High loading toluene treatment in a compost based biofilter using up-flow and down-flow swing operation

Area of Science:

• Environmental Engineering
• Biotechnology
• Air Pollution Control

Background:

• Industrial processes often release volatile organic compounds (VOCs) like toluene into the atmosphere.
• Conventional treatment methods can be costly or inefficient for high VOC concentrations.
• Biofiltration offers a sustainable and cost-effective alternative for VOC abatement.

Purpose of the Study:

• To evaluate the performance of a laboratory-scale compost/ceramic biofilter for treating high toluene vapor concentrations.
• To investigate the impact of different operational modes (up-flow and down-flow) on biofilter efficiency.
• To determine the maximum elimination capacity of the biofilter under varying toluene loading rates.

Main Methods:

• A three-section biofilter packed with a compost/ceramic mixture (1:1, v/v) was used.
• The biofilter was inoculated with acclimated activated sludge and operated continuously for 102 days.
• Gas flow rates varied from 0.108-0.15 m³/h, with inlet toluene concentrations ranging from 0.5-13 g/m³.
• The operational mode was periodically switched between down-flow and up-flow.

Main Results:

• Removal efficiencies ranged from 48% to 100%, with elimination capacities between 26 and 180 g/m³/h.
• A maximum elimination capacity of 180 g/m³/h was achieved at an inlet toluene concentration of approximately 13 g/m³.
• Periodic switching of the operational mode (up-flow and down-flow) improved biofilter performance, especially at high toluene concentrations (> 4 g/m³).

Conclusions:

• Compost/ceramic biofilters are capable of treating high concentrations of toluene vapors, exceeding typical literature findings.
• Optimizing operational modes is crucial for maximizing biofilter efficiency in treating challenging VOC streams.
• This study supports the potential of biofiltration for industrial-scale air pollution control of high VOC loads.