What do pH meters measure?

pH meters are specifically designed to measure the concentration of hydrogen ions (H⁺) in a solution, which directly correlates with the acidity or alkalinity (pH) of that solution. The pH scale ranges from 0 to 14, where lower values indicate higher hydrogen ion concentrations and therefore greater acidity, while higher values indicate lower concentrations of hydrogen ions and greater alkalinity.

The pH meter works by using electrodes that respond to the hydrogen ion activity in the solution, providing a digital readout of the pH level. Knowing the pH is essential for various wastewater treatment processes and environmental assessments, as it affects the solubility and biological availability of many substances, including nutrients and pollutants, in the water.

Measurements of electrical conductivity, temperature, and oxygen levels are important in wastewater treatment, but they are separate parameters and require different instruments for accurate evaluation. Therefore, while those options may be relevant to the broader field of water quality assessment, the primary and specific measurement made by pH meters is the hydrogen ion concentration.