Induction time measurements in two brackish water reverse osmosis plants for calcium carbonate precipitation

AbstractIn this research work, the induction time of two brackish water reverse osmosis (BWRO) plants was measured with and without antiscalant (AS) operation with focus on calcium carbonate precipitation. This study focused on two BWRO plants in the Netherlands. The scaling potential of RO concentrate in the plant at recovery of 80% was calculated using the PHREEQC program. Induction times in RO concentrates were measured by collecting RO concentrates directly from the plants, with and without an AS dose in an air-tight glass reactor. The solution was continuously stirred for homogenization and maintained at room temperature using a thermostat. The change in pH of the solution over time was monitored. The time required to change the nucleation phase to just the start of the crystal growth was noted from the pH versus time graph, which was defined as induction time. At the end of the experiments, precipitate with RO concentrate with and without AS dose (plant B) were collected and an X-ray powder diffract...