Will calcium carbonate really scale in seawater reverse osmosis

The elimination of antiscalant chemicals in SWRO plants will result in a more environmentally friendly, sustainable and cheaper process. Practically, this can be achieved by determining the real scaling limits of calcium carbonate in SWRO. In supersaturated solutions the period of metastability before the start of crystal growth is commonly indicated as induction time (τind). Induction time longer than the average retention time of concentrate in a single-stage SWRO suggests that scaling will probably not occur. This research project aims to determine the induction times as a function of the saturation index and ionic strength for synthetic seawater. The experimental procedure utilized in this research is a sensitive and stable pH meter with accuracy of 0.01 pH units. The pH meter used was able to detect precipitation as low as 0.3 mg/l of CaCO3. Induction time experiments were performed with synthetic concentrates with low and high ionic strength. The synthetic high ionic strength solution had the same i...

[1]  H. Elfil,et al.  Kinetics of the precipitation of calcium sulfate dihydrate in a desalination unit , 2003 .

[2]  C. Kontoyannis,et al.  Precipitation of calcium carbonate in aqueous solutions , 1984 .

[3]  M. Al-Shammiri,et al.  Maximum recovery from seawater reverse osmosis plants in Kuwait , 1997 .

[4]  R. Sheikholeslami,et al.  Assessment of the scaling potential for sparingly soluble salts in RO and NF units , 2004 .

[5]  J. Gal,et al.  Mechanisms of scale formation and carbon dioxide partial pressure influence. Part II. Application in the study of mineral waters of reference. , 2002, Water research.

[6]  Ahmed Hannachi,et al.  Reconsidering water scaling tendency assessment , 2006 .

[7]  Eli Oklejas,et al.  Minimizing RO energy consumption under variable conditions of operation , 2003 .

[8]  L. N. Plummer,et al.  The solubilities of calcite, aragonite and vaterite in CO2-H2O solutions between 0 and 90°C, and an evaluation of the aqueous model for the system CaCO3-CO2-H2O , 1982 .

[9]  P. Zuddas,et al.  Kinetics of calcite precipitation from seawater: I. A classical chemical kinetics description for strong electrolyte solutions , 1994 .

[10]  F. Rahman,et al.  Characterization of foulants by autopsy of RO desalination membranes , 1997 .

[11]  David Hasson,et al.  Detection of fouling on RO modules by residence time distribution analyses , 2007 .

[12]  S. E. Ingle.  Solubility of calcite in the ocean , 1975 .

[13]  H. Elfil,et al.  Role of hydrate phases of calcium carbonate on the scaling phenomenon , 2001 .