Treatment of hydrophobic VOCs in trickling bed air biofilter: Emphasis on long-term effect of initial alternate use of hydrophilic VOCs and microbial species evolution

Figures & data

Figure 1. Schematic of the TBAB.

Table 1. Operating conditions and performance for TBABs A and B degrading n-hexane at pH 4

	n-Hexane
	TBAB A				TBAB B
Experimental conditions	I	II	III	IV	I	II	III	IV
Inlet concentration (ppmv)	203	300	400	450	203	300	400	450
Loading rate, g m^−3 hr^−1	21.1	31	41.5	47.7	21.1	31	41.5	47.7
Biomass control strategy	S + FS	S + FS	S + FS	S + FS	S + FS	S + FS	S + FS	S + FS
Operating conditions
Day of operation	1–56	57–89	90–131	132–188	1–56	57–89	90–131	132–188
Average removal efficiency (%)	87.1	88.5	82.5	83.2	89.8	90.0	82.8	84.0
Standard deviation (%)	3.7	3.3	1.6	2.5	3.0	3.9	4.3	2.0
Elimination capacity, g m^−3 hr^−1	18.4	27.4	34.2	39.7	18.9	27.9	34.4	40.1
Standard deviation, g m^−3 hr^−1	0.8	1.0	0.7	1.2	0.6	1.2	1.8	1.0

Notes: TBABs A and B previously received methanol to n-hexane of 3:1 and 5:1, respectively. S: stagnation, FS: flow switching.

Figure 2. Performance of TBAB A with time for degrading n-hexane at pH4.

Figure 3. Performance of TBAB B with time for degrading n-hexane at pH 4.

Table 2. Operating conditions and performance for TBABs C and D degrading n-hexane at pH 7

	n-Hexane
	TBAB C			TBAB D
Experimental conditions	I	II	III	I	II	III
Inlet concentration (ppmv)	203	300	400	203	300	400
Loading rate, g m^−3 hr^−1	21.1	31	36.3	21.1	31	36.3
Biomass control strategy	S + FS	S + FS	S + FS	S + FS	S + FS	S + FS
Operating conditions
Day of operation	1–56	57–121	122–178	1–56	57–121	122–178
Average removal efficiency (%)	68.8	62.0	63.2	68.2	67.3	64.4
Standard deviation (%)	6.6	8.0	5.8	7.3	7.7	4.2
Elimination capacity, g m^−3 hr^−1	14.5	19.2	22.9	14.4	20.9	23.4
Standard deviation, g m^−3 hr^−1	1.4	2.5	2.1	1.5	2.4	1.5

Notes: TBABs C and D previously received methanol to n-hexane of 3:1 and 5:1, respectively. S: stagnation, FS: flow switching.

Figure 4. Performance of TBAB C with time for degrading n-hexane at pH 7.

Figure 5. Performance of TBAB D with time for degrading n-hexane at pH 7.

Figure 6. Overall n-hexane elimination capacities versus loading rates in all TBABs.

Figure 7. First-order removal rate constants for different n-hexane loading rates.

Table 3. Fungi species present within TBAB A and B at the start and the end of the experiment

TBAB	Period	Port number	Species	Accession number	Length (bp)	Identity (%)	Dominance (%)
TBAB A	Start	*H1	Fusarium solani	AB305107.1	671	100	61
			Aspergillus niger	AB305102.1	611	100	21
		**H2	Fusarium solani	AB305107.1	671	100	100
	End	H1	Gibberella moniliformis (Fusarium verticillioides)	AM946177.1	881	100	100
		H2
TBAB B	Start	H1	Fusarium solani	AB305107.1	671	100	65
			Aspergillus niger	AB305102.1	611	100	17
		H2	Fusarium solani	AB305107.1	671	100	100
	End	H1	Gibberella moniliformis (Fusarium verticillioides)	AM946177.1	884	100	100
		H2

Notes: *H1, first sampling port within the media.

**H2, last sampling port within the media.