Minimizing the Use of Chemicals to Control Scaling in Sea Water Reverse Osmosis: Improved Prediction of the Scaling Potential of Calcium Carbonate

UNESCO-IHE PhD Thesis
1. Auflage 2011
ISBN: 978-0-415-61578-5
Verlag: Taylor & Francis Ltd

Buch, Englisch, 186 Seiten, Format (B × H): 159 mm x 235 mm, Gewicht: 290 g

Reihe: IHE Delft PhD Thesis Series

A comprehensive and detailed study on the scaling potential of calcium carbonate in seawater reverse osmosis systems (SWRO), this book provides a new approach for calculating the degree of supersaturation and the pH of the SWRO systems concentrates with the assistance of the feed-water pH and the inorganic carbon constituents. Furthermore, the book highlights the weakness in the present supersaturation indices and membrane manufacturers programs. Finally, the research suggested that SWRO concentrate is much lower undersaturated with respect to calcium carbonate than previously thought. This was confirmed by comprehensive pilot testing where acids and antiscalants used to prevent calcium carbonate scaling were completely eliminated from the pilot plant.

Zielgruppe

1- Desalination and water treatment professionals 2- Crystallization professionals 3- Environmental professionals

Autoren/Hrsg.

Waly, Tarek Kamal Abdalla

Fachgebiete

• Technische Wissenschaften Umwelttechnik | Umwelttechnologie Abwassertechnologien, Meerwasserentsalzung

Inhaltsverzeichnis

Chapter 1
1.1 Background

1.2 Problem definition

1.3 The Overall Aim of the research

1.4 Research objectives

1.5 References
Chapter 2

2.1 Abstract

2.2 Background

Introduction
Induction time
Measurement tools

Effect of exchange CO2 on induction time

2.3 Materials

Inductively coupled plasma

Conductivity meter

pH meter

Reactors

Synthetic seawater concentrate preparation
2.4 Methods
Measurement of calcium with ICP

Salinity and accuracy of direct measurement of calcium in solution
Measurement of calcium carbonate retained on membrane filters

Effect of salinity, stability and accuracy of conductivity and pH measurment

Effect of mixing on the induction time

2.5 Results
Effect of salinity on the ICP measurements and accuracy

Accuracy of measurement of calcium carbonate retained on membrane filters

The effect of salinity on the conductivity and the pH measurments

The effect of carbon dioxide exchange in an open system
2.6 Conclusions

2.7 List of Symbols

2.8 References

Chapter 3

3.1 Abstract

3.2 Background

3.3 Materials

Synthetic seawater concentrate preparation
3.4 Methods

The effect of particles in synthetic seawater on the induction time

The effect of particle addition

Mixing effect

3.5 Results and discussion

The effect of particles in synthetic seawater on the induction time

The effect of particle addition

The effect of mixing speed on the induction time

The nucleation mechanism

3.6 Conclusions

3.7 List of symbols

3.8 References

Chapter 4

4.1 Abstract

4.2 Background
Introduction

Solubility of salts

Common methods used to determine the precipitation potential of CaCO3:

Stiff & Davis Stability Index (S&DSI)

Saturation Index (SI)

Saturation Ratio (Sa)

Mechanism of nucleation

Homogenous nucleation

Heterogeneous nucleation in a solution

Induction time

CaCO3 phases

The formation of hydrated CaCO3 forms

4.3 Materials

pH meter

Reactors

Synthetic seawater concentrate preparation

4.4 Methods

Induction time measurements

Solutions concentrations

Calculation of SI using PhreeqC

4.5 Results

The solubility product used by the S&DSI

Homogenous and heterogeneous nucleation

4.6 Conclusions

4.7 List of symbols

4.8 References

Chapter 5

5.1 Abstract

5.2 Introduction

5.3 Background

Saturation indices

Calculation of pH in SWRO concentrates

Effect of salinity on dissociation constants

Effect of salinity on the ion activity

5.4 Materials and Methods

Pilot plant

Concentrate pH in SWRO systems

5.5 Results and Discussion

pH calculations using equilibrium equations

pH calculations using manufacturers software

pH prediction using Phreeqc evaporation model

Field seawater concentrate measurements

5.6 Conclusions

5.6 List of Symbols
5.7 References

Chapter 6
6.1 Abstract

6.2 Background

Introduction

Calcium carbonate phases

The role of inorganic ions

Solubility of salts
Common methods used to determine the precipitation potential of CaCO3:

Saturation indices (SI and Sa)

Mechanism of nucleation

Induction time

6.3 Materials
pH meter
Reactors

Synthetic seawater concentrate preparation

6.4 Methods
Induction time measurements

Determination of co-precipitation

Determination of the final crystal phase of calcium carbonate
6.5 Results and discussion

Chapter 7

7.1 Conclusions
7.2 Recommendations for future work

Über Autor(innen)

Dr Tarek Waly has 13 years experience in management, consultancy, sales, marketing and research in the water and wastewater treatment field. He is currently a lead R&D engineer at DOW Chemicals. He obtained his MSc from the UNESCO-IHE Institute for Water Education in Delft, and his Doctorate degree from the Delft University of Technology in Delft, The Netherlands.