Parameter estimation

Treatment

Electric power of the FWDM [29]

· Energy consumption of the FWDM per ton of food waste: 3481 kWh (= 55 kWh/household/month ÷ 0.0158 ton/month/household).

· Cost to purchase the FWDM per ton of food waste: 154 USD/ton (= 295 USD/10 years ÷ 1.92 ton/10 years).

· The electric charges of the FWDM per ton of food waste: 192 USD/ton (= 3481 kWh × 0.0551 USD/kWh).

Electric power of the FWD [29]

· Energy consumption of the FWD per ton of food waste: 95 kWh (= 1.5 kWh/household/month ÷ 0.0158 ton/household/month).

· Cost to purchase the FWD per ton of food waste: 380 USD (= 730 USD/10 years ÷ 1.92 ton/10 years).

· The electric charges of the FWD per ton of food waste: 5.2 USD (= 95 kWh × 0.0551 USD/kWh).

Water use of the FWD [13]

· Water consumption of the FWD per ton of food waste: 27 m³ (= 0.12 m³/month/p × 3.5 p/household ÷ 0.0158 ton/household /month).

· Rate of water for the FWD per ton of food waste: 8.6 USD (= 27 m³ × 0.32 USD/m³).

Electric power of pretreatment facilities [29]

· Conditions of the facilities: For the quality standards of discharge water, BOD is less than 100 mg/L, SS is less than 300 mg/L, n-Hexane is less than 300 mg/L. The treatment capacity is 400 households and the quantity of discharge water per day is 49 m³. The construction cost is 206 thousand USD (erection of frameworks is 86 thousand USD, the equipment work is 120 thousand USD, this is just used for treatment of food waste by using the combined treatment plant of food waste and human excrement). The persisting period is 10 years and the annual quantity to treat food waste is 0.192 tons.

· Energy consumption of the pretreatment: 688 kWh(= 4350 kWh/month ÷ 400 household ÷ 0.0158 ton/household /month).

· Construction cost per ton of food waste: 268 USD (= 206 thousand USD ÷ 400 household ÷ 1.92 ton/household/10 years).

· Electricity cost per ton of food waste: 38 USD (= 688 kWh × 0.0551 USD/kWh).

· Maintenance cost per ton of food waste: 47 USD (= 300 USD/month ÷ 400 household ÷ 0.0158 ton/household/month).

Electric power of the aerobic compositing facilities

· Electric energy consumption per ton of food waste: 111.7 kWh [29] .

· Treatment cost per ton of food waste: 80 USD [18] .

Electric power of the public WWTP [29]

· Energy consumption per ton of food waste (sludge treatment, supply of air): 10.3 kWh.

· Cost per ton of food waste (sludge treatment, supply of air): 15 USD.

· 1 kWh/ton-food waste was applied in treatment (supply of air only in the inflow part) of the pretreatment facilities.

· 1.5 USD/ton-food waste was applied in treatment (supply of air only in the inflow part) of the pretreatment facilities.

· 1.5 USD/ton-food waste was applied in treatment (supply of air only in the inflow part, the inflow part of human excrement was ignored) of the biogas facilities.

Generation of methane gas in a septic tank

· The conditions of calculation: The amount of human excrement per person per day: 100 g, The amount of human excrement per population (6667 persons, equivalent of 1 ton of food waste generation): 0.6667 ton (= 0.7 ton).

· Generation of methane gas per population (6667 persons): 7.054 kg (= 1.058 g/person/day × 6667 person/ton-food waste ÷ 1000 g/ton).

· The emissions of methane gas to the air was ignored by forcibly collecting methane gas when 1 ton of food waste and 0.7 ton of human excrement (= mixture 1.7 tons) were combined and treated.