Estimating emissions from open burning of municipal solid waste in municipalities of Nepal
Introduction
Solid waste management (SWM) has become a major concern, especially in urban areas of developing countries. Many municipalities are experiencing extreme environmental degradation as well as public health risks due to ill-timed waste management and unsanitary disposal practices (Alam et al., 2008, Nagpure et al., 2015). Recently, the open burning of solid waste was implicated as a major cause for soiling the Taj Mahal and impairing the health of Agra residents (Lal et al., 2016). In Nepal, population growth, rapid expansion of sprawling urban municipalities, increasing amounts of industrial and commercial activity, and rising consumption of packaged goods has resulted in severe air and water quality issues, poor sanitation, and the spread of diseases (Alam et al., 2008, Dangi, 2009, Pokhrel and Vivaraghavan, 2005).
At an elevation of 1400 m, the bowl-shaped Kathmandu valley lies at the foothills of the Himalayas and is surrounded by mountains and forests. The total urban area of Kathmandu valley is 96.68 km2 (KVDA, 2017) and this area has the highest population density in Nepal. The valley contains five densely-inhabited urban centres which were previously designated as municipalities: Kathmandu Metropolitan City (KMC), Lalitpur Sub-Metropolitan City (LSMC), Bhaktapur, Kirtipur and Madhyapur Thimi. Around the time of study, the Government of Nepal designated 16 municipalities (dividing many of the earlier five into smaller areas) in the valley partly in response to the booming urban population (KVDA, 2017).
Fig. 1 contains a map of the five original municipalities referred to throughout this study and their location within Nepal. KMC is home to the nation’s capital and is the most populated municipality in Nepal with an area of 49.45 km2 (CBS, 2013) subdivided into 35 wards (KMC, 2014). LSMC was the country’s third most populous municipality and is located in the south-central part of the valley, covering an area of 24.94 km2 that was subdivided into 30 wards (LSMC, 2016). Bhaktapur is an ancient city in the eastern part of the valley, 16 km east of the KMC centre. It was divided into 17 wards and covered only 6.88 km2 (Bhaktapur Municipality, 2016). Kirtipur municipality is less populated than the others and has grown around another ancient kingdom southwest of the KMC centre. Madhyapur Thimi is the newest of the five municipalities, which resulted from population infill between Bhaktapur and KMC.
Although Kathmandu valley is the most developed place in Nepal and covers the largest number of commercial and institutional sectors, the SWM in much of the valley remains unsatisfactory. In Kathmandu, SWM has become a chronic problem that has challenged and evaded development efforts for decades (Dangi, 2009). Many statistics related to SWM in Kathmandu valley are highly uncertain, as evidenced by the large variability across studies (Nippon Koei Co., Ltd and Yachiyo Engineering Co., Ltd., 2005, Solid Waste Management and Resource Mobilization Center (SWMRMC), 2008, Dangi et al., 2011). A brief summary is provided here with the acknowledgement that these data are not necessarily consistent with each other.
About 50% of the waste from municipalities of Kathmandu valley is generated by households, 43% from commercial, 6% from the institutional, and relatively little (1%) from parks and gardens, street sweeping, and from neighboring villages (ADB, 2013). In 2012, the average per capita municipal solid waste generation rates (MSWGR) for KMC, LSMC, Kirtipur, Bhaktapur and Madhyapur Thimi were 0.46 kg/capita/day (kcd), 0.37 kcd, 0.25 kcd, 0.35 kcd, and 0.27 kcd, respectively. The most recent study (SWMTSC, 2015) showed the average MSWGR for a sub-urban neighborhood of KMC (i.e., Budanilkantha) and LSMC (i.e., Mahalaxmi/Gwarko) in 2014 to be 0.48 kcd and 0.36 kcd, respectively. Comparing ADB (2013) to the past studies (Nippon Koei Co., Ltd and Yachiyo Engineering Co., Ltd., 2005, Alam et al., 2008), the per capita MSWGR has increased steadily in the valley municipalities. This is likely due to increased consumption of packaged goods and gradual rise of commercial and industrial activities. Moreover, a research-grade study by Dangi et al. (2011) indicates that the MSWGR is even higher than all of the aforementioned reports.
Although 71% of MSW generated in Kathmandu is organic (Dangi et al., 2011), very few neighborhoods have systems in place to compost this material (Sherpa, 2017). Within the valley municipalities, only 35.3% of waste from Kirtipur, Madhyapur Thimi (52.2%), LSMC (71.2%), Bhaktapur (86.5%) and KMC (86.9%) are collected (ADB, 2013). The situation in other low-income countries appears to be similarly abysmal despite the sizeable expenditure of financial resources on SWM (World Bank, 2012, Hazra and Goel, 2009). At present, urban areas receive more attention for MSW open burning because they are highly populated (Wang et al., 2017).
