Title Indonesian Journal of Environmental Management and Sustainability e-ISSN:2598-6279 p-ISSN:2598-6260 Research Paper Composting system improvement by life cycle assessment approach on community composting of agricultural and agro industrial wastes Rizki Aziz1*, Panalee Chevakidagarn2, Somtip Danteravanich3, 1Faculty of Engineering, Universitas Andalas, Kampus Limau Manis, Padang, 25163, Indonesia 2Faculty of Environmental Management, Prince of Songkla University, Hat Yai Campus, Hat Yai, 90112, Thailand 3Faculty of Science and Industrial Technology, Prince of Songkla University, Surat Thani Campus, Surat Thani, 84100, Thailand *Corresponding author e-mail: rizkiaziz@ft.unand.ac.id Abstract In order to improve a community composting system, three scenarios have set based on the critical points of initial system from sensitivity analysis result of Life Cycle Assessment of community composting system of agricultural and agro industrial wastes composting. Sensitivity analysis of initial system revealed two critical points that used as consideration on setting of improvement system scenarios. On initial system, composting process contributed the highest impact potency on acidification, eutrophication, global warming, and photochemical oxidation, while distribution was responsible for the highest impact on human toxicity potential. By comparison of initial composting system with three improvement scenarios, it found that the third improvement scenario (SC3) was the best scenario that recommended to be implemented. SC3 promoted application of compost blanket for gases emission reduction of compost pile, and substitution diesel fuel of pick-up with CNG fuel for transportation emission reduction. This scenario reduced impact of initial composting system by 29% with the highest impact reduction was on global warming potential by 54%. Keywords life cycle assessment, composting system, agricultural and agro industrial wastes, sensitivity analysis, improvement scenarios Received: 18 July 2018, Accepted: 2 August 2018 https://doi.org/10.26554/ijems.2018.3.3.69-75 1. INTRODUCTION Composting has been applied as basic method to treat, minimize, and utilize organic wastes that produced by municipality, agri- cultural and agro industrial activity, because of its simplicity and cheapness. It produces compost which is safe and beneficial to apply for land and more environmentally friendly than chemical fertilizer (Andersen et al., 2012). In Thailand, application of composting has been introduced to the communities in order to increase their participation on providing organic compost for their own needs, as well as to improve their income through composting plant development program (Siriwong et al., 2009; Aziz et al., 2012). Composting plant treats animal manures as the main material for composting such as cow dung, chicken, swine, duck and bat manures, besides palm oil mill waste, rice mill, and rubber wood manufacturing wastes (Chevakidagarn et al., 2013). Operation of these com- posting plants can reduce waste generation of agricultural and agro industrial activities such as rice plantation, sugarcane, corn, cassava, oil palm, rubber, soybean, mug bean and peanut bean (DEDE, 2012), and from animal farming such as cow manures, buffalo, chicken, pig and duck farming on provinces of Nakhon Si Thamarat, Phatthalung, Surat Thani, and Songkhla (Sridang et al., 2013). Performance evaluation of community composting plants in Southern Thailand revealed that composting plant was facing problem on low efficiency of composting technique, and improvement of composting technology was recommended to be done (Siriwong et al., 2013) Application of Life Cycle Assessment (LCA) has been in- troduced in last decade due to assessing impact of composting system on the environment (Komilis and Ham, 2004; Cadena et al., 2009; Andersen et al., 2010; Colón et al., 2010; Martı́nez- Blanco et al., 2010; Rigamonti et al., 2010). The studies inves- tigated various composting methods such as windrows, tunnels, static pile, and composter. Previous studies was concerned on organic fraction of municipal solid wastes as pruning waste, yard waste, organic household waste, garden waste, and left over raw fruits and vegetables. It concluded that composting process im- pacted the environment through global warming, acidification, https://doi.org/10.26554/ijems.2018.3.3.69-75 Rizki Aziz et. al. Indonesian Journal of Environmental Management and Sustainability, 3 (2018) 69-75 photochemical oxidation, eutrophication, ozone depletion and human toxicity impacts (Andersen et al., 2012; Cadena et al., 2009; Martı́nez-Blanco et al., 2010). LCA has also been applied in comparing composting method due to system improvement (Lundie and Peters, 2005; Liamsan- guan and Gheewala, 2008; Martı́nez-Blanco et al., 2009; van Haaren et al., 2010; Boldrin et al., 