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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Publications at this Location » Publication #365013

Research Project: Characterization and Mitigation of Bacterial Pathogens in the Fresh Produce Production and Processing Continuum

Location: Environmental Microbial & Food Safety Laboratory

Title: Evaluation of zero-valent iron filtration to reduce Escherichia coli in agricultural irrigation water in laboratory and field trials

item KIM, SEONGYUN - University Of Maryland
item BRADSHAW, RHODEL - US Department Of Agriculture (USDA)
item KULKARNI, PRACHI - University Of Maryland
item CHIU, PEI - University Of Delaware
item ALLARD, SARAH - University Of Maryland
item SAPKOTA, AMY - University Of Maryland
item Handy, Eric
item East, Cheryl - Roberts
item KNIEL, KALI - University Of Delaware
item Sharma, Manan

Submitted to: International Association for Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Introduction: Surface water is a critical source of irrigation water which may contain bacterial foodborne pathogens that can contaminate produce intended for human consumption. Zero-valent iron (ZVI) filtration may provide a cost-effective strategy to reduce pathogens in surface water. Purpose: To evaluate the effectiveness and longevity of a ZVI and sand (S) in a unique filter designed to reduce E. coli in irrigation water in laboratory and field trials. Methods: ZVI (50% ZVI: 50% sand) and sand (S) (100% sand) were constructed with Schedule 40 PVC pipes (2” diameter). Autoclaved pond water (8 L) was inoculated with E. coli TVS 353 (104 CFU/mL) and introduced to ZVI and S filters, followed by 16 L of uninoculated pond water. Effluent was collected to determine E. coli populations. Six laboratory filtration events and two field irrigation trials on spinach plants with ZVI- or S-filtered water, along with control (unfiltered) water, were conducted. Results: ZVI filtration resulted in significantly (p<0.001) lower populations in water of E. coli than S filtration. E. coli populations were reduced by 70% by ZVI filtration but were not reduced by S filtration (-10%) over six laboratory trials. ZVI filtration removed E. coli populations in early trials 1-3 (mean reduction: 96%) more effectively than in trials 4-6 (44%). For field irrigation trials, soil samples irrigated with ZVI-filtered water had E. coli populations below the detection limit (<2 log CFU/g) and were significantly lower than E. coli in soils irrigated with S filtration (2.11 log CFU/g) or control water (1.75 log CFU/g). Prevalence of E. coli was lower on spinach plants irrigated with ZVI-filtered compared to S- or unfiltered irrigation water. Significance: ZVI filtration reduced E. coli populations in surface water and on irrigated spinach plants, and may aid produce growers in meeting irrigation water standards of the Food Safety Modernization Act.