Desempenho de um reator de leito fixo contínuo: dupla filtração em areia e carvão ativado granular para potabilização de água

Abstract

Water, an essential resource for maintaining human life, is increasingly suffering the effects of pollution caused mainly by contaminants from industrial waste discharges, agricultural practices, and sanitary sewage. In this scenario, it is essential to explore new approaches and technologies for water treatment. This study presents the development and preliminary performance of a new technology configuration used to treat supply water, the Continuous Fixed Bed Reactor (CFBR), which operates with combined processes of rapid downward filtration in sand and filtration/adsorption ascending in granular activated carbon (GAC). The development and construction of the CFBR were presented retrospectively from the precursor studies, going through the pilot scale stage to the full scale. The CFBR's performance was evaluated through three operations using two different aqueous matrices, two initial operations with underground water (UAW) and the third operation with surface water (SAW). Operational parameters of pressure loss and surface application rate (SAR), physical-chemical parameters of apparent color, turbidity, pH, conductivity, alkalinity, hardness, and free chlorine, and microbiological parameters of total coliforms and Escherichia coli (E. coli) were analyzed. The potability standard recommended by Annex XX – Consolidation Ordinance nº 05/2017 amended by Ordinance nº 888/2021 of the Ministry of Health (MS) was considered, comparing samples of raw water (RW), water treated by filtration (WTF) and water treated by filtration and adsorption (WTF-A) collected during operations. The results of analyses of the physicochemical parameters of the three CFBR operations were subjected to statistical analysis to determine the significance of the differences between the groups (RW, WTF, and WTF-A) in each operation. The CFBR operated with a maximum average SAR of 76.12 m³ m-2 d-1 and achieved maximum apparent color removals of 77.6% and 83.5% of turbidity. The pH tended towards neutrality, with no significant effect of the treatment. Conductivity was not affected by the treatment, except in the first operation with UAW in initial WTF-A samples. Alkalinity, hardness, and free chlorine were not influenced by the treatment. There was no effect of the treatment on the microbiological load, with microbiological analyses indicating the absence of total coliforms and E. coli in the RW, WTF, and WTF-A samples in operations with UAW matrix and the presence of total coliforms in these samples in operation with SAW. Statistical analysis indicated that the differences observed between RW and WTF-A were significant (p<0.05) for apparent color in, the second and third operations; turbidity, in the three operations; pH, in the three operations; and conductivity in, the second and third operations. The preliminary analysis of the performance of the CFBR demonstrated the potential of the new technology configuration for application in the treatment of supply water.