Sulfide response analysis for sulfide control using a pS electrode in sulfate reducing bioreactors

Area of Science:

• Environmental Biotechnology
• Biochemical Engineering
• Wastewater Treatment

Background:

• Sulfide production is a common challenge in sulfate-reducing bioreactors (SRBs).
• Effective sulfide control is essential for optimizing SRB performance and preventing operational issues.
• Automated monitoring and control systems are needed for real-time management of bioreactors.

Purpose of the Study:

• To investigate sulfide responses in SRBs under varying organic loading rates (OLR).
• To develop parameters for a proportional-integral-derivative (PID) controller for sulfide management.
• To evaluate the effectiveness of a sulfide ion-selective electrode (pS) for bioreactor control.

Main Methods:

• Experiments were conducted in an inverse fluidized bed bioreactor with automated LabVIEW control.
• Step changes in organic loading rate were applied by altering influent chemical oxygen demand (CODin) or hydraulic retention time (HRT).
• Sulfide concentration was measured using a pS electrode to obtain data for PID controller parameter calculation.

Main Results:

• Increasing CODin concentration resulted in a rapid sulfide response and significant increment.
• Decreasing HRT led to a slower sulfide response with a smaller increment.
• The pS electrode response was time-varying and required correction for pH and high sulfide concentrations (>200 mg/L).

Conclusions:

• The pS electrode is an informative tool for monitoring and controlling sulfide levels in SRBs.
• Stepwise changes in CODin and HRT provide distinct sulfide responses useful for control strategy design.
• PID controller parameters can be effectively derived from pS electrode measurements for automated sulfide management.