Treatment technology and standards for agricultural wastewater reuse: a case study in Mexico

This paper explains how regulations and technology required for efficient and safe reuse of wastewater in irrigated agriculture were developed, considering both farmers' needs and health protection measures in Mexico, where a significant amount of municipal wastewater is reused for agriculture. Instead of considering nutrients and organic matter as pollutants, new legislation was developed allowing them to be present in appropriate concentrations in wastewater, while pathogens, especially helminth ova, had to be removed prior to wastewater reuse. Therefore, tailor‐made research work to develop technology that would treat wastewater to fit the new definition of effluent quality was undertaken. To illustrate the process, the Tula Valley case, where the biggest compact irrigation area using wastewater in the world is located, is discussed. The more than 100‐year experience in reusing wastewater in the Tula Valley has made it possible to study the short‐ and long‐term effects discussed below. The technology developed is called APT (advanced primary treatment) that basically consists of a coagulation–flocculation process coupled with high‐rate sedimentation. It is concluded that with an appropriate regulation and wastewater treatment technology a win–win approach to safely reuse wastewater in agriculture at an affordable cost may be possible. Copyright © 2005 John Wiley & Sons, Ltd.