2011; Aziz and Chevakidagarn, 2016). In comparing composting systems some improvements that recommended such as improvement of purities of being com- posted wastes and reduction of gaseous emission by gas treat- ment (Cadena et al., 2009), transportation distance arrangement (Martı́nez-Blanco et al., 2010), and fuel fossil substitution (An- dersen et al., 2010). In order to study the composting technique that practiced on community composting and its impact to the environment, LCA study was done on community composting of agricultural and agro industrial waste. By considering some improvements that recommended by Aziz and Chevakidagarn (2016), this study aims to find the better improvement scenario in order to improve the initial composting system of agricultural and agro industrial wastes. 2. EXPERIMENTAL SECTION 2.1 Investigated Composting System Studied composting plant is located on Rattaphum District in Songkhla Province, Southern part of Thailand. Composting sys- tem consisted of feedstock collection, composting process which included electricity consumption and transfer material onsite plant, and distribution of compost product to customer. On com- posting process, agricultural and agro industrial wastes (AWW) is mixed with phosphate rock and bio-activator mixture before being fermented for 20 days. AWW contains with agricultural wastes which consists of goat manure, chicken manure, and bat manure, and agro industrial wastes consists of rice husk, rice bran, and decanter cake. Bio-activator mixture is made up with molasses, liquid fertilizer, and seed from government to produce powder compost. Composting process applies static pile method with intermit- tent aeration, with no leachate produced and no air emission reduction technology applied. Compost products quality has been certified and could be applied for fruit farming and oil palm and rubber plantation. Figure 1 configured diagram of related phases in the composting systems. 2.2 Life Cycle Assessment LCA defines as a method to assess the impacts of a product, process or service throughout the product’s life cycle into the en- vironment that includes from raw materials acquisition to disposal of the product at the end of its life (UNEP/SETAC, 2009). LCA has four phases; goal and scope definition; inventory analysis; impact assessment; and interpretation. Analysis of environmental impacts of initial composting system and scenarios of system improvements was performed by software SimaPro v.7.3.0 (PRe- Consultants, 2012). Figure 1. Flowchart of studied composting system Figure 2. Comparison of Composting System Scenarios In the first step, goal and scope were defined. Goal of this study is to find a better composting system by comparing initial composting system that composted agricultural and agro indus- trial wastes with other improvement scenarios. The study scoped on comparing initial composting system that produced powder compost and three improvement scenarios based on reduction of composting gaseous emission, and substitution of fossil fuel to al- ternative fuels consists of biodiesel 5% (B5), Liquefied Petroleum Gas (LPG) and Compressed Natural Gas (CNG). The functional unit (FU) is management of 1 ton of AAW to gain compost. System boundary of the study includes of collection of feed- stock, composting process and distribution of compost to cus- tomers. Otherwise, impact of material handling, fabrication of transportation vehicles, composting station, and related equip- ment were out of concern of this study due to the impacts were not related directly to the operation of composting system. Allo- cation procedure is related to production process of composting that treated base on mass of compost produced, environmental burden of waste only related to dumped waste referred to cut-off method (Ekvall et al., 1998). On the second step, inventory analysis, data of initial system were collected from related study by Aziz and Chevakidagarn (2016). Meanwhile, data for improvement scenarios were col- lected from references related to application of compost blan- ket as gaseous emission reduction (CIWMB, 2007; Utami et al., © 2018 The Authors. Page 70 of 75 Rizki Aziz et. al. Indonesian Journal of Environmental Management and Sustainability, 3 (2018) 69-75 Table 1. Inventory of Initial Composting System Phases Items Volume Unit Input Collection truck and pick up van 64.08 tkm Composting - feedstock AAW 1,000.00 kg phosphate rock 142.39 kg bio-activator mixture 6.98 kg - water consumption water 98.38 kg - electricity mixer, conveyor, blower, crusher, sewing machine 5.72 kWh - transfer material mini tractor 0.18 tkm Distribution truck and pick up van 148.05 tkm Output Gaseous emissions CH4 0.49 kg NH3 1.54 kg N20 0.15 kg Compost product compost 987.03 kg packaging 4.01 kg Waste total 4.92 kg - dumped plastic (bag, rope, packaging) 