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Alhamzah A.,University of New England of Australia | Alhamzah A.,Saline Water Desalination Research Institute | Fellows C.M.,University of New England of Australia
Desalination | Year: 2014

The thermal decomposition of the hydrogencarbonate ion has been previously described by a bimolecular mechanism or a unimolecular mechanism. In this work the Gibbs free energy of the competing reactions for both the unimolecular and bimolecular mechanisms was calculated for typical concentrations found in thermal desalination plants. Activity coefficients were estimated using the Pitzer equations. At low temperature the bimolecular mechanism is thermodynamically favored, while above 80°C the unimolecular mechanism is favored, consistent with observations of alkaline scale formation in thermal desalination plants. The rate coefficient of thermal decomposition of HCO3- at 97.2°C in the absence and presence of 10ppm of poly(acrylic acid) (PAA) with different end groups and molar mass was determined. PAA was found to retard the rate of decomposition by up to 49% and for all end groups of PAA the rate coefficient of thermal decomposition of 40ppm HCO3- increased with increasing molar mass. The results are consistent with PAA preventing heterogeneous decomposition of HCO3- on interfaces. The rate of partitioning of PAA to these interfaces should increase with decreasing molar mass and resulting mobility of PAA, and may also be affected by self-assembly behavior. © 2013 Elsevier B.V.


Al-Hamzah A.A.,University of New England of Australia | Al-Hamzah A.A.,Saline Water Desalination Research Institute | East C.P.,Queensland University of Technology | Doherty W.O.S.,Queensland University of Technology | Fellows C.M.,University of New England of Australia
Desalination | Year: 2014

The ability of poly(acrylic acid) (PAA) with different end groups and molar masses prepared by Atom Transfer Radical Polymerization (ATRP) to inhibit the formation of calcium carbonate scale at low and elevated temperatures was investigated. Inhibition of CaCO3 deposition was affected by the hydrophobicity of the end groups of PAA, with the greatest inhibition seen for PAA with hydrophobic end groups of moderate size (6-10 carbons). The morphologies of CaCO3 crystals were significantly distorted in the presence of these PAAs. The smallest morphological change was in the presence of PAA with long hydrophobic end groups (16 carbons) and the relative inhibition observed for all species were in the same order at 30°C and 100°C. As well as distorting morphologies, the scale inhibitors appeared to stabilize the less thermodynamically favorable polymorph, vaterite, to a degree proportional to their ability to inhibit precipitation. © 2014 Elsevier B.V.


Al-Hajouri A.A.,Saline Water Conversion Corporation | Al-Amoudi A.S.,Saline Water Desalination Research Institute | Farooque A.M.,Saline Water Desalination Research Institute
Desalination and Water Treatment | Year: 2013

Saline Water Conversion Corporation is the pioneer in developing applications and operation of nanofiltration (NF) pretreatment for seawater desalination which was developed by its research arm, namely, the Saline Water Desalination Research Institute. Initial work on a pilot plant scale, resulted in its application in one of the commercial seawater reverse osmosis (SWRO) plants at Ummlujj currently in operation since September 2000. During this long term of operation of NF-SWRO system, a number of improvements were made on the system operation based on operational experiences as well as research, which ultimately resulted in smooth operation of the same. This long-term operation revealed that it is possible to operate NF at 65% recovery at pH= 6 utilizing only low feed pressure of <25 bar. This led to increase in SWRO production by 42%. Also, no chemical cleaning or membrane replacement was required for SWRO membranes. These achievements make the NF-SWRO process economically attractive and feasible. This paper provides an overview of long-term operation of NF-SWRO plant as well as different research programs which were undertaken and results obtained following the application of the same. Major obstacles in the smooth operation of the NF pretreatment and future direction of improvement and research to be adopted are also addressed. © 2013 Desalination Publications. All rights reserved.


Hamed O.A.,Saline Water Desalination Research Institute | Al-Otaibi H.A.,Saline Water Desalination Research Institute
Desalination | Year: 2010

Control of scale formation on heat transfer surfaces is one of the basic problems in thermal desalination processes. There are several commercial antiscalants available in the market mostly derived from condensed polyphosphates, polyelectrolytes and organophosphonates. A comprehensive study was carried out for direct performances in comparison of three of the most widely used antiscalants. They include a maleic acid based copolymer antiscalant #1, a maleic acid based copolymer antiscalant #2 and a phosphonate based antiscalant #3. The comparative study was performed in a MSF pilot plant under harsh operating conditions. For each of the three antiscalants, the MSF pilot plant was operated at a TBT of 119°C, a dose rate of 1. ppm and a brine recycle concentration factor of 1.9 for one month. A baseline test was performed under the same TBT and concentration factor without the use of an antiscalant. Test results reveal that antiscalants were quite effective in suppressing scale formation under the selected operating conditions. It is recommended to reconsider current scale control operating conditions of commercial MSF plants especially with regards to optimization of antiscalant dose rate and brine concentration factor. © 2010 Elsevier B.V.


