Analysis of Global Warming Potential in Tofu Industry (Case Study: Industry X, Gresik)
Ekki Rahmawati1, Shinfi Wazna Auvaria2, Sulistiya Nengse3, Yusrianti4, Teguh Taruna Utama5
1,2,3,4,5Environmental Engineering Department, Universitas Islam Negeri Sunan Ampel, Surabaya Indonesia
*Correspondent author: [email protected]
Received: September 25, 2022 Accepted: October 1, 2022
Abstract
Tofu industry is one of the many SMEs operating in Indonesia. These industrial activities have the potential to have an impact on the environment. Industry X, Gresik has an average production capacity of 600-900 kg of tofu every day. The main energy used to produce tofu is firewood. The average daily use of firewood in this industry is 1,520 kg. Burning wood has the potential to cause global warming. In addition, this industry also does not manage its liquid waste which has the potential to cause pollution in aquatic ecosystems. The purpose of this research is to analyze the potential environmental impact of the tofu production process. Data collection methods include observation, interviews, and direct measurement. Data analysis using Life Cycle Assessment method and SimaPro 9.4 Software. Environmental impact assessment using the CML-IA (baseline) method. Based on the results of Simapro analysis, the global warming potential impact is 2,95 x 108 kgCO2-eq
Keywords: tofu industry, life cycle assessment, SimaPro, CML-IA (Baseline)
Abstrak
Industri tahu merupakan salah satu industri kecil menengah atau disebut UMKM yang banyak beroperasi di Indonesia. Kegiatan industri tersebut berpotensi menyumbangkan dampak terhadap lingkungan. Industri X, Gresik ini memiliki kapasitas produksi rata-rata 600 hingga 900 kg tahu setiap harinya. Energi utama yang digunakan untuk memproduksi tahu adalah kayu bakar. Rata-rata penggunaan kayu bakar di industri ini setiap harinya adalah sebesar 1.520 kg. Pembakaran kayu berpotensi terhadap potensi global warming.
Selain itu, industri ini juga tidak melakukan pengelolaan terhadap limbah cair yang dihasilkan. Limbah tersebut berpotensi menyebabkan pencemaran pada ekosistem perairan. Tujuan dari adanya penelitian ini adalah untuk melakukan analisis potensi dampak lingkungan dari proses produksi tahu. Metode pengumpulan data meliputi observasi, wawancara, dan pengukuran secara langsung. Analisis data menggunakan metode Life Cycle Assessment dan Software SimaPro 9.4. Penilaian dampak lingkungan menggunakan metode CML-IA (baseline). Berdasarkan hasil analisis Simapro, didapatkan nilai dampak global warming potential adalah sebesar 2,95 x 108 kgCO2-eq.
Kata Kunci: industri tahu, life cycle assessment, SimaPro, CML-IA (Baseline)
1. Introduction
Tofu is a lump of soybean juice produced by protein deposition from the addition of coagulation materials such as acetic acid (CH3COOH) and/or other coagulation materials [1]. Each process of making tofu produces by-products, namely liquid waste that comes from the use of clean water, as well as soybean dregs, and air emissions from the cooking process [2] . The large amount of liquid waste that is not balanced with proper processing can cause problems for the environment. Tofu liquid waste influences chemical and physical properties as well as aquatic organisms if it is not managed [3]. Small and medium industries are characterized as industries that have low energy efficiency and high levels of pollution [4].
The environmental impact resulting from the tofu production process can be estimated using a life cycle assessment. LCA is a methodology used to assess and analyze the environmental burden and potential environmental impact of a material, product, or activity over its lifetime from extraction and processing of raw materials through manufacturing, transportation, use, and final disposal [5]. LCA can assist decision- making in identifying environmental impacts based on their activities [6].
The tofu industry "UD.X" is one of the industries in the Sidojangkung village, Gresik. The industry has an average production capacity of 703 kg of soybeans per day with the main energy being firewood for the cooking process. The by-products produced in this industry are not managed properly. This industry was selected as a sample in the application of the life cycle assessment.
This study aims to analyze the global warming potential from the production process of “UD.X” tofu, Sidojangkung Village, Menganti sub-District, Gresik.
2. Material and Methods Sample
The sample used in this study is a small tofu industry "UD.X" which is located in Sidojangkung Village, Menganti sub-District, Gresik for 1 month from 23 April 2022 to 22 May 2022. Every day, the industry has an average production capacity of as much as 703 kg of soybeans. The industry has 17 workers with production operating hours of 6 hours, from 08.00 WIB to 14.00 WIB. The distribution areas for tofu products are in Gresik Regency, Surabaya City, and Lamongan Regency.
