Hygienic evaluation of reclaimed water used to irrigate food crops - A case study

The study was designed to test the continued validity of a field pilot proj ect (completed in 1987) that had found irrigation of food crops with tertia ry-treated reclaimed municipal wastewater to be safe. It was also designed to determine whether or not pathogenic microorganisms of Concern to food sa fety, such as E. colt 0157:H7, Cyclospora, enteric viruses and Salmonella w ere present in disinfected tertiary recycled water. Sampling of the tertiar y water was conducted at intervals over a period of three months. In additi on, at the same time, samples were taken from the raw incoming wastewater, from secondary effluent, and from a control source, local well water. The r esults from samples of recycled water are comparable to similar tests at ot her well-operated, tertiary recycled water treatment plants and compare wel l with sources of drinking water supply. Other parasites, of lesser concern to food safety than to drinking water safety, were either absent or were d etected at extremely low concentrations of empty, non-viable cysts. The Ter tiary Water Food Safety Study did not detect any Salmonella, Cyclospora and E. coli 0157:H7 in any of the samples of tertiary recycled water from the Monterey County Water Recycling Projects (MCWRP). (C) 1999 IAWQ Published b y Elsevier Science Ltd. All rights reserved.