A simplified headspace biochemical oxygen demand test protocol based on oxygen measurements using a fiber optic probe

Area of Science:

• Environmental Science
• Analytical Chemistry
• Water Quality Analysis

Background:

• Conventional biochemical oxygen demand (BOD) methods are time-consuming and require sample dilution.
• Batch respirometric tests, like headspace biochemical oxygen demand (HBOD), offer advantages but lack simple gas-phase oxygen measurement.
• Accurate oxygen measurement is crucial for respirometric wastewater analysis.

Purpose of the Study:

• To evaluate a new fiber optic oxygen probe for headspace biochemical oxygen demand (HBOD) tests.
• To assess the probe's accuracy and speed compared to existing methods.
• To determine if the probe can reliably predict 5-day biochemical oxygen demand (BOD5) values.

Main Methods:

• Gas-phase oxygen concentrations were measured using the new fiber optic HBOD probe.
• Measurements were compared against a gas chromatograph for accuracy validation.
• Field tests were conducted on wastewater samples from two treatment plants (UAJA and PSU).

Main Results:

• Fiber optic probe measurements were rapid (seconds) and highly correlated with gas chromatography (R² = 0.9995).
• The HBOD probe significantly reduced sample analysis time and improved precision compared to traditional BOD tests.
• Predicted BOD5 values from 2-day and 3-day HBOD measurements showed strong correlations with actual BOD5 for both UAJA and PSU wastewater.

Conclusions:

• The fiber optic HBOD probe is a reliable tool for accurate gas-phase oxygen measurement in batch respirometric tests.
• This technology enhances the efficiency and precision of wastewater oxygen demand analysis.
• The HBOD probe facilitates rapid prediction of 5-day BOD, improving wastewater treatment monitoring.