Impact of the reusing of food manufacturing wastewater for irrigation in a closed system on the microbiological quality of the food crops

- There are health concerns over the use of reclaimed wastewater in agriculture.
- Treated wastewater of poor microbial quality was used to irrigate crop fields for food industries.
- Soil and crops irrigated with wastewater did not show higher fecal indicators level.
- Produces were of good microbial quality, even for wastewater irrigated plots.
- Pathogens were occasionally detected by qPCR in the crop environment independently from water source.

In order to evaluate if the reuse of food industry treated wastewater is compatible for irrigation of food crops, without increased health risk, in the present study a cropping system, in which ground water and treated wastewater were used for irrigation of tomato and broccoli, during consecutive crop seasons was monitored. Water, crop environment and final products were monitored for microbial indicators and pathogenic bacteria, by conventional and molecular methods. The microbial quality of the irrigation waters influenced sporadically the presence of microbial indicators in soil. No water sample was found positive for pathogenic bacteria, independently from the source. Salmonella spp. and Listeria monocytogenes were detected in soil samples, independently from the irrigation water source. No pathogen was found to contaminate tomato plants, while Listeria monocytogenes and E. coli O157:H7 were detected on broccoli plant, but when final produce were harvested, no pathogen was detected on edible part.The level of microbial indicators and detection of pathogenic bacteria in field and plant was not dependent upon wastewater used. Our results, suggest that reuse of food industry wastewater for irrigation of agricultural crop can be applied without significant increase of potential health risk related to microbial quality.