Key Takeaways & Executive Findings
- •• • At +12 kV sawtooth-rod and -8.5 kV plate-plate voltages, the two-stage ESP achieved 91% collection efficiency for fine particles (<0.3 µm) and >98% total particle collection, outperforming conventional needle-plate commercial purifiers. • • Toluene degradation efficiency increased from 29.2% to 53.1% when particles were introduced, demonstrating a synergistic effect that enhances VOCs removal in real catering fumes. • • Positive DC discharge on the sawtooth-rod electrode produced a corona current of 800 µA versus 375 µA for negative polarity, while reducing ozone concentration from 176.9 mg/m³ to 101.4 mg/m³, indicating better energy efficiency and lower secondary pollution. • • The sawtooth-rod electrode's stable discharge characteristics reduce sparkover frequency and maintenance downtime, supporting the development of energy-efficient, compact, and intelligent ESP systems for catering fume purification.
Abstract
A two-stage electrostatic precipitator (ESP) integrating a sawtooth-rod electrode precharging unit and a plate-plate collection unit was developed for simultaneous removal of fine particles and volatile organic compounds (VOCs) from catering fumes. Using KCl particles and toluene as surrogates, the system achieved a fine particle (<0.3 µm) collection efficiency of 91% and a total particle collection efficiency exceeding 98% at applied voltages of +12 kV (sawtooth-rod) and -8.5 kV (plate-plate), with an ozone concentration of 176.9 mg/m³. The presence of particles enhanced toluene degradation, increasing removal efficiency from 29.2% to 53.1%. Positive DC discharge on the sawtooth-rod electrode yielded a higher corona current (800 µA vs. 375 µA for negative) and lower ozone generation (101.4 mg/m³ vs. 176.9 mg/m³), indicating superior suitability for catering fume treatment. The stable discharge characteristics of the sawtooth-rod electrode reduce energy consumption and extend operational cycles, offering a promising technical pathway for efficient, compact, and intelligent ESP systems in catering fume purification.
1. Introduction
Commercial electrostatic precipitators (ESPs) dominate catering fume purification, with over 90% installation in large and medium restaurants. However, 42.9% of these units exhibit negative VOCs removal efficiency, and particle deposition on electrodes causes frequent sparkover, shortening cleaning cycles and increasing operational costs. Existing modifications, such as adjusting dielectric barrier discharge frequency or combining DC and AC sources, either yield lower particle removal (79%) or significantly raise energy consumption. The core bottleneck lies in electrode design: conventional wire electrodes fail to sustain stable corona discharge under particle loading, limiting both particle charging and VOCs oxidation.
This study introduces a sawtooth-rod electrode structure as the discharge and precharging unit in a two-stage ESP. The highly non-uniform electric field generated by the sawtooth-rod configuration enhances corona intensity, producing more charges for fine particle capture and generating reactive species for VOCs degradation. Experimental results demonstrate that this design achieves superior particle collection (>98%) and toluene removal (53.1% with particles) while maintaining stable discharge and lower ozone generation under positive DC polarity. These findings directly address the operational and efficiency limitations of current ESPs, offering a viable path for simultaneous control of particulate and gaseous pollutants in catering fumes.
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ZHAI Yicong, WANG Hongchang, JIANG Nan, SHENG Zunrong, LI Jie (2026). Simultaneous Removal of Fine Particles and VOCs by a Two-Stage Electrostatic Precipitator Based on Sawtooth-Rod Electrode Discharge Charging. Journal of Environmental Engineering Technology. https://doi.org/10.13205/j.hjgc.202604019
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Frequently Asked Questions
What are the failure mechanisms of the sawtooth-rod electrode under prolonged operation with real catering fumes, and how does it compare to conventional electrodes in terms of maintenance frequency?
The sawtooth-rod electrode's stable discharge characteristics reduce sparkover frequency, as evidenced by the sustained corona current of 800 µA at +12 kV. This stability minimizes particle deposition on the electrode, extending the cleaning cycle compared to conventional needle-plate systems, which typically require more frequent maintenance due to sparkover-induced fouling.
How does the energy consumption of this two-stage ESP compare to commercial electrostatic purifiers, considering the applied voltages and corona currents?
At +12 kV and 800 µA, the power consumption is approximately 9.6 W for the charging stage, which is comparable to or lower than conventional systems that often require higher voltages or additional energy for VOCs removal. The enhanced VOCs degradation (53.1%) without extra energy input suggests better overall energy efficiency.
What is the scalability potential of this electrode configuration for large-scale catering facilities, and are there any constraints on gas flow rate or particle loading?
The sawtooth-rod electrode can be modularly scaled to accommodate larger gas flows. However, at high particle loadings, the corona current may decrease due to space charge effects, potentially reducing collection efficiency. Further optimization of electrode spacing and voltage is needed for high-load conditions, but the design's stability supports scalability.
How does the presence of particles enhance toluene degradation, and is this effect consistent across different VOCs species?
Particles likely enhance toluene degradation by providing surfaces for adsorption and increasing residence time in the discharge zone, promoting reactions with reactive species. This synergistic effect was observed with toluene (29.2% to 53.1%), but the extent may vary for other VOCs depending on their reactivity and adsorption affinity. Further studies are required to generalize.
What are the implications of the ozone concentration (176.9 mg/m³) for indoor air quality, and how can it be mitigated?
The ozone concentration exceeds typical indoor safety limits (e.g., 100 µg/m³ for 8-hour exposure). However, the study shows that positive polarity reduces ozone to 101.4 mg/m³, still high. For practical applications, additional ozone decomposition catalysts or adsorption filters would be necessary to meet regulatory standards.
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