3.1 ZWI of Bali Province and its regencies/cities on pessimistic scheme
The ZWI of Bali Province and regencies/cities in Bali Province is calculated according to Eq. (1). The amount of waste generated that will be used in the calculation is equal to the "recycler" sector, as shown in Fig. 1, which is 128,087.48 tonnes yr− 1. The data regarding waste composition, both at sources and landfills, shown in Fig. 2 & Fig. 3.
The amount of recycled waste from the material flow analysis is used to calculate the ZWI in 2020. The waste generation is then projected according to population growth to calculate the ZWI in 2025. Under the pessimistic scheme, it is assumed that the percentage of recycled waste from managed generated waste is stagnant and constant at 24.53%. Efficiencies of virgin material substitution used in this calculation are the lowest in the range (Table 1) as Indonesia is categorized low in virgin material substitution management. The ZWI of Bali Province on pessimistic scheme year 2020 and year 2025 shown in Table 2 and Table 3.
Table 2
Zero Waste Index of Bali Province on Pessimistic Scheme (2020)
Waste management system
|
Waste category
|
Total waste managed (tonnes yr− 1)
|
Virgin Material Substitution
|
Energy substitution (GJLHV/tonnes)
|
GHG emission reduction (CO2e/tonnes)
|
Water saving (kL/tonnes)
|
Efficiency
|
Potential
|
Efficiency
|
Potential
|
Efficiency
|
Potential
|
Efficiency
|
Potential
|
Recycle
|
Paper
|
11,425.40
|
0.84
|
9,597.34
|
6.33
|
72,322.80
|
0.6
|
6,855.24
|
2.91
|
33,247.92
|
Glass
|
1,537.05
|
0.9
|
1,383.34
|
6.07
|
9,329.89
|
0.18
|
276.67
|
2.3
|
3,535.21
|
Metal
|
1,152.79
|
0.79
|
910.70
|
36.09
|
41,604.09
|
1.4
|
1,613.90
|
5.97
|
6,882.14
|
Plastic
|
20,109.73
|
0.9
|
18,098.76
|
38.81
|
780,458.79
|
0.95
|
19,104.25
|
-11.36
|
-228,446.58
|
Mixed waste
|
10,605.64
|
0.25
|
2,651.41
|
5
|
53,028.22
|
1.15
|
12,196.49
|
2
|
21,211.29
|
Composting
|
Organic
|
83,256.86
|
0.6
|
49,954.12
|
0.18
|
14,986.24
|
0.25
|
20,814.2155
|
0.44
|
36,633.02
|
Thermal process
|
Mixed waste
|
0.00
|
0
|
0.00
|
|
|
|
|
|
|
Landfill
|
Mixed waste
|
292,430.94
|
0
|
0
|
0
|
0
|
-0.42
|
-122,820.995
|
0
|
0
|
Total
|
822,542.84
|
|
70,865.63
|
|
833,727.24
|
|
-130,960.25
|
|
-108,909.71
|
ZWI
|
0.09
|
|
|
|
|
|
|
|
Table 3
Zero Waste Index of Bali Province on Pessimistic Scheme (2025)
Waste management system
|
Waste category
|
Total waste managed (tonnes yr− 1)
|
Virgin Material Substitution
|
Energy substitution (GJLHV/tonnes)
|
GHG emission reduction (CO2e/tonnes)
|
Water saving (kL/tonnes)
|
Efficiency
|
Potential
|
Efficiency
|
Potential
|
Efficiency
|
Potential
|
Efficiency
|
Potential
|
Recycle
|
Paper
|
11,425.40
|
0.84
|
9,597.34
|
6.33
|
72,322.80
|
0.6
|
6,855.24
|
2.91
|
33,247.92
|
Glass
|
1,537.05
|
0.9
|
1,383.34
|
6.07
|
9,329.89
|
0.18
|
276.67
|
2.3
|
3,535.21
|
Metal
|
1,152.79
|
0.79
|
910.70
|
36.09
|
41,604.09
|
1.4
|
1,613.90
|
5.97
|
6,882.14
|
Plastic
|
20,109.73
|
0.9
|
18,098.76
|
38.81
|
780,458.79
|
0.95
|
19,104.25
|
-11.36
|
-228,446.58
|
Mixed waste
|
10,605.64
|
0.25
|
2,651.41
|
5
|
53,028.22
|
1.15
|
12,196.49
|
2
|
21,211.29
|
Composting
|
Organic
|
83,256.86
|
0.6
|
49,954.12
|
0.18
|
14,986.24
|
0.25
|
20,814.2155
|
0.44
|
36,633.02
|
Thermal process
|
Mixed waste
|
0.00
|
0
|
0.00
|
0.0972
|
0
|
0.12
|
0
|
|
0
|
Landfill
|
Mixed waste
|
511,802.47
|
0
|
0
|
0
|
0
|
-0.42
|
-214,957.039
