Figure 1.
Schematic diagram of the laboratory-scale biofilter.
Each biofilter comprised a central cylinder with an inner diameter of 15(i.e. above the bottom cap), a stainless steel screen (1 cm-mesh size) was inserted as a support for the coal bed. A thermocouple was inserted through the side of the cylinder for monitoring the temperature within the centre of the packing. The biofilter temperature was maintained by continuously circulating heated water through a tube coiled around the central component of the biofilter. The temperature of the heating water reservoir was adjusted so that the temperature within the biofilter was 30°C.
Table I.
Gas flow rates, corresponding empty bed residence times (EBRT) and equivalent methane inlet loads used during biofilter experiments.
Table II.
Parameters used to quantify biofilter performance.
Figure 2.
Effect of methane inlet load on the methane elimination capacity (A); and on the methane removal efficiency (B).
Biofilters were operated at 1% methane (v/v) in humidified air; 30°C; non-sterilised coal as packing material. Each data point is the mean of eight measurements during two weeks of steady state operation, with error bars representing the standard deviation.
Figure 3.
Carbon dioxide production rate (PCO2) in biofilter 1 (▪) and biofilter 2 (▴).
Biofilters were operated at 1% methane (v/v) in humidified air; 30°C; non-sterilized coal as packing material. Biofilter 1 was inoculated with M. sporium. Each data point is the mean of eight measurements during two weeks of steady state operation, with error bars representing the standard deviation.
Table III.
Carbon mass balances and estimated carbon accumulation rates (CACC) in the biofilters at varying methane inlet loads (IL).
Figure 4.
Rarefaction curve of unique sequences at 0.03 sequence identity cut-off for the 16S rRNA gene of the microbial communities of three replicates for biofilter 1 and 2.
Table IV.
Mean abundance of OTUs in biofilter 1 and 2 and their taxonomic assignment.
Table V.
Comparison of biofilter performance in the present work with biofiltration results from other studies at similar empty bed residence times (EBTR).