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Table 2 Energy analysis of EOP with mesophilic anaerobic digestion compared to other pre-treatment methods,

From: Efficiency of integrated electrooxidation and anaerobic digestion of waste activated sludge

Pre-treatment method (conditions) Energy consumptiona BMPc, in L-N CH4 (kWh) per kg VS
Pre-treatment (kWh/kg VS) Electricityb (kWh/kg VS) Thermal energyb (kWh/kg VS) Total, (kWh/kg VS)
Non-pretreatment 0.29 0.50 0.79 190 (2.09)
Thermal hydrolysis (170 °C for 15–30 min) 0.94 0.29 0.50 1.73 291 (3.20)
Sonication (100 W, 16 s, 30 kW m−3) 0.37 0.29 0.50 1.16 241 (2.65)
Ball milling 1.04 0.29 0.50 1.83 241 (2.65)
High pressure (200 bar) 0.33 0.29 0.50 1.12 261 (2.87)
Present study, EOP at: 14.3 A m−2, 30 min 0.25 0.29 0.50 1.03 251 (2.76)
21.4 A m−2, 30 min 0.38 0.29 0.50 1.17 305 (3.36)
28.6 A m−2, 30 min 0.51 0.29 0.50 1.30 312 (3.43)
  1. aAnalysis assumes a hydraulic retention time of 16 days for mesophilic anaerobic digestion and the energy consumption as pre-treatment, electricity and thermal energy is considered
  2. bDetails on electrical and thermal energy calculations are in section (a) of the Additional file 1, and details on energy consumption by the EOP is provided in the Additional file 2
  3. cA simple mathematical correlation representing a calorific value of 11 kWh N-m−3 CH4 was set, this value was obtained from the conversion of the methane energy molar in temperature (0 °C) and atmospheric pressure (1 atm) standard conditions, section (b) of the Additional file 1