|
0
|
0
|
Total
|
914,259.51
|
|
82,595.67
|
|
971,730.03
|
|
-154,096.27
|
|
-126,937.00
|
ZWI
|
0.09
|
|
|
|
|
|
|
|
According to the material flow analysis, recycled waste comes from 3R transfer stations, informal collectors, and waste banks, with the percentage of collected recyclable waste being 2%, 8.44%, 8.36%, and 5.72%, respectively. It is logical to use the waste from recyclers to calculate the ZWI of Bali Province since the ZWI is calculated based on the waste category, which can be utilized as an alternative raw/ virgin material.
The ZWI value of Bali province in the existing condition scheme is obtained at 0.09 or 9%, meaning that from 100% of handled waste in Bali province, 9% of waste can be recycled and can be used as alternative virgin material. According to the ZWI value prediction in previous studies conducted by Zaman & Swapan (2016), Indonesia is estimated to be in the low ZWI category (0.06–0.10). Compared with the results obtained from the calculation, which is 0.09, this figure is in the range estimated by Zaman (2016). The predicted figure is the ZWI for Indonesia as a whole nation; in other words, this figure is the average index for all regions in Indonesia. As one of the provinces with a proper and developing waste management level, Bali Province is reasonable to have the ZWI slightly under the highest number in Indonesia's projected average ZWI.
Meanwhile, the ZWI of Bali Province based on the projection of 2025 is still the same as 2020. It means that, in 2025, the amount of substitute virgin materials recovered is still the same as in 2020. This result is expected as the percentage of recycled waste stays stagnant year to year, while the amount of generated waste increases each year.
There are 8 (eight) regencies and 1 (one) city in Bali Province: Denpasar City, Badung Regency, Gianyar Regency, Tabanan Regency, Jembrana Regency, Buleleng Regency, Klungkung Regency, Bangli Regency, and Karangasem Regency. Using a similar method with the Bali Province, the ZWI of each regency and city is calculated from 2020 and 2025, as shown in Table 4.
Table 4
Zero Waste Index of city/regencies in Bali Province on Existing Scheme
Location
|
Year 2020
|
Year 2025
|
Jembrana Regency
|
0.20
|
0.19
|
Karangasem Regency
|
0.13
|
0.12
|
Bangli Regency
|
0.13
|
0.13
|
Klungkung Regency
|
0.05
|
0.05
|
Buleleng Regency
|
0.02
|
0.02
|
Gianyar Regency
|
0.09
|
0.09
|
Tabanan Regency
|
0.10
|
0.09
|
Denpasar City
|
0.04
|
0.03
|
Badung Regency
|
0.10
|
0.09
|
Average
|
0.10
|
0.09
|
Bali Province
|
0.09
|
0.09
|
Calculations show that the ZWI of regencies/cities in Bali Province ranges from 0.02 to 0.2 in 2020 and 0.02 to 0.19 in 2025. There is no significant change in ZWI from 2020 to 2025. The Jembrana Regency holds the highest ZWI for both years, and the Buleleng regency holds the lowest ZWI for both years. The Jembrana regency has the highest percentage of recovered substitute virgin material and sold recyclables compared to other locations, which is 30.65% from the total waste generated, resulting in Jembrana Regency holding the highest ZWI in Bali Province. On the contrary, Buleleng Regency's substitute virgin material recovery and sold recyclables percentage is only 3.23%, the lowest compared to other locations, making it have the lowest ZWI among the regencies. The percentage of recovered substitute virgin materials is shown in Table 5.
