The reduction of carbon dioxide emission at 3R Superdepo Sutorejo waste processing unit (TPS), Surabaya

This research aims to know waste volume, waste composition, and emission reduction through sorting and without sorting at Superdepo Sutorejo Waste Processing Unit (TPS), Surabaya. The calculation of waste volume and composition was carried out in accordance with SNI 19-3964-1994, while the calculation of carbon dioxide emission was based on the United States-Environmental Protection Agency (US-EPA). The results showed that the solid waste volume in Superdepo Sutorejo Waste Processing Unit was 0.7 kg/person/day with organic waste composition percentage of 63%, plastic waste of 15.22%, paper of 5.36%, aluminium of 2.22%, glass of 1.31%, rubber 0.78%, and residual waste of 12.09%. Carbon dioxide emission without waste sorting was amounted to 9,087.05 MTCO2E/year while carbon dioxide emissions through waste sorting was amounted to 8,512.5 MTCO2E/year. Therefore, the sorting at 3R Superdepo Sutorejo Waste Processing Unit (TPS) Surabaya could store the emission of carbon dioxide by 6.3%.


Introduction
Population growth in Indonesia, especially in Surabaya, which continues to grow is not only one of the reasons why urbanization is increasingly high, but also a cause of changes in consumption patterns and lifestyles which ultimately results in more types of waste, the volume of waste, and waste characteristics [1,2].
Constitution number 18 year 2008 about waste management implies the changes of waste management towards waste management and waste reduction. Waste reduction can be conducted by limiting the volume of waste, recycling, and reusing waste which is known as reduce, reuse, and recycle (3R).
3R Waste Processing Unit is a place where the activity of collecting, sorting and using waste in regional scale are conducted. The waste found in Waste Processing Units is brought to 3R Waste Processing Unit, and the residual waste from the 3R Waste Processing Unit is then disposed to the landfill.
3R Superdepo Sutorejo Waste Processing Unit has an area of 1.400 m2 and receives waste from Dukuh Sutorejo vvillage (4253 KK) and Kalisari (4311 KK) village which reaches to 250 -300 ton/month [5]. 1. Household Waste Household waste is solid waste originating from the rest of daily activities in the household, not including specific feces and garbage, and from natural processes that originate from the household environment. This waste is sourced from home or from a housing complex.

Household-like Waste
Household-like waste is a household waste which originates not from household and household environment, but from other sources like traditional markets, trade centers, schools, offices, hospitals, restaurants, hotels, terminals, seaports, industries, city parks, and others.

Specific Waste
Specific waste is household waste or household-like waste which because of its nature, concentration and / or amount, it requires special treatment. It includes waste containing hazardous and toxic materials (B3) such as used batteries, used toner, etc., waste containing B3 waste (medical waste), disaster-related waste, debris, waste which is technically not yet able to be processed, and periodic waste that arises (waste from community service). The increasing community needs caused an increasing amount of waste generated from its activities. Waste which is accumulated and buried in a relatively long time will experience decomposition and produce gas that is classified as greenhouse gas and spreads in the air [6].
The further efforts to achieve good environment are treatment improvement and waste volume reduction. Thus, the occurrence of waste reduction will also reduce carbon gas emissions and reduce the impact of global weather changes.

Determining the volume rate and the composition of waste
The measurement of volume rate and composition of waste was conducted in accordance with SNI 19-3964-1994 [7] 2.2. Calculating carbon dioxide gas emissions according to US-EPA Calculating CO2 gas emissions can be done by multiplying CH4 and 1 emissionsvolume fraction of CH4 per volume fraction of CH4 substituted with oxidation factor with molecular weight of CO2 per molecular weight of CH4 [8].

Result
Waste volume per unit of population was obtained from the amount of waste that enters the 3R Superdepo Sutorejo Waste Processing Unit per population served by 3R Superdepo Sutorejo Waste Processing Unit. Superdepo Sutorejo 3R Waste Processing Unit serves two villages in Mulyorejo Subdistrict, namely Dukuh Sutorejo village and Kalisari village which have a total population of 31,585 people [9].
Waste volume of this area which was handled by 3R Superdepo Sutorejo Waste Processing Unit was 0,7 kg/person/day.
The biggest waste composition in 3R Superdepo Sutorejo Waste Processing Unit was kind of waste that can be composed, which was 63%. This kind of waste was the largest composition because daily household activities produced food waste or domestic waste.

Discussion
Surabaya is included as a metropolitan city because it has a population of more than 2 million people. According to SNI-3242-2008, metropolitan cities have waste volume reaching 3 L/person/day. The rate of waste volume in Surabaya is 3.2 L/person/day or 0.96 kg/person/day [3]. This means that the waste volume at 3R Superdepo Sutorejo Waste Processing Unit is lower, it is only 0.7 kg/person/day.
The composition of the waste is mostly in the form of organic waste, then followed by the type of plastic waste and residue respectively (Fig 1)

Figure 1. Waste Composition at 3R Superdepo Sutorejo Waste Processing Unit
The residual waste in question is mixed waste which is not sorted by TPS 3R Superdepo Sutorejo Waste Processing Unit, such as: diapers, tissue papers, fabrics, glasses, rubbers, and organic waste which are not composed (durian skin, corn, etc).
3R Superdepo Sutorejo Waste Processing Unit does not sort residual waste, glasses, and rubbers so that they will be disposed directly to the landfill.
The biggest number of plastic waste composition is mixed plastic waste, followed by LDPE, PET, and LDPE plastic waste (Fig 2) The