Wastewater Treatment in Mexico

Abstract

This chapter presents a global perspective and analysis of the current situation of the legal and regulatory framework of Mexico for wastewater treated for discharge and reuse. Also, a comparative discussion of the situation of the installed Mexican wastewater treatment trains and facilities is shown. Finally, it presents an overview of the research and development trends of new wastewater treatment processes and applications of treated wastewater in Mexico. These three issues are discussed with respect to other countries.

In the first section, a comparative and critical analysis of the normative frameworks of Mexico and several countries worldwide for wastewater treated for discharge and for reuse is presented. Specifically, three official Mexican standards will be analyzed for the regulation of the permissible maximum limits of pollutants in residual water: the NOM-001-SEMARNAT-1996 (PROY-NOM-001-SEMARNAT-2017) that establishes the permissible limits of pollutants in wastewater discharges into receiving water bodies owned by the nation; the NOM-002-ECOL-1996 that establishes the maximum permissible limits of pollutants in wastewater discharged into municipal or urban sewer systems to prevent and control the pollution of national water and its goods; and the NOM-003-SEMARNAT-1997 that establishes the permissible limits of pollutants for treated wastewater for reuse in public services.

In the second section, regarding the sanitation infrastructure, data on the number and types of wastewater treatment trains and facilities of Mexico, as well as of the effluent quality, are presented and compared in the context of some Latin American countries. The comparison is made to establish the situation of the country and to propose some recommendations to solve the problems associated with these issues. For example, of the total wastewater flowrate generated in Mexico, only 92% is collected. Nevertheless, only 63% of the collected wastewater is treated in 2536 plants with an installed capacity of 123.4 m³/s. The processes used to treat most of this flowrate are as follows: lagoon systems, 776 wastewater treatment plants (WWTPs), and 732 activated sludge WWTPs.

Finally, in the third section “Overview of the research and development trends of new wastewater treatment processes and applications of treated wastewater in Mexico,” wastewater is regarded as a source of high value-added by-products such as biohydrogen, biogas, biodiesel, bioalcohols, fertilizers, and bioplastics. This can make more sustainable the wastewater treatment processes since, historically, the Mexico treatment systems have required considerable energy and resources, which is a scenario that drains investments and is not viable in a low-carbon economy. Thus, several case studies are discussed and compared to some works reported in the literature worldwide to establish trends and the degree of development in Mexico for new wastewater processes to produce fuels and bioplastics.