Characterization and Identification of Organic Molecules in Thermal Desalination Plant Scale

Scale samples from a 144,000 m(3)/d Arabian Gulf multi-stage flash (MSF) desalination plant were collected and assayed for organic, biological, and inorganic compounds. Samples were collected from the bottom side of the deaerator and the first flash chamber of a 24,000 m(3)/d MSF unit. For the first time, organic compounds and adenosine triphosphate were characterized and identified in both selected locations. Within predominantly calcium carbonate (in the deaerator) and magnesium hydroxide (in the first stage of MSF) scale samples, organics were detected, and their potential sources suggested based on related literature. Organic compounds found are consistent with degradation components of bacterioneuston with some contribution from species present in the seawater source and pretreatment chemicals. These findings raise the possibility of a significant role of organic compounds in alkaline scale nucleation and growth in the MSF process.