A new biosensor for rapid BOD estimation by using immobilized growing cell beads.

Area of Science:

• Environmental Science
• Biotechnology
• Analytical Chemistry

Background:

• Biochemical Oxygen Demand (BOD) is a critical parameter for assessing water quality.
• Conventional BOD testing methods are time-consuming, often requiring 5-day incubation periods.
• Developing rapid and reliable BOD estimation techniques is essential for effective wastewater management.

Purpose of the Study:

• To develop and validate a novel, rapid sensor system for estimating Biochemical Oxygen Demand (BOD).
• To utilize immobilized whole cells of Bacillus polymyxa D-21 for enhanced sensor performance.
• To evaluate the sensor's accuracy, reproducibility, and stability for wastewater analysis.

Main Methods:

• A closed, reactor-type sensor system was designed using immobilized Bacillus polymyxa D-21 cells in kappa-carrageenan and an oxygen electrode.
• The system incorporated a transformer, recorder, thermostated water bath, magnetic stirrer, and oxygen electrode.
• Assays involved measuring oxygen consumption rates of immobilized cells exposed to wastewater samples.

Main Results:

• The sensor system provided rapid BOD estimations in under 15 minutes.
• Calibration curves demonstrated a linear relationship between oxygen consumption rate and standard wastewater concentration.
• The sensor exhibited high reproducibility (average relative error of 5.89%) and stability, remaining unchanged for approximately 30 days.
• Good correlation was observed between BOD5 values determined by the proposed sensor and conventional methods.

Conclusions:

• The developed immobilized whole-cell sensor system offers a rapid, reproducible, and stable method for BOD estimation.
• This technology has the potential to significantly reduce the time required for wastewater quality assessment.
• The sensor's performance suggests its utility for real-time monitoring and analysis of wastewater from industrial sources.