Reuse of softening pellets for remineralizing

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MSc Thesis Presentation
Reuse of softening pellets for remineralizing
desalinated water
Li Gao
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Contents
1. Introduction
2. Theory
3. Materials and methods
4. Results and discussion
5. Practical consideration
6. Conclusions and recommendations
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1. Introduction
Desalination
Membrane filtration process (RO)
Thermal processes (MSF)
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Desalinated water
pH lt 6
Ca2 concentrationlt 0.1mmol/L
HCO3- concentrationlt 0.2mmol/L
SI -4lt0
Corrosive and Instable
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Remineralization
Drinking Water Guidelines
-- Global Water Research Coalition
1. 0.5mmol/LltCa2lt2mmol/L
2. 1mmol/LltHCO3-
3. 7.8ltpHlt8.3
4. -0.2ltSIlt0.3
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Remineralization
Alternatives
1. Dosing chemical solution
CaCl2 and NaHCO3
CaCl2 2NaHCO3 Ca(HCO3)22NaCl
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Remineralization
Alternatives
2. Mixing with other water sources
Desalinated water
Groundwater
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Remineralization
Alternatives
3. Dissolving calcium rich filter material by CO2
Shell
Limestone
Softening pellet
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Reuse of softening pellet
(1) Pellet softening process
Ca2CO32- CaCO3
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Reuse of softening pellet
(1) Pellet softening process
(2) Pellet
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Reuse of softening pellet
(1) Pellet softening process
(2) Pellet
(3) Alternatives
? Dissolution process
? Filtration process
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Reuse of softening pellet
(1) Pellet softening process
(2) Pellet
(3) Alternatives
? Dissolution process
? Filtration process
Softening pellet
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Reuse of softening pellet
(1) Pellet softening process
(2) Pellet
(3) Alternatives
? Dissolution process
? Filtration process
Softening pellet
Softening pellet
? Combination of dissolution process and
filtration process
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2. Theory
(1). Calcium carbonic acid equilibrium
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(2). SI (Saturation Index)
SI0 Equilibrium
SIlt0 Corrosion
SIgt0 Scaling
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(3). Henrys law
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(4). Kinetics of CaCO3 dissolution process
K0.005
K0.002
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3. Materials and methods
(1). For dissolution experiments
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(1). For dissolution experiments
Bottle of CO2
Pressure vessel
Stirrer
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(1). For dissolution experiments
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(2). For filtration experiments
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(2). For filtration experiments
Column
Mixing point
Pressure vessel
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4. Results and discussion
(1). Results of theoretical calculation
Water quality of the chemical solution
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(1). Results of theoretical calculation
Water quality of the directly mixed solution
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(1). Results of theoretical calculation
Water quality of the directly mixed solution
Water quality of the mixed solution in
equilibrium state
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(2). Results of dissolution experiments
?. Different diameters lead to limited difference
in reaction constant
?. Different pressures do not lead to difference
in reaction constant
?. Different dosages of pellets lead to big
difference in reaction constant
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(3). Results of filtration experiments
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(3). Results of filtration experiments
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5. Practical consideration
(1). Application of dissolution process
(2). Application of filtration process
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(3). Process scheme
Existing
CO2
Sea water
Desalinated water
Drinking water
Limestone
Alternatives
CO2 Ca2 HCO3-
Sea water
Desalinated water
Drinking water
Limestone
CO2 Ca2 HCO3-
Sea water
Desalinated water
Drinking water
Softening pellet
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6. Conclusions and recommendations
Conclusions
(1). Softening pellets can be reused in
dissolution process
(2). Softening pellets can be reused in
filtration process
(3). Kinetics of reaction constants
Recommendations
(1). Investigating the influences of impurities
and nuclear sand of softening pellets
(2). Reuse of chemical solution and nuclear sand
in other application
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Thank you for your attention!
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