Microbiological Water Quality in Irrigation Water, Treated Wastewater, and Untreated Wastewater and Its Impact on Vegetables in Sonora, Mexico

Abstract

In Mexico, wastewater recycling is an important alternative source of water, particularly in arid regions like the state of Sonora, Mexico. In El Valle del Yaqui, Sonora, Mexico, where 500 million m3 per year of wastewater is available for recycling in agriculture activities . The main objective of the three studies presented in this dissertation was to assess the microbial water quality of surface water, untreated wastewater, and treated wastewater for produce irrigation, as well as the impact of microbial water quality on vegetable contamination. The results suggest that the three sources of water meet Mexican and international guidelines for use in production of food crops.Despite wide differences in the concentration of bacterial indicators (Escherichia coli, Clostridium perfringens) and enteric pathogens (Cryptosporidium, Giardia, and enteroviruses) in the various types of water studied there was little impact on contamination of the produce studied (carrots, lettuce, tomatoes, and peppers) at harvest. Apparently, the time between the last irrigation event and harvesting was sufficient to allow for die-off of enteric organisms that may have contaminated the produce.