0.66 kg - reused plastic (bag, rope) 4.24 kg - recycled Cardboard 0.02 kg Source: [19] Table 2. Impact Characterization Result of Initial System Impact Unit/FU Total C Co D AP kg SO2 eq. 2.643 0.063 2.471 0.109 % 100 2.400 93.470 4.130 EP kg PO4 −3 eq. 0.582 0.015 0.541 0.026 % 100 2.640 92.820 4.540 GWP kg CO2 eq. 102.740 16.642 57.501 28.597 % 100 16.200 55.970 27.830 HTP kg 1,4-DB eq. 0.557 0.144 0.165 0.248 % 100 25.890 29.620 44.490 POP kg C2H4 0.005 0.001 0.003 0.001 % 100 15.590 57.620 26.790 Note: C: collection, Co: composting, D: distribution 2012), and gaseous emission from biodiesel B5, LPG and CNG consumption on transportation (TGO, 2013). Impact assessment as the third step was conducted by using the CML 2 baseline 2000 method that developed by Centre of En- vironmental Science of Leiden University (Martı́nez-Blanco et al., 2010). Impact categories considered categories that have selected on related studies (Cadena et al., 2009; Martı́nez-Blanco et al., 2010) which included abiotic depletion potential (ADP), acidifica- tion potential (AP), eutrophication potential (EP), global warming potential (GWP), ozone depletion potential (ODP), human toxic- ity potential (HTP), and photochemical oxidation potential (POP). Finally on interpretation step, the interpretation of initial sys- tem was followed by sensitivity analysis. It was done to find critical points to be considered as system improvement spots. All improvement scenarios then were compared in order to find the best scenario to be applied for system improvement. The best scenario was the scenario that has higher impacts reduction in comparison with initial system and more applicable with less consequences of economic and technology impact. Moreover, the best scenario was compared with initial composting system to observe detail impact reduction that occurred. © 2018 The Authors. Page 71 of 75 Rizki Aziz et. al. Indonesian Journal of Environmental Management and Sustainability, 3 (2018) 69-75 Table 3. Sensitivity Analysis Scenarios Impact initial Sensitivity analysis scenarios (%) category (%) SA1 SA2 SA3 SA4 SA5 AP 100 100 77 53 99.7 100 EP 100 100 77 54 100 100 GWP 100 100 87 75 99.98 93 HTP 100 99.997 93 86 99.9 100 POP 100 99.999 86 72 94 100 Impact initial Sensitivity analysis scenarios (%) category (%) SA6 SA7 SA8 SA9 SA10 AP 100 100 100 100 99 98 EP 100 100 100 100 99 98 GWP 100 86 99.98 99.97 100 100 HTP 100 100 100 100 89 79 POP 100 100 95 90 100 100 Impact initial Sensitivity analysis scenarios (%) category (%) SA11 SA12 SA13 SA14 AP 100 99.89 99.89 99.999 99.997 EP 100 99.9 99.9 99.998 99.997 GWP 100 98 98 99.99 99.98 HTP 100 99.1 99.1 99.99 99.97 POP 100 99 99 99.99 99.98 3. RESULTS AND DISCUSSION 3.1 Initial Composting System On initial system, data collected on inventory analysis showed in Table 1. It depicted that in providing feedstock of 1 ton to be composted AAW took 64.26 tkm on collection phase. Com- posting process input were 1 ton AAW, 142.39 kg phosphate rock, 6.98 kg bio-activator mixture (consisted of molasses, fluid bio fertilizer, and seeds), consumed 98.38 kg water, 5.72 kWh electricity for machineries, and 0.18 tkm on transferring material onsite plant. On distributing compost to customers 148.05 tkm was needed. Meanwhile composting process emitted gaseous consisted of methane, dinitrogen monoxide, and ammonia. Com- posting process was also generated wastes which later recycled, reused, and the rest were dumped and burnt. Data inventory of initial system were classified and charac- terized for environmental impact assessment. CML 2 baseline 2000 method was used, and no discussion was performed about ADP and ODP impact categories due to no impact from present study on these categories. Impact on environmental of each steps of initial composting system was summarized in Table 2. It can be seen that higher sensitivity was shown on the change of gaseous emission quantity from composting process and trans- portation activities. Reduction of gaseous emission (SA2 and SA3) were significantly reduced environmental impacts on AP, EP, GWP, HTP and POP which exceeded 47%, 46%, 25%, 14% and 28%, respectively by 50% emission reduction. Meanwhile, on gaseous emission reduction on transportation activities (SA4 to SA10) reduction all emission of CH4 and SO2 (SA4) only reduce 6% of impact of POP, 0.3% of AP, and 0.1% of HTP. Reduction of CO2 (SA5 and SA6) and CO (SA7 and SA8) emission by 50% could reduce impact on GWP and POP by 14% and 10%, respectively, while reduction of N2O emission (SA9 and SA10) by 50% could reduce impact on HTP by 21%. Otherwise, sensitivity analysis (SA11 to SA14) shows that efficiency on electricity consumption (SA11 and SA12) by 50% were not sensitively reduced environmental impact, similar condi- tion concluded from reduction of transfer material distance onsite plant (SA13 and SA14). It revealed that improvement of com- posting system could be performed by application of gaseous emission reduction from composting process and transportation activities. 