Location Determination

This study used data obtained from field sampling. The required samples were related to open waste burning activities conducted by communities in the Demak Regency. The sample locations were determined before sampling. The Demak Regency, which consists of 14 subdistricts and 249 villages, was grouped using cluster analysis. Cluster analysis is a technique for grouping several objects (in this case, urban villages) into groups based on their characteristics [14]. The subdistricts in the Demak Regency were classified into four clusters according to their similarities: rural, outer peri-urban, inner peri-urban, and urban. Data from the Demak Regency Central Bureau of Statistics and other sources were used in the classification process. The data variables included topography, land use, population density, public facilities, accessibility, activity intensity, and economic structure.

Transect Walk

Once the sampling location was determined, a survey was conducted using the transect walk method. A transect walk is a survey method performed along a predetermined road route [12]. Effective and efficient implementation of the transect walk method begins by determining the route at each location. The route was created randomly by forming a loop or straight line along 10 km in each village. This route was made through the main roads and residential areas at the location. The route will not pass through the same road repeatedly, or even if the road is passed more than once, it will still be counted only once. The route was created using the Google Earth application, with the map as a guide. Every time a garbage pile was found along the route, the garbage pile location geographical coordinates were recorded. In addition, a digital photograph of the waste pile, along with its dimensions, were recorded.

The survey was conducted in two stages. The first stage of the survey was conducted in the morning and afternoon, indicating that there are frequent open waste burning activities during this period. The map marker application marks open burning points along the transect walking route. The first step was to estimate the open waste burning point distance from the road and conduct a brief interview with the residents who were burning waste. Brief interviews were conducted to obtain information related to the reasons and objectives of residents who practiced waste burning, and to determine the waste burning intensity. In addition, the conditions at each open waste burning point were recorded: whether the garbage pile had completely burned, was burning, half-burned, or not. A few days later, during the survey second phase, the transect walk was repeated along the identical route [15]. This was conducted to check whether there was any recent activity at the previously found open waste burning points, or whether new open waste burning points would be found. One of the open waste burning points found in the villages was taken as a sample to determine the waste composition in the Demak Regency.

Data Processing and Analysis Technique

Data in this study were obtained from surveys and direct interviews in the field, which were then processed, descriptively evaluated and analyzed. Secondary data were obtained from the local agencies; the Demak Regency Central Bureau of Statistics for location maps, population data, demographic and monographic area conditions, and an overview of the general conditions; and the Environmental Agency for data on existing waste management conditions, air pollution regulations, and waste generation and composition.

Clustering determination involves data processing and analysis using SPSS, because the data come from various units. K-means clustering must meet two criteria, the first being regression analysis [16]. Regression analysis in statistics is a method used to determine the causal relationship between one variable and another, where the regression VIF value must be < 10 [17]. The second is to conduct KMO and Bartlett’s tests, where the KMO value must range between 0.5–1 while the Bartlett’s test significance value must be 0 [18]. Standardized data can be entered into a cluster if they meet the requirements. Using SPSS, the results were obtained in the form of cluster members, distances between clusters, and distances between cluster members and the cluster center. The smaller the distance between cluster members, the closer and more valid the cluster [19].

Based on primary and secondary data collection related to waste generation and open waste burning activities, a waste management process flow/chain was obtained or created for the Demak Regency informal sector. The waste management process flow was developed using the material flow analysis (MFA) method, assisted by substance flow analysis (STAN) software. STAN is software developed to apply the MFA method using the ONORM S 2096 standard with applications in waste management [20]. [21] noted that emissions generated from open waste burning activities can be analyzed using the IPCC. The IPCC was used to enter waste management related data obtained from a transect walk survey [22, 23]. Specific data related to open waste burning activities occurring in the field through transect walks were then processed and analyzed with Microsoft Excel using a predetermined emission calculation formula to obtain emission calculations generated from open waste burning activities.

