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Abstract(s)
Atualmente as estações de tratamento de águas residuais (ETAR) com áreas húmidas
construídas (Constructed Wetlands - CWs) apresentam-se como uma solução
ambientalmente sustentável e eficaz no tratamento de águas residuais domésticas de
pequenos aglomerados populacionais, devido aos seus baixos custos de implementação e
operação, menores exigências energéticas e de manutenção, e elevada eficiência de
remoção de contaminantes. Neste sentido, este trabalho tem por objetivo identificar e
validar os fatores que influenciam a qualidade dos efluentes tratados em ETAR com CWs.
Em resposta a estas questões foram determinadas as eficiências de tratamento de cinco
ETAR no sul de Portugal, com tratamento primário, constituído por fossa séptica, e CWs.
Os resultados demonstraram que a utilização deste tipo de sistemas pode ser exequível nos
dias atuais, com remoções de Carência Química de Oxigénio (CQO) a variar entre 78,8 –
93,9 %, Carência Bioquímica de Oxigénio (CBO5) entre 