A Proven Concept: New Large-Scale Nature-Based WWTP Project in Mexico for 14,000 People
We continue our work in the field of nature-based wastewater treatment in Mexico. In the State of Mexico, a new treatment plant is being built for the residential development Los Héroes Acolman, designed for 14,000 population equivalents. The concept follows the same technological approach used in our projects in Rayón and Cihuatlán: robust primary treatment, natural sludge humification, and efficient purification through vertical-flow constructed wetlands, followed by a naturally designed polishing pond that offers significant ecological value.
A sustainable and operationally reliable concept
The plant is designed for a daily inflow of 2,100 m³ of wastewater (24.3 L/s) and complies with the local guideline NOM-001-SEMARNAT-2021. As with our other projects, we combine low-energy processes with simple, low-maintenance operation—an essential factor for ensuring long-term operational reliability in the region.
The preliminary treatment includes an inlet channel with sand trap, a pumping station, a static fine screen, and two Imhoff tanks. The system is complemented by two clarification lagoons that hydraulically stabilize the flow feeding the planted filters.
For sludge management, two sludge humification beds are used. Sludge is removed from the Imhoff tanks by gravity at short intervals. In the humification beds, the sludge dewaters and mineralizes over several years—a resource-efficient method that produces a humus-rich substrate suitable for reuse.
Constructed wetland with 14,000 m² of filter area
The core of the system is a vertical-flow constructed wetland with a total filtration area of 14,000 m². The filter substrate consists of locally sourced tezontle, a porous volcanic rock well suited for use in constructed wetlands. Intermittent loading ensures proper aeration and a stable microbial environment, both essential for organic matter degradation and nitrification.
Biodiversity and ecological benefits
After passing through the vertical filter, the treated water flows into a 3,200 m² polishing pond, designed as a shallow-water ecosystem. This final treatment stage further improves water quality while creating a valuable aquatic habitat.
The planted beds and the subsequent wetland area provide habitat for numerous species—an ecological benefit that is increasingly important in rapidly growing urban regions. The treated water can be used for irrigating urban green spaces or for agricultural purposes, supporting local water cycles.
Cooperation with local partners
The project is being developed in collaboration with Grupo Sadasi and local authorities. It demonstrates how technical innovation, robust operation, and ecological functions can be integrated into a unified concept. With the Acolman plant, we further expand our series of large-scale constructed wetland systems in Mexico.
