Fate of Pathogens In Tomato Plants and Soil Irrigated With Secondary Treated Wastewater

Pathogenic indicators, namely total coliform, E. coli and Enterococcus were measured on harvested tomato fruits and leaves and in soil irrigated with fresh water, effluent of extended aeration wastewater treatment plant and effluent of upflow anaerobic sludge blanket-rotating biological contactors integrated pilot treatment system. Plantation was taking place in a greenhouse during summer in Jordan. A drip irrigation system was applied in which laterals were covered with mulch to minimize contact between irrigation water and plants. Results showed that total coliform and Enterococcus counts in all tomato fruit samples (except one) and E. coli count in all harvested tomato fruit samples were less than 1 MPN/g dry plant. Although secondary treated wastewater had indicator pathogenic counts of 2 to 5 log units, a considerable reduction was noticed in the collected soil samples after 10 days of the last irrigation. All soil samples contained less than 1 MPN/g dry soil of E. coli, while total coliform counts ranged from less than 1 to 19.23 MPN/g dry soil. The results suggest that disinfection of the reclaimed wastewater may not be necessary with respect to the measured indicator pathogens when proper agricultural practices are applied.