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A Study of Membrane-less Electrolyzed Water fogging-
spread for Airborne Bacteria and Fungus Decontamination
in Hen House
Chi-Yu Chuang and Wei Fang Shinhao Yang
Department of Bio-Industrial Mechatronics Engineering Department of Environmental and Occupational Health
National Taiwan University Toko University
Taipei City, Taiwan
{d97631001 & weifang}@ntu.edu.tw Chia Yi County, Taiwan
shinhaoyang@ntu.edu.tw
Min-Yih Chang Po-Chen Hung and Cheng Ping Chang
Department of Biomechatronics Engineering Institute of Occupational Safety and Health
National Ilan University Council of Labor Affairs
I lan City, Taiwan
mychang@niu.edu.tw
New Taipei City, Taiwan
{hungpc & jimmycla}@mail.iosh.gov.tw
Abstract – Bioaerosols in the animal feeding facility might
be the potential health risk factors to agricultural workers.
A novel on-site membrane-less electrolyzed water(MLEW)
generating and fogging-spread system was designed and
installed in selected experimental hen house for evaluating
the airborne decontamination efficiency. The result shows
that the bacterial aerosols reached to 105 CFU/m3 levels,
10 min of MLEW fogging-spread operation can has 70%
bacterial and fungal aerosols neutralizing efficiency.
Index Terms - bioaerosols, membrane-less electrolyzed water,
decontamination, hen house.
I. INTRODUCTION
The air quality of agricultural animal feeding facility has
been concerned to be potentially hazardous to the workers and
producers in recent years. Literatures have demonstrated the
health problems, respiratory symptoms, airborne bacteria and
fungus concentration. Predicala et al., 2002 use six-stage
impactor to investigate the bioaerosols concentrations in swine
barn. 8.6 × 104 colony forming unit (CFU)/m3 was found. The
mean respirable concentrations was 9.0 × 103 CFU/m3,
indicated the workers was exposure to high respiratory risk
[1]. Donham et al., 1989 reported that 60% of workers in the
swine house suffered from respiratory symptoms including
dry cough, chest tightness and irritation of the nose [2]. 53×
107 CFU/m3 and 62 ×106 CFU/m3 of total bacteria and
staphylococcus species was measured by quantitative
polymerase chain reaction method of bird catchers in chicken
house [3]. From the standing points of occupational health
and environmental quality, the technology for airborne
decontamination of bioaerosols was highly demanded.
Membrane-less Electrolyzed water (MLEW) is
generated by electrolysis of saline brine in a container within
anodic and cathodic electrodes. Its product contains high
oxidation-reduction potential (>1,000 mV), free available
chlorine (FAC) compounds. The traditional membrane built-in
mechanism generates strong acidic and alkali products in the
same time. Only the acidic products can be utilized for
microbial disinfection after dilution. Nevertheless, the
MLEW, generated from membrane-less mechanism in single
container could maintain in slightly acidic to neutral, resulting
higher yielding efficiency. While the pH of the MLEW range
from 5.0~6.5, the effective form of chlorine-related
compounds in is the hypochlorous acid (HOCl), presents the
strong antimicrobial property. Originated from the natural
material, economic production, environmentally friendly,
biological compatible and broad decontamination to
microorganisms, the MLEW shows high potential as the
alternative disinfectant [4] [5].
In the study, an on-site MLEW generating and fogging-
spread system was designed and installed in selected
experimental hen house for bioaerosols decontamination.
Airborne bacteria and fungus density was measured by viable
impacting collection for evaluating the performance.
II. MATERIAL AND METHODS
A. Experimental Hen house
The study was conducted in a hen house located at
Tainan, southern Taiwan. The experimental hen house is a
closed; fan and pad ventilating building with dimension of
180 m × 20 m. over 500 hens were reared in four-layer cage
rack with four rows, separated by three aisles, as Fig.1 shows.
(a) (b) (c)
2011 International Conference on Agricultural and Biosystems Engineering
Lecture Notes in Information Technology Vols. 3-4
978-0-9831693-9-0/10/$25.00 ©2011 IERI ICABE2011
2011 International Conference on Agricultural and Biosystems Engineering
Advances in Biomedical Engineering Vols. 1-2
978-0-9831693-9-0/10/$25.00 ©2011 IERI ICABE2011
393
Fig. 1 The bioaerosols sampling situation in the experimental hen house. (a)
The sampling site in the aisles and middle. (b) The sampling site near the pad.
(c) Two hens are reared in single cage.
B. Bioaerosols Sampling Strategy and Analysis Methods
In order to clarify the efficiency of MLEW fog-spread
decontamination in the hen house, 3-day successive
experiment was performed from January 7 to January 9, 2009
consists of two parts: the pre-experiment for monitoring daily
variation of bioaerosols concentration as the background at
the first day and the main decontamination experiment at the
next two days. In the first day pre-experiment for monitoring,
the bioaerosols sampling with triplicates were conducted at 19
sampling sites at 09:00, 13:00 and 17:00. Temperature (Temp)
and relative humidity(RH) were also measured and recorded
at the same time . In the main two days decontamination
experiment, the bioaerosols sampling with triplicates began at
9:00. After finishing the sampling at 09:00, the airborne
disinfectant started to spread in fog-phase for 10 min. The
successive sampling was then carried out at only at sampling
site 19 in the interval of 30 minutes for next 3 hours. The
reductions of the bioaerosols concentration between
background and after decontamination were calculated as the
index of the efficiency of the system.
