Techno-Economic Analysis of Waste Processing Machines at the Jabon Sidoarjo TPA, Capacity 3 Tons/Hour for the Characteristics of Indonesian Waste Which has High Water Content, is Mixed and is Dominantly Organic

Abstract

The low awareness of the Indonesian people in sorting waste is indicated to be the main problem. It is believed that waste processing machines can be a short-term solution. However, the characteristics of mixed waste and moisture often make the machine fail to operate properly, even if it succeeds it often requires quite large costs and is not economically feasible. The waste processing machine examined in this research is claimed to be by the characteristics of Indonesian waste and economically feasible. This machine can convert waste into recycled raw materials and become Refuse Derived Fuel (RDF) as a renewable energy source. It is necessary to carry out a techno-economic analysis of the performance of the machine and the products produced

 

Keywords

Waste to energy; Indonesian waste; Renewable energy; Refuse derived fuel; Economically feasible

Introduction

Lack of awareness in sorting waste means that Indonesian people often mix any waste in the same plastic trash bag, and then throw it in the trash [1]. Be it diapers, sanitary napkins, kitchen waste, bones, food cans, fruit seeds and skins, used clothes, and often household B3 waste, metal waste and construction waste are also thrown in the same plastic trash bag. Mixing waste in one plastic bag creates a level of difficulty in waste processing in Indonesia. Waste processing machines are widely used in Indonesia, both from abroad and domestically [2]. Mixed types of waste, high water content and organic dominance often become obstacles for waste processing machines to operate properly. The high humidity is caused by the composition of waste in Indonesia being dominated by organic waste and the average waste bin in Indonesia is located in space opened without a cover and transported by truck with an open bed [3]. Apart from the characteristics of the waste, the low-cost allocation for processing waste is also a problem in itself [4]. So it is necessary to carry out a techno-economic analysis for the waste processing machine in this research, to ensure that the waste processing machine is suitable for the characteristics of the waste and that the resulting processed product can become recycled material and a source of new, renewable energy in the form of RDF [5]. Apart from that, the techno-economic analysis in this research will also measure whether processing waste using this machine is still feasible from an economic analysis [6]. The analysis in this research will also analyze whether the machine in this research can be operated at an affordable cost, with easy and cheap maintenance. The implementation of this research consists of 3 stages, namely: Analysis of how waste processing machines work, Analysis of processed results and economic analysis [7].

Materials and Methods

Composition of municipial solid waste

This research was conducted at TPA Jabon, Sidoarjo, East Java, Indonesia. By taking random samples from municipal solid waste and traditional market waste, the results obtained are as shown in the Figure 1.

Figure 1. Waste composition in Sidoarjo, Indonesia.

Waste processing machines work

The machine that will be analyzed in this research is a local Indonesian waste processing machine, which was installed at TPA Jabon, Sidoarjo, East Java, Indonesia [8]. At the Jabon TPA currently a machine has been installed to process waste into RDF on a scale of 2.5 tons/hour [9]. This waste processing machine has a domestic component level certificate for small industrial scale reaching 36% of the maximum value of 40% (Figure 2) [10].

Figure 2. Full set of waste processing machine with a capacity of 2 tonnes/hour.

Waste processing

As shown in Figure 2, the waste processing machine in this study uses a combination of several machines. In less than 24 hours, municipal waste material will be processed into RDF [11]. The longest process is the drying process of organic RDF material. For other processes 45 such as sorting and chopping, it takes no more than 1 hour, starting from municipal waste material to RDF material that is ready to be dried. Only the sorting recycle material process is carried out manually by humans, the other processes use machines [12]. All machines are locally made, original Indonesian products, the machine set in this research is divided into eight processing stages:

Open the plastic trash bag: It is the habit of Indonesian people to put all their waste into one plastic bag [13]. To make the sorting process easier, it is necessary to open the plastic bag using a bag opener machine so that the contents of the waste in the plastic can come out [14].

Manual sorting: This sorting process is carried out manually by humans, taking recycled materials that can be used as raw materials for the recycling industry is the main concern of workers [15]. Apart from that, workers will take hard materials larger than 50 mm which can damage the vertical chopper machine blades [16].

