Waste to energy: air pollutant emissions from the steam boilers using recycled waste wood

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

Associations between Arsenic in Drinking Water and Pterygium in Southwestern Taiwan

[[abstract]]BACKGROUND: Pterygium is a fibrovascular growth of the bulbar conjunctiva and underlying subconjunctival tissue that may cause blindness. The mechanism of pterygium formation is not yet fully understood, but pterygium has some tumorlike features. OBJECTIVES: The objective of this study was to evaluate the association between arsenic exposure through drinking water and the occurrence of pterygium in southwestern Taiwan. METHODS: We recruited participants > 40 years of age from three villages in the arseniasis-endemic area in southwestern Taiwan (exposure villages) and four neighboring nonendemic villages (comparison villages). Each participant received an eye examination and a questionnaire interview. Photographs taken of both eyes were later graded by an ophthalmologist to determine pterygium status. RESULTS: We included 223 participants from the exposure villages and 160 from the comparison villages. The prevalence of pterygium was higher in the exposure villages across an age groups in both sexes and increased with cumulative arsenic exposure. We found a significant association between cumulative arsenic exposure and the prevalence of pterygium. After adjusting for age, sex, working under sunlight, and working in sandy environments, we found that cumulative arsenic exposure of 0.1-15.0 mg/L-year and >= 15.1 mg/L-year were associated with increased risks of developing pterygium. The adjusted odds ratios were 2.04 [95% confidence interval (CI), 1.04-3.99] and 2.88 (95% CI, 1.42-5.83), respectively. CONCLUSIONS: Chronic exposure to arsenic in drinking water was related to the occurrence of pterygium, and the association was still observed after adjusting for exposures to sunlight and sandy environments