The analytical hierarchy process (AHP) ranks decision alternatives and chooses the best one based on several criteria [24]. [13] noted that the AHP method develops a numerical value to rank each decision alternative based on the extent to which each alternative meets the decision-making criteria. The AHP method was applied using an Expert Choice application. The Expert Choice application facilitates analysis using the AHP method [25] to form a hierarchy for determining emission reduction policies. The values were entered into the application by clicking on the pairwise numerical comparison toolbar according to the respondents’ completed questionnaires. After respondents’ answers were entered, the determination value of potential emission reduction policies was obtained [13, 26].

Total GHG Emissions

GHG emission calculation using IPCC 2006 Chapter 5: Incineration and waste open burning guidelines use the tier 2 accuracy method which is based on specific waste generation, composition, and management practice data. Based on the calculations that were carried out, the GHG emission inventory results from open burning activities in the Demak Regency were obtained. In 2021, it accumulated to 16.81 Gg CO₂-eq/y. The high open burning activity in the Demak Regency is proportional to the high GHG emissions produced. GHG emission calculation generated from open waste burning activities in the Demak Regency is shown in Table 2.

Air Pollution Modelling

Based on open waste burning points and emissions obtained from the transect walk, air pollution modeling was conducted in each village to determine emission distribution generated from open waste burning activities. ArcGIS was used to determine emission numbers in areas not transected during the walk survey [34]. Modeling of N₂O air pollution shows the N₂O emissions in Bintoro Village. Most areas in this village are green, which means that the air quality is still healthy and safe when people perform outdoor activities. However, continued open waste burning can harm the environment and human health. CH₄ air pollution modeling revealed the amount of CH₄ emissions in the Bintoro Village area. CH₄ air pollution conditions remain safe and healthy, however, if open waste burning activities continue, they will potentially affect human health and the environment [35].

Emission Reduction Strategy Planning

The AHP method was used to determine open waste burning emission reduction strategies in the Demak Regency. Emission reduction efforts are based on existing waste management and processing conditions [36]. Inadequate facilities and infrastructure, an incorrect mindset in managing waste, and minimal public awareness of environmental cleanliness and health have increased the percentage of people who burn waste.

Based on these considerations, efforts should be made to reduce emissions through educational approaches. This countermeasure can be implemented by providing various kinds of knowledge about the environment to improve understanding and change behaviors [37]. Some approaches can be implemented by providing socialization regarding waste and the environmental impact of burning waste, as well as education regarding applying the 3Rs in everyday life within the community [38, 39]. This approach can be implemented by various parties such as the government, environmental activists, researchers, or institutions engaged in the environment. Law No.18 of 2008 concerning waste management Chapter X, Article 29, paragraph 1, point (g), states that everyone is prohibited from burning waste that does not meet the technical requirements of solids. This implies that a binding regulation or legal basis exists wherein people should not burn waste openly. However, this regulation needs to be properly implemented. Thus, it is necessary to impose strict sanctions on the community so that incorrect forms of waste management activities can be minimized or even eliminated.

Providing waste facilities in an area is necessary to support this change. The main facility was a container or temporary dumpsite. The field observation results showed that several areas still require temporary dumpsites; therefore, there is a need for additional container facilities to accommodate waste. In addition, providing retribution services with a consistent transportation schedule is necessary to ensure that waste is transported properly. Related agencies such as the Demak Regency Environmental Agency can provide this waste service. Implementation of a community involvement 3Rs/simple recycling culture, an important factor in emission reduction from open waste burning, reduces or emphasizes the amount of waste generated from the source [40]. To personally avoid reusing and reducing efforts, other processing strategies can be implemented, such as creating a Waste Bank in each village.

Centralized Open Waste Burning Design

The community conducts waste management by burning to quickly eliminate waste generated. Open burning activities conducted by the community and the resulting emissions can endanger human health [41]. Centralized open waste burning in the Demak Regency was designed as an effort by the community to reduce open waste burning activities. The regulation on the ban on burning waste in households has been launched by the government in Law Number 18 of 2008 concerning Waste Management, in Chapter X regarding prohibitions, Article 29 point F, which states that every person is prohibited from burning waste that does not meet the technical requirements of waste management [11]. However, in practice, the enforcement of this prohibition has yet to be thoroughly carried out, given the lack of adequate infrastructure in Demak Regency to manage waste, such as an efficient waste collection and processing system. As a result, some people may feel that they have no other option but to burn their waste. The community still needs to be better educated regarding the importance of enforcing this ban. Therefore, there is a need for increased law enforcement, campaigns that educate the public on the negative impacts of burning waste, and improvements to waste management infrastructure through more environmentally friendly alternatives, such as centralized burning.