Al-Amoudi A.,Saline Water Desalination Research Institute
Separation and Purification Technology | Year: 2013

In membrane process industries, membrane cleaning is one of the most important concerns from both economic and scientific points of view. Though cleaning is important to restore membrane performance, the inappropriate selection of cleaning agents may result in unsatisfactory cleaning or irreparable membrane damage. In this study, the cleaning performance was studied by measuring membrane pore size; by positron annihilation spectroscopy and salt rejection as well as by flux measurement. Thin film composite nanofiltration (NF) membranes, supplied by GE Osmonics NF-DK were used in this study. Tests were carried out on virgin membranes. Several different cleaning agents were investigated. Some of them were of analytical grade such as HCl and NaOH. Others such as SDS and mixed agents were of commercial grade already in use in commercial plants. Pore size and salt rejection as well as the flux of virgin membranes before and after chemical cleaning were measured and compared. After the chemical cleaning of the virgin membranes, the membrane pore size was measured revealing interesting results, which may be used to characterize membrane surface cleanliness. The membrane pore size results showed that the cleaning agents affect membrane surface properties by enlarging the pore size of the treated virgin membranes. The flux and rejection were correlated with pore size after low and high pH cleaning, and these findings were investigated and reported in this paper. © 2013 Elsevier Ltd. All rights reserved.


Malik A.U.,Saline Water Desalination Research Institute | Al-Fozan S.A.,Saline Water Desalination Research Institute
Corrosion Reviews | Year: 2011

The chemically aggressive environment generated in some parts of equipment at multi-stage flash (MSF) desalination plants can cause corrosion problems. The proper selection of materials with higher resistance to corrosion is considered as one of the most prospective approaches for smooth and efficient running of the plants. Because of this, the study of the corrosion behavior of selected materials is an important issue in the realm of desalination technology. This paper reviews the performance of materials used in different MSF desalination plants. The corrosion behavior of materials in different sections of plants, under surrounding environmental conditions, is discussed. Various types or forms of corrosion occurring in different units of plant are described and the strong role of local attack is emphasized. Case histories dealing with failure of components in different plants are cited. The criteria for the selection of materials, which depend upon the nature of environment and operating conditions, are exemplified. The merits and demerits of materials currently employed are highlighted and introduction of new materials either in existing plants as the possible replacements or in future plants are discussed. © 2011 by Walter de Gruyter.


Al-Amoudi A.,Saline Water Desalination Research Institute
Desalination and Water Treatment | Year: 2016

In membrane process industries, membrane cleaning is one of the most important concerns from both economical and scientific points of view. Though cleaning is important to recover membrane performance, an inappropriate selection of cleaning agent may result into unsatisfactory cleaning or irreparable membrane. In this study, the cleaning performance has been studied with measurements of membrane contact angle values, surface roughness, zeta potential and pore size by positron annihilation spectroscopy, and salt rejection as well as flux measurement. Thin-film nanofiltration membranes such as DK, provided by GE-Osmonics are used in this study. Tests were carried out with virgin DK. Several cleaning agents were investigated, some of them were of analytical grade such as HCl, NaOH, and others such as SDS mix agents were commercial grade agents that are already in use in commercial plants. Contact angle values, surface roughness, zeta potential and pore size, and salt rejection as well as flux of virgin membranes before and after chemical cleaning were measured and compared. The membrane contact angle values, surface roughness, zeta potential, and pore size measurements with and without chemical cleaning of virgin membranes were measured and revealed very interesting results which may be used to characterize the membrane surface cleanliness. The membrane contact angle values, surface roughness, zeta potential, and pore size results revealed that the cleaning agents are found to modify membrane surface properties. The details of these results were investigated and are reported in the paper. The salt rejection levels of divalent ions before and after cleaning by high- and low-pH cleaning agents were looked into it. © 2015 Balaban Desalination Publications. All rights reserved.


Al-Amoudi A.S.,Saline Water Desalination Research Institute
Desalination | Year: 2010

Membrane fouling is a major problem in brackish and seawater desalination as well as in membrane mediated waste water reclamation. Fouling of nanofiltration (NF) membranes is typically caused by inorganic and organic materials present in water that adhere to the surface and pores of the membrane and results in deterioration of performance (reduced membrane flux) with a consequent increase in costs of energy and early membrane replacement. Natural organic matter (NOM) fouling of NF membranes involves interrelationship between physical and chemical interactions and it is described in this review. Membrane fouling in the presence of NOM can be influenced by: membrane characteristics, including surface structure as well as surface chemical properties, chemistry of feed solution including ionic strength, pH and concentration of monovalent ions and divalent ions, NOM properties, including molecular weight and polarity, and hydrodynamic and operating conditions including permeate flux, pressure, concentration polarization, and the mass transfer properties of the fluid boundary layer. These factors will be discussed in details in this review.Inorganic fouling due to scale formation of sparingly soluble inorganic salts occurs whenever the ionic salt concentration stream exceeds the equilibrium solubility. Scale formation take place by homogenous or heterogeneous crystallization and its factors will be also investigated in this review. © 2010 Elsevier B.V.


Patent
Saline Water Desalination Research Institute | Date: 2012-02-02

The removal of boron from saline water based (10) using alkalized NF membrane pretreatment (14) can be adopted at 90% recovery and pH 8-9.5 to produce softened and alkalized NF permeate having SDI<1 with significant reduction in feed boron, TDS and scale-forming ions depending on the properties of the NF membrane polymer structure. NF process (14) acts as a partial desalination process, a softening process, as well as a boron removal process. An additional RO membrane alkalization (16) can be adopted at a wide range of RO feed at pH 8.5-10, resulting in production of desalinated water (18) with almost nil boron content.


Patent
Saline Water Desalination Research Institute | Date: 2011-09-02

The removal of boron from saline water based using alkalized NF membrane pretreatment can be adopted at 90% recovery and pH 8-9.5 to produce softened and alkalized NF permeate having SDI<1 with significant reduction in feed boron, TDS and scale-forming ions, depending on the properties of the NF membrane polymer structure. NF process acts as a softening process, as well as a boron removal process. An additional RO membrane alkalization can be adopted at a wide range of RO feed at pH 8.5-10, resulting in production of desalinated water with almost nil boron content.

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