Emprego de reator de leito fixo bi-fluxo contínuo® para a potabilização de água de abastecimento público em área desassistida por companhia de tratamento de água

Abstract

The supply and potability of water in rural areas is deficient in Brazil, with only the disinfection process, when existing, which is not considered effective to make water potable depending on the supply source, as established by Consolidation Ordinance nº 5 /2017 amended by Ordinance nº 888/2021. Therefore, studies are needed using new technologies with alternative solutions for water treatment in underserved areas, following the potability standards described in Ordinance nº. 888/2021. In this sense, the aim of this study was to analyze and evaluate the construction of a continuous bi-flow fixed bed reactor (RLF-BFC) used for purifying water for supply in underserved areas, as well as to analyze the quality of the water before and posttreatment. The RLF-BF was made of stainless steel material, containing two beds, a filtering bed (descending) and an adsorbent bed (ascending), operating in bi-flow direction. The filtering bed consisted of medium sand (0.25 mm) and the adsorbent bed of granular activated carbon (GAC), both allocated above the support layer of rolled pebbles. In the RLF-BF operation, surface application rates (TAS) of 120 m³ m-2 d-1 were used for the filtering bed and adsorbent bed, with a 200 L water reservoir being allocated upstream to supply the Reactor. The efficiency of the RLF-BF was evaluated using samples of raw water (AB) collected at the reservoir outlet and treated by filtration (ATF), as well as water treated by filtration and adsorption (ATF-A), both sampled every 20 min of treatment, the following parameters being analyzed: apparent color, free residual chlorine, pH, turbidity, total and thermotolerant coliforms and glyphosate+AMPA, considering maximum values allowed (VMP) by Ordinance GM/MS Consolidation nº 5, of September 28 of 2017 of the Ministry of Health (MS) and its amendments in Ordinance nº 888, of May 4, 2021 of the MS. Parameters not recommended in the Ordinances such as absorbance (λ – 254 nm), alkalinity, electrical conductivity and head loss of the filtering bed and adsorbent bed were also analyzed. The study took place on the premises of the Water and Ecotoxicology Laboratory of the Federal University of Fronteira Sul, Campus Cerro Largo – RS. The RLF-BFC operation succeeded in 22 samplings. The removal efficiency was verified in relation to the parameters analyzed in the sampled water treated by filtration and adsorption (ATF-A): absorbance λ – 254 nm (22.4 %), electrical conductivity (6.8 %), apparent color ( 94.6%), pH (7.2 to 8.9) and turbidity (63.22%), glyphosate+AMPA (27.2%), and only one of the analyzed parameters, free residual chlorine, was in disagreement with the established by MS Ordinance nº 888/2021. It can then be concluded that the operationalization of the RLFBFC is capable of contributing to the potability of water for human consumption. It is suggested for future studies: i) operating the RLF-BFC for a longer period of time, in order to determinethe operating time until complete clogging of the filtering bed and clogging and saturation of the adsorbent bed; backwash tests; carrying out the operation at different flow rates and TAS.