Open Bin Composter Method as An Alternative to Organic Waste Processing in Temanggung Regency

Domestic waste generation in Temanggung Regency is about 182,562.96 ton/year contain 51,75% of organic waste, where this organic waste has the potential to be processed into compost. As an alternative method that can be used to process organic waste is the open bin composter method. The data used in this study is secondary data that taken from Dinas Perumahan Rakyat, Kawasan Permukiman, dan Lingkungan Hidup Kabupaten Temanggung in 2022, this data contain measurements of weight, volume, and composition of waste. From this data, the weight of waste that can be composted, volume of organic waste that composted, and the weight of compost can be calculated. From the calculation results, the area that needed for composting area is 20,8 m2, and open bin composter method can process 12.11 m3/day of organic waste to 6.1 m3/day of compost or equal with 1376 kg/day.


Introduction
Temanggung Regency is one of the regions in Central Java Province with a population of 794,403 in 2021 and a population growth rate of 0.59 [1] An increase in the amount of waste generation will have a negative impact if there is no proper handling.Negative impacts that can be caused by improper waste handling include water pollution, disease vectors, odors and dust, aesthetics, and flooding [2] Waste that is not managed properly can have an impact on the environment and the health of the surrounding community.Therefore, waste utilization is an important component in waste management to reduce the negative impact on the environment [8] One alternative in organic waste management is composting.Composting itself is a method that can be used to reduce and change the composition of organic waste into more useful products.In the composting process, microbes such as bacteria and fungi play an active role in breaking down complex organic matter into simpler ones.Composting can decrease the amount of organic waste up to 70% [6].To accelerate the proliferation of these microbes, one way is by adding bioactivators such as Effective Microorganisms-4 (EM4) [13] Sari et al (2022) has conducted research on alternative composting systems, where the study compared Open Bin and Windrow.Open bin is a system made of permanent boxes in the shape of a box or rectangle like an open tub that can accommodate stacks of waste inside.Meanwhile the windrow composting method is a system that piled up the organic waste without heavy equipment during operation, and the pile is can be made with a flexible shape.Method selected is windrow because in the study need is judging from the distance between composters for worker movement space [10].Eventough the selected method is windrow, open bin is still can be considered because it's doesn't really complex for the operation and have a medium reversal time.Beside that, the advantages of open bin composter method are that the waste is not visible from the outside, the composting area looks neat, and the volume of waste processed is the same.As for the drawbacks, namely limited space for workers and limited land use [5].The novelty of this study lies in the material on the tubs, the tubs used is made from bricks that is open at the top and has a hole for door at the front.This door functions as a facility for taking mature fertilizer so that harvesting can be done easily.
Based on data on solid waste management coverage for Temanggung Regency in mid-2022, a total of 174 villages/urban village have had their solid waste served from a total of 289 villages/urban village.So that the solid waste services carried out by the Public Housing, Settlement Areas and Environment Services of Temanggung Regency have reached 60.21%.Waste collection in Temanggung Regency uses TPS, Village TPS and 3R TPS.In planning waste management in Temanggung Regency, the facility to be used is TPS with the 3R principle.The implementation of TPS 3R is directed at the concept of Reduce, Reuse and Recycle, which made to reduce waste from the source on a communal or regional scale, to reduce the burden of waste that must be processed directly at the TPA.Therefore, this study aims to reduce organic waste in Temanggung Regency with one alternative to reduce it is to process it using an open bin composter.

Methods
This study was conducted at Temanggung Regency, and the data were collected from secondary data which is taken from Dinas Perumahan Rakyat, Kawasan Permukiman, dan Lingkungan Hidup Kabupaten Temanggung in 2022.
The composting method used in alternative waste processing in Temanggung Regency is the open bin method with Effective Microorganisms-4 (EM4) as a starter in the composting process.This method was chosen because of consideration of the need for equipment and operational costs which tend to be cheaper and easier to obtain.The time needed for this composting process is about 30 days.The calculation for the open bin composter is: (1) Volume of composted waste = (time × shredded waste weight (kg/day))/ (chopped waste density (kg/day)), (2) Tub volume = (length × width × height), (3)

Size of compost heap = (length × width × height), (4) Surface area of the tub (cube) = 2 x (length × width + width × height + length × height), (5) Volume of compost heap = volume of cubevolume of tub, (6) Number of tanks needed = volume of composted waste/volume of compost generated, (7) Tub area = tub volume × total tub units, (8)
Composting area = tub area + moving area.The size of the tub that used for composting is 1 m × 1 m × 1 m, the volume of the tub is 1 m 3 .

Results and Discussion
Data on waste generation in Temanggung Regency in 2021 is 182,562.96tons/year with per capita waste generation of 0.63 kg/person/day or 2.52 liters/person/day [4].The composition of waste can be seen in Figure 1.From the waste generation in Temanggung Regency, it is known that the composition consists of food waste, wood/branches, plastic, paper-cardboard, metal, cloth, rubber-leather, glass, and others.Organic waste is the largest, with a percentage of 51.75%, consisting of food waste and wood/branches.It can be seen in Figure 2 that food waste dominates organic waste in Temanggung Regency [3]

FIGURE 2. Percentage of Organic Waste Composition in Temanggung Regency
Based on the composition of waste generation in Temanggung Regency, the potential for reusing organic waste is very high, dan terdapat berbagai macam metode pengolahan sampah organik yang dapat dilakukan.However, in Temanggung Regency, they chose to process organic waste by composting.This is done considering the conditions in Temanggung Regency, where there are still many plantations and agriculture so that the compost can be used as plant fertilizer.
The selected composting method is open-bin composting.The open-bin composting method was chosen because of the ease of processing that the community can carry out, has a fast process of about 30 days, an easy processing process that does not require heavy equipment, and a neatly organized composting room.In the processing process, it is assisted by the addition of EM4, which aims as a bio activator.The addition of EM4 in compost production has been proven to boost the composting process [7,9,11,12].The method used is an open bin composter with a composted organic waste volume of 13.38 m 3 /day.An open bin composter is calculated, so it is known that the number of tubs used is 16 units, the tub area is 16 m 2 , and the total land required is 20.8 m 2 .After learning the necessary composting area in TPS 3R, the open bin composter method calculation results can be seen in Table 1.Waste that has been composted and has been processed for 30 days is then screened first to obtain the same particle size.At the time of composting organic waste there is a shrinkage of 40-50%.For open bin composter the percentage of shrinkage is 50%, so that the volume after composting is 6.1 m 3 /day and the weight of compost is 1376 kg/day.The resulting compost can be traded and used as a plant fertilizer for the community.

Conclusion
The conclusion that can be drawn from this study is the method used in the planned TPS 3R for organic waste processing in Temanggung Regency is the open bin composter method.This method can be an alternative for processing organic waste because of the need for equipment and operational costs, which are cheaper and easier to obtain.The time needed for this composting process is about 30 days.Using the open bin composter method, the TPS 3R planned for the Temanggung Regency can process 12.11 m 3 /day of organic waste to 6.1 m 3 /day of compost or equal with 1376 kg/day.

TABLE 1 .
Open Bin Composter Method Results