Separation of organic and inorganic materials (Stage I): At this stage, organic and inorganic waste will be separated using a Trommel screen machine with a filter size of 30 mm. Waste mixed with high moisture tends to clump [17]. To make the work of the trommel screen machine easier, the lumpy waste is first crushed using a vertical chopper machine, the resulting organic material composition still contains 20% inorganic material measuring less than 30 mm [18].

Separate hard materials that can damage the shredding machine blade: In this stage, hard materials that can damage the crusher blade are separated using a de-stoner machine, Because the hard materials being separated do not all come from metal, the separation process uses an air separator. The air source is blown using a centrifugal blower machine in Figure 3.

Figure 3. Destoner machine, using air separator.

Crusher of inorganic materials (plastic): The process of destroying inorganic materials depends on the off-taker’s request (customized). The crushed inorganic material is guaranteed to be safe for the crusher machine blade, because the hard material has been separated beforehand.

Drying of inorganic materials: The crushed inorganic material will be dried until the water content is below 25%. The drying process uses a vertical centrifugal dryer machine.

Drying organic materials: Organic material that is still mixed with 20% inorganic material will be dried until the water content is below 25%. The drying process uses a spinner machine which works similar to a tub washing machine dryer, and also uses a rotary dryer with a heat source using a burner.

Drying organic materials: Organic material that is still mixed with 20% inorganic material will be dried until the water content is below 25%. The drying process uses a spinner machine which works similar to a tub washing machine dryer, and also uses a rotary dryer with a heat source using a burner.

Flow process

Waste processing in TPA jabon, sidoarjo depicted in Figure 4, can be seen how complicated the process is just to separate waste that has been mixed at the source, and the high humidity of Indonesian waste makes separating organic and inorganic waste complicated. The separation process cannot be done in a simple process. Subsection figures flow process.

Figure 4. Flow process waste processing machine.

What differentiates the waste processing process at the Jabon TPA, compared to processing in other areas, is that the drying process is not carried out at the beginning of the process, but is carried out after the organic waste material which tends to be small in size (<30 mm) has been separated from the inorganic waste material which tends to be large (>30 mm). After separating the organic material and inorganic material, they are dried respectively. The drying process for organics which tend to have higher moisture is carried out using a rotary dryer for 24 hours and for inorganic materials (plastics) after being chopped to a size of more than 50 mm, they are dried using a vertical centrifugal dryer system with a duration of less than 20 minutes.

The processing process at the TPA Jabon, Sidoarjo produces three processed products, shown in Table 1: Recycle materials,Organic RDF, Inorganic/plastic RDF.

Table 1. Total results of processed waste at TPA Jabon, Sidoarjo (per day, month, year).

The waste processing machines in this study have an average capacity of 3 tonnes/hour. The machine is operated an average of 16 hours/day. With the volume of waste processed reaching 48 tons/day. Of the 48 tons of waste processed, only 8.98 tons of processed products were obtained or around 18.7% of the input waste volume. Details of processed waste products are in Table 1. The waste processing machines in this study have an average capacity of 3 tonnes/hour. The machine is operated an average of 16 hours/day. With the volume of waste processed reaching 48 tons/day. Of the 48 tons of waste processed, only 8.98 tons of processed products were obtained or around 18.7% of the input waste volume. Details of processed waste products are in Table 1. From the measurement results, the percentage between the processed waste compared to the input waste and the moisture from each processed product obtained from the machine process in this research is obtained, as shown in Figure 3. The moisture content of the input waste (Municipal solid waste) is quite high. It does not make it difficult for the waste processing machine in this research to produce processed products that comply with the moisture standards desired by the off-taker.

Drying rate

In the measurement, the municipal solid waste moisture input reaches 73%, and the drying rate of the machine set at the TPA Jabon requires testing. The higher the drying rate, the lower the investment because the area that must be provided to accommodate raw materials and products becomes smaller (Figure 5).

Figure 5. Mass balance and moisture input and output waste processing in TPA Jabon, Sidoarjo.

From Figure 5, the above calculations were obtained from moisture (W) measurements using a moisture meter and mass material (Ms) the results of scales, and the water weight of each material was obtained from formula calculations:

Mw=W(%)∗Ms (1)

and the result of formula we can see on Table 2.

Table 2. Mass balance table.