Research Method
This study aims to analyze global warming potential of tofu industry "UD.X”, Gresik from the use of raw materials or materials and fuels as well as the output of each process in the form of products and waste using the Life cycle assessment (LCA) method.
Goals and scope definition
Determination of goals and scope is the most important part of conducting an LCA analysis [5].
Calculation of global warming potential using SimaPro 9.4 software with the CML-IA impact assessment method (baseline) and conducting an analysis of global warming potential. While the limit of the assessment system is "gate to gate" which is only in the production process
Inventory Analysis
This phase use to collect the data that includes all inputs and outputs and is obtained from the entire tofu production process [7]. The inputs needed in this process are soybeans, water, vinegar, and fuel. While the output is products and by-products. Products in the form of clean soybeans, soy porridge, soy juice, lumps of soy juice, and tofu. The by-products produced are wastewater, air emissions, and soybean dregs.
All input and output data are obtained from direct measurements when the tofu industry operates and literature studies from previous research.
Life cycle impact assessment
Impact assessment aims to evaluate and understand the resulting environmental impacts based on the objectives, scope, and inventory analysis [8]. The process of analyzing environmental impacts on the CML- IA method (baseline) and analyzing the largest impacts produced.
Interpretation
The purpose of the life cycle assessment is to obtain conclusions that can support understanding decisions [9]. At this stage, an analysis of the contribution of the overall input-output will be carried out so that predictions of the environmental impact of the tofu production process can be carried out.
3. Results and Discussion Tofu Production Process
The process for processing soybeans into tofu at UD. X District Menganti starts from the soaking process for ± 3-4 hours which aims to soften the soybean seeds to facilitate the milling process. UD.X has 25 soaking tubs filled with 16 kg of prebaked or cooked soybeans. The second process is washing to clean soybeans from dirt. The third process is soybean milling which aims to grind soybean seeds into soy porridge for the cooking process. The fourth process is cooking, the soybean porridge will boil to ripen the soybean porridge. The next process is filtering soybean slurry to separate the liquid and solid parts. After filtering, the soybean juice will be coagulated using vinegar (CH3COOH) so that the soybean juice can blend and clot as the basic ingredient for tofu or curd. The lumps of soy juice will then be inserted into the printing press to unite the tofu lumps into the printing container. After being placed into a container and stacked on 4 levels, the lumps will then be pressed using a weight of ±5-15 kg. The final stage after the lump has solidified is the cutting process. Tofu is cut as much as ± 50 pieces of printing.
Goals and scope definition
The purpose of this study was to assess the production process of the tofu industry "UD.X" Menganti sub- District with the scope is gate-to-gate system.
Functional Unit
The functional unit is a functional measure used when reviewing the environmental impact of some product systems. Its purpose is to provide a normalized reference unit of inventory data [10]. Functional units are often based on the mass of the product under study. The functional unit used in this study is 1 kg of tofu [9].
Boundary System
The system boundary is a flow diagram of the entire process that will be assessed. The system limitations in this study can be seen in Figure 1.
Figure 1. Boundary system of tofu production Source: Process analysis (2022)
Input-Output Tofu Production Process
The Tofu production process at UD. X District Menganti produces 2.770 kg of tofu every day on average. The input-output flow in the tofu production process is used to calculate the total flow of components that enter and leave the production process. The amount of material that enters will be equal to the amount of material that goes out [11]. The input-output in the tofu production process can be seen in Figure 2.
The input-output data were obtained from direct measurements in the field, interviews, and literature studies on life cycle assessment in the tofu production process. In each process, the production of tofu produces waste, either in the form of liquid, solid, or emission. All waste generated is immediately disposed of without any prior management. Based on Figure 1 above, the average soybean cooked per day is 703 kg of soybeans with an average consumption of 9.389 liters of clean water per day. Meanwhile, 8,045 liters of liquid waste are also generated per day. Soybean dregs produced as much as 1450 kg. The main energy source for the cooking process comes from wood, while in the milling process, the main energy source is electricity. The coagulation process in this industry uses CH3COOH. In this process, the output of wastewater and the source is returned. In this case, the vinegar which cannot coagulate will be discarded and some of it will be returned to be used in the next coagulation process.
Figure 2. Input-output quantity of tofu production process Source: Process analysis (2022)
Life Cycle Impact Assessment
The entire inventory data or input-output data above are then analyzed using Simapro 9.4 software.
