Low pH wastewater is neutralized by adding?

Neutralizing low pH wastewater involves raising the pH to a more neutral level, typically around 7. Sodium hydroxide (NaOH) is a strong base that effectively increases the pH of acidic wastewater. When added to low pH wastewater, sodium hydroxide dissociates in water to release hydroxide ions, which react with hydrogen ions (the source of acidity) to form water. This reaction reduces the concentration of hydrogen ions, thereby elevating the pH of the wastewater towards neutrality.

The other options, while relevant in other contexts, do not serve the purpose of raising pH in low pH wastewater. Calcium carbonate can indeed raise pH by reacting with acids, but it does so through a slower reaction compared to sodium hydroxide, making NaOH the more effective choice for immediate neutralization. Sulfuric acid would lower the pH even further, exacerbating the acidity. Ammonium sulfate is a salt that does not have a significant effect on pH when dissolved in water. Thus, the use of sodium hydroxide is appropriate for achieving rapid and effective neutralization of low pH wastewater.