Why are composite samples prepared in wastewater analysis?

Composite samples are prepared in wastewater analysis primarily to create a representation of flows over time. This method involves collecting multiple samples over a specified period and combining them into a single sample. By doing so, analysts can obtain a more accurate and comprehensive assessment of the water quality, as it accounts for variations in contaminant concentrations and flow rates that might occur at different times during the sampling period.

This approach is particularly valuable because wastewater characteristics can change significantly based on factors such as time of day, industrial discharges, and weather conditions. A composite sample, therefore, provides a better overall picture of the wastewater's characteristics, enabling more informed decision-making for treatment and regulatory compliance.