Centralized burning is implemented using a waste burner designed according to waste management needs. The waste burner was designed to overcome the limited waste management services coverage in the Demak Regency, which is only 35%. With centralized open waste burning, communities are no longer exposed to emissions from direct waste combustion. The waste burner is designed with emission control devices such that the emissions generated from burning waste with the device are not harmful [42]. This tool must be able to burn waste completely and exhaust the waste that enters the waste incinerator. Complete combustion is related to the amount of oxygen entering the chamber and determines the first combustion [43].

The design of a waste combustion device begins by determining the design parameters. Required parameters are: combustion chamber volume, amount of air required for combustion, type and amount of waste to be burned [44]. Installing the designed waste combustion device is an urban waste management system, especially in settlements in the Demak Regency. Domestic waste includes paper, dry leaves, twigs, wood, and plastic solid waste. The expected combustion processes are complete combustion and combustion. The designed waste burner refers to a design constructed by PT Sankyo, which has a combustion chamber with combustion capacity, namely, if the waste mixture comprises 50% wet and 50% dry, that is, 80-160 kg/h, the maximum waste burned is 3,840 kg/24 h at a temperature of 600-900ºC, while a waste mixture (25% wet and 75% dry) is 80-210 kg/h and the waste maximum burning is 5,040 kg/24 h. Waste managed by burning is residual waste that has gone through previous sorting at the integrated waste management site.

Materials used in the design of this waste incinerator included SK-34 refractory bricks [45], fiber ceramics, iron structures of at least 6 mm thickness, iron plates of at least 3 mm thickness, and rubber-resistant iron chimneys.

Further specifications are dimensions of width (1,080 mm) × length (2,100 mm) × height (1,670 mm), chimney height from the floor 8,000 mm, foundation 2 x 2.7 m, controlled air combustion system, and two combustion chambers, total weight 4,000 kg, that can operate for 24 h continuously. These waste combustion devices are placed at an integrated waste management site in areas where there is no waste service. Waste incineration equipment is placed far from residential areas but can still be reached so that waste burners can be centrally managed, and residents are not directly exposed.

This waste incinerator is used for non- B3 household waste and has the advantages of a simple and practical design with a controlled air system [46], and continuous burning at high temperatures, which only uses waste as fuel. It requires only fuel, electricity, gas, or oil when operating, and is designed and manufactured with the correct engineering to control the combustion chamber airflow and heat power to burn waste, smoke, odors, and gasses, without complicated engines or electrical systems.

The operating procedure is simple, namely: dry waste enters the combustion chamber through the sliding door (feeding door), and a gas or wood match is used to ignite the dry waste through the bottom door (cleaning door). Dry waste is added gradually until the room temperature reaches more than 600ºC, measured through the monitoring hole using a Thermogun. The quality of air released from the chimney meets the quality standards following Permen LHK No. P70 of 2016 and the incinerator has been registered as an environmentally friendly technology from the Ministry of Environment and Forestry of the Republic of Indonesia. In addition, the burned waste shrinks to 2-4% ash. For example, a ton of waste becomes 20-40 kg of ash. This ash can be used as an additional material for creating paving blocks [47].

Expert Choice Result Analysis

The AHP method was applied to determine emission reduction strategies using Expert Choice software [48, 49]. Before choosing to use the AHP method, it is necessary to determine the elements related to emission reduction strategies for open waste burning activities, which are divided into several levels [50, 51]. The AHP method consists of four levels: main goal, factors, objectives, and alternative strategies [52]. The four levels to determine emission reduction strategies for open waste burning are as follows. Level 0 (main objective) covers data collection and processing using the AHP method, namely, determining emission reduction strategies for open waste burning activities in the Demak Regency. Level 1 (causal factor) is the factor that causes the problems discussed, in this case, waste burning by the community. Three factors were identified: the Demak Regency’s waste collection services that still need to be improved, legal regulations that are not firm or binding, and a lack of public knowledge. Level 2 (objectives) are the goals to be achieved by implementing the selected strategy to reduce emissions from open waste burning activities in the Demak Regency. There are two objectives: improving the Demak Regency waste management system and increasing people’s knowledge of the Demak Regency’s proper and correct waste management. Level 3 (alternative strategies) are several strategies that can be chosen to achieve the Level 2 objectives. Alternative strategies include strengthening legal policies related to open waste burning activities that are firmer and more binding; increasing public awareness by providing education, support, and regular supervision to the community to dissuade open waste burning; and fostering a recycling culture in the community from the household level to improve waste management. Improved waste management facilities decrease the need for people to manage waste by burning.