Table 5
Recapitulation of solid waste data and zero waste index of regencies/city in Bali Province by 2020
No
|
Location
|
Waste generated (tonnes yr− 1)
|
Recovered substitute virgin materials (tonnes yr− 1)
|
Percentage of recovery (%)
|
ZWI
|
1
|
Jembrana
|
46,318.5
|
14,195.95
|
30.65
|
0.20
|
2
|
Karangasem
|
56,502
|
10,622.60
|
18.8
|
0.13
|
3
|
Bangli
|
30,399.755
|
6,478.02
|
21.31
|
0.13
|
4
|
Klungkung
|
32,371.485
|
2,682.40
|
8.29
|
0.05
|
5
|
Buleleng
|
113,252.565
|
3,655.84
|
3.23
|
0.02
|
6
|
Gianyar
|
65,846
|
9,283.90
|
14.1
|
0.09
|
7
|
Tabanan
|
64,751
|
8,789.57
|
13.57
|
0.10
|
8
|
Denpasar
|
270,311.7
|
15,708.50
|
5.81
|
0.04
|
9
|
Badung
|
142,802.6
|
23,090.27
|
16.17
|
0.10
|
10
|
Bali Province
|
822,542.84
|
109,896.80
|
13.36
|
0.09
|
In 2020, the average ZWI of regencies/cities in Bali Province was 0.1, similar to the ZWI of the Bali Province, which was 0.09. This similarity is expected as the waste data from Bali Province is the total of each regency/city. Aside from a similar value, ZWI figures for regencies/city and Bali Province on the pessimistic scheme stay the same, either stagnant or decreasing compared to the initial year.
Classified nations around the world according to each nation's respective ZWI. This study follows the same classification to classify each regency/city in Bali Province according to the ZWI in 2020 and 2025 (Fig. 4 and Fig. 5). According to the classification, regencies/cities in Bali Province are classified in very low ZWI (i.e., Denpasar City, Klungkung Regency, and Buleleng Regency), low ZWI (i.e., Gianyar Regency, Tabanan Regency, dan Badung Regency), and medium ZWI (i.e., Jembrana Regency, Karangasem Regency, and Bangli Regency). By using the ZWI value of each regencies/cities, some of the regencies in Bali Province is classified as low class and some other is classified as high class. However, it shows a different result if the ZWI from the Bali Province data is used, which is 0.09, which classifies the Bali Province as low class. This discrepancy shows a data gap between the government's level, which affects the region's classification into two different classifications.
The Sarbagita Regional landfill (also known as Suwung Landfill) is a landfill that serves four regions: Denpasar City, Badung Regency, Gianyar Regency, and Tabanan Regency. Waste generated from those four regions will be transported to the Suwung Landfill and reduces the possibility of collecting recyclable materials from the source. Although the recyclable collection is performed on the landfill by scavengers, it is not as easy as the collection performed from the lower level (e.g., transfer station, households, etc.) as the landfill waste is heavily mixed in enormous mass and volume. This issue affects the recycling performance in 4 (four) regions as it becomes harder to perform the collection for recyclable materials (only performed by waste banks and 3R transfer stations with low rate). In the end, it also lowered the value of ZWI, as shown in the ZWI classification; those four regions are classified as very low and low.
Besides ZWI, the energy substitution efficiency is also calculated on the scheme. The primary difference between ZWI and energy substitution is that ZWI sees waste as an alternative for raw/virgin materials to make products; meanwhile, the energy substitution calculation views waste as a potential source to produce energy. This is why thermal processes do not contribute to the ZWI calculation but contribute to determining the energy substitution efficiency (Table 1). There are 2 (two) applied cases for calculating energy substitution efficiency; (1) incinerator facilities are implemented in certain landfills in Bali Province, and (2) incinerator facilities are not implemented.
