Optimization of a horizontal-flow biofilm reactor for the removal of methane at low temperatures

Figures & data

Figure 1. Schematic of the experimental setup; biofilm growth is supported on the surface and fustrums of the horizontal sheets.

Table 1. Flow and loading parameters for HFBR reactors

Parameter	Value
Air mixture flow rate (m^3/m^3 reactor volume/hr)	1.2
Air mixture flow rate (m^3/m^2 TPSA/hr)	0.6
Gas loading rate (g/m^3 reactor volume/hr)	8.6
Gas loading rate (g/m^2 TPSA/hr)	4.3
Average concentration (% volume CH4/volume air)	1.3
Empty bed retention time (EBRT, minutes)	50

Table 2. Composition of SWW (Odegaard and Rusten, 1980)

Component	SWW 1 (g/L)	SWW 2 (g/L)	SWW 3 (g/L)	SWW 4 (g/L)
Glucose	0.2	nil	0.2	nil
NaHCO3	0.13	0.13	0.13	0.13
Yeast extract	0.03	0.03	0.03	0.03
MgSO4·7H2O	0.05	0.05	0.05	0.05
Dried milk	0.12	nil	0.12	nil
FeSO4·7H2O	0.002	0.002	0.002	0.002
Urea	0.03	0.03	0.03	0.03
MnSO4·H2O	0.002	0.002	0.002	0.002
NH4Cl	0.06	0.06	0.06	nil
CaCl2·6H2O	0.003	0.003	0.003	0.003
Na2NPO4·12H2O	0.1	0.1	0.1	0.1
KHCO3	0.05	0.05	0.05	0.05
NaNO3	nil	nil	0.25	0.25

Table 3. Initial removal efficiency data for the CH₄ HFBR units

HFBR	Average Removal (%)	Maximum Removal (%)	Minimum Removal (%)	Number of Samples
HFBR 1	28.5 (5.1)	37.7	15.5	50
HFBR 2	34.3 (7.7)	48.6	18.6	50
HFBR 3	33.9 (5.4)	45.9	17.6	50
Overall average	32.2 (6.7)	48.6	15.5	50
Note: Standard deviations are given in parentheses.

Table 4. Removal efficiency data for each sampling region in CH₄ HFBR units

		HFBR 1		HFBR 2		HFBR 3
Region	Sheets	Average Discrete Removal (%)	Average Cumulative Removal (%)	Average Discrete Removal (%)	Average Cumulative Removal (%)	Average Discrete Removal (%)	Average Cumulative Removal (%)
1	1–4	1.03 (2.79)	1.03 (2.79)	0.66 (2.16)	0.66 (2.16)	0.88 (0.76)	0.88 (0.76)
2	5–12	3.79 (2.86)	4.83 (2.35)	5.26 (4.97)	5.90 (4.96)	9.23 (1.73)	10.02 (2.29)
3	13–21	6.65 (1.68)	11.16 (2.70)	6.22 (4.83)	11.93 (2.70)	6.51 (3.12)	15.88 (3.48)
4	22–30	8.22 (2.48)	18.46 (3.23)	8.46 (2.10)	19.38 (3.04)	8.31 (2.60)	22.84 (4.46)
5	31–40	4.77 (2.10)	22.36 (3.35)	5.19 (1.97)	23.55 (3.58)	7.33 (4.34)	28.42 (6.34)
6	41–50	5.95 (3.48)	26.98 (4.13)	8.04 (2.47)	29.67 (4.37)	8.04 (2.47)	33.66 (6.44)
7	51–60	3.92 (1.98)	28.50 (4.35)	9.92 (2.53)	34.30 (5.35)	1.10 (1.57)	33.90 (6.06)
Note: Standard deviations are given in parentheses.

Table 5. Removal efficiency data following modifications to feed

HFBR	Average Removal (%)	Maximum Removal (%)	Minimum Removal (%)	Number of Samples
HFBR 1	57.5 (16.1)	88.3	34.0	31
HFBR 2	49.0 (11.0)	74.8	28.8	31
HFBR 3	55.0 (6.60)	69.7	43.4	31
Note: Standard deviations are given in parentheses.

Figure 2. Removal efficiency data during Phase 1 and Phase 2 for (a) HFBR 1, (b) HFBR 2, and (c) HFBR 3.

Table 6. Carbon dioxide production for each HFBR unit

	CO2 Concentration (ppmv)			% Production
Sample	HFBR 1	HFBR 2	HFBR 3	HFBR 1	HFBR 2	HFBR 3
Influent	716	761	650
Effluent	10571	8079	5838	1376	962	798

Table 7. Carbon mass balance for each reactor

	HFBR 1			HFBR 2			HFBR 3
Carbon (C) Source	Influent C (mol/day)	Effluent C (mol/day)	C Used in Biomass Growth (mol/day)	Influent C (mol/day)	Effluent C (mol/day)	C Used in Biomass Growth (mol/day)	Influent C (mol/day)	Effluent C (mol/day)	C Used in Biomass Growth (mol/day)
CO2	0.0183	0.240		0.0192	0.16		0.015	0.141
CH4	0.264	0.046		0.2867	0.14		0.255	0.131
SWW^a	0.020	0.0042		0.0425	0.005		0.020	0.0083
Total	0.3023	0.29	0.0123	0.3484	0.305	0.0434	0.29	0.282	0.008
Note: ^aOnly biodegradable organic carbon was considered.

Figure 3. Relationship between CH₄ oxidation and CO₂ production for HFBRs 1, 2, and 3.

Table 8. Potential and in situ activity for each reactor

		HFBR 1		HFBR 2		HFBR 3
Sampling Port Location (In Situ, Sheet No.)	Biofilm Sampling Region (Potential)	Potential Activity (mol CH4/g VSS/day)	In Situ Activity (mol CH4/m^2 TPSA/day)	Potential Activity (mol CH4/g VSS/day)	In Situ Activity (mol CH4/m^2 TPSA/day)	Potential Activity (mol CH4/g VSS/day)	In Situ Activity (mol CH4/m^2 TPSA/day)
4	1–6	3.43	0.10	2.75	0.04	3.65	0.04
12	7–12	3.51	0.09	3.22	0.01	3.67	0.06
21	19–24	0.47	0.12	2.07	0.06	0.38	0.05
30	30–36	3.02	0.09	3.99	0.04	2.83	0.04
40	37–42	0.77	0.08	1.67	0.06	0.43	0.06

Odegaard , H. and Rusten , B. 1980 . “ Nitrogen removal in rotating biological contactors without the use of external carbon source ” . In Proceedings of the First National Symposium/Workshop On Rotating Biological Contactor Technology, Champion, PA, February 4–6, 1980 , Vol.2 , 1301 – 1317 . US Army Construction Engineering Research Laboratory .

 Google Scholar