Enhanced biogas production from penicillin bacterial residue by thermal-alkaline pretreatment

Figures & data

Table 1. Main properties of the inoculated anaerobic granular sludge and the penicillin bacterial residue.

Parameter	Anaerobic sludge	Penicillin bacterial residue
pH	7.28	−
TS	51.82 g/L	20.24 (wet, %)
VS	41.58 g/L	17.91 (wet, %)
SS	47.29 g/L	9.52 (wet, %)
VSS	24.62 g/L	90.73 (wet, %)
NH4^+−N	1187.77 mg/L	−
Fat	4.93 (dry, %)	6.86 (dry, %)
Kjeldahl nitrogen	26.17 (dry, %)	12.66 (dry, %)
SCOD	4113.04 mg/L	14.69 mg/g
TCOD	57182.61 mg/L	16.43 mg/g

Table 2. Orthogonal test factors and levels.

Levels	Factors
	Temperature (°C)	Alkali concentration (%)	Pretreatment time (min)	Moisture content (%)
1	25	2	30	85
2	70	4	60	90
3	100	6	120	95

Table 3. Scientific experimental conditions obtained from nine representative sample sets.

Set no.	1	2	3	4
	Temperature (°C)	Alkali concentration (%)	Pretreatment time (min)	Moisture content (%)
1	25	2	30	85
2	25	4	60	90
3	25	6	120	95
4	70	2	60	95
5	70	4	120	85
6	70	6	30	85
7	100	2	120	90
8	100	4	30	95
9	100	6	60	90

Figure 1. Change of SCOD solubilization and pH.

Note: Set no. with different conditions described in Table 3 (1–9).

Figure 2. Change of SS solubilization during the nine experiments with different conditions.

Note: Set no. with different conditions described in Table 3 (1–9).

Figure 3. Accumulated biogas production for 30 days at different pretreatment conditions and at conditions without pretreatment.

Note: Set no. with different conditions described in Table 3 (1–9).

Figure 4. Biogas production and methane production after 30 days at different pretreatment conditions.

Note: Set no. with different conditions described in Table 3 (1–9); Set no. 10 was the control group with no pretreatment.

Table 4. Performance data during the anaerobic process of the penicillin bacterial residue as feedstock at different pretreatment conditions.

Set no.	Design variable				Biogas production (mL/gVS)
	A Temperature (°C)	BAlkali concentration (%)	CPretreatment time (min)	DMoisture content (%)
1	25	2	30	85	205.7
2	25	4	60	90	198.1
3	25	6	120	95	136.9
4	70	2	60	95	170.7
5	70	4	120	85	126.5
6	70	6	30	85	267.5
7	100	2	120	90	83.4
8	100	4	30	95	145.2
9	100	6	60	90	249.6
K1	540.7	459.8	618.4	581.8
K2	564.7	469.8	618.4	549.0
K3	478.2	654.0	346.8	452.8
k1	180.2	153.3	206.1	193.9
k2	188.2	156.6	206.1	183.0
k3	159.4	218.0	115.6	150.9
R	86.5	194.2	271.6	129.0

Note: K is the total biogas production of each factor, and k is the average value of K. R is the extreme value, which represented the influence degree of the various factors in the anaerobic process. The larger the R value, the greater the degree of influence of the various factors in the anaerobic process.