Effects of biochar addition on the anaerobic digestion of carbohydrate-rich, protein-rich, and lipid-rich substrates

Figures & data

Table 1. Physicochemical properties of the raw sludge (RS) and sewage sludge derived biochar (SSB).

Parameter	RS	SSB
Moisture	77.9 ^a	4.8
Proximate analysis (ad, %)
Volatile matter	56.0 ^c	16.2
Ash	33.6 ^c	17.0
Fixed carbon	10.5 ^c, d	66.9
Ash composition analysis (%) ^b
Al2O3	11.3	23.0
SiO2	9.6	18.8
P2O5	5.3	16.5
Fe2O3	2.6	20.5
CaO	1.9	11.8
K2O	0.8	4.2
TiO2	0.2	1.3
SO3	0.2	2.0
ZnO	0.2	1.2
MnO	0.03	0.16
CuO	0.01	0.13
Cr2O3	0.01	0.17
PbO	0.004	0.03
pH	-	7.22 ± 0.04
BET-surface area (m^2 g^−1)	-	54.18 ± 1.03
Electrical conductivity (µS·cm^−1)	-	700 ± 20

Notes. ^aOn as-received basis.

^bOn dry basis.

^cOn moisture free basis.

^dDetermined by the difference (Fix carbon = 100% – Volatile matter – Ash).

Table 2. The characteristics of the inoculum, substrates in the batch experiment.

Parameter	Inoculum	Steamed Rice	Cooked Egg white	Cooked Lard
Total solids% ww	1.80	18.92	11.89	72.96
Volatile solids% ww	1.15	18.88	11.49	72.81
VS/TS%	63.83	99.77	96.68	99.79
Moisture% ww	98.20	81.08	88.11	27.04
Total carbohydrate*	-	89%	6%	0%
Protein*	-	9%	91%	0%
Total fat*	-	2%	3%	100%

Notes. *(U.S. Department of Agriculture 2019).

Figure 1. The change of (a) cumulative methane yield; (b) pH, (c) VFAs in C-SSB, and (d) VFAs in C-control.

Figure 2. The comparison of (a) bacteria at the phylum level and (b) archaea at the genus level among the inoculum, C-SSB, and C-control in the early (e), and final (f) stages.

Figure 3. The change of (a) cumulative methane yield, (b) pH, (c) VFAs in P-SSB, and (d) VFAs in P-control.

Figure 4. (a) Methane generation rate and (b) ammonia-nitrogen concentration in P-SSB and P-control.

Figure 5. The comparison of (a) bacteria at the phylum level and (b) archaea at the genus level among the inoculum, P-SSB, and P-control in the early (e), and final (f) stages.

Figure 6. The change of (a) cumulative methane yield, (b) pH; (c) VFAs in L-SSB, and (d) VFAs in L-control.

Figure 7. The comparison of (a) bacteria at the phylum level and (b) archaea at the genus level among the inoculum, L-SSB, and L-control in the early (e), and final (f) stages.

U.S. Department of Agriculture, Agricultural Research Service. 2019. Accessed March 1, 2019. https://ndb.nal.usda.gov/

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