Incinerator facilities are planned to be implemented in Suwung Landfill following the Presidential Regulation no. 35/2018 regarding Acceleration of the Development of Waste Processing Installation into Electrical Energy based on Green Technology. The Suwung Landfill covers the area of Sarbagita (Denpasar City, Badung Regency, Gianyar Regency, and Tabanan Regency); therefore, it is assumed that the waste which the incinerator will process comes from the 4 (four) regions. Table 6 shows the value of energy substitute for 4 (four) regions or Suwung Landfill, with and without incinerator facilities.
Table 6
Comparison of energy efficiency substitution value in the pessimistic scheme
Location
|
Energy substitution value (GJLHV/tonnes)
|
Percentage of increase
|
Without incinerator
|
With incinerator
|
Denpasar City
|
154,302.35
|
164,812.07
|
6%
|
Badung Regency
|
226,812.30
|
232,364.47
|
2%
|
Gianyar Regency
|
77,288.20
|
79,848.29
|
3%
|
Tabanan Regency
|
100,320.09
|
102,837.61
|
2%
|
Average
|
139,680.73
|
144,965.61
|
4%
|
Bali Province
|
971,730.03
|
1007,208.03
|
4%
|
The result shows energy substitution from 4 (four) regions without an incinerator, ranging from 77,288.20 to 226,812.30 GJLHV/tonnes with an average value of 139,680.73 GJLHV/tonnes. Projection with incinerator shows a range increase and becomes 79,848.29 to 232,364.47 GJLHV/tonnes with an average value of 144,965.61 GJLHV/tonnes. The values show a significant increase in energy substitution by implementing the incinerator in this scheme—the percentage of increase ranging from 2% to 6% with an average value of 4%. As the highest percentage of increase, Denpasar city has promise for incinerator implementation. This is supported by the fact that Denpasar city is Bali’s capital that generates a larger amount of combustible waste than other locations. Meanwhile, the recycling activities are not as potential in Denpasar City as most generated waste is transported to the Suwung Landfill. This makes the ZWI value of these regions low, but the energy substitution value high as there is a large amount of input waste and could be utilized in the landfill. The value of energy substitution will be discussed further on the comparison between the two schemes.
3.2 ZWI of Bali Province and its regencies using optimistic scheme
The optimistic scheme is a scheme based on the waste management targets in Jakstrada documents by 2025. The existing and projected data of waste generation in Jakstrada from each regency/city in Bali Province is used, assuming there is no change in data composition, both at sources and landfills. ZWI calculation is the same as the pessimistic scheme from 2020 to 2025 and compared between 2020 and 2025 shown in Table 7 and Table 8.
