A sample of plant effluent must be tested for pH within:

Testing a sample of plant effluent for pH is a critical aspect of wastewater management. The pH of a sample can change over time due to various factors such as chemical reactions, biological activity, or atmospheric exposure. Therefore, it is essential to analyze the sample promptly to obtain an accurate measurement.

The standard guideline for testing the pH of wastewater samples generally recommends conducting the test within 15 minutes of sample collection. This time frame ensures that the pH readings reflect the actual conditions of the effluent at the time of collection, minimizing the impact of any changes that could alter the pH level thereafter.

If the sample is tested beyond this timeframe, the reliability of the results may diminish significantly, which can lead to incorrect assessments of the treatment process or compliance with regulatory standards. Hence, the requirement of testing within 15 minutes is a well-established practice in wastewater management to maintain the integrity of the sample and the accuracy of the results.