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Decontamination of irrigation water using a combined sand filtration and UV‐C light treatment
Author(s) -
ShermanWood Robert,
Tikekar Rohan V.
Publication year - 2020
Publication title -
journal of food safety
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 43
eISSN - 1745-4565
pISSN - 0149-6085
DOI - 10.1111/jfs.12744
Subject(s) - turbidity , filtration (mathematics) , slow sand filter , filter (signal processing) , irrigation , environmental science , contamination , environmental engineering , water treatment , chemistry , pulp and paper industry , zoology , mathematics , biology , agronomy , ecology , statistics , computer science , computer vision , engineering
Surface irrigation water is a food safety risk due to susceptibility to contamination and varying turbidity that affects chlorination efficacy. Effectiveness of a combined high‐throughput, commercially available sand filter and UV‐C system to inactivate Escherichia coli (K12, and attenuated O157:H7) in simulated irrigation water of varying turbidity and actual irrigation water was investigated. Sand filtration reduced the water turbidity from ~600 nephelometric turbidity units (NTU) to ~200 NTU but did not effectively filter out E. coli (K12) [<1 log colony forming units (CFU)/ml]. UV‐C‐induced inactivation of E. coli (attenuated O157:H7) was modeled for various levels of turbidity (0–500 NTU), and the relationship between the D value for inactivation and turbidity was found to be linear ( R 2 > .97). Predicted UV treatment time to achieve 5 log reduction in water with turbidities of 100 and 300 NTU was 110 and 370 s, respectively. Validation performed with irrigation water (turbidity of 330 ± 82 NTU) showed that sand filtration reduced turbidity to 180 ± 57 NTU. Based on this, the duration of UV treatment required for 5 log reduction of E. coli O157:H7 was calculated (average of 237 s). Observed levels of inactivation, 4.7 ± 0.31 log CFU/ml, were not significantly different ( p > .05) from the predicted level, 5 log CFU/ml, indicating a good model fit.