The SHATTO Project Turns Urine into Clean Water

To recycle wastewater from the urinals and sinks of the men's restrooms, adjacent to Auditoriums A and B of the Faculty of Chemistry (FQ) of the UNAM, this entity started the Technical Artificial Wetland System for Urine Treatment (SHATTO).

This installation responds to a joint initiative of the FQ, through the Interdisciplinary Environmental Academic Group (GAIA), with the support of the University Coordination for Sustainability (CoUS), within the framework of the Comprehensive Plan for the Sustainability of the University.

The director of the FQ, Carlos Amador Bedolla, emphasized that cleaning urine is complicated; a common wetland cannot fulfill that function. Ours has an electrochemical system that produces a initial chemical reaction that simplifies the subsequent work of the microorganisms.

The system uses electricity, but it is planned to use photovoltaic cells, he announced. Likewise, a rainwater collection system will be installed, to store and use it. For now, the purified water is used for irrigation.

In front of Eduardo Vega López, head of the CoUS, Amador Bedolla described the wetland as a living project, which “reinforces our commitment to combine our knowledge, from the departments of Biology, Chemical Engineering, Organic Chemistry, Inorganic Chemistry, etc.”

Víctor Manuel Luna Pabello, academic of the FQ and academic head of the project, said that the wetland “belongs to everyone”; it is the result of 34 years of continuous work and the effort of students from different careers and from the postgraduate program, who participated with their theses, social service and stays. Students of architecture and civil engineering also joined in.

Although it is small compared to others that GAIA has built, such as the one-hectare system in the San Juan de Aragón Forest, this system has more technology, including one for treating urine that is partially diluted with water from the toilets, and which is collected in tanks, from where it is pumped to flow by gravity in the system.

In this wetland, contaminants are removed gradually. It contains plants selected to withstand high concentrations of urine, which help clean the water, in addition to being used for composting, construction, and even for making crafts.

“An artificial wetland is a set of elements that allow the cleaning of water and is mainly made up of vascular plants, microorganisms and a support medium that, together, eliminate contaminants present in wastewater or contaminated water, achieving acceptable quality levels for irrigation or reuse,” explained Luna Pabello, also head of the Experimental Microbiology Laboratory of the Biology Department of the FQ, in an interview.

In addition to cleaning the vital liquid, the specialist added, these systems can be wildlife reservoirs and serve to recirculate organic matter, produce and take advantage of useful inputs in construction, ornamental plants, recycling organic matter, in addition to helping to generate oxygen and capture CO2; they also allow for a more pleasant environment, improving the aesthetics of the place where they are installed and preventing sources of infection.

The artificial wetlands technique has been developed at the FQ since the beginning of the 1990s and Luna Pabello, one of the pioneers in working on this type of project, has two patents.

The first pilot systems were installed in the Faustino Miranda Greenhouse, in the Camino Verde and in the General Directorate of Works at Ciudad Universitaria; recently two wetlands were located in the Bosque de San Juan de Aragón, designed by the GAIA, which are among the largest in Mexico City.

At UNAM there are others, such as those located at the National School of Earth Sciences and at the College of Sciences and Humanities, Oriente campus, and another one is about to be inaugurated at the Faculty of Political and Social Sciences, for example.

System design

Basically, the SHATTO consists of a container that holds the waste water from the urinals, from which it passes to three containers or artificial wetlands connected in series, two with horizontal flow and one vertical. The effluent is led to a disinfectant filter and from there to a treated water collection tank for reuse or recirculation, as required.

Its plant component is made up of purifying and ornamental species that take organic and inorganic compounds present in urine to incorporate them into their biomass, which can be used for artisanal use, fodder, ornamentation and composting.

Additionally, the system fixes CO2 and provides oxygen. The microbial component is represented by bacteria and protozoa involved in the biotransformation of nitrogen, carbon and phosphorus compounds.

This wetland, Luna Pabello added, in addition to being a purification system and having pollinating plants, has the particularity that it is not only for treatment, but also for research, teaching, dissemination and interaction with students and academics, since through QR codes and on-page queries, you can do everything from word searches to proposing new experiments.

The external design of SHATTO contains various symbols. For example, the shape alludes to the Periodic Table of Chemical Elements; likewise, in it, you can see formulas such as urea, ammoniacal nitrogen or ammonium, as part of the molecules present in the waste water that is being treated, and in the background, in low relief, you can see the representation of some microorganisms; in addition, metal plates that simulate waves were integrated to symbolize the way in which contaminants change, through an exchange where oxygen rises and organic matter falls.

Currently, Luna Pabello concluded, “there is an enormous lack of water; “Dealing with this situation has to do with its availability and quality; this city is a major generator of wastewater, and a system like this is a way of helping to solve this problem.”