth, vol. 186, pp. 283-290, 1998
The kinetics of dissolution
and crystal growth of hydroxyapatite were studied at variable Ca/P
ratios (0.1-20) and
explained as being controlled by a polynuclear surface mechanism.The
dissolution rate depends upon the degree of
undersaturation with respect to calcium ([Ca]s
– [Ca]).
The growth rate is explained by two steps, namely calcium ions entering
their crystallographic sites followed by phosphate
ions, which are delayed by a slow production of hydroxyl ions (by
water dissociation) at the surface.
Department of Medical Biochemistry and Genetics, Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
Clark J.S.
Solubility criteria for the existence of hydroxyapatite
Canadian journal of chemistry, Vol. 33, pp. 1696-1700, 1955
The solubility of a synthetic
hydroxylapatite was determined through precipitation and dissolution
experiments in a pH-drift,
carbon dioxide free environment. The solubility constant found was
between 114.24 and 116.56. Stable conditions were
established after 24 hr.
Chemistry division, Science Service, Department of Agriculture, Ottawa, Canada.
Clark* T. Stephenson T. and Pearce P.A.
PHOSPHORUS REMOVAL BY CHEMICAL PRECIPITATION IN A BIOLOGICAL AERATED FILTER
Wat. Res., Vol. 31, No 10, pp. 2557-2563, 1997
High levels of phosphorus in aquatic systems have been associated with eutrophication. Phosphorus removal from sewage feed is tested in two pilot-scale columns, an aerated filter packed with seeded expanded shale and an anoxic filter packed with plastic media. Ferrous iron is used for to induce precipitation of phosphate, and was dosed onto the top of the aerated filter at varying ratios of total phosphorus to iron. To meet EC requirements, the most favourable chemical dosing ratio was I: 1.25 (weight ratio P:Fe).
*School of Water Sciences,
Cranfield University, Cranfield, Bedford, MK43 OAL, U.K
Cohen L.H.* and Ribbe P.H.
Magnesium phosphate mineral replacement at mono lake, California
American Mineralogist, vol. 51, 1755-65, 1966
A possible mechanism for the
replacement of struvite (MgNH4PO4*6H2O)
with newberyite (MgHPO4*3H2O)
is discussed.
The paper suggests that newberyite has formed by the decomposition
of struvite in lake sediments, and provides
crystallographic parameters and chemical data for newberyite.
* Department of Geological Sciences, University of California, Riverside California.
Cole C.V. Sterling R. Olsen and Scott C.O.
The nature of phosphate sorption by calcium carbonate
Soil Society of America Proceedings, vol. 17, pp. 352-356, 1953
Phosphate sorption by calcium
carbonate was investigated in batch experiments. At low phosphate
concentrations it was
found that phosphate adsorbes to calcite particles, while at higher
phosphate levels a calcium phosphate precipitated as
dicalcium phosphate (CaHPO4).
Division of Soil and plant relationships B.P.I.S.A.E., U.S. Dept. of Agriculture, Fort Collins, Colo.
Dalas E. and Koutsoukos P.G.*
Crystallisation of hydroxyapatite from aqueous solutions in the presence of cadmium
Journal of the Chemical Society, FaradayTransactions 1, vol 85, pp. 3159-3164, 1989
The influence of cadmium on
the crystallisation of hydroxylapatite (HAP, Ca5(PO4)3OH)
was studied in HAP seeded
experiments at pH 7.4 and 25C using the constant composition method.
It was found that cadmium causes a reduction in
the crystallisation rate. This reduction is a function of the concentration
of cadmium. No cadmium was found incorporated
into the HAP structure. The experimental observations, however,
cannot be fully explained by a simple adsorption
mechanism.
*Department of Chemistry, Physical Chemistry Laboratory and the Research Institute of Chemical Engineering and Chemical Processes at HighTemperatures, P.O. box 1239, University Campus, GR-26110, Patras, Greece.
Danen-Louwerse* H.J. Lijklema L. and Coenraats M.
Coprecipitation of phosphate with calcium carbonate in lake Veluwe
Water Research, vol. 29, pp. 1781-1785, 1995
The co-precipitation of phosphate
with calcite was studied under lab-conditions to model precipitation
of phosphate in lakes.
It was found that co-precipitation only takes place at P concentrations
lower than 0.3 mg/l, a pH higher than 8.5 and the
presence of calcite crystals.
*Agricultural University, Department of Water Quality Management and Aquatic Ecology, P.O. Box 8080, 6700 DD Wageningen, The Netherlands.
