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Table 1 The resource usage, waste generation, GHG emission, and land use of the Thai CSPP (per 1000 kg of starch). Three scenarios of starch production are (1) a factory without integrated biogas system, (2) a factory with integrated biogas installation using wastewater as a raw material, and (3) a factory with biogas system using both wastewater and cassava pulp as raw materials

From: Implementing circular economy concept by converting cassava pulp and wastewater to biogas for sustainable production in starch industry

 

Scenario 1

Scenario 2

Scenario 3

Resource usage

 Cassava root (kg dry basis)

1.56 × 103

1.56 × 103

1.56 × 103

 Fresh water (m3)

16.7

15.1

15.1

 Chemical (kg)

0.26

0.26

0.66

 Recycled water (m3)

0

1.57

4.45

 Biogas production (m3)

0

59.3

357.7

 Electricity from grid (kWh)

197.8

176.6

0

 Electricity from biogas (kWh)

0

21.2

197.8

 Fuel oil consumption (m3)

4.52 × 10−2

1.57 × 10−2

0

 Biogas for drying (m3)

0.0

64.5

98.8

Waste generation

 Wastewater to final open lagoons (m3)

19.2

14.7

17.6

 COD of wastewater to final open lagoons (g m−3)

12,200

715

715

 Cassava pulp (kg dry basis)

1.55 × 103

1.55 × 103

1.01 × 103

 Peel (kg dry basis)

50

50

50

 Rhizome (kg dry basis)

530

530

530

 Sand/soil (kg dry basis)

400

400

400

GHG emission

 Wastewater (kg CO2eq)

398.7

15.7

15.7

 Cassava pulp fermentation (kg CO2eq)

0.71

0.71

0.47

 Electricity consumption in biogas system (kg CO2eq)

0

0.15

19.93

 Electricity consumption in cassava starch production (kg CO2eq)

115.2

106.4

33.3

 Thermal consumption in biogas system (kg CO2eq)

0

0

3.00 × 10−3

 Thermal consumption in cassava starch production (kg CO2eq)

121.4

89.6

74.9

 Total (kg CO2eq)

636.0

212.6

144.3

 Land use (m2)

5.92 × 105

4.72 × 105

1.89 × 105