Bosque de San Juan de Aragón is a Public Park, located in the Gustavo A. Madero City Hall of Mexico City, it receives approximately 4.2 million visitors a year. One of its main attractions is its artificial lake. This lake is fed with the effluent of a municipal wastewater treatment plant, conventional activated sludge type, with the following quality: 6.2 X 103 NMP/100 mL Fecal Coliforms; 180 mg/L TSS; 170 BOD5 mg/L; 170 mg/L Total Nitrogen; 3 mg/L Total Phosphorus and pH 8.2. The concentration of nutrients, together with the excreta of fishes and birds that inhabit it, promote their eutrophication. To improve the quality of the water contained in the lake and obtain additional environmental benefits, an interdisciplinary work team was formed, which designed a Double Spiral Artificial Wetland System (SHADE) between February and April 2019. It was inaugurated on February 2, 2020. The spiral geometry allows treating more volume of water in less area and also is a symbol of water and movement for the ancient people of Mexico (Fig. 1 and 2).
Figure 1. Stages of construction of SHADE (Photo: Victor Luna)
Figure 2. Final stage of SHADE (Photo: Victor Luna)
The wetland SHADE has a total area of 3108 m2, with an average treatment capacity of 140 m3 per day. Structurally, the cells that make it up contain, separately, different packing means, which will allow the removal of carbonaceous, phosphorous and nitrogenous compounds preferentially and in successive stages. The operation is in batches, with vertical and horizontal flow (Fig. 4). Currently, it receives 100 m3 per day and as it stabilizes, the cost will be progressively increased until reaching 140 m3.
Figure 3. Construction of SHADE (Photo: Victor Luna)
Figure 4. Water flow diagram and arrangement of the treatment cells that make up the SHADE