In Table 2. It can be seen, with a waste input of 48 tons and humidity of 73%. You will get:

• Recycled material with a dry material weight of 1.548 tonnes with a water content of 0.516 tonnes;
• Organic RDF with a dry material weight of 4,032 tons with a water content of 1,344 tons;
• Inorganic RDF with a dry material weight of 1.299 tons with a water content of 0.307 tons.
• Residue with a dry material weight of 2,880 tons with a water content of 2,880 tons.

To count the rate of water release during drying we use the formula from reference            (1)

M_w released=M_w input−M_w output           (2)

M_d=M_w release (kg)/t Pengeringan (detik)                (3)

M_w input=W (%) input * M_s input

M_w input=73% * 48 Ton=35,04 Ton

M_w output=M_w recycle+M_w RDF organic+M_w RDF inorganic+M_w residu

M_w output=0,516+1,344+0,307+2,880=5,047 Ton

M_w released=35,04-5,047=29,993 Ton

Md=29.993/3.600=8,3 Kg/second

M_w: Mass of water

W: Moisture

M_s: Mass of material (solid)

M_d: Rate of water release during drying (Kg/second)

To count weight reduction, moisture reduction we use the formula from reference         (2)

Weight Reduction (%)=(M_s input−M_s result)/Ms input ∗ 100%    (4)

Weight reduction (%)=(48-14,74)/48*00%=69,25%

Moisture Reduction (%)=(W input−W result)/W input ∗ 100% (5)

Moisture reduction (%) recycle material=(73-25)/73*100%=65,85%

Moisture reduction (%) RDF organic=(73-25)/73*100%=65,85%

Moisture reduction (%) RDF inorganic=(73-20)/73*100%=72,6%

The drying technique carried out by a set of machines in the TPA Jabon, Sidoarjo uses a combination of thermal drying and mechanical drying. This reference (2) explains various ways of drying municipal solid waste, indeed this reference does not explain the method of combined drying, as is done at TPA Jabon, Sidoarjo. By using the formula in this reference how the waste processing machine works at Jabo TPA, Sidoarjo results obtained weight reduction 69,25% and moisture reduction 65,85-72,6%.

From the results of measurements and observations in the field, the capabilities of the machine in this research have some advantages that other waste processing machines, the advantages of the waste processing machine in this research are:

•Able to sort organic waste and inorganic waste in a short time with a fairly high tonnage (4 tons/hour), with high inputwaste moisture (73%); •Able to separate hard materials that are harmful to crusher blades, where these hard materials are often mixed withkitchen waste/household waste;
•The processed waste from the machine in this research has a moisture content that is in accordance with thestandards of the offtaker, both the RDF offtaker and the recycled material offtaker. In SNI 8966_2021: Solidjumputan fuel for power plants in various class classifications requires moisture content <25%.

Results and Discussion

Waste processed products at TPA Jabon, Sidoarjo

Recycle material: One of the processed products products from the machines in this research are recycled industrial materials and RDF. From Figure 6 There are seven recycled materials that sell well on the market with prices ranging from IDR 500,000–IDR 4,000,000/ton. And metal material is the most expensive material.

Figure 6. Types of recycled materials and prices per ton.

In (3) explain that even though it is the fifth largest plastic waste producing country in the world. In an effort to meet the need for raw materials for the recycling industry, Indonesian recycling factory are still importing waste from other countries. The lack of supply of quality raw materials is considered to be a production obstacle for business actors in the waste or waste processing or recycling industry. the process of sorting raw materials is ineffective. At the same time, the quality of the raw materials is not optimal. The level of utilization or recycling of waste/garbage in Indonesia is still low. For plastic products, Indonesian people’s consumption level reaches more than 7 million tons a year. However, only around 1 million tons of products are recycled. Based on data collected, the volume of plastic waste imports in 2010 was 40 thousand tons. The value of plastic waste imports is US$ 15 million. At that time the exchange rate was at IDR 9,078 per US dollar. Thus, the economic value obtained was Rp. 135 billion. A year later, the volume of plastic waste imports more than doubled to 91 thousand tons in 2011. The import value at that time was Rp. US$ 66 million. At that time the exchange rate was at IDR 8,773 per US dollar. The economic value collected reached IDR 580 billion. Imports of plastic waste continue to increase. In 2013, the volume of plastic waste imports reached 136 thousand tons. The value of plastic waste imports was recorded at US$ 82 million. In that year the exchange rate was at IDR 10,563 per US dollar. In this way, the economic value of plastic waste imports reached IDR 861 billion. This number continued to grow until it reached its peak in 2018. The volume of plastic waste imports reached 321 thousand tons. The value of plastic waste imports was recorded at US$ 102 million. In 2018, the exchange rate was at IDR 14,267. Thus, the economic value derived from plastic waste imports is IDR 1.46 trillion. Indeed, after 2018, the volume of plastic waste imports has decreased. Just look, in 2022, the volume of plastic waste imports will reach 194 thousand tons. The value of plastic waste imports reached US$ 103 million. At that time the exchange rate was at IDR 14,917 per US dollar. So the economic value of plastic waste import activities reaches IDR 1.54 trillion.