Large quantities of uncollected waste can be found along the banks of urban waterways such as Bagmati and Bishnumati (Pokhrel and Vivaraghavan, 2005). The water from these rivers is used for domestic purpose, cultivating agriculture and also has religious significance for Hindus. Sometimes uncollected waste is found in close proximity to small-scale agricultural fields where it contaminates the food supply. In communities that are far from waste-collection routes (Subedi, 2016), refuse is commonly dumped in privately-owned lots that are neither developed nor maintained (Bajracharya, 2016). Any waste that remains uncollected after a few weeks of biodegradation emits a foul odor, prompting nearby residents to burn it (Bajracharya, 2016, Sherchan, 2016).
At this point, it is useful to note that the primary issue discussed in this paper is from MSW that is burned in the open, where combustion conditions (i.e., low temperature, suboptimal air-to-fuel ratio, high moisture content) are favorable to pollutant formation (Wiedinmyer et al., 2014). This paper provides no commentary about the high-temperature, carefully-controlled incineration that is practiced in some developed countries. Open burning of MSW has a major impact on human health because the emitted smoke contains life-threatening particulate matter (PM) enriched in organic carbon (OC) and elemental carbon (EC), carcinogenic dioxins, and numerous other harmful pollutants like nitrogen oxides (NOx), sulfur dioxide (SO2), carbon monoxide (CO), non-methane volatile organic compound (NMVOC) (Nagpure et al., 2015, Guttikunda et al., 2014, Guttikunda, 2007, Hodzic et al., 2012, Wiedinmyer et al., 2014, Pokhrel and Vivaraghavan, 2005). High exposure to PM may lead to respiratory and cardiovascular disease, cancer and adverse birth outcomes (McDonnell et al., 2000). It also exacerbates local/regional warming because the carbon dioxide (CO2) and black carbon (BC) emitted from burning both have a high global warming potential. Even if it is dumped and never burned, the gradual degradation of MSW emits methane (CH4) which is another potent greenhouse gas. MSW open burning also emits ammonia (NH3) which can enhance the formation of PM in the atmosphere.
Unlike vehicle exhaust and industrial emissions, the common public and elected officials are relatively unaware of the significance and harmful impacts of open burning (Sherchan, 2016). In the few emission inventories that have been made, open burning of MSW is either completely neglected (Pradhan et al., 2012) or very crudely estimated (Wiedinmyer et al., 2014, Gautam, 2006). This is mainly because of the difficulties and large uncertainty in estimating how much MSW is actually burned (Nagpure et al., 2015). The only urban-scale estimate of emissions from open burning of MSW in Kathmandu was made a decade ago and it arbitrarily assumed that 1% of the waste generated is burned (Gautam, 2006). Other sources of uncertainties are: (i) emissions factors; (ii) activity parameters such as the fraction of population that burns their waste and the fraction of waste that is combustible; and (iii) spatial allocation of waste-burning activities. The purpose of the present study is to constrain some of these uncertainties so that the importance of MSW burning relative to other air pollution sources in Kathmandu Valley may be better understood.
Section snippets
Data and methods
This study estimates the MSW open burning in selected urban and sub-urban neighborhoods of Kathmandu valley, following a method that was successful in Delhi and Agra (Nagpure et al., 2015).
Population demography
The numbers of households counted along the study routes are shown in Table 3. Their population is determined using the average household size calculated from the survey results. The data of urban population for 2011 and projected population for 2016 for Nepal were 4,523,821 and 5,552,712 respectively (CBS, 2014a, CBS, 2014b). The total population of 2011 for KMC, LSMC, Kirtipur, Bhakatapur and Madhyapur Thimi was 1,426,641 (CBS, 2012). Based on the above information, the projected population
Conclusion
In Nepal, this study for the first time attempted to estimate real-world emission parameters, which have been used for estimating MSW open burning. Moreover, it also accounts daily waste burning incidence in the Kathmandu valley. This study presents a clear picture that more MSW open burning prevails at the sub-urban neighborhoods than the municipality core. This is due to lower waste collection frequency (or efficiency) at sub-urban area than the municipality core. Pfrac has strong linkage
Acknowledgements
All the following institution/firms are highly acknowledged for supporting in various ways: Nepal Academy of Science and Technology (NAST), Government of Nepal for PhD fellowship; Solid Waste Management and Technical Support Centre (SWMTSC), Government of Nepal for field expenses; and Nepal Energy and Environment Development Services Pvt. Ltd (NEEDS) for office utilities. Especial thanks goes to Mr Bishwomani Gyawali (Executive Director, SWMTSC); Mr Dipendra B. Oli (Legal Officer, SWMTSC); and
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