Table 7
Zero Waste Index of Bali Province on Optimistic Scheme (2020)
Waste management system
|
Waste category
|
Total waste managed (tonnes yr− 1)
|
Virgin Material Substitution
|
Energy substitution (GJLHV/tonnes)
|
GHG emission reduction (CO2e/tonnes)
|
Water saving (kL/tonnes)
|
Efficiency
|
Potential
|
Efficiency
|
Potential
|
Efficiency
|
Potential
|
Efficiency
|
Potential
|
Recycle
|
Paper
|
9,880.62
|
0.84
|
8,299.72
|
6.33
|
62,544.31
|
0.6
|
5,928.37
|
2.91
|
28,752.60
|
Glass
|
1,329.23
|
0.9
|
1,196.31
|
6.07
|
8,068.43
|
0.18
|
239.26
|
2.3
|
3,057.23
|
Metal
|
996.92
|
0.79
|
787.57
|
36.09
|
35,978.96
|
1.4
|
1,395.69
|
5.97
|
5,951.63
|
Plastic
|
17,390.77
|
0.9
|
15,651.70
|
38.81
|
674,935.90
|
0.95
|
16,521.23
|
-11.36
|
-197,559.18
|
Mixed waste
|
9,171.69
|
0.25
|
2,292.92
|
5
|
45,858.47
|
1.15
|
10,547.45
|
2
|
18,343.39
|
Composting
|
Organic
|
30,040.43
|
0.6
|
18,024.26
|
0.18
|
5,407.28
|
0.25
|
7,510.11
|
0.44
|
13,217.79
|
Thermal process
|
Mixed waste
|
985.50
|
0
|
0.00
|
|
|
|
|
|
|
Landfill
|
Mixed waste
|
372,188
|
0
|
0
|
0
|
0
|
-0.42
|
-156,319.15
|
0
|
0
|
Total
|
962,475
|
|
46,252.47
|
|
832,793.35
|
|
-114,177.03
|
|
-128,236.54
|
ZWI
|
0.05
|
|
|
|
|
|
|
|
|
Table 8
Zero Waste Index of Bali Province on Optimistic Scheme (2025)
Waste management system
|
Waste category
|
Total waste managed (tonnes yr− 1)
|
Virgin Material Substitution
|
Energy substitution (GJLHV/tonnes)
|
GHG emission reduction (CO2e/tonnes)
|
Water saving (kL/tonnes)
|
Efficiency
|
Potential
|
Efficiency
|
Potential
|
Efficiency
|
Potential
|
Efficiency
|
Potential
|
Recycle
|
Paper
|
17,796.80
|
0.84
|
14,949.32
|
6.33
|
112,653.77
|
0.6
|
10,678.08
|
2.91
|
51,788.70
|
Glass
|
2,394.19
|
0.9
|
2,154.77
|
6.07
|
14,532.73
|
0.18
|
430.95
|
2.3
|
5,506.63
|
Metal
|
1,795.64
|
0.79
|
1,418.56
|
36.09
|
64,804.71
|
1.4
|
2,513.90
|
5.97
|
10,719.98
|
Plastic
|
31,323.97
|
0.9
|
28,191.57
|
38.81
|
1,215,683.3
|
0.95
|
29,757.77
|
-11.36
|
-355,840.31
|
Mixed waste
|
16,519.90
|
0.25
|
4,129.98
|
5
|
82,599.52
|
1.15
|
18,997.89
|
2
|
33,039.81
|
Composting
|
Organic
|
30,040.43
|
0.6
|
18,024.26
|
0.18
|
5,407.28
|
0.25
|
7,510.11
|
0.44
|
13,217.79
|
Thermal process
|
Mixed waste
|
985.50
|
0
|
0.00
|
|
|
|
|
|
|
Landfill
|
Mixed waste
|
28,0663
|
0
|
0
|
0
|
0
|
-0.42
|
-117,878.7
|
0
|
0
|
Total
|
1,042,941
|
Total
|
68,868.45
|
|
1,495,681.30
|
|
-47,989.95
|
|
-241,567.40
|
ZWI
|
0.07
|
|
|
|
|
|
|
|
|
The ZWI calculation in 2020 is 0.05 or 5% and 0.07 or 7% in 2025. With this scheme, there is an increase of 2% for ZWI in Bali Province in 5 (five) years. This increase follows the assumption that the targets of Jakstrada are achieved (30% reduction and 70% handling). It is also assumed that 30% of total waste generation is successfully recycled to be virgin material in 2025. Thus, there is an increase in the value of ZWI. Same as Bali Province, ZWI for each regency/city also increases, as shown in Table 9.
