In the lime-soda ash process, what will cause increased solubility of taste and odor causing compounds?

• A. Elevated temperatures
• B. Reactions between carbonate ions and negatively charged organics
• C. Ionic bonding of calcium and magnesium carbonates with tannic and fulvic acids
• D. Elevated pH values

Answer: (D)

Raising the pH is the main factor that increases the solubility of taste- and odor‑causing compounds. In the lime-soda ash process, pH is driven up, often into the high-alkaline range. Many odor-causing organics contain acidic functional groups; when the pH climbs, these groups lose protons and the molecules become negatively charged, which makes them more water-soluble. So at higher pH, more of these compounds stay dissolved rather than partitioning into the air or being removed by precipitation or adsorption. Elevated temperatures can enhance volatilization of some T&O compounds rather than solubility, and the other options describe interactions that would tend to remove or complexify organics rather than simply increasing their solubility, making elevated pH the best explanation.