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...