3.2 Improvement Analysis Based on sensitivity analysis result, improvement scenarios were developed in order to find the better system, three scenarios were introduced with improvement options by considering: a) better operation on composting gaseous emission reduction by choosing the application of compost blanket on the surface area of com- posting pile, refers to Utami et al. (2012) and CIWMB (2007), this application could reduce emission of methane and dinitrogen monoxide up to 70% and 75%, respectively; and b) reduction of gaseous emission from transportation by shifting types of fuel consumed, based on emission factor that issued by TGO (2013), three alternatives of fuels including biodiesel B5, LPG and CNG were selected as pick up van fuel with consideration of com- © 2018 The Authors. Page 72 of 75 Rizki Aziz et. al. Indonesian Journal of Environmental Management and Sustainability, 3 (2018) 69-75 Table 4. Impact Characterization of Improvement Scenarios System Impact Unit/FU Initial SC1 SC2 SC3 AP kg SO2 eq. 2.643 2.643 2.557 2.56 EP kg PO4 −3 eq. 0.582 0.582 0.562 0.562 GWP kg CO2 eq. 102.74 62.286 47.256 47.121 HTP kg 1,4-DB eq. 0.557 0.559 0.366 0.371 POP kg C2H4 0.005 0.003 0.007 0.002 Figure 3. Impact Comparison of Initial System and Improvement Scenarios mercially provision of fuel. Comparison of initial system and improvement scenarios was shown on Figure 2. First scenario (SC1) considered application of compost blan- ket; and shifting of fuel of pick-up van on collection and distribu- tion by using biodiesel B5, and pick-up truck use diesel. Scenario 2 (SC2) applied improvement through shifting of fuel of pick-up van as collection and distribution vehicle with LPG. And scenario 3 (SC3) applied shifting of fuel of pick-up van into CNG fuel. Comparison of impact of initial and improvement scenarios showed on Table 4 and Figure 3. Table 4 and Figure 3 revealed that all improvement scenarios were contributed lower impact than initial system, except for impact category AP, EP and HTP on SC1 and POP category on SC2. Higher impact on category of AP, EP and HTP were attributed by consumption of biodiesel B5 that emitted more NO2 to the environment than diesel. Higher impact on POP category was contributed by emission of CO of LPG fuel that higher than diesel fuel. SC3 showed impact reduction on all impact categories with the higher impact reduction was performed on GWP by 54% of initial impact. By comparing percentage of total impact reduction on Figure 3, it could be concluded that SC3 was the best scenario of improvement. Table 5 and Figure 4 represented impact characterization re- sults of SC3. In SC3 all sub systems were contributed to all impact categories, similar with initial composting system. Com- posting process was responsible for the highest contribution to all Figure 4. Impact Comparison of Initial and SC3 Composting System impact categories, except for POP which was supplied by distri- bution sub system. Composting process was contributed 2.464 kg SO2 eq./FU (96.26%), 0.539 kg PO4 −3 eq./FU (95.87%) and 0.154 kg 1,4-DB eq./FU (41.52%) of total impact on AP, EP and HTP, respectively. Distribution sub system was responsible for contribution of 19.815 kg CO2 eq./FU (42.05%) and 0.001 kg C2H4/ FU (40.48%) of total impact on POP. In detail, in comparison with initial composting system (see Table 2, Table 5 and Figure 4), it can be observed that all impacts reduction was occurred in all impact categories. Impact reduction were contributed by collection, electricity and distribution sub systems in all impact categories, while composting process sub system was attributed impact reduction only on GWP and POP categories, and for other impact categories were similar with initial composting system as well as transfer sub system since no improvement option applied on it. © 2018 The Authors. Page 73 of 75 Rizki Aziz et. al. Indonesian Journal of Environmental Management and Sustainability, 3 (2018) 69-75 Table 5. Impact Characterization Result of SC3 Impact Unit Total C Co D AP kg SO2 eq. 2.55 0.025 2.471 0.064 (%) -100 -0.99 -96.51 -2.51 EP kg PO4 −3 eq. 0.562 0.006 0.54 0.016 (%) -100 -1.12 -96.08 -2.8 GWP kg CO2 eq. 47.121 9.164 18.142 19.815 (%) -100 -19.45 -38.5 -42.05 HTP kg 1,4-DB eq. 0.371 0.059 0.165 0.147 (%) -100 -15.83 -44.45 -39.72 POP kg C2H4 0.002 0.0004 0.0008 0.0008 (%) -100 -18.03 -41.49 -40.48 Note: C: collection, Co: composting, D: distribution 4. 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Page 75 of 75 INTRODUCTION EXPERIMENTAL SECTION Investigated Composting System Life Cycle Assessment RESULTS AND DISCUSSION Initial Composting System Improvement Analysis CONCLUSIONS ACKNOWLEDGEMENT