1st Edition

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

By Tarek Kamal Abdalla Waly Copyright 2011
    186 Pages
    by CRC Press

    184 Pages
    by CRC Press

    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.

    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

    Biography

    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.