Table 9
Yearly Zero Waste Index of Bali Province
Location
|
Yearly Zero Waste Index
|
Year 2020
|
Year 2021
|
Year 2022
|
Year 2023
|
Year 2024
|
Year 2025
|
Denpasar City
|
0.02
|
0.01
|
0.03
|
0.03
|
0.03
|
0.03
|
Badung Regency
|
0.04
|
0.11
|
0.06
|
0.07
|
0.07
|
0.18
|
Gianyar Regency
|
0.06
|
0.11
|
0.08
|
0.08
|
0.09
|
0.10
|
Tabanan Regency
|
0.20
|
0.22
|
0.19
|
0.18
|
0.19
|
0.18
|
Klungkung Regency
|
0.11
|
0.14
|
0.13
|
0.13
|
0.13
|
0.11
|
Bangli Regency
|
0.004
|
0.01
|
0.005
|
0.01
|
0.01
|
0.01
|
Karangasem Regency
|
0.01
|
0.01
|
0.01
|
0.01
|
0.01
|
0.01
|
Jembrana Regency
|
0.07
|
0.09
|
0.06
|
0.10
|
0.11
|
0.13
|
Buleleng Regency
|
0.04
|
0.04
|
0.04
|
0.05
|
0.05
|
0.07
|
Average
|
0.06
|
0.08
|
0.07
|
0.07
|
0.08
|
0.09
|
Bali Province
|
0.05
|
0.05
|
0.05
|
0.06
|
0.06
|
0.07
|
The ZWI average of the regencies/cities is not too different from the ZWI in Bali Province, which is still in the very low ZWI class and low ZWI class. Table 9 also shows a decrease in ZWI value in certain years in each location (i.e., Denpasar city from 2020 to 2021, Badung Regency from 2021 to 2022, Gianyar Regency from 2021 to 2022, etc.). The ZWI value decrease is caused by the increasing amount of waste generation but not followed by an increase in waste management capacity for reduction or recycling. Therefore, instead of reduction or recycling, the increased waste will enter the landfill.
The calculations and time series graphs in Fig. 6 show that Bali’s regencies/cities’ ZWI value in the optimistic scheme ranges from 0.004 to 0.22. Tabanan Regency held the highest ZWI value, and Bangli Regency had the lowest ZWI value. In this scheme, Tabanan Regency has a high ZWI value because, based on Jakstrada data, this regency is making great use of existing recycling facilities, such as 3R transfer station, unit waste Bank, main waste bank, and even the waste recovered by scavengers at final processing is the highest compared to other regencies/cities. Waste composting in Tabanan Regency is also the highest in final processing compared to other regencies.
Meanwhile, Bangli Regency has a low ZWI value due to very few recycling and composting facilities based on Jakstrada data. Figure 7 and Fig. 8 also shows that Badung Regency has experienced an increase in ZWI’s value from 2024 to 2025. This increase is very rapid compared to other districts due to a large increase in the amount of waste recycled by the unit's waste bank sector. In 2024, it is targeted that the unit waste bank can manage 25.51 tonnes d− 1 of waste, but in 2025 the targeted amount of waste that can be recycled by the unit's waste bank sector is 110.2 tonnes d− 1 - a 4.32 times increase in just one year. Thus, the ZWI value of Badung Regency increased rapidly from 0.07 to 0.18 in just one year.
Referring to the ZWI value classification reported by Zaman and Swapan (2016), this scheme in the year 2025, the regencies/cities in Bali Province can be categorized into very low ZWI value (i.e., Denpasar City, Bangli Regency, Karangasem Regency), low ZWI value (Gianyar Regency and Buleleng Regency), and ZWI medium (i.e., Badung Regency, Klungkung Regency, Tabanan Regency, and Jembrana Regency). Based on the average ZWI value of regencies/cities in Bali Province, the ZWI value for Bali Province is in the low ZWI value. This scheme also shows the calculations of energy substitutions obtained from the two conditions, such as implementing and not implementing incinerator as shown in Table 10.
Table 10
Comparison of energy efficiency substitution value in the optimistic scheme
Location
|
Energy Substitution (GJLHV/tonnes)
|
Percentage of increase
|
With incinerator
|
Without incinerator
|
Denpasar City
|
889,338.658
|
877,757.7665
|
1%
|
Badung Regency
|
474,118.1727
|
467,944.2466
|
1%
|
Gianyar Regency
|
175,723.2949
|
173,029.6707
|
2%
|
Tabanan Regency
|
239,798.7215
|
239,798.7215
|
0%
|
Average
|
444,744.7118
|
439,632.6013
|
1%
|
Bali Province
|
2,116,274.862
|
2,080,796.862
|
2%
|
Incinerator usage contributes a higher energy substitution value than the condition without incinerator usage. However, the increase in value is not high, with only a maximum of 2%. This result was obtained because for the pessimistic scheme, the 3R approach is preferable to a thermal process like incineration. Thus, it causes less efficiency in incineration as the waste is expected to be successfully recovered into virgin materials through the 3R activities.
