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Water Monitoring and Contamination Agricultural Water Juan L. Silva, Vladimir Escalante, Taejo Kim, Lorena Luna Guevara, Juan Jose Luna, Miguel Angel de los Santos
Water Monitoring and ContaminationAgricultural Water
Juan L. Silva, Vladimir Escalante, Taejo Kim, Lorena Luna Guevara, Juan Jose Luna,
Miguel Angel de los Santos
Thank you
• Dr. Alex Castillo, Ms. Cindy Anderson
• PSA
• JIFSAN (Dr Jim Rushing)
• My collaborators and students
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Outline
• Microbiological water contaminants
• Produce Safety Rule, 21CFR112
• Water microbial indicators and standards
• Agricultural water treatments
– Filtration/suspension
– Conventional
– Oxidation (AOP)
• Conclusions
3
Produce related outbreaks
4
Contamination Routes
5Zhu et al, 2017
Selected outbreaks caused by contaminated water
• S. Muenchen, ice for juice
• S. Javiana y Montevideo, wash water for tomatoes
• S. Saintpaul, jalapenos
• Salmonella, mangos, cold water
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• Shigella, green onions
• Hepatitis, water green onions
• V. cholarae, contaminated water in vegetables
• Cryptosporidium, berries
Harris et al, 2003
2006Spinach contamination with irrigation water?E coli O157.H7 by wild boar– 276 cases, 5 deaths
UC Davis Extension
Agricultural Water
• Agricultural water: water that touches harvestable or edible product or food contact surfaces
• Production Water
– Water used in contact with produce during growth: irrigation, fertigation, foliar sprays, frost protection
• Postharvest Water
– Water used during or after harvest: washing, clean containers
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Potential Sources of Surface Water Contamination
Surface Water Source
Wildlife & Domesticated Animal Feces
ManureApplication/
CompostingOperations
Agricultural Runoff
Septic Tank Leakage
Waste Water Discharge
Urban and Environmental
Runoff
Things We Never Thought
Of
Flooding
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San Francisco Chronicle, 2017 Purdue U, 2017
Pathogen survival in water
Patógeno
Giardia
Cryptosporidium
Salmonella
Campylobacter
Yersinia
E. coli O157:H7
Frozen
< 1día
> 1 año
> 6 meses
2-8 semanas
> 1 año
> 6 meses
Cold (5oC)
2 meses
> 1 año
> 9 meses
< 2 semanas
> 1 año
> 9 meses
Warm (30oC)
< 3 semanas
< 3 meses
> 6 meses
< 1 semana
< 2 semana
< 3 meses
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12
Higher Risk
Agricultural water P(contamination)
Lower Risk
Public Water Supply
Treated
Surface Water
Open to Environment
Ground Water
Microbiological Testing of Water
• The only way to verify that water after
sanitation treatment is effective
• Typically we evaluate using indicator
microorganisms
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Microbial Water Quality Profile: Survey of Surface Water Sources
§
Source Initial and Annual Testing Requirement
Surface
20 or more times over a period of 2 to 4 years
5 or more samples rolled into profile every year after initial survey
• Profile samples must be representative of use and must be
collected as close in time as practicable to, but before, harvest
Indicator microorganisms in surface and groundwater
• 136 samples of surface water and 143 underground water
• Surface water: total coliforms in 99%, Escherichia coli in
97%, & Clostridium perfringens in 73% of surface water
• Total coliforms in 20%, E. coli <1%, & C. perfringens ND in
groundwater
• The use of land - more significant in the concentrations of
bacterial indicators in water
• Presence of septic systems near the sampling site and
depth of the well may be related to coliforms in
groundwater
Struck et al, 2005 15
Séptic System
Well head
30m from septic system
Possible fecal contamination indicator m.o.
Clostridium perfringens: – spore-forming anaerobe
– feces-specific?
– very (too?) resistant spores (can persist for decades of centuries!)
– may be an indicator for protozoan cysts
Bacteroides spp. and Bifidobacteria spp.:– most plentiful in feces (100X more than FC, FS and E. coli)
– strict anaerobes
– poor survival in the presence of air (oxygen)
– poor detection methods: requires strict anaerobic conditions
– Some Bacteroides species may be human-specific
Rhodococcus coprophilus: – plentiful in feces of some animals
– possible animal fecal contamination indicator
BACTERIA ARE NOT ALWAYS GOOD INDICATORS OF VIRUSES AND PROTOZOANS !
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Water Microbial Indicators
• WHO international standard:
– 1000 fecal coliform bacteria / 100 ml of water
• Standard recommended by the USA (recreational water EPA)
– Indicator 126 MPN of E. coli / 100 ml water
• Agricultural Water (under FSMA PSR):
– No E coli in hand water, ice, direct contact
– MG <126MPN / 100ml and VUE <410MPN
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Relationship between Total, Fecal
Coliforms, E. coli & Patogenos
Total Coliforms
Fecal Coliforms
Escherichia coli
Salmonella
Parasites
Enterobacter
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Water standards
• Test results must be used to calculate Geometric Means and Statistical Threshold Values to compare to water quality criteria in the FSMA Produce Safety Ruleo The geometric mean (GM) is a log-scale
average, the “typical” value
o The statistical threshold value (STV) is a measure of variability, the estimated “high range” value (approximated 90th percentile)
o In the image to the right, both the GM andthe STV values for the data meet criteria
• Tools are available to assist in calculatingthese values
§
GM
(Typ
ica
l va
lue
)
ST
V
(Hig
h-ra
nge)
Contamination (water) microbial indicators
• Total coliforms:
– drinking, bathing and shellfish water standards
– not feces-specific (environmental sources).
