Bacterial Contamination of Vegetables Irrigated with Wastewater

Population densities and freshwater resources are not equally distributed around the world.This has forced farmers to use wastewater for the irrigation of food crops Although wastewater is an important source of essential nutrients for plants, many environmental, sanitary, and health risks are also associated with the use of wastewater for crop irrigation due to the presence of microbes and pathogenic bacterial strains that have health risk importance which may transfer to the plant crops when this water used for irrigation and affect human health especially when this crops eaten raw (fresh vegetables).Like many other countries, wastewater is frequently used for crops irrigation without any prior treatment in peri-urban areas of Egypt.Present study demonstrates contamination level of irrigation water canals that branched from river Nile and receives wastewater from nearby drains or urban human activities or village around the water canals that dump their waste in the irrigation canals and effect of such wastewater on contamination of soil and fresh vegetables like lettuce, arugula and cucumber that growing in some areas (Qalubia, Giza and Sharkia) that irrigated by such water.Microbial load within the vegetable samples ranged from 5.2 log cfu/gm to 7.9 log cfu/gm, from 4.7 log cfu/gm to 6.3 log cfu/gm for total coliforms and from 4.0 log cfu/gm to 5.6 log cfu/gm for staphylococci counts.The observed mean counts in both irrigation water and the fresh vegetable samples were higher than the recommended standards of 1.0x10 2 cfu/ml (or cfu/gm) for THB and 1.0x10 1 cfu/ml (or cfu/gm) for total coliform.There was a positive correlation between water contamination and vegetable contamination during study period.Also many pathogenic bacterial species have been isolated from examined samples (wastewater, soil and raw vegetables) as E.coli sp., Salmonella sp., proteus sp., klebseilla, citrobacter sp., S. aureus, pseudomonas sp. and providencia sp.The results obtained from this study gives information not only on the microbial load but also on their origins (wastewater) and stimulate concerned entities in Egypt for the necessarily treatment of wastewater before use.