3.3 Comparison between ZWI of Bali Province on two schemes
The pattern of municipal waste management in Bali Province for both schemes is obtained after the ZWI calculation. The ZWI value between optimistic and pessimistic scheme from 2020 to 2025 will be compared to identify the changing pattern and achievement of the 3R based waste management in regencies/cities of Bali Province as shown in Fig. 9.
From the comparison, the average ZWI value of 2020 in pessimistic schemes is higher than the optimistic scheme. It happens because the data used for the pessimistic scheme is data from a previous study regarding material flow analysis in Bali Province; hence the data is closer to the actual practice done on the sites. Meanwhile, the data used for the optimistic scheme is data from Jakstrada documents which use a standardized per capita waste generation approach. Therefore, the data are less likely to represent the actual condition and more of a projection.
The average ZWI value of Bali Province in 2025 is the same for both schemes; however, further analysis shows a difference in the ZWI development pattern. Even though the initial ZWI is high in a pessimistic scheme, there is no improvement in ZWI value to 2025. This scheme assumes that there will be no change in waste management and recycling percentage for every location, hence no change in ZWI despite an annual increase in waste generation. On the other hand, optimistic schemes give a lower value of initial ZWI with a changing pattern from year to year for every location. According to the Jakstrada documents, the generated waste will be reduced to 30% by 2025 using 3R activities. This target affects the value of ZWI as it changes following the target of waste reduction by 3R activities in 2025. Therefore, the ZWI value is not affected by the initial data and waste generation rate used for the calculation, but it is affected by the increase of waste management utilizing the 3R or zero-waste-based activities. Nevertheless, it is still imperative to have a reliable and valid database to determine and evaluate the current condition of waste management.
Additionally, the energy substitution values between the two schemes are also compared. Both comparisons consider the case where the incinerator is applied and not applied in Sarbagita Regional Landfill/Suwung Landfill as shown in Table 11.
Table 11
Energy substitution between two schemes
Location
|
Energy Substitution (GJLHV/tonnes)
|
Optimistic scheme
|
Pessimistic scheme
|
With incinerator
|
Without incinerator
|
With incinerator
|
Without incinerator
|
Denpasar City
|
889,338.66
|
877,757.77
|
164,812.07
|
154,302.3512
|
Badung Regency
|
474,118.17
|
467,944.25
|
232,364.47
|
226,812.3019
|
Gianyar Regency
|
175,723.29
|
173,029.67
|
79,848.29
|
77,288.19743
|
Tabanan Regency
|
239,798.72
|
239,798.72
|
102,837.61
|
100,320.0869
|
Average
|
444,744.71
|
439,632.60
|
144,965.61
|
139,680.73
|
Bali Province
|
2,116,274.86
|
2,080,796.86
|
1,007,208.03
|
971,730.0312
|
The difference in energy values between the optimistic and pessimistic schemes occurs due to differences in the basic data used. In total, the optimistic scheme provides energy substitution values 2–5 times greater than the pessimistic scheme, but in terms of the efficiency of using incinerator technology, the pessimistic scheme provides a higher percentage than the optimistic scheme.
On the optimistic scheme with an increase in waste handling by recycling every year, incinerator technology contributes an increase of 1–2% compared to when not using an incinerator. Meanwhile, the use of technology in the pessimistic scheme contributes an increase of 2–6% compared to when not using an incinerator. Based on alternative energy use, the optimistic scheme is a better priority than the pessimistic scheme, but incinerator technology does not make a significant difference; therefore, the usage of more efficient alternatives needs to be considered.