Table 2. Performance of self-recovery and recovered sludge by various strategies, with the colors ranging from the high performances in dark red to low performance in light red.

Strategies	Initial pH	Final pH	Methane yield (mL-CH4/ g-VS added)	Methane Production rate (mL-CH4/d)	kH (d−1)	Lag phase (d)	Recovery time (d)
Self-recovery	5.7	7.8	209	40.8	0.005	21.2	49.4
Dilution with TW 9:1	6.2	7.3	190	42.7	0.007	15.1	41.7
Dilution with TW 8:2	6.3	7.4	187	40.6	0.006	12.4	39.2
Dilution with TW 7:3	6.3	7.4	178	46.0	0.007	14.3	38.1
Dilution with TW 6:4	6.5	7.5	173	46.4	0.007	10.9	36.5
Dilution with TW 5:5	6.5	7.5	177	62.5	0.006	9.9	33.2
Dilution with BE 9:1	6.7	7.3	214	53.4	0.008	12.3	42.0
Dilution with BE 8:2	6.8	7.4	282	91.4	0.009	7.1	36.4
Dilution with BE 7:3	6.9	7.5	253	108.0	0.008	7.7	30.8
Dilution with BE 6:4	6.5	7.6	229	100.4	0.009	7.2	31.2
Dilution with BE 5:5	6.5	7.8	230	92.8	0.008	9.9	32.8
0.10%w/v NaOH	6.5	8.6	218	85.9	0.007	9.5	30.8
0.11%w/v NaOH	6.6	8.8	238	87.3	0.007	9.5	30.0
0.12%w/v NaOH	6.8	8.8	278	87.0	0.006	8.9	35.0
0.13%w/v NaOH	7.0	8.2	263	85.9	0.006	9.1	34.1
0.14%w/v NaOH	7.3	8.5	383	111.7	0.006	9.0	35.0
0.85%w/v NaHCO3	6.7	7.2	223	31.8	0.004	14.0	45.8
1.00%w/v NaHCO3	6.8	7.3	224	24.2	0.004	14.0	58.8
1.25%w/v NaHCO3	6.9	7.5	268	27.2	0.005	14.0	61.6
1.45%w/v NaHCO3	6.9	7.6	168	20.8	0.004	16.0	58.5
1.50%w/v NaHCO3	7.0	7.7	158	22.0	0.004	16.0	53.4
0.10%w/v Ca(OH)2	6.7	8.1	319	103.8	0.008	7.6	36.7
0.20%w/v Ca(OH)2	6.8	8.1	333	129.5	0.007	9.0	35.3
0.30%w/v Ca(OH)2	6.8	8.0	368	112.0	0.007	8.3	35.3
0.40%w/v Ca(OH)2	7.0	8.3	373	151.4	0.008	9.1	33.8
0.50%w/v Ca(OH)2	7.1	8.6	360	137.7	0.006	9.4	33.9
6.00%w/v Oil palm ash	6.5	7.5	239	155.4	0.007	7.9	33.2
7.00%w/v Oil palm ash	6.9	7.8	265	155.2	0.006	8.6	32.1
8.00%w/v Oil palm ash	6.9	8.0	347	226.3	0.007	8.2	32.4
9.00%w/v Oil palm ash	6.9	8.3	218	147.5	0.006	9.2	33.0
10.00%w/v Oil palm ash	6.9	8.7	211	152.2	0.006	9.1	32.5