Tratamento a nivel terciário de esgoto sanitário em um wetland francês seguido de um filtro reativo de escória
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Data
2023-10-30
Autores
Lima, Janaína Simões
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Universidade Federal do Espírito Santo
Resumo
The scarcity of phosphorus is a growing challenge impacting food security and global sustainability. As an essential resource in agricultural production, phosphorus has become increasingly scarce due to intensive extraction and a lack of effective recycling methods. A significant source of this element is sewage, which, when discharged untreated into water bodies, triggers a process called eutrophication. However, several technological innovations have emerged to aid in addressing this issue, offering solutions to efficiently and sustainably remove and recover phosphorus from sewage. These technologies not only tackle the imminent shortage of this vital resource but also aim to transform sewage into a potential source of recoverable phosphorus, aligning with a more circular and responsible approach to using this essential element. This study examined the tertiary treatment of sewage in a French wetland followed by a reactive slag filter. It assessed the removal of total phosphorus, P-PO4 3- , NTK, N-NH4 + , DBO5,20, DQO, TSS, turbidity, and thermotolerant coliforms in a pilot WWTP consisting of a French wetland (1st stage) and a LD steel slag reactive filter (2nd stage). The French wetland was vegetated with the Typha domingensis macrophyte, endemic to the study region. The system's performance was evaluated over 350 days under variable operating conditions, with the French wetland's superficial hydraulic loading rate ranging from 0.1 m3 /m2 . d to 0.8 m3 /m2 . d and the hydraulic retention time (HRT) in the reactive filter from 2,3 to 10,7 days concerning its apparent volume. The system proved efficient in removing TSS, organic matter, and nitrogen, resulting in treated effluent concentrations TSS < 2 mg/L, BOD5,20 < 2 mg/L e NTK < 10 mg/L. Results indicate consistent attainment of total phosphorus concentrations below 1 mg/L with superficial hydraulic loading rates of 0.4 m3 /m2 . d in the French wetland and a hydraulic retention time of 3 days in the RFS (Reactive Filter of Slag). The high pH within the reactive filter led to highly efficient removal of thermotolerant coliforms from sewage, achieving concentrations of 0.0 MPN/100mL in the system's final effluent. The crystalline and morphological structures of the precipitates formed in the reactive filter were investigated using X-ray diffraction, X-ray fluorescence, scanning electron microscopy, and energy-dispersive spectroscopy techniques. The crystalline indices of each sample were determined through XRD diffractograms and the CELREF software, calculating lattice parameters and unit cell volumes for each crystal structure present in the samples. Based on each crystal's reference indices, calcite (CaCO3), hydroxyapatite (Ca5(PO4)3OH), gismondine (CaAl2Si2O8·4H2O), newberyite (MgHPO4·3H2O), and monetite (CaPO3 (OH) crystals were identified. With CELREF's aid, it was verified that the crystalline parameters of the samples resembled those in the reference sheets for each crystal.
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Palavras-chave
Esgoto sanitário , Tratamento terciário , Wetland francês , Escória , Fósforo , Adsorção , Cristalização