Microbial transformations by sulfur bacteria can recover value from phosphogypsum: A global problem and a possible...

Area of Science:

• Environmental microbiology
• Biotechnology
• Chemical engineering

Background:

• Growing global population increases demand for food and phosphorus fertilizers.
• Phosphogypsum (PG) is a major byproduct of phosphoric acid production, with low current recycling rates (~15%).
• Effective management of phosphogypsum is crucial for sustainable resource utilization.

Purpose of the Study:

• To review microbial valorization strategies for phosphogypsum (PG).
• To focus on recovering elemental sulfur (S0) from PG using sulfur-transforming bacteria.
• To provide understanding of the microbiological, chemical, and technological aspects of S0 recovery from PG.

Main Methods:

• Utilizing sulfate-reducing bacteria (SRB) for sulfate reduction to sulfide.
• Employing sulfur-oxidizing bacteria (SOB) for sulfide oxidation to elemental sulfur (S0).
• Discussing key factors: electron donors for SRB, oxygen control for SOB, and nutrient requirements.

Main Results:

• Microbial reclamation of S0 from PG is feasible through SRB and SOB processes.
• Efficiency of these bacterial processes has been demonstrated at laboratory and industrial scales.
• Elemental sulfur (S0) recovery enables its use in sulfuric acid production for phosphoric acid manufacturing.

Conclusions:

• Microbial valorization of PG presents a promising biotechnological approach for waste management.
• Further advancements in SRB and SOB technologies can enhance S0 recovery efficiency.
• This strategy contributes to a circular economy by recovering valuable resources from industrial byproducts.