Regarding to representative bioaerosols sample collection,
6 sampling sites were set at each aisles in the interval of 30 m
range (site 1 to 18). Another sampling site near the pad was
determining (site 19) for understand the air flow field mixing
situation of the hen house, as Fig 2 shows. The height of all
sampling sites was 1.5m from ground to simulate the
respiratory area of the workers (as Fog.1 (a)).
Fig. 2 The bioaerosols sampling sites distribution plan in the experimental hen
house.
SKC Biostage impactor calibrated at flow rate of 28.3
L/minutes for 10 seconds was used for bioaerosols collection
on culture plates. Two different culture media were used for
two types of bioaerosols: Tryptic Soy Agar (TSA, Difco,
USA) for bacteria incubation at 30°C for 48 hours and Malt
Extract Agar (Difco, MEA, USA) for fungus incubated at
25°C for 5 days. After incubating, the numbers of colony on
each plate was counted and converted into the airborne
density concentration in CFU/m3.
C. On-site MLEW generation and fogging-spread system
A novel MLEW generation system was designed,
fabricated and installed in experimental hen house. The
system consists of 1-L electrolysis container filled with
saturated brine. Two 10 cm × 2 cm Pt/Ti base electrodes
module (as Fig.3 (a)) was set inside the container as cathode
and anode with the gap of 0.8 cm between electrodes. The
current density is 25 Amp/dm2 in the electrolysis container.
With 30 minutes of electrolyzing process, the FAC
concentration of brine would rise up to 20,000 mg/L. This 1-
liter solution with high FAC concentration was diluted to 100
fold with tap water as the ready-to-use disinfectant (FAC 200
mg/L) by a proportional dosing pump. The disinfectant was
then pumped to the spinning atomizer (as Fig.3 (b)) stand on
the ground. The spinning atomizer can transfer the liquid
phase disinfectant (rate: 80 mL/ min) to fog-phase (mean
particle size: 43 μm) and spread to treat the air inside the hen
house.
For avoiding disturbing the hens, the MLEW
decontamination system was operated in the sampling site 19
for on-site disinfectant generation, automated dilution,
automated pumping, delivery and spread.
Fig. 3 (a) The Pt/Ti base electrodes module. (b) The spinning atomizer
III. RESULT AND DISCUSSION
A. Background Concentration of Bioaerosols in Hen House
All the background bacterial and fungus concentrations
measured first day pre-experiment at January 7, 2009. The
concentrations were shown in Table.1 and 2. In the hen house,
the airborne fungal concentration (2261-8763 CFU/m3) was
higher than bacteria (1.03×105-2.34×105 CFU/m3), shows the
same trend with previous studies [3].
TABLE I
THE BACKGROUND AIRBORNE FUNGAL CONCENTRATION OF THE HEN HOUSE
9:00
fungal concentration
(CFU/m3)
13:00
fungal concentration
(CFU/m3)
17:00
fungal concentration
(CFU/m3)
sampling
sites RH 55%
Temp 15 oC
RH 56%
Temp 16oC
RH 57%
Temp 14oC
1 4,688 3,463 5,371
2 5,230 3,675 6,360
3 3,958 3,199 7,208
4 3,887 3,540 4,735
5 3,392 3,110 4,876
6 3,816 2,827 5,145
7 4,170 3,110 3,958
8 3,110 2,544 3,110
9 4,240 2,615 5,583
10 3,675 2,261 6,926
11 3,821 2,403 8,763
Cage rack 1
Cage rack 2
Cage rack 3
Cage rack 4
19
1 2 3 4 5 6
7 8 9 10 11 12
13 14 15 16 17 18
(a) (b)
394
12 4,382 2,898 5,159
13 4,170 2,898 4,240
14 3,958 2,625 4,664
15 3,392 2,824 3,615
16 3,746 2,654 6,542
17 3,543 2,432 4,531
18 4,567 3,154 5,323
19 1,542 1,312 2,114
Table II
THE BACKGROUND AIRBORNE BACTERIAL CONCENTRATION OF THE HEN
HOUSE
9:00
bacterial
concentration
(CFU/m3)
13:00
bacterial
concentration
(CFU/m3)
17:00
bacterial
concentration
(CFU/m3)
sampling
sites
RH 55%
Temp 15 oC
RH 56%
Temp 16oC
RH 57%
Temp 14oC
1 1.87×105 1.23×105 1.89×105
2 1.43×105 1.10×105 1.69×105
3 1.23×105 1.01×105 2.34×105
4 1.61×105 1.10×105 1.76×105
5 1.54×105 1.09×105 1.58×105
6 1.43×105 1.12×105 1.78×105
7 1.32×105 1.03×105 1.67×105
8 1.45×105 1.23×105 1.89×105
9 1.37×105 1.43×105 1.66×105
10 1.42×105 1.11×105 1.77×105
11 1.54×105 1.15×105 1.64×105
12 1.43×105 1.26×105 1.55×105
13 1.52×105 1.21×105 1.78×105
14 1.15×105 1.02×105 1.54×105
15 1.66×105 1.08×105 1.69×105
16 1.32×105 1.11×105 1.78×105
17 1.43×105 1.17×105 1.65×105
18 1.55×105 1.06×105 1.89×105
19 1.14×105 1.03×105 1.66×105
The airborne fungal concentration from aisles sites (site 1
to 18) were higher than pad location (site 19), but all still at
103 CFU/m3 level. All airborne bacterial concentrations from 19
sampling sites were at the 105 CFU/m3 levels. These data
reveals that the air flow was well-mixing inside the hen house
and different locations in the house would not affect the
concentration of fungal and bacterial aerosols. Hence, even
operated near pad location (site 19), our newly designed
MLEW fogging-spread system can still processing
decontamination uniformly. Besides, the bioaerosols
concentration in late afternoon (17:00) was higher than
morning (09:00) and noon (13:00).
