Pontificia Universidad Católica de Chile: Academics participate in a project that reuses gray water

One of the great challenges we must face as a country is water scarcity. According to the National Water Balance recently published by the Ministry of Public Works , the regions between Atacama and Maule register rainfall deficits between 62% and 80% compared to the historical average 1981-2010, placing July 2021 as the month driest since 1998.

Considering this complex scenario, which has been affecting access to drinking water in rural areas of our country for years, the INNOVA-CORFO project was developed “Implementation of a sustainable prototype for the reuse of gray water in schools belonging to areas with critical water deficit ”, Which had the participation of teachers and researchers from UC Hydraulic and Environmental Engineering , the UC Faculty of Chemistry and Pharmacy, the UC Institute of Geography , the School of Biotechnology of the Universidad Mayor , the Fundación un Alto en el Desierto and the Municipality of Ovalle .

“The drought is advancing more and more and affects more rural areas,” explains Eduardo Leiva, professor at the Faculty of Chemistry and Pharmacy and director of the project, detailing that in Chile 72% of the surface suffers drought, 156 of the 345 communes of the country are at risk of desertification and 38% of the population has been affected by drought. In the specific case of Coquimbo, he stressed that 80% of the water deficit has occurred in that region, which has been declared a Water Scarcity Zone and an Agricultural Emergency Zone. “The reuse of greywater can be a response to drought. Instead of using drinking water for irrigation, we can use gray water for the same purpose ”, says the academic.


Gray water reuse: providing solutions for the water crisis
But what is gray water? Unlike sewage, gray water comes from domestic use resulting from washing hands, showers and dishwashers and can be recovered by installing cleaning and purification mechanisms of medium complexity and serving for filling toilets, irrigation or cleaning outdoor. For its part, sewage is wastewater contaminated by fecal elements and detergents or non-biodegradable substances that require much more complex canalization systems and treatments.

“The reuse of greywater can be a response to drought. Instead of using drinking water for irrigation, we can use gray water for the same purpose ”- Eduardo Leiva, professor at the UC Faculty of Chemistry and Pharmacy.

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The objective of the gray water reuse project was to optimize and implement a treatment system for these waters, based on a filtration prototype, which would allow to improve the quality of the water, reaching the standards required for its reuse in the irrigation of ornamental and fruit trees. and other plants of the different localities .

This initiative arose thanks to a Corfo contest to finance projects that had a prototype already developed and that had the objective of solving a social and / or environmental problem in a sustainable way And, as a similar one had previously been carried out in the province of Limarí in 2017, the researchers took advantage of this experience and proposed a project focused on generating gray water reuse systems, now also incorporating educational establishments in the provinces of Elqui and Choapa .


Six receiving educational establishments had the execution of a physical work in the school for the installation of the gray water filter. Photo credits: UC Geography.

Sustainable work with the community
Professor Eduardo Leiva, specifies that the project was carried out in schools because they are “an ideal structure to transfer knowledge and allow us to develop an effective project, given that to generate the reuse of gray water, certain levels of water are needed that are difficult to achieve. in the houses”.

For his part, the UC Geography professor and member of the project’s executing team, Rafael Sánchez, adds that, according to the data obtained on the use of drinking water in the region, they discovered that a teacher opens the tap on average 4, 3 times a day, for 12.5 seconds each time, while a student opens the tap on average 3.4 times a day, for 21.1 seconds each time. “There is a relationship between the number of students in an educational establishment and the amount of gray water generated. The greater the number of students, the greater the amount of gray water generated ”, he points out.

To implement this project , 15 educational establishments from different locations in the Region were selected.: six receiving educational establishments, which included the execution of a physical work in the school for the installation of the gray water filter, three environmental workshops, a day of exchange of experiences and a scientific seminar, and nine visiting educational establishments, with a day of exchange of experiences in which a practical work related to the construction and handling of the filter will be carried out and a scientific seminar where they saw the result of the operation of the gray water reuse system. It should be noted that the recycled water was used depending on the needs of each school, but mainly for irrigation of ornamental and recreational spaces.

According to the data obtained on the use of drinking water in the region, a teacher opens the tap on average 4.3 times a day, for 12.5 seconds each time, while a student opens the tap on average 3.4 times a day, for 21.1 seconds each time.

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Another fundamental aspect in choosing educational establishments was the possibility of generating an effective knowledge transfer. “ We seek to enhance the long-term sustainability of this project and for that, collaboration with the community is essential and that it becomes part of the project. The treatment system not only serves as a technological system that improves the management of water resources for the educational community, but also serves as a model to study water quality, understand the chemistry and biology of water, because there are many microorganisms in the treatment process and also to understand aspects of sustainable technologies ”, pointed out Professor Leiva.

Professor Rafael Sánchez, who was in charge of establishing the transfer process to each of the schools according to their context, specifies that he participated “in the social insertion of the project in the educational communities through the realization of educational workshops environment and care of water resources ”.

The importance of interdiscipline
Working together was essential to develop this initiative, says Eduardo Leiva: “Through all this we established a project that not only covers technological aspects, but also social aspects of each of the communities. We do not deliver a standardized treatment system, without seeking to create a tailor-made suit associated with the local reality. Our objective was not to develop a project that while we are in it can operate, but to operate beyond the limits in which there is financing for the project. We install it, design it, co-build it with the students and then they take over the system, operate it and make it sustainable over time ”, he concludes.

Natalia Rebolledo, executive director of the Fundación un Alto en el Desierto, values ​​and highlights the link between all the actors who participated in this important project: “We are very happy to belong to this project as co-executor and to have a relationship of several years with UC and sharing this process with schools ”.

To learn more about the prototype that was designed and built for this purpose and the conclusions of the project, you can see the webinar here “Implementation of a sustainable prototype for the reuse of gray water in schools belonging to areas with critical water deficit.”

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