Optimization of a wet scrubber with electrolyzed water spray—Part II: Airborne culturable bacteria removal

ABSTRACT

Airborne microorganisms, especially the pathogenic microorganisms, emitted from animal feeding operations (AFOs) may harm the environment and public health and threaten the biosecurity of the farm and surrounding environment. Electrolyzed water (EW), which was considered to be an environmentally friendly disinfectant, may be a potential spraying medium of wet scrubber for airborne microorganism emission reduction. A laboratory test was conducted to investigate the airborne bacteria (CB) removal efficiency of the wet scrubber by EW spray with different designs and operating parameters. Both the available choline (AC) initial loss rate and AC traveling loss rate of acidic electrolyzed water (AEW; pH = 1.35) were much higher than those of slightly acidic electrolyzed water (SAEW; pH = 5.50). Using one spraying stage with 4 m sec⁻¹ air speed in the duct, the no detect lines (NDLs) of SAEW (pH = 5.50) for airborne Escherichia coli, Staphylococcus aureus, and Salmonella enteritidis removal were all 50 mg L⁻¹, whereas the NDLs of AEW (pH = 1.35) for airborne E. coli, S. aureus, and S. enteritidis removal increased to 70, 90, and 90 mg L⁻¹, respectively. The NDLs of SAEW (pH = 5.50) for airborne E. coli, S. aureus, and S. enteritidis were lower than those of AEW (pH = 1.35) at single spraying stage. Increase in the number of stages lowered the NDLs of both SAEW (pH = 5.50) and AEW (pH = 1.35) for airborne E. coli, S. aureus, and S. enteritidis. EW with a higher available chlorine concentration (ACC) was needed at air speed of 6 m sec⁻¹ to reach the same airborne CB removal efficiency as that at air speed of 4 m sec⁻¹. The results of this study demonstrated that EW spray wet scrubbers could be a very effective and feasible airborne CB mitigation technology for AFOs.

Implications: It is difficult to effectively reduce airborne bacteria emitted from animal feeding operations (AFOs). Electrolyzed water (EW) with disinfection effect and acidity is a potential absorbent for spray in wet scrubber to remove microorganisms and ammonia. Based on the field test results, a laboratory experiment we conducted this time was to optimize the design and operation parameters to improve the airborne bacteria removal efficiency. A better understanding of the EW application in the wet scrubber can contribute to the mitigation of airborne bacteria from animal houses and improve the atmosphere air quality.

Additional information

Funding

This study was funded by the National Key R&D Program of China (2018YFD0500700) and Agricultural Research System of China (CARS-40).

Notes on contributors

Zonggang Li

Zonggang Li is a Ph.D. candidate in the College of Water Resources & Civil Engineering, China Agricultural University, Beijing, China.

Baoming Li

Baoming Li is a professor in the College of Water Resources & Civil Engineering, China Agricultural University, Beijing, China.

Weichao Zheng

Weichao Zheng is an associate professor in the College of Water Resources & Civil Engineering, China Agricultural University, Beijing, China.

Jiang Tu

Jiang Tu is a master candidate in the College of Water Resources & Civil Engineering, China Agricultural University, Beijing, China.

Hongya Zheng

Hongya Zheng is a Ph.D. candidate in the College of Water Resources & Civil Engineering, China Agricultural University, Beijing, China.

Yang Wang

Yang Wang is a Ph.D. candidate in the College of Water Resources & Civil Engineering, China Agricultural University, Beijing, China.