{"id":9909,"date":"2025-04-03T20:28:43","date_gmt":"2025-04-03T23:28:43","guid":{"rendered":"https:\/\/solvefortomorrowlatam.com\/pratica\/filtro-de-baixo-custo-criado-por-jovens-elimina-toxinas-e-cria-biofertilizante\/"},"modified":"2025-04-03T20:41:38","modified_gmt":"2025-04-03T23:41:38","slug":"filtro-de-baixo-custo-criado-por-jovens-elimina-toxinas-e-cria-biofertilizante","status":"publish","type":"pratica","link":"https:\/\/solvefortomorrowlatam.com\/en\/case\/filtro-de-baixo-custo-criado-por-jovens-elimina-toxinas-e-cria-biofertilizante\/","title":{"rendered":"A low-cost filter created by young people eliminates toxins and creates biofertilizer"},"content":{"rendered":"\n

Based on their knowledge in STEM<\/a> (Science, Technology, Engineering, and Mathematics), four teenagers from the countryside of Pernambuco state, Brazil, were inspired to create a project that combines health and environmental benefits. The \u201cFiltropinha\u201d project won the Solve for Tomorrow in Brazil in 2024 and aims to build filters with pine cone shells to treat manipueira<\/em>, a toxic liquid discarded from cassava flour production.<\/p>\n\n\n\n

In the flour mills of Quilombo Travess\u00e3o do Caro\u00e1, in northeastern Brazil, cassava is used to produce a crunchy and tasty flour highly appreciated in the country\u2019s cuisine. Despite being an important source of income for the community, the production of the flour leaves behind a yellowish liquid rich in hydrocyanic acid, an extremely volatile chemical compound.<\/p>\n\n\n\n

The group visited the quilombo and flour mills to develop the project. There, they were able to talk to the cassava producers and see the negative effects of improper disposal of it. \u201cWe noticed that around the flour mill we visited, there was soil degradation; that nothing grew around where the waste was dumped. And the workers complained a lot about headaches and dizziness,\u201d recalls teacher Bezerra. The students also returned to the quilombola community to show the results of the studies and tests, always using simple language.
If ingested or inhaled, manipueira<\/em> can lead to death and, if disposed of directly into the environment, can cause soil infertility and water contamination. With this in mind, the students created a prototype<\/a> of a low-cost filter that reduces the toxicity level of cassava starch by up to 80%, enabling the reuse of water in the production of flour and the manufacture of organic fertilizer with the concentrate that is retained during filtration.<\/p>\n\n\n\n

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Manipueira is a toxic liquid discarded from the production of cassava flour.<\/em>
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Chemistry teacher Gustavo Bezerra, mediator<\/a> of the project, says that the idea came from the students themselves, including two young women who live in Travess\u00e3o do Caro\u00e1. \u201cDuring the Sustainable Construction and Inventions class, some students had already suggested doing a study on these flour mills, which are a source of income for some rural communities here in the municipality of Carna\u00edba, but these communities have always been neglected,\u201d explains the teacher from the Professor Paulo Freire State Technical School<\/em>. In addition to him, teacher Carla Rob\u00e9cia was co-mediator of the project that involved four teenagers aged 16 and 17 in the 2nd year of high school (the penultimate year of compulsory education).<\/p>\n\n\n\n

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\n Eureka moment! <\/h5>\n

The students intended to assemble the filter using dehydrated pine cone shells, which have natural porosity, reusing the part of the fruit that is not consumed. However, the pine cone shells did not remove the toxicity of the <\/span>manipueira<\/span><\/i> due to the acidity of the fruit itself. That\u2019s when the idea came up of creating activated charcoal by carbonizing the shells at temperatures above 400\u00baC. The students tested the filter using only pine cone shells, then only charcoal, but the best result was obtained with the combination of the two materials.<\/span><\/p>\n<\/div>\n\n\n

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We were in the last week of mentoring the project without achieving satisfactory results. We filtered the manipueira, and the liquid became even more acidic. Until we added activated carbon, and everything started to work. The liquid became clearer, the conductivity and pH reduced and the toxicity test further confirmed the improvement, says Gustavo Bezerra.
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Practical tests led to a prototype<\/strong>
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Before getting the filter to work, the team tried out different methods<\/a>. One of the first ideas for reducing the acidity of manipueira<\/em> was decantation, a method of separating heterogeneous mixtures between solid-liquid and liquid-liquid. They also thought about installing a membrane to reduce the acidity of the manipueira<\/em>, but the problem persisted. After consulting bibliographical references and deciding on the use of activated cardboard, they set out to build a filter on a 3D printer that could be attached to a box containing the manipueira<\/em>. Inside, the filter was filled with a layer of cotton, a paper filter, pine cone shell flour, and activated carbon made from the same shell. Without considering labor, each complete prototype costs around R$4.41 (about 0,80 USD), and the refill alone costs around R$0.25 (about 0,05 USD).<\/p>\n\n\n\n

To ensure effective results, the toxicity of manipueira<\/em> was tested before and after filtration. To do this, the students used a low-cost methodology with lettuce seeds. They were exposed to the liquid before and after passing through the filter and then planted. Before the addition of activated carbon to the prototype, only 20% of the seeds germinated. Afterward, 80% of the planted seeds developed.<\/p>\n\n\n\n

The numerical scale used to specify the acidity or basicity of a solution is the pH. After filtration, this scale was measured, and the indicators also showed an improvement in the toxicity of manipueira<\/em>. According to tests carried out in the school\u2019s laboratory, after filtration, the liquid reached close to pH 7, considered neutral, which shows a significant loss of acidity in the sample.<\/p>\n\n\n\n

The next steps are to improve the prototype so that it can be attached to water tanks to filter large volumes of manipueira<\/em>. Another goal of the project is to use the pine cone shells and activated carbon after filtering as a slow-release fertilizer since the material becomes rich in nitrogen and carbon.<\/p>\n\n\n\n

\u201cThe idea now is to try to secure financial support from the city government to buy some additional materials to carry out these tests. For example, we want to provide the filter to three flour mills, and after the treatment, we also want to test the fertilizers to contribute even more to the community,\u201d highlights Gustavo Bezerra.<\/p>\n\n\n\n\n