• Fecal coliform ("thermotolerant") (FC):
– detect by growing at elevated temperature of 44-45oCTotal
– ditto coliforms, but less so
• E. coli: the "fecal" coliform
– Detect and distinguish from other total and fecal coliforms by Beta-
glucuronidase activity
– may occur naturally in tropical environments (and possibly elsewhere)
• Fecal Streptocococus (FS):
– Mostly Lancefield group D (and some group Q) streptococci and enterococci
– not feces-specific.
• Enterococci:
– More feces-specific sub-set of FS: Enterococcus faecalis & E. faecium
– EPA guideline for bathing water quality
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Possible sources of pathogens in greenhouses
• Water source
• Tanks / pools that store water
• Pipes (biofilms)
• Waste from plants
• Surfaces
• Workers
• Reused containers
22Wick, Fisher & Harmon, 2008
Relationship between the indicator organism concentration and
the risk of exposure of individuals
Risk
# Indicator m.o.
Sobsey, 201623
Water Treatment Technologies
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Conventional Technologies
• Chemical methods– Coagulation, flocculation, combined with flotation
and filtration, precipitation, ion exchange, electroflotation, electrokinetic coagulation.
• Physical methods– Filtration and membrane filtration processes
(nanofiltration, reverse osmosis, electrodialysis, ...) and adsorption techniques.
• Biological treatments– Biodegradation methods such as fungal
discoloration, microbial degradation, adsorption by microbial biomass (live or dead) and bioremediation systems
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Coagulation
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Floculation
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Factors Influencing Disinfection Efficacy and
Microbial InactivationMicrobe type: Resistance to chemical disinfectants:
• Vegetative bacteria: Salmonella, coliforms, etc.: low
• Enteric viruses: coliphages, HAV, Noroviruses: Moderate
• Bacterial Spores
• Fungal Spores
• Protozoan (oo)cysts, spores, helminth ova, etc.
– Cryptosporidium parvum oocysts
– Giardia lamblia cysts
– Ascaris lumbricoides ova
– Acid-fast bacteria: Mycobacterium spp.
Least
Most
High
Resistance:
Cryptosporidium Removals by Coagulation
(Jar Test Studies)
Coagulant Dose
(mg/L)
Oocyst Removal, % (log10)
Alum 5
1
99.8 (2.7)
87 (0.9)
Iron 6
5
99.5 (2.3)
97 (1.5)
From Sobsey, 2007
Sedimentation y Centrifugation
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Filtration
31lindsay.com
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Water disinfection
• Chlorine/hipochlorites
• Chlorine dioxide
• Ozone
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Inactivation of Cryptosporidium Oocysts in Water
by Chemical Disinfectants
Disinfectant CT99 (mg-min/L) Reference
Free Chlorine 7,200+ Korich et al., 1990
Monochloramine 7,200+ Korich et al., 1990
Chlorine Dioxide >78 Korich et al., 1990
Mixed oxidants <120 Venczel et al., 1997
Ozone ~3-18 Finch et al., 1994
Korich et al., 1990
Owens et al., 1994
CT99 – Concentration* contact time for 2D reduction
C. parvum oocysts inactivated by low doses of UV radiation: <10 mJ/cm2
Advanced Oxidation Processes (AOP)
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Science Direct
Water treatment
36Sustainable Sanitation and Water Management Toolbox
Oxidizing substances
• Hydrogen peroxide and other inorganic peroxides• Nitric Acid and Nitrates• Chlorides, chlorate, perchlorate and other analogous
halogenated compounds• Hypochlorite and other hypohalite compounds such
as bleach• Fluorine and other halogens• Ozone• Nitrous oxide (N2O)• Silver oxide• Permanganate salts
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Radical formation
38www.sbmc.or.jp
Chlorine byproducts breakdown
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Some applications AOP
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Avocado Agricultural Water Treatment
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Water Treatment Pesticide Application
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ClO2 Effectiveness
43lenntech.com http://isiasistemi.it
Surface wáter- contaminated?
Water remediation at source
• Contaminated wáter can be treated for ag use
• Can use multiple ttreatment steps
– Multiple Filtration (en multi-etapas), irradiación UV,
desinfectanes
– Have to validate to verify their effectiveness
Green onions irrigation using canal water- micro hazards?
Filtration & CL injection for Surface wáter to be
used in drip irrigation
Unidad de Tratamiento del Agua Agricola
Mobile ClO2 wáter treatment unit
Recontamination?
?
Field washing
Hazard?/
Advanced Oxidation Process
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Ruiz-Aguirre et al, 2017
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Conclusions
• Water is a contaminant of F & V
• Appropriate indicators for the contaminant
• Treatment can be the only alternative (Agricultural water)
• The treatment has to be appropriate
• PAO can be effective and do not affect the environment
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