Florida Drinking Water Operator "B" Practice Test

What are the most common scaling compounds encountered in the reverse osmosis process?

1. Magnesium chloride and ammonium sulfate

2. Calcium carbonate and calcium sulfate

3. Sand and silt

4. Carbon dioxide and sodium bicarbonate

The correct answer is: Calcium carbonate and calcium sulfate

The most common scaling compounds encountered in the reverse osmosis process are calcium carbonate and calcium sulfate. These compounds are prevalent due to their tendency to precipitate when concentrated in water, especially when conditions such as temperature, pH, and ionic strength change. Reverse osmosis operates by pushing water through a semi-permeable membrane, and as the water is forced through, the dissolved minerals can become supersaturated, leading to precipitation. Calcium carbonate can precipitate out of solution if the water is too alkaline or if the concentration of calcium and carbonate ions is high, which is typical when water is treated through reverse osmosis. Similarly, calcium sulfate can precipitate when the solubility limits are exceeded, particularly in waters with high sulfate concentrations. The presence of these scaling compounds not only reduces the efficiency of the reverse osmosis process by blocking the membranes but also can lead to increased maintenance costs and more frequent cleaning of the systems. Understanding scaling compounds is crucial for operators to implement preventative measures and maintain optimal performance in water treatment facilities.