T. P. Feenstra* and P. L. de Bruyn
FORMATION OF CALCIUM PHOSPHATES IN MODERATELY SUPERSATURATED SOLUTIONS
The Journal of Physical Chemistry, Vol. 83, No. 4, 1979 475
Calcium phosphate precipitation was achieved under conditions of controlled supersaturation. OCP is the intermediate phase in the apatite formation via heterogeneous nucleation.
* Vanít Hoff Laboratory, Transitorium 3, Padualaan 8. Utrecht, The Netherlands
J.F. Ferguson*, D. Jenkins and J. Eastman
CALCIUM PHOSPHATE PRECIPITATION AT SLIGHTLY ALKALINE pH VALUES
Journal WPCF, p. 620
A low pH calcium phosphate precipitation method is proposed for the removal of P from wastewater. The method is investigated in batch- and continuous-flow reactors, and the effects of variables, such as the concentration of bicarbonate, magnesium, calcium, H+, and residence time are evaluated. The authors propose that the cost of the method is substantially less than that of alternative precipitation techniques using lime, alum or iron salts.
*
J.-C. Heughebaert*, J.F. De Rooij and G.H. Nancollas
THE GROWTH OF DICALCIUM PHOSPHATE DIHYDRATE ON OCTACALCIUM PHOSPHATE AT 25°C
Journal of Crystal Growth, Vol. 77, pp. 192-198, 1986
This paper investigates the crystallisation of calcium phosphates as a function of supersaturation. OCP is used as a seeding material and the experiments are carried out at 25°C and pH 6. At low supersaturation (s<1.02) the phase growing on the seeds is also OCP, whereas at higher supersaturation DCPD is precipitating instead.
*Laboratoire de Physico-Chimie des Solides, , Institut National Polytechnique de Toulouse, 38 Rue des 36 Ponts, F-31400, Toulouse, France.
I. Hirasawa* and Y. Toya
FLUIDIZED-BED PROCESS FOR PHOSPHATE REMOVAL BY CALCIUM PHOSPHATE CRYSTALLIZATION
ACS Symposium Series, Vol.438, pp.355-363, 1990
The paper describes a fluidized bed process for the removal of 2-23 mg/l of P from 1-4 m3/day of waste water. Supersaturation, recirculation ratio and space velocity were identified as the key factors controlling crystallisation rate of phosphate and thus removal efficiency.
* Ebara Research Company, Ltd., 4-2-l Honfujisawa Fujisawa, Kanagawa 251, Japan
M.J.J.M. Van Kemenade* and P.L. de Bruyn
A KINETIC STUDY OF PRECIPITATION FROM SUPERSATURATED CALCIUM PHOSPHATE SOLUTIONS
J. of Colloid and Interface Sci., vol. 118, pp.564-585, 1987
A study of calcium phosphate (DCPD, OCP, HAP, amorphous) formation as a function of pH and supersaturation. Homogeneous crystallisation of HAP is not observed; instead HAP is always preceded by one of the other phases acting as a precursor. The extent of heterogeneous nucleation of HAP on OCP surfaces increases as a function of supersaturation.
* Van Hoff Laboratory, Transitorium 3, Padualaan 8, 3584 CH Utrecht, The Netherlands
W. Kibalczyc*, J. Christoffersen, M.R. Christoffersen, A. Zielenkiewicz and W. Zielenkiewicz
THE EFFECT OF MAGNESIUM IONS ON THE PRECIPITATION OF CALCIUM PHOSPHATES
Journal of Crystal Growth 106, 355-366, 1990
The presence of magnesium
ions in solution were found to inhibit the formation of amorphous
calcium phosphate and the growth of OCP, although no incorporation
of the Mg ion in the calcium phosphate lattice was observed.
*Institute of Physics, Technical University of Lodz, Wolczanska 219, 93-005 Lodz, Poland
Y. Liang*, D.R. Baer, J.M., McCoy, J.E. Amonette, and J.P. LaFemina
DISSOLUTION KINETICS AT THE CALCITE-WATER INTERFACE
Geochimica et Cosmochimica Acta, vol. 60, pp. 4883-4887, 1996
The dissolution kinetics of calcite (1014) surface is investigated using Atomic Force Microscopy, a terrace-edge-kink model and kinetic Monte Carlo simulations. The paper assesses elementary rates and activation energies for dissolution at specific kink sites on the calcite surface.
* Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 993 52, USA
D. Marant*, A.C. Di Pinto, R. Ramadori and M.C. Tomei
PHOSPHATE REMOVAL FROM MUNICIPAL WASTEWATER WITH LOW LIME DOSAGE
Environmental Technology, vol. 18, pp. 225-230, 1997
The paper discusses the potential of liming as a pre-treatment of municipal wastewater, prior to biological processing. A model was calibrated with results from lime addition tests to sewage. The model assumes phosphate and carbonate solubility controlled by a metastable phosphate [Ca4H(PO4)3] and amorphous calcium carbonate respectively. It is predicted that lime addition up to pH 9 can cause efficient P removal and prevent carbonate precipitation even at high pH.
* Water Research Institute, Via Reno 1, 00198 Rome, Italy
J.L McCoy, L.J. Sikora, and R.R. Weil*
PLANT AVAILABILITY OF PHOSPHORUS IN SEWAGE SLUDGE COMPOST
Jour. Environ. Qual., 15:404-409, 1986
Aerobically digested sewage sludge clarified with ferric chloride steel Industry by-products was composted to produce a stable product in which contained 12 to 14% total P, of which 52% to 84% was dithinonite citrate bicarbonate extractable (that is associated with iron). This material not an effective P fertilizer for maize in a P-deficient soil, even when rates of total P applied exceeded 1000 kg/ha.
* University of Maryland, College Park, MD 20742, USA
F.S. Payer and R.R. Weil*
PHOSPHORUS RENOVATION OF WASTEWATER BY OVERLAND FLOW LAND APPLICATION
J. Environ, Qual., 16:391-397, 1987
An overland flow waste water renovation system removed an average of 66% of the total P in the incoming wastewater. Most of the removed P was in the suspended form. Uptake of P by reed canary grass grown on the site accounted for some 17 kg/ha of P removed.
* University of Maryland, College Park, MD 20742, USA
M.H. Salimi *, J.C. Heughebaert and G.H. Nancollas
CRYSTAL GROWTH OF CALCIUM PHOSPHATES IN THE PRESENCE OF MAGNESIUM IONS
Langmuir, Vol.1, No.1, pp.119-122, 1985
Magnesium ions retard the rate of octacalcium phosphate growth, but have no detectable effect on the growth of dicalcium phosphate dihydrate, at constant supersaturation. The crystallisation of the thermodynamically more stable hydroxyapatite is even more strongly inhibited.
* Chemistry Department, State University of New York at Buffalo, Buffalo, New York 14214, USA
Van Dijk* J. C. and H. Braakensiek
PHOSPHATE REMOVAL BY CRYSTALLIZATION IN A FLUIDIZED BED
Wat. Sci. Tech., Vol. 17, Amsterdam, 133-142, 1984
Phosphate removal from sewage
treatment plant is achieved via the crystallisation of calcium phosphate
in a fluidised bed
reactor. The process produces pellets that have the potential to
be reused. Plans for building the first demonstration plant
are in place; costings are discussed.
* DHV Consulting Engineers, P.O. Box 85, 3800 AB Amersfoort, The Netherlands
A.G. Walton* W.J. Bodin H. Furedi and A. Schwartz
NUCLEATION OF CALCIUM PHOSPHATE FROM SOLUTION
Canadian Journal of Chemistry, Vol. 45, p. 2695, 1967
The paper describes a method of determining the stoichiometry of metastable phases from their nucleation characteristics. The method is applied to the precipitation of calcium phosphate at pH 7.0-9.1 and [Ca]/[P] ratio of 1.49. The precipitate is an amorphous metastable material rather than the expected hydroxyapatite.
* Dept. of Chemistry, Case Institute of Technology, Cleveland, Ohio, USA
D. Zhao* and A. K. Sengupta
SELECTIVE REMOVAL AND RECOVERY OF PHOSPHATE IN A NOVEL FIXED-BED PROCESS
Wat. Sci. Tech., Vol. 33, No. 10-11, pp. 139-147, 1996
This study shows that a polymeric ligand exchanger (PLE) can selectively remove phosphate from wastewater. Phosphate may be recovered and the PLE can be reused.
* Dept. of Civil & Environmental Engineering, 13 E. Packer Avenue, Lehigh University, Bethlehem, PA 18015, USA
D. Zhao* and A. K. Sengupta
ULTIMATE REMOVAL OF PHOSPHATE FROM WASTEWATER USING A NEW CLASS OF POLYMERIC ION EXCHANGERS
Wat. Res., Vol. 32, No. 5, pp. 1613-1625, 1998
A new class of sorbents, referred to as polymeric ligand exchangers (PLE) are shown to selectively remove phosphorus in laboratory studies. The method is based on anion exchange accompanied by Lewis acid-base interaction. PLEs are amenable to regeneration.
* Dept. of Civil & Environmental Engineering, 13 E. Packer Avenue, Lehigh University, Bethlehem, PA 18015, USA