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GREY WATER FILTER
The biological filter is a system for filtering grey water, i.e. water from sink drains, showers and laundry tubs. This system consists of four filter boxes and a circle of banana trees. The first box consists of a common grease trap; the second is a box with gravel; the third is a box with sand and the fourth is a box with charcoal. In this way, the water that leaves homes returns to the environment with more than 70% purity, avoiding excess organic matter, soaps, grease and chemicals in community streams. The system filters the coarser material and grease and promotes the development of bacteria that decompose the particulate matter.
PROBLEM SOLVED
Traditional communities face serious problems due to the lack of basic sanitation. The lack of sewage treatment means that grey water is discharged directly into rivers or onto the ground, often only passing through a grease trap, which is insufficient to remove pollutants. As a result, rivers are becoming increasingly polluted, and the isolation of these communities makes access to public sanitation services difficult.
The use of grey water filters has emerged as a viable solution to mitigate this environmental problem, which directly impacts the health of residents and visitors. These filters are a cheap and easy-to-implement alternative, providing a significant improvement in water quality and, consequently, in the community's quality of life.
SOLUTION ADOPTED
The person responsible for disseminating the technology, Ticote (Francisco Xavier Sobrinho), installed the first filter in his home during a workshop in 2011, with the support of the group "Raízes e Frutos" - an extension project at UFRJ. The experience was so successful that they decided to mobilize other people to install the filter in other homes. Families began to learn how the filter works and realized that it is a viable alternative for the region.
To promote the technology and its benefits, workshops are held during the installation of the filters, with the presence of young people and adults from various locations, including nearby communities and distant places, such as São Miguel, in Paraná. These workshops are meetings that usually last a weekend, and the group interested in learning about the new technology stays in the house or near the place where the filter will be installed.
The Biological Filter consists of four boxes connected by PVC pipes and a circle of banana trees at the end. Each box has a different filtering function: Box 1 is the traditional grease trap that separates the fat; Box 2 is filled with gravel, retaining particulate matter; Box 3 is filled with coarse sand, decomposing chemical and organic compounds; and Box 4 is filled with charcoal, performing the final filtering. The circle of banana trees promotes the removal and decomposition of the remaining compounds, through a process carried out by fungi and bacteria present in the banana pits. Banana trees also have the function of evapotranspiring the water contained in the circle, being very efficient in this process.
The construction of the filter follows several steps. First, the plastocement plates are built, using cement, plastic material from onion bags and medium sand in the proportion of 2 bags of sand to 1 bag of cement. Wooden molds (0.5 x 0.5 m) are used on a tarpaulin, where a layer of cement is placed, then the plastic screen and, finally, another layer of cement. Pieces of wire are placed at the vertices of the plates to facilitate the assembly of the boxes. 24 plates are made, 8 of which have 40 mm holes for the PVC pipes.
After the plates are dry, they are joined together with wires and a mixture of sand and cement (1:1 ratio), forming a cube without the final lid, with holes on two opposite sides at the top of the box. During the installation stage of the boxes and the circle of banana trees, corrections are made to the ground to ensure a slope that favors the flow of water through the 4 boxes to the final part of the filtration system. The pit for the circle of banana trees is made 40 cm deep by 1 m in radius, filled with remains of branches, leaves, soil and banana clumps.
The assembly and closing of the filter follow the filtration sequence: Box 1 > Box 2 > Box 3 > Box 4 > Circle of Banana Trees. Box 1 is filled with fat, Box 2 with gravel, Box 3 with coarse sand and Box 4 with charcoal. To close the tanks with the lid plates, a light mass is used (sand + clay + cement in a ratio of 1:1:1/3), facilitating periodic cleaning of the system. After the mass dries, the filter is ready to use.
Monitoring the system is essential, observing its operation and creating a relationship of care with the installed filter. Periodic cleaning usually occurs annually, depending on the volume of water used in the homes.
The dissemination of the Biological Filter technology, initiated by Ticote and supported by the group "Raízes e Frutos", has proven to be an effective and sustainable solution for the treatment of gray water in traditional communities. The implementation workshops and the active participation of families have been fundamental to the dissemination of this technology, which improves water quality and public health, in addition to promoting environmental sustainability.
RESULT ACHIEVED
By September 2024, Fiocruz and FCT had installed a total of 17 gray water filters with banana circles in Bocaina, all of which were working perfectly. Since this is an environmental issue related to water, a common good of the community, countless people benefit directly and indirectly from the implementation of this technology. The participation of social groups in this process is of utmost importance for the construction of a democratic educational process, encouraging the critical education of citizens and aimed at guaranteeing their constitutional rights to an ecologically balanced environment.
In order for the filter to meet the standards established by the National Environmental Council (CONAMA), complementing it with the banana circle is essential. This component not only improves the efficiency of the filtration system, but also contributes to the sustainability of the process, using plants that help with evapotranspiration and the decomposition of organic compounds.
Involving the community in the process of installing and maintaining the filters promotes a sense of collective responsibility and environmental awareness, strengthening social cohesion and the capacity for self-management of natural resources. In this way, technology not only solves immediate sanitation problems, but also contributes to environmental education and the empowerment of the communities involved.