B. Bioaerosols Reduction after MLEW decontamination
The MLEW fogging-spread decontamination was
performed at January 8 and 9, 2009. At the first day of
experiment, only bacterial aerosols reduction was measured
because it was the major target of the decontamination. At the
second day, the bacterial and fungal aerosols were measured
at the same time. Fig.4 was the decontamination efficiency of
the first day for bacterial aerosols at the first day experiment.
The initial bacterial aerosols concentration was 120,000
CFU/m3 and decreased near 50 % after MLEW fogging-
spread. The concentration reduction phenomena persisted to
90 minutes and then increased back to initial concentration
level. In other word, single fogging-phase spread treatment
can maintain bacterial aerosols neutralizing capacity about 80
minutes.
Fig. 4 The first day bacterial aerosols decontamination efficiency using
MLEW fogging-spread system
At the second day, the initial bacterial concentration was
lower, reach to 100,000 CFU/m3. After 10 minutes MLEW
fogging-spread treatment, the concentration decreased near 70
% after MLEW fogging-spread. Similarly, the bacterial
concentration increased again at the 90 minutes sampling, as
Fig.5 shows.
Fig.5 The second day bacterial aerosols decontamination efficiency using
MLEW fogging-spread system
The fungal aerosols concentration was also been observed
to decreased to 70% from the 3,000 CFU/m3 level after
MLEW fogging-spread treatment, as Fig.6 shows.
MLEW
Fogging-spread
MLEW
Fogging-spread
MLEW
Fogging-spread
395
Fig.6 The second day fungal aerosols decontamination efficiency using
MLEW fogging-spread system
The fungal aerosols increased again at the 120 minutes
sampling, means that the fungal aerosols neutralizing capacity
about 110 minutes. Fungal aerosols were believed to be
stronger against the disinfectant due to rigid and complex
wall. Here, the faster recovery of bacterial aerosols should be
contributed to the additional and disturbing contamination
sources inside the hen house, such as manure, urine and used
bedding. In the field operation, we recommend that the
MLEW should be spread in 90 minutes or shorter interval to
maintain the indoor microbial air quality in the hen house.
IV. CONCLUSION
At this preliminary study, one novel on-site MLEW
generate and fogging-spread system was designed and
evaluated in the hen house field. Through the background
monitoring, the bacterial aerosols concentration reached to 105
CFU/m3 levels, means that the agricultural workers are
potentially exposed under allergen, endotoxin and
opportunistic infectious agents. The MLEW system provided
the acceptable performance to neutralizing the bioaerosols
(70% to bacteria and fungus) and revealed high potential in
reducing the health risk and create better working
environment.
ACKNOWLEDGMENT
Thanks to Institute of Occupational Safety and Health,
Council of Labor Affairs, Taiwan for financial support
(IOSH98-H311)
REFERENCES
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Filtration and Impaction," Current Microbiology, vol. 44, pp. 136-140,
2002.
[2] K. J. Donham, et al., “Environmental and health studies of farm workers
in Swedish swine confinement buildings, “ Brit. J. Ind. Med. vol. 46, no.
1, pp.31–37. 1989.
[3] A. Oppliger, et al., "Exposure to bioaerosols in poultry houses at different
stages of fattening; use of real-time PCR for airborne bacterial
quantification," Ann Occup Hyg, vol. 52, pp. 405-12, 2008.
[4] Y. Huang, et al., "Application of electrolyzed water in the food industry,"
Food Control, vol. 19, pp. 329-345, 2008.
[5] S. Koseki, et al., "Decontamination of lettuce using acidic electrolyzed
water," J Food Prot, vol. 64, pp. 652-8, May 2001.
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