California Wastewater Treatment Operator Practice Exam

What is a common way to determine the organic strength of wastes in the influent?

1. test for the biochemical oxygen demand

2. measure the pH

3. conduct a turbidity test

4. check for nitrates

The correct answer is: test for the biochemical oxygen demand

Testing for biochemical oxygen demand (BOD) is a common method used to determine the organic strength of wastes in the influent. BOD measures the amount of oxygen that bacteria will consume while decomposing organic matter under aerobic conditions over a specific time period, typically five days. This measurement provides insight into the level of organic pollutants present in the wastewater, which is crucial for assessing the wastewater treatment process's performance and efficiency. Other methods mentioned can provide useful information about water quality, but they do not effectively indicate the organic strength of the influent. Measuring pH helps to assess the acidity or alkalinity of the wastewater, which can affect biological and chemical processes but does not directly quantify organic matter. Turbidity tests measure the cloudiness of water caused by suspended solids, but like pH, they do not specifically indicate organic load. Checking for nitrates can give insights into the nitrogen content in the waste but does not reflect the organic material present. Therefore, BOD is the most relevant parameter for assessing organic strength in wastewater.