Figure 1 shows the process for the recycling services in this study. This process is divided into the three unit processes: 1) Collection and Transportation; 2) Sorting; and 3) Compressing and Baling.

1) Collection and Transportation

The used beverage cans (aluminum cans and steel cans) and the waste papers (cardboard, magazine and newspaper) in the stock yards of companies and municipalities are collected and transported to the recycling service company by the collection vehicles.

2) Sorting

The collected cans (the mixture of aluminum cans and steel cans) are sorted by the permanent magnet of sorting machine in the recycling service company.

Regarding the waste papers, the collected waste papers are without the sorting process because those have been already sorted before the transportation.

3) Compressing and Baling

The sorted cans and papers are compressed and baled (as baled materials) by each machine. Regarding the baling for papers, the papers are bailed by the steel wire.

Figure 2 shows the major equipment (capital equipment) for this recycling service.

1) Collection and Transportation

• Collection vehicle: Figure 2(a)

Truck type: Cargo truck (Flat body truck and Garbage truck)

Maximum loading capacity: 2 ton

Fuel type: Diesel.

2) Sorting for aluminum cans and steel cans

• Sorting machine: Figure 2(b)

Sorting method: Permanent magnet

Carrying system: Belt conveyor system (by electric motor drive)

Motor power: total 2.7 kW.

3) Compressing and Baling

• Compressing machine for aluminum cans and steel cans: Figure 2(c)

Compression method: Oil hydraulic press (by electric motor drive)

Motor power: 2.2 kW

• Compressing and baling machine for cardboard, magazine and newspaper: Figure 2(d)

Compression method: Oil hydraulic press (by electric motor drive)

Motor power: total 41 kW.

Table 1 and Figure 3 show the baled size and weight of baled materials.

The system boundary for the recycling services includes the three unit processes: 1) collection and transportation, 2) sorting, and 3) compressing and baling), as shown in Figure 1. On the basic rules of “General Principles” and “Basic instructions” of CFP [7] [8] , the process 1), 2) and 3) correspond to (a) Raw material acquisition stage as 1) and (b) Production stage as 2) and 3), respectively,

and the baling process in this study is the end of system boundary in whole life cycle of the product system on the aforementioned basic rules [7] [8] .

The calculation method in this study was based on the rules of “Requirements for CFP-PCR” [9] , “Requirements for CFP quantification and declaration” [10] and the aforementioned principles and instructions of CFP [7] [8] . The amounts of GHG emissions were calculated in each process as referred to in Figure 1 and summed up according to the equation given below:

where _i stands for a process.

“Activity”, that is to be multiplied by GHG emission factor, e.g. the amounts of material consumption (unit: kg or ton), electricity consumption (unit: kWh) and fuel consumption (unit: kg or liter) for production and transportation processes, etc. Each GHG emission factor was based on rules and requirements of the CFP Communication Program [11] [12] [13] and quoted from “Basic secondary data” of the CFP Communication Program [14] , e.g. GHG emission factor to produce material per kilogram (unit: kg-GHG/kg-material), GHG emission factor to generate electricity per kilowatt hour (kWh) (unit: GHG/ kWh) and GHG emission factor to burn fuel per liter (unit: kg-GHG/liter-fuel in this study).

In this study, the each GHG emission per kilogram-baled material (unit: g- CO₂e/kg-baled material) was calculated as the functional unit in each process, and the data collecting time of the inputs in each process is one year.

Regarding the estimation of the amounts of GHG emissions from the capital equipment (e.g. collection vehicles, sorting machine, compressing machine and baling machine), the calculation method was based on the scenario of aforementioned PCR [6] , the basic rules and the requirements of CFP [7] [8] [9] [10] , in addition, the calculation process was divided into two categories (1: Raw materials of capital equipment, and 2: Manufacture (processing and assembling) of capital equipment), and the amount of GHG emission per one year (i.e. the data collecting time) from each capital equipment was calculated by dividing the used years of each capital equipment.

Regarding the allocation of the amount of GHG emission from the capital equipment, the amounts of fuel consumptions of collection vehicles, electricity consumptions of sorting machine and compressing and baling machine were allocated by the weight of each baled material.

Table 2 shows the CFP of each recycling process. In all recycling cases, the amounts of GHG emissions (as g-CO₂e emission per 1 kg of the baled material) from the collection and transportation process were the largest and accounted for approximately 89% - 94% of the total amounts of GHG emissions, and those of the compressing and baling process and the sorting process followed and accounted for approximately 3% - 11% and 3% (excluding the amounts of GHG emissions for papers) of the total amounts of GHG emissions, respectively. The reason that the collection and transportation process emits the largest amounts of GHG emissions is that the collection vehicles (trucks) consume the large amounts of diesel fuel and expendable supplies (e.g. tires, engine oil, repair parts and miscellaneous expendable parts). The amounts of GHG emissions from the collection and transportation process and expendable supplies accounted for approximately 68% - 90% and 10% - 32% of the amounts of GHG emissions from the collection and transportation process, respectively.

Regarding the difference of the amounts of GHG emissions of cans and papers in the collection and transportation process, the amounts of GHG emissions of the baled cans are approximately 1.5 - 2.1 times as large as in comparison with those of papers. This is due to the difference of transport efficiency of cans and papers (i.e., the papers usually have been already sorted and packed, and the bulk densities of papers are higher than those of cans).

Table 3 shows the CFP of capital equipment of each recycling process. In all recycling cases, the amounts of GHG emissions from the collection vehicles in the collection and transportation process were the largest and accounted for approximately 78% - 89% of the total amounts of GHG emissions, and those of the

sorting process and the compressing and baling process accounted for approximately 13% - 15% (excluding the amounts of GHG emissions of papers) and 7% - 17% of the total amounts of GHG emissions, respectively.

Regarding the amounts of GHG emissions from the trucks as the collection vehicles in the capital equipment were largest, this is because the trucks require various raw materials, parts and manufacturing processes in comparison with those of the sorting machine and compressing and baling machines, and the amounts of GHG emissions from the manufacturing processes are larger than those of raw materials of the total amounts of GHG emissions from the collection vehicles and accounted for approximately 55% of the total amounts of GHG emissions from the collection vehicles.

Table 4 shows the CFP of whole life cycle of each recycling service as one of LCA study. In all recycling cases, the amounts of GHG emissions from the collection and transportation process were the largest and accounted for approximately 75% - 81% of the total amounts of GHG emissions, and those of the capital equipment and the sorting, compressing and baling processes followed and accounted for approximately 13% - 18% and 5% - 9% of the total amounts of GHG emissions, respectively.

Regarding the amounts of GHG emissions from the capital equipment, the amounts of those GHG emissions have not been taken into account as the subject of calculation for industrial products and farm products because the amounts of those GHG emissions for various industrial products do not have a significant impact on a result of the total amounts of GHG emissions in general (i.e. the CFPs of capital equipment of industrial products and farm products are almost negligibly small.). However, it was found that the amounts of those GHG emissions in the recycling services had a large impact on a result of the total amounts of GHG emissions in this calculation.