RDF organic

RDF organic/(solid waste fuel) is fuel that comes from house hold waste which has gone through a sorting and processing process which is then chopped into small grain sizes of around 5 mm which can be used as a substitute for fossil fuels. Solid waste fuel itself is categorized as biomass for the co-firing program at PLTU. Co-firing biomass at PLTU reduces coal use by utilizing biomass fuel as a partial replacement for coal while still paying attention to fuel quality according to needs. The Biomass co-firing program is targeted to use 8.4 million tons of biomass in 2025 and 22 million tons in 2050. Potential biomass raw materials: Energy plants, agricultural/plantation waste, wood industry waste, municipial solid waste (Figure 7).

Figure 7. RDF organic, as one of the materials for the power plant co-firing program program.

In the measurements we carried out, 56% of the municipal waste from the Jabon, Sidoarjo landfill was organic material, where this organic material can be processed and converted into organic RDF to be used as an alternative fuel in the power plant. With a large enough volume, the waste at the Jabon landfill, Sidoarjo has the potential to be used as a supply of raw materials needed to become organic RDF. For the co-firing program, the Power plant follows the 1 standard, in the standard the RDF for the co-firing program is divided into 3 classifications, according to organic composition and inorganic composition (Table 3).

Table 3. Standard specifications for solid fuel for power plants.

RDF Inorganic

In the general guidebook (Table 4). It was explained that RDF with a minimum calorie of 3,000 kcal/kg with a size <50 mm is very suitable for RDF in cement factories. If you look at the chopped form of inorganic RDF and the calories produced by inorganic RDF/SRF from the Jabon, Sidoarjo landfill, it is very suitable for use in cement kilns (Figure 8).

Figure 8. RDF inorganic, inorganic RDF or known as Solid Recovered Fuel (SRF).

Table 4. COA RDF compare to standard.

From the Table 4, it can be concluded that the RDFs produced at TPA Jabon, Sidoarjo are in accordance with standards both for use in power plants in accordance with (4) and in cement factories in accordance with (5) (Figure 9).

Figure 9. COA RDF organic and RDF inorganic/SRF.

Certificate of analysis from RDF produced at TPA Jabon, Sidoarjo shown in Figure 9. Comparison of the moisture of the RDF product produced by the TPA Jabon with the RDF standard was good and the results were still in accordance with the standard. The calories from RDF produced at the Jabon landfill are also higher than the minimum. Sulfur levels are also still lower than the maximum limit. From comprehensive Strengths, Weaknesses, Opportunities, and Threats (SWOT) analysis of waste incineration technologies is presented in Table 5.

Table 5. RDF SWOT.

Figure 10. Delivery of RDF from TPA Jabon to power plant.

Every month from TPA Jabon, Sidoarjo. Routinely sends RDF results of 160 tonnes per month. Each time the delivery uses a 26 m3 capacity truck as shown in Figure 10. This 160 tons of RDF is divided into two destinations, 80 tons to the Paiton power plant and 80 tons to the Tanjung Awar-awar Tuban power plant.

Economic analysis

Investasi

The processing area will be divided into 4 areas, shown in Figure 12.

• Area 1: Municipal waste drop area;
• Area 2: Processing area;
• Area 3: RDF stock pile and recycled material;
• Area 4: Leachate treatment;

Figure 12. Layout of the waste processing site at TPA Jabon, Sidoarjo.

