A Comparative Study of Stack Emissions from Straight-Line and Zigzag Brick Kilns in Nepal

Abstract

Nepal has approximately 1000 operational brick kilns, which contribute significantly to ambient air pollution. They also account for 1.81% of the total bricks produced in the South Asian region. Little is known about their emissions, which are consequently not represented in regional/global emission inventories. This study compared emissions from seven brick kilns. Four were Fixed Chimney Bull’s Trench Kilns (FCBTKs) and three were Induced-Draught Zigzag Kilns (IDZKs). The concentrations of carbon dioxide (CO2), sulfur dioxide (SO2), black carbon (BC), and particulate matter (PM) with a diameter less than 2.5 µm (PM2.5) were measured. The respective emission factors (EFs) were estimated using the carbon mass balance method. The average fuel-based EF for CO2, SO2, PM2.5, and BC were estimated as 1633 ± 134, 22 ± 22, 3.8 ± 2.6 and 0.6 ± 0.2 g per kg, respectively, for all FCBTKs. Those for IDZKs were 1981 ± 232, 24 ± 22, 3.1 ± 1, and 0.4 ± 0.2 g per kg, respectively. Overall, the study found that converting the technology from straight-line kilns to zigzag kilns can reduce PM2.5 emissions by ~20% and BC emissions by ~30%, based on emission factor estimates of per kilogram of fuel. While considering per kilogram of fired brick, emission reductions were approximately 40% for PM2.5 and 55% for BC, but this definitely depends on proper stacking and firing procedures.

Nepal Ambient Monitoring and Source Testing Experiment (NAMaSTE): emissions of particulate matter and sulfur dioxide from vehicles and brick kilns and their impacts on air quality in the Kathmandu Valley, Nepal

“…These were the only available observational data in Nepal at the time of this study. A more recent study by Nepal et al (2019) reported that the mean value of the SO 2 emissions factor from zigzag kilns is 24 ± 22 g kg −1 of fuel, which is almost twice as high as that used in our study. If we doubled our SO 2 emissions for brick kilns, the modeled SO 2 concentrations would be much closer to the observations.…”

“…Weyant et al (2014) estimate the total emissions from the brick industry in South Asia to be 120 Tg yr −1 carbon dioxide, 2.5 Tg yr −1 CO, 0.19 Tg yr −1 PM 2.5 (PM with an aerodynamic diameter less than 2.5 µm), and 0.12 Tg yr −1 EC. Pariyar et al (2013) report that brick kilns contribute more than 60 % of total SO 2 and PM emissions in the Kathmandu Valley. Using a source apportionment method, Kim et al (2015) found that brick kilns contribute 40 % of EC concentrations in the Kathmandu Valley in winter.…”

Nepal emission inventory – Part I: Technologies and combustion sources (NEEMI-Tech) for 2001–2016

“…For biogas lamps, all EFs were considered to be similar to biogas stoves (Table S3 in For the industrial sector, technology-linked EFs were used from the EPA AP-42 repository that identified the combustion and process activities for different sources and industries (Table S4). The measured EFs for brick production were compiled from Weyant et al (2014), Stockwell, et al (2016), Jayarathne et al (2018) and Nepal et al (2019) for zigzag and straight firing in FCBTKs and clamp kilns (Table S5). For diesel generators, the recently measured EFs from the NAMaSTE campaign were considered for all pollutants ex-cept CO and SO 2 ( Table S6).…”

Artisan Brick Kilns: State-of-the-Art and Future Trends

“…The principal index for an energetic assessment is the Specific Energy Consumption (SEC), which is measured in MJ/kg. Widely varying data are found in the literature of SEC values for brick kilns [51,85,94]. This can be reasonably attributed to differences in the (1) fuel heating power, (2) size of bricks, (3) weight of bricks and (4) quality of fired bricks [25,52].…”