Energy balancea
|
AD
|
Hydrolysis/detoxificationb
|
Fungal fermentationc
|
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Energy input (MJ/1000 kg dry mixed feed)
|
−1971.96d
|
−1593.48e
|
−9048.27f
|
Energy output (MJ/1000 kg dry mixed feed)
|
8450.00g
|
3830.80h
|
344.00i
|
Net energy (MJ/1000 kg dry mixed feed)
|
6478.04
|
2237.32
|
−8704.27
|
Overall net energy (MJ/1000 kg dry mixed feed)
|
11.09
|
- All inputs are assigned “−”, and all outputs are assigned “+”. The system includes AD, hydrolysis/detoxification, and fungal fermentation (Fig. 5)
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aData were calculated and adjusted based on 1000 kg dry mixed feed
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bHydrolysis/detoxification includes unit operations of pretreatment, enzymatic hydrolysis, and detoxification
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cThe fungal fermentation includes unit operations of fungal fermentation and biomass drying
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dThe energy input for the AD unit includes both heat and electricity, which is calculated from the data in Table 1
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eCompared to the pretreatment and enzymatic hydrolysis, the energy demand for the detoxification (under 50 °C and 5 h) is negligible. Thus, the energy consumption of 262 MJ/m3 reaction solution for the pretreatment and enzymatic hydrolysis was used for the calculation [25]. The energy input of the hydrolysis/detoxification is 1593.48 MJ/1000 kg dry mixed feed
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fThe energy input of the fungal fermentation operation is 10,286.67 MJ/1000 kg dry mixed feed according to the reference numbers of 1938.77 MJ/m3 fermentation broth and 1.99 MJ/kg wet biomass [25]. The amount of the fermentation broth is 4511 kg. The amount of the wet fungal biomass is 152 kg
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gThe energy output of the AD is the methane energy. Low heating value of methane of 50 MJ/kg methane was used for the calculation
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hThe lignin has a low heating value of 24.4 MJ/kg lignin. 157 kg lignin/1000 kg mixed feed was generated from the process
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iThe lipid as the product is used for biodiesel production. The lipid has a low heating value of 40.0 MJ/kg lipid