In Table 5, shown The total investment in the waste processing project with a capacity of 3 tonnes/hour is as shown in table 4 amounting to IDR 18,515,968,000, consisting of investment of IDR 15,303,309,000 and working capital of IDR 3,212,659,000. Of the total investment, 70% of the investment value will be financed by the bank, namely Rp. 12,896,778,000, consisting of investment credit of Rp. 10,647,916,000 and working capital credit of Rp. 2,248,861,000, while the remaining 30% will be borne internally, namely Rp. 5,619,190,000, consisting of investment of IDR 4,655,393,000 and working capital of IDR 963,798,000 (Tables 6 and 7).

Table 6. Investment costs.

Table 7. Capacity.

Investment is used to build hangars 12, purchase furniture and equipment, manufacture machines, where the machines are made by yourself so that the price can be cheaper and can be adjusted to suit your needs (Figure 13). For land, the lease is for 10 years. The land used is Sidoarjo district government asset land, where the land was previously used as TPST land, but previously it had not been able to function optimally (Tables 7-9).

Figure 13. Waste processing site at TPA Jabon, Sidoarjo.

Profit and loss

Table 7. Calculation of profit and loss.

Financial outline

Table 8. Financial outline of a 4 ton/hour capacity waste processing project.

Table 9. Table NPV, BOC, IRR, COC, PP.

From Table 9, we can conclude:

Internal Rate Return (IRR): Internal rate of return is the interest rate used when the return on the project investment value is zero. Based on calculations for waste processing projects in this research, an IRR value of 28.19% was obtained. With an IRR value > MARR (9%) the project in this research is said to be feasible.

Cost of Capital (COC): Cost of Capital is a cost incurred by the company to obtain funding. This project uses funding from the bank with 9% interest. With the required capital costs of IDR 10,647,916,000, with a COC of 12.89%, the cost to obtain capital is IDR 1,372,516,372.

Net Present Value (NPV): One way to determine the feasibility of a project is with present value analysis. Through present value analysis, the present value can be calculated from the cash flows of future costs and benefits. Based on the calculation of 6 kWh using diesel fuel, the NPV is obtained at IDR 7,289,872,000 (NPV>0) which means the project is feasible.

Benefit Cost Ratio (BCR): Benefit Cost Ratio is a calculation method of comparing production costs with the benefits of a business project. If the BCR calculation result>1, it means that the expected benefits exceed the costs incurred, and the project is considered feasible. Conversely, if BCR<1, it indicates that the project costs exceed the benefits generated, and the project is considered not feasible. Based on the calculations for the waste processing project in this research, a BCR value of 1.6 was obtained, meaning that the project in this research was feasible.

Payback Period (PP): Payback period is a method for determining the time period required for a project to return the amount of investment used for the project. Based on the calculations for the waste processing project in this research, the payback period obtained was 5 years and 6 months. The project feasibility indicators in this research are NPV>0, IRR>MARR. Based on these criteria, the waste processing project in this research is feasible.

Conclusion

As of the time this article was written, the waste processing project at the TPA Jabon, Sidoarjo in 2023 has succeeded in producing hundreds of tons of RDF every month and supplying tens of tons of recycled industrial materials. The low price of RDF, around IDR 400,000/ton, where the price includes shipping costs, makes it impossible for the waste processing project at the Jabon landfill, Sidoarjo, to turn the proceeds from the sale of processed waste into the main income. The main income from waste processing at the Jabon TPA comes from a community fee that pays IDR 35,000 every month by the Sidoarjo. The waste processing project into RDF and recycled industrial materials carried out at the TPA Jabon, Sidoarjo, is quite effective as a solution for eliminating waste in Sidoarjo Regency.

• Area 1: Able to process high moisture and mixed waste as characteristic of Indonesian waste
• Area 2: The residue produced is quite small (around 12%)
• Area 3: Does not require a large land area, just around 2,000 m²

Processed products from RDF and recycled materials, by off-taker standards Due to the low prices of RDF and recycled materials, by relying on the main income from community fees, waste processing using this method is feasible and feasible to scale up. The economic analysis in this research produced indicators, NPV >0, IRR >MARR, BCR >1 and payback period 5 years 6 months.

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