The results of the impact category generated in the SimaPro 9.4 analysis can be seen in Table 1. From these results, an analysis is carried out for the environmental impact of global warming potential. Processes that contribute to this impact from the largest to the smallest, respectively in characterization phase, are boiling 2,68 x 108 kgCO2-eq, clumping 2,61 x 107 kgCO2-eq, and grinding 6,79 x 105 kgCO2-eq. Global warming potential (GWP) measures how much heat is trapped by greenhouse gases (GHG) in the atmosphere. The higher the GWP, the more heat is trapped by the gas, therefore, the higher the GWP the more harmful it is to the climate. In relation to global warming, the main greenhouse gases such as carbon dioxide (CO2), methane (CH4), and nitrogen oxides (N2O) have a GWP value at an exposure time of 5-200 years [12]. The GWP value is expressed in units of kg CO2 equivalent. All compounds that have a contribution to global warming potential will be converted into weight CO2 [8]. The global warming potential impact network can be seen in Figure 3.
Table 1. Characterization value of 1 kg tofu
Impact Category Total Unit
Global Warming Potential (GWP100a) 2,95 x 108 kgCO2-eq
Eutrophication 1,95 x 105 kgPO4-eq
Marine aquatic Ecotoxicity 3,61 x 1010 kg1,4-DB-eq Photochemical Oxidation 4,79 x 104 kgC2H4-eq Abiotic Depletion (fossil fuels) 7,32 x 108 MJ
Human Toxicity 1,21 x 108 kg1,4-DB-eq
Freshwater aquatic ecotoxicity 1,47 x 107 kg1,4-DB-eq
Acidification 1,47 x 105 kgSO2-eq
Terrestrial Ecotoxicity 5,094 x 104 kg1,4-DB-eq
Abiotic Depletion 332 kgSb-eq
Ozone Layer Depletion 6,58 kgCFC-11-eq
Source: Simapro 9.4 Analysis (2022)
Figure 3. Network of global warming potential impact Source: Simapro analysis (2022)
The cooking stage of soybean porridge gives the highest GWP value because the main energy source used is firewood. The input of firewood at this stage is 1.520 kg which produces CO2, CH4, and N2O emission values of 1,48 x 107 kgCO2-eq, 1,11 x 108 kgCO2-eq, and 1,48 x 108 kgCO2-eq. The amount of energy for the cooking process can be caused by the low efficiency of the furnace. This causes the energy lost during the combustion process is also quite high. Wood burning has an efficiency of around 16% lower when compared to the efficiency of burning petroleum gas (LPG) which can reach 60% [13]. In addition, wood-burning activities are also continuously carried out 30 minutes before the factory operates until the production is finished, which is for 6-7 hours.
Furthermore, at the milling stage, the GWP characterization value is 6,79 x 105 kgCO2-eq. The milling stage is also a contributor to the GWP impact. This is because the milling stage uses the main energy from electricity. Emissions produced by electricity are CO2. This substance is one of the substances that cause global warming [14]. Another stage that is a contributor to global warming potential is the clotting stage. At this stage, the coagulating material used is CH3COOH. The use of these materials can cause the formation of CO2 and CH4 gases. Acetic acid CH3COOH which is oxygenated into volatile organic compounds is found in remote and urban environments in the form of gases and particles [15].
4. Conclusion
The results of the global warming potential impact analysis at the impact characterization stage show are 2,95 x 108 kgCO2-eq. The process that is the main contributor to the impact of global warming potential
8,5E6 kg Wood fuel, hardwood,
kiln-dried, at planar mill, SE/kg/RNA 0,65 %
1,66E7 kg Acetic acid, without water, in 98% solution state {GLO}| market for 8,86 %
5,59E3 kg proses pemasakan
90,9 %
8,45E3 kg proses penggumpalan
8,86 % 1 p
PROSES PRODUKSI TAHU UD X SIDOJANGKUNG 100 %
is the cooking process. This is because the cooking process uses wood as the main energy to cook soybean porridge. can be concluded that by-product of palm oil plantation and mill had good nutritional value.
Therefore, this feedstuff can be used to formulate complete feed for sheep. It also proved that this effort successfully increased the nutrient digestibility.
5. Acknowledgment
Authors thank our colleagues from department of Environmental, Faculty of Sains and Technology Sunan Ampel Surabaya State Islamic University, for the supports during the research
6. Abbreviations
GWP Global Warming Potential
GHG Green House Gas
CH3COOH Acetic Acid
LCA Life Cycle Assessment
CML-IA (baseline) CML-IA is one of the environmental impact assessment methods developed by the institute of the Faculty of Science of Leiden University.
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