A biofilter for treating toluene vapors: performance evaluation and microbial counts behavior.

Area of Science:

• Environmental Engineering
• Biotechnology
• Chemical Engineering

Background:

• Volatile organic compounds (VOCs) like toluene pose environmental and health risks.
• Biofiltration is a promising technology for treating VOC-contaminated air streams.
• Efficient and cost-effective biofilter packing materials are crucial for successful VOC removal.

Purpose of the Study:

• To evaluate the efficacy of a lab-scale biofilter packed with mixed materials for toluene degradation.
• To determine the optimal empty bed residence times (EBRTs) and assess performance under varying inlet concentrations.
• To investigate the contribution of different packing layers and microbial activity to toluene elimination.

Main Methods:

• A lab-scale biofilter with mixed packing materials was operated under different EBRTs (148.3, 74.2, and 49.4 s).
• Inlet toluene concentrations ranged from 0.2 to 1.2 g/m³.
• Elimination capacity, carbon dioxide production, and microbial distribution were monitored.

Main Results:

• The biofilter achieved a maximum elimination capacity of 36.0 g/(m³ h) at an inlet loading rate of 45.9 g/(m³ h).
• The lower layer of the biofilter consistently demonstrated the highest elimination capacity.
• Toluene degradation correlated with carbon dioxide production and microbial population distribution.

Conclusions:

• Mixed packing materials are effective carriers for biofilter applications in toluene removal.
• The biofilter system exhibited a low pressure drop (< 84.9 Pa/m), indicating operational efficiency.
• This study supports the use of mixed packing materials for treating air streams contaminated with VOCs.