Determinants on an efficient cellulase recycling process for the production of bioethanol from recycled paper sludge under high solid loadings

Table 5 Multiple rounds of nRPS hydrolysis with cellulase recycling (20 FPU/g cellulose; 50% fresh enzymes)

Round	Glucose₁₂₀ (g/L)^a	Ethanol₂₃ (g/L)^b	Glucan conversion (%)
1	50.14 ± 0.55	25.86 ± 0.67	80.68 ± 0.44
2 (recycling 1)	41.86 ± 1.06	20.94 ± 0.85	70.55 ± 1.34
3 (recycling 2)	42.31 ± 0.76	21.39 ± 0.08	70.26 ± 0.13
4 (recycling 3)	40.74 ± 0.36	20.28 ± 0.15	70.18 ± 0.35

Hydrolysis was conducted for 120 h (40 °C) followed 24 h of fermentation (35 °C)
^aGlucose produced at 120 h of hydrolysis
^bEthanol produced at 23 h of fermentation

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