Background

CESPT, one of the best run water utilities in Mexico, is responsible for providing water and wastewater services in both Tijuana and Playas de Rosarito. In 2010 water coverage in Tijuana was estimated at 99.6% and wastewater collection at 97%. Wastewater treatment is provided through three activated sludge treatment plants: the San Antonio de los Buenos Wastewater Treatment plant (WWTP) with a 25 million gallon a day (mgd) capacity; the International WWTP in San Ysidro, CA (25 mgd); and the Arturo Herrera WWTP (11 mgd).

As part of its master plan to extend wastewater collection and treatment services to 100% of the city’s population and achieve zero discharges of untreated sewage into rivers and streams, CESPT undertook the construction of two additional wastewater plants—La Morita to serve residents in the southeastern area of the city and Tecolote-La Gloria to serve residents in the southwestern area of the city. The La Morita plant has been completed and
began operations in August 2010. The Tecolote-La Gloria plant is currently under construction and approximately 55% complete.

The two treatment plants also form part of the utility’s reclaimed water plan. The treated effluent from these plants can be used for non-potable uses, such as irrigation of green areas.

Description

CESPT proposes increasing its wastewater treatment capacity through two projects.

Construction of the La Morita WWTP
The 5.8 mgd plant has a biological treatment process using extended aeration/activated sludge (EA/AS). The system includes nitrification, denitrification, phosphorus removal and UV disinfection, as well as a sludge digester and sludge pumping station. Treated effluent will be discharged into the Matanuco creek, which flows into the Tijuana River downstream of the Abelardo L. Rodriguez dam.

Construction of the Tecolote-La Gloria WWTP
The 8.7 mgd plant has a biological treatment process using extended aeration/activated sludge (EA/AS). The system includes nitrification, denitrification, phosphorus removal and UV disinfection, as well as a sludge digester and sludge pumping station and will be constructed in three 2.9 mgd modules. Treated effluent will be discharged into the San Antonio Creek, which empties into the Pacific Ocean.

Benefits

With these two plants, CESPT will achieve close to 100% wastewater treatment coverage in Tijuana, thus reducing environmental and health hazards associated with untreated sewage discharges that affect local residents, as well as other communities along the Pacific coast, including California. Specifically, an estimated 4 mgd of existing sewage discharges will be prevented from flowing into the Pacific Ocean.