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ARS Home » Southeast Area » Athens, Georgia » U.S. National Poultry Research Center » Quality and Safety Assessment Research Unit » Research » Publications at this Location » Publication #426226
Research Project: Smart Optical Sensing of Food Hazards and Elimination of Non-Nitrofurazone Semicarbazide in Poultry

Location: Quality and Safety Assessment Research Unit

Title: Fate of Salmonella from wastewater to hydroponic lettuce in a pilot-scale treatment system

Author
item ARTHUR, WELLINGTON - Auburn University
item MORGAN, ZACH - Auburn University
item REINA, MARCO - Auburn University
item DRABOLD, EDWARD - Auburn University
item WELLS, DANIEL - Auburn University
item BOURASSA, DIANNA - Auburn University
item HIGGINS, BRENDAN - Auburn University

Submitted to: Alabama Water Resources Conference
Publication Type: Abstract Only
Publication Acceptance Date: 9/6/2024
Publication Date: 9/6/2024
Citation: Arthur, W., Z. Morgan, M. Reina, E.T. Drabold, D.E. Wells, D.V. Bourassa, B.T. Higgins. 2024 “Fate of Salmonella from Wastewater to Hydroponic Lettuce in a Pilot-Scale Treatment System” Alabama Water Resources Conference. Orange Beach, Alabama, US, September 4-6

Interpretive Summary:

Technical Abstract: The objective of this study was to evaluate a pilot-scale wastewater treatment system's capacity in safely utilizing poultry processing wastewater (PPW) for hydroponic lettuce irrigation, with a focus on the fate of sudden Salmonella influx and their potential attachment or uptake into lettuce. The treatment system comprised of bioreactors inoculated with consortia of algae and nitrifying bacteria, clarifiers, membrane filters, UV disinfection, and hydroponic grow beds. Bioreactors were dosed with Salmonella at two concentrations: 3 and 5 log CFU/ml, daily. Water and lettuce samples were analyzed across three stages: pre-inoculation (days 0-10), inoculation (days 11-20), and post-inoculation (days 21-30). Water samples were serially diluted and plated for Salmonella enumeration. Lettuce samples were homogenized, suspended in buffered peptone water, enriched, plated, and presumptive colonies were confirmed. At the lower concentration (3 log CFU/ml), pre-inoculation samples showed no detection of Salmonella. During inoculation, direct plating yielded no Salmonella counts in water samples, but enrichment revealed its presence. UV disinfection eliminated Salmonella from water samples, with no detection in lettuce. There was no detection of Salmonella in both water and lettuce samples at the end of the recovery phase (Day 30). When challenged with higher Salmonella concentration (5 log CFU/ml), pre-inoculation samples showed no detection of Salmonella. By day 15 of inoculation, Salmonella counts in reactors, clarifiers, and filters were reduced to approximately 3 log CFU/mL. Although no Salmonella was detected via direct plating in UV effluents and holding tanks, enrichment methods indicated potential pathogen persistence or reactivation. By the end of the recovery phase, the system had restored to baseline pathogen levels, with no detection of Salmonella in UV effluents, grow beds, and lettuce samples. This study confirms the effectiveness of the treatment system in managing varying Salmonella loads, enhancing food safety, and contributing to sustainable agriculture practices.