When performing BOD testing, what component is necessary for accurate results?

In biochemical oxygen demand (BOD) testing, the inclusion of a control sample is critical to ensure that the results obtained are valid and reliable. A control sample allows for the comparison of the test results against a baseline that represents normal conditions. This helps to identify any potential errors or anomalies in the testing process, such as contamination or mishandling of samples.

Using a control sample helps to assess the accuracy of the BOD readings by providing a reference point that is not influenced by the specific water being tested. This is especially important in BOD testing because the outcomes can be affected by various external factors such as temperature, microbial activity, and dilution methods. Therefore, having a control sample alongside the test samples ensures that the experiment is under controlled conditions, enabling the identification of any deviations that could affect the overall assessment of the water quality.

In contrast, spoiled water samples, high nutrient samples, and sediment samples do not serve the purpose of establishing a reliable baseline for comparison. A spoiled sample would introduce variables that could skew the results, while specific nutrient concentrations or sediments could influence BOD readings unpredictably. Thus, using a control sample is fundamental to obtaining accurate and trustworthy BOD test results.