Fig. 3.

Waste treatment flow.

Furthermore, experts in the field prepared a questionnaire form to be completed. The respondents were the Heads of Divisions 1 and 3 of the Demak Regency Environmental Agency. Both respondents were chosen because they understood the existing conditions and problems related to waste management and the Demak Regency community conditions that result in air pollution from open waste burning activities. Respondents completed the questionnaire form provided by assigning a score to each point related to strategy selection to reduce emissions from open waste burning activities. Level 1 compares each causal factor role in open burning activities for managing waste that produces air pollution in the Demak Regency. Level 2 compares the importance or influence of the two objectives, namely improving waste management and increasing public knowledge, of each causal factor at level 1. Level 3 compares the importance or influence of each alternative strategy that can be selected against each objective at Level 2.

Respondents completed the value scale on the questionnaire form following the instructions. The completed questionnaire scale value was then processed using the Expert Choice application to determine the selected strategy. Processed questionnaire data results were obtained using the AHP method using the Expert Choice application [25]. The strategy to reduce emissions from open waste burning activities in the Demak Regency, which was selected with a score of 581, is to increase public awareness by providing education, support, and routine supervision to the community to inhibit open waste burning.

The Demak Regency in Central Java Province consists of 14 subdistricts, 243 villages, and 6 urban villages with a population of 1,212,377 and an average population growth rate of 0.93% in 2021. Currently, the amount of waste generated in the Demak Regency is 1,294,217 tons per day. Meanwhile, the Demak Regency waste service reached only 35%. The unserviced waste generation in the Demak Regency is 841,241 tons daily, of which 571,847 tons of waste is estimated to be managed by the population daily by burning. Open waste burning harms the environment by producing GHG emissions. Therefore, it is necessary to conduct waste management planning in the Demak Regency to reduce open waste burning activities so that GHG emissions can be significantly reduced. Fig. 3 shows the selected waste processing flow.

Based on the Central Java Governor Regulation No. 11 of 2019 concerning Policies and Strategies for Central Java Province in the Management of Household Waste and Waste Similar to Household Waste, the waste reduction target in 2025 is 30%, and the waste handling target is 70%. Therefore, with planned waste management, it is expected that no waste disposal, landfilling, or burning activities will occur because all the waste has been managed. The three subdistricts with the highest open waste burning rates requiring waste management planning were Wedung, Bonang, and Karangawen. Waste management planning includes the five aspects described earlier, and the processing implemented at the integrated waste management sites in each subdistrict. Processing includes composting of organic waste, incineration of other mixed waste, and sale of inorganic waste. However, 30.28% of the waste is still transported to the nearest landfills, namely, the Berahan Kulon and Candisari landfills. The amount of waste burned using incinerators was 10.77% of the total waste entering the integrated waste management site daily. With the same calculation from IPCC 2006 Chapter 5: Incineration and Open Burning of Waste, using tier 2 accuracy, the calculation of GHG emissions can be compared before and after waste management in Table 3.

Projections of open waste burning in the Demak Regency predict an increase from open waste burning annually. Statistical value analysis shows significant differences in the totals, as shown in Table 3. In 2022, emissions from open burning were 48.69 Gg/year and are predicted to increase to 55.08 Gg/year by 2031. After waste management, the emission rate from open burning in 2022 was 27.87 Gg/year and 31.53 Gg/year in 2031. The percentage reduction calculated through the total difference is significant, around 42.76%. This means that waste management is able to reduce emissions.