Jiun-Horng Tsai1,2, Kuo-Hsiung Lin3, Vivien How4, Yu-An Deng5, Hung-Lung Chiang This email address is being protected from spambots. You need JavaScript enabled to view it.5

1 Department of Environmental Engineering, National Cheng Kung University, Tainan 70101, Taiwan
2 Research Center for Climate Change and Environment Quality, National Cheng Kung University, Tainan 70101, Taiwan
3 Department of Environmental Engineering and Science, Fooyin University, Kaohsiung 83102, Taiwan
4 Department of Environmental and Occupational Health, Universiti Putra Malaysia, 43400 Selangor, Malaysia
5 Department of Safety Health and Environmental Engineering, National Yunlin University of Science and Technology, Yunlin 64002, Taiwan

Received: November 2, 2021
Revised: November 19, 2021
Accepted: November 21, 2021

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

Download Citation: ||https://doi.org/10.4209/aaqr.210301  

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Cite this article:

Tsai, J.H., Lin, K.H., How, V., Deng, Y.A., Chiang, H.L. (2021). Waste to Energy: Air Pollutant Emissions from the Steam Boilers Using Recycled Waste Wood. Aerosol Air Qual. Res. https://doi.org/10.4209/aaqr.210301


  • Waste wood constituents were C: 45.3%, H: 5.96%, N: 0.29%, S: 0.21%, and Cl: 0.022%.
  • PM, SOx, and NOx emissions were 0.71, 0.86 and 5.24 kg (ton-wood)1, respectively.
  • PM, SOx, and NOx emissions were 0.21, 0.29, and 1.09 kg (ton-steam)1, respectively.


In Taiwan, combustible wood mostly comes from waste pallets and scrap packaging materials discarded by factories, which produced a total of 278,067 tons of waste wood in 2019. In this study, the heat value of waste wood was 18.3 ± 1.07 MJ kg–1. The measured volatile fraction was 76.5 ± 7.34%, the fixed carbon was 15.7 ± 3.19%, the ash content was 2.96 ± 2.45%, and the moisture content was 21.6 ± 10.2%. The proportions of the elemental constituents in the waste wood were 45.3 ± 4.95%, 46.9 ± 3.94%, 5.9 ± 0.44%, 0.21 ± 0.17%, 0.29 ± 0.26%, and 0.02 ± 0.02% for carbon, oxygen, hydrogen, sulfur, nitrogen, and chlorine, respectively. The average boiler capacity was 11.5 ± 6.84 ton hr–1, the average fuel consumption of the boilers was 1.47 ± 1.81 ton hr–1, the average operating temperature of the boilers was 853 ± 228°C, the average steam generation of the boilers was 7.63 ± 5.97 ton hr–1, and the average exhaust flow rate was 246.6 ± 200.9 m3 min–1. The main air pollution control systems used in the waste wood combustion boilers were systems combining a cyclone, a baghouse and a scrubber (37.8%), a cyclone and a baghouse (28.4%), a cyclone and a scrubber (10.2%), and systems using a baghouse only (9.8%). Based on our fuel consumption data, the air pollutant emission factors were 0.71 ± 1.44 kg per ton of wood for PM, 0.86 ± 1.47 kg per ton of wood for SOx, and 5.24 ± 9.56 kg per ton of wood for NOx. In July 2022, new emission standards for boilers will be implemented, and emission reductions of at least 30% for PM, 35% for NOx and 7% for SO2 will be required.

Keywords: Waste wood, Boiler, Air pollution control system, Emission factor

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