What is commonly used to indicate the organic strength of wastewater?

The organic strength of wastewater is commonly indicated by the biochemical oxygen demand (BOD), which is a measure of the amount of oxygen that microorganisms will consume while decomposing organic matter in a sample of water at a specified temperature over a set period, usually five days. BOD is a critical parameter in wastewater treatment because it reflects the degree of pollution present in the water and the potential impact on the environment if the water is discharged untreated.

By measuring BOD, operators can assess the effectiveness of treatment processes and determine the necessary level of treatment required to meet regulatory standards. A higher BOD indicates higher organic content, suggesting that the wastewater has a greater potential to deplete oxygen in receiving waters, which can harm aquatic life.

Other parameters like chemical oxygen demand (COD) and dissolved oxygen (DO) also relate to water quality but serve different purposes. COD measures all oxygen-demanding substances, not just biodegradable ones, and DO indicates the amount of oxygen available in the water for aquatic organisms rather than organic strength. Nitrogen content is more focused on nutrient levels rather than organic loading, making BOD the best indicator for assessing the organic strength of wastewater.