The Assessment of Indoor Formaldehyde and Bioaerosol Removal by Using Negative Discharge Electrostatic Air Cleaners

This study investigated the single-pass performance of a negative corona electrostatic precipitators (ESP) in removing suspended particulates (PM_2.5 and PM₁₀), formaldehyde (HCHO), and bioaerosols (bacteria and fungi) and measured the ozone (O₃) concentration generated by ESP. The experimental results revealed that if the operational conditions for the ESP were set to high voltage (-10.5 kV) and low air flow rate (2.4 m³/min), ESP had optimal air pollutant removal efficiency. In the laboratory system, its PM_2.5 and PM₁₀ removal rates both reached 99% at optimal conditions, and its HCHO removal rate was 55%. In field tests, its PM_2.5, PM₁₀, HCHO, bacteria, and fungi removal rates reached 89%, 90%, 46%, 69%, and 85% respectively. The ESP in the laboratory system (-10.5 kV and 2.4 m³/min) generated 7.374 ppm of O₃ under optimal conditions. Under the same operational conditions, O₃ generated by ESP in the food waste storage room and the meeting room were 1.347 ppm and 1.749 ppm, respectively. The removal of HCHO and bioaerosols was primarily attributed to their destruction in the corona, as well as ozone oxidation, and collection on the dust collection plate.