Scientists develop an arsenic water removal system for rural schools in Chaco

Researchers from the National University of the Northeast (UNNE) and the National University of the South (UNS) are working on the development of a remediation system for water contaminated with arsenic to be installed in rural schools in Chaco. It is a low-cost, simple-to-operate and easy-to-size device, designed so that it can be easily replicated in other institutions with the same problem.

Our system is based on the adsorption method and is ecologically correct because, instead of using chemical agents to remove arsenic, it uses agricultural biomass residues.”, explains the engineer Sergio Roshdestwensky, researcher at the Faculty of Engineering at UNNE and director of the project. In addition, this method is cheaper than others that are commonly implemented, such as reverse osmosis, which uses resins that are expensive to replace and generate a greater amount of waste.

Arsenic is a natural contaminant present in a large part of Argentine territory, especially in the Chaco-Pampiana plain. Prolonged ingestion of water or food with a high arsenic content can cause different pathologiessuch as chronic regional endemic hydroarsenicism (HACRE), a disease that can cause cancer and skin problems.

The drinking water odyssey

UNNE researchers have been studying the arsenic problem since 2014. The first thing they did was to map the entire province to analyze the arsenic content in groundwater. Once the map was finished, they decided to promote several actions. Thus, they began to work with two rural schools in the Almirante Brown and General Güemes departments, which they arrived at for another project. “We were making a repellent for dengue, but the covid came and turned into gel alcohol. Working with them, we saw that they had a water problem,” says the engineer.

Meanwhile, in the city of Bahía Blanca, in Buenos Aires, a group from the Institute of Southern Chemistry (Inquisur–Conicet/UNS), led by doctors Veronica Lasalle and Fernanda Horst, had been working for some time on the design of adsorbent nanomaterials to be applied in water remediation. Within the framework of Natalia Scheverin’s doctoral scholarship, they were able to test the efficiency of these materials in a rural school in the municipality of Villarino. “The teachers brought cans of water from their homes to distribute to the students”remembers Lasalle. Years later, the Chaco Institute of Science, Technology and Innovation (ICCTI) acted as a link between the two research groups and they began to work together.

The system developed by the scientists is based on the adsorption filtering method. It consists of a filtration column composed of agricultural biomass and inorganic nanoparticles. “Through adsorption, multiple chemical interactions are generated that make the arsenic stick to the adsorbent material”, says Lasalle. It can also remove other elements such as salts and heavy metals.

This is how the treatment circuit that will be placed in schools works. First, water is drawn from a well with a pump and stored in a reservoir tank about four feet in diameter and four feet high. Another pump then passes the water through the filtration system designed by the researchers. Finally, the treated water goes to a second tank, ready for consumption. “The idea is to use pumps that run on solar energy because rural schools often have problems with the supply of electricity, especially in times of high temperatures.”, says Roshdestwensky.

Towards the final prototype

The team is currently working on the design of a suitable filter for the water quality of the Chaco schools. UNNE researchers are responsible for everything related to sampling and microbiological analysis of the water to determine the arsenic content of each well. These samples are sent to INQUISUR, where the system is being tested on a small scale.

We have already checked the efficiency of the material. We are now working to move from the laboratory to a pilot-scale prototype, which is the step before full-scale”, points out Lasalle. Researchers from other groups and institutes also participate in this stage, such as engineering specialists who will be responsible for building the prototype. They estimate that the pilot tests will end this year and that, by the middle of next year, they will install the system on a large scale in schools. They suggest that the final version can treat between 1,000 and 2,000 liters of water.

Other aspects to be evaluated will be the useful life of the adsorbent and possible final disposal alternatives for these materials. They will also discuss using two columns instead of one to speed up treatment time. “Our goal is to have the system installed in both schools, but we hope that, later on, other institutions that need it will be able to replicate it. That’s why we design equipment that is easy to operate and build,” comments Roshdestwensky.

real challenges for science

The lack of access to drinking water is a problem that affects a large part of Argentina. For this reason, the project by the researchers from Chaco and Buenos Aires was one of those selected by the “ImpaCT.AR” Program, a call from the Ministry of Science, Technology and Innovation of the Nation (MINCyT) which seeks to promote institutional research projects that contribute with solutions for specific demands of public bodies.

In this case, ICCTI presented the problem of access to potable water in rural schools in Chaco and the UNNE project and UNS scientists obtained funding for two years to respond to this challenge. For Lasalle, this form of interdisciplinary and interprovincial work is very beneficial. And he adds: “To be able to resolve such a problem Serious as access to water is a great satisfaction for us. It represents a way of looking at science that I happily share with many colleagues and that has to do with what we do in the laboratory that helps solve specific problems in society”.

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