Decontamination of irrigation water under field conditions: preliminary results

• Published in: Acta Horticulturae Vol. 922; no. 922; pp. 61 - 66
• Main Authors: Alsanius, B.W, Alam, M, Larsson, C, Rosberg, A.K, Ahrné, S, Molin, G, Jensén, P
• Format: Journal Article Conference Proceeding
• Language: English
• Published: International Society for Horticultural Science 01-01-2011
• Subjects: Campylobacter; coliform bacteria; decontamination; Enterococcus; Escherichia coli; farm to fork; filtration; foodborne illness; green leafy vegetables; guidelines; heat tolerance; heterotrophs; Horticulture; indicator species; irrigation water; Norovirus; oxidation; Salmonella; Shigella; Trädgårdsvetenskap/hortikultur; water quality; water treatment; British Columbia; Germany
• ISBN: 9066055340; 9789066055346
• ISSN: 0567-7572; 2406-6168; 2406-6168
• DOI: 10.17660/ActaHortic.2011.922.7

Outbreaks of foodborne diseases (Norovirus, Salmonella spp., verotoxin producing E. coli, Campylobacter spp., Shigella spp.) related to fruit and vegetable have increased worldwide. Microbial hazards cause considerable and in some cases life-long suffering. Contamination may occur during the entire farm-to-fork continuum with irrigation water as one of the major vehicles for contamination. Therefore, the potential of photocatalytic oxidation water treatment (POWT) to improve inferior irrigation water quality was studied. A prototype of a photocatalytic unit was installed on an irrigation ramp at a commercial field site growing leafy vegetables. Water samples were collected at five distinct sites within the water pipe namely from (i) the irrigation pond, (ii) after coarse filtration, (iii) at the beginning of the field water pipe as well as (iv) before and (v) after treatment using photocatalysis at three occasions with three independent replicates at each event. The water samples were analyzed with respect to indicator organisms for water quality (heterotrophic microorganisms at 22°C, total coliform bacteria, thermotolerant coliform bacteria, E. coli, intestinal enterococci, Salmonella spp.). After the photocatalytic treatment, the number of indicator organisms in the irrigation water decreased with respect to all monitored organisms. This was also observed for Salmonella spp. which was detected at a couple of incidents at the sampling sites prior to the photocatalytic unit. Indicator organisms in the treated water at the irrigation ramp were beyond the thresholds stipulated by guidelines for irrigation water quality in examples such as British Columbia in Canada and Germany.