Prolonged operation of a methane biofilter from acclimation to the failure stage

ABSTRACT

Global warming needs immediate attention to reduce major greenhouse gas emissions such as methane (CH₄). Bio-oxidation of dilute CH₄ emissions in packed-bed bioreactors such as biofilters has been carried out over recent years at laboratory and large scales. However, a big challenge is to keep CH₄ biofilters running for a long period. In this study, a packed-bed lab-scale bioreactor with a specialized inorganic-based filter bed was successfully operated over four years for CH₄ elimination. The inoculation of the bioreactor was the active leachate of another CH₄ biofilter which resulted in a fast acclimation and removal efficiency (RE) reached 80% after seven weeks of operation for CH₄ inlet concentrations ranging from 700 to 800 ppmv and an empty bed residence time (EBRT) of 6 min. During four years of operation, the bioreactor often recorded REs higher than 65% for inlet concentrations in the range of 1900–2200 ppmv and an EBRT of 6 min. The rate and interval of the nutrient supply played an important role in maintaining the bioreactor’s high performance over the long operation. Forced shutdowns were unavoidable during the 4-year operation and the bioreactor fully tolerated them with a partial recovery within one week and a progressive recovery over time. In the end, the bioreactor’s filter bed started to deteriorate due to a long shutdown of twelve weeks and the extended operation of four years when the RE dropped to below 8% with no sign of returning to its earlier performance.

GRAPHICAL ABSTRACT

KEYWORDS:

• Biofiltration
• methane
• long-term operation
• climate change
• nutrient starvation

Acknowledgments

M. Heitz and J.-P. Jones would like to acknowledge the Natural Sciences and Engineering Research Council of Canada (NSERC) (discovery grant) for the financial contribution to this study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available from the corresponding author, upon reasonable request.

Additional information

Funding

This work was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC).