What measurement is used to indicate the clarity of wastewater?

The measurement used to indicate the clarity of wastewater is turbidity. Turbidity refers to the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye. It is an important parameter in assessing water quality because higher turbidity levels often indicate the presence of suspended solids, which can harbor pathogens and affect the effectiveness of disinfection processes.

Percent transmittance, while related to turbidity, measures how much light passes through a sample. It can be a useful indicator of water clarity but does not provide a direct measurement of the particles causing the cloudiness as turbidity does. Other options like pH levels and hardness pertain to different aspects of water quality, such as acidity and mineral content, and do not specifically measure clarity. Thus, turbidity serves as the most accurate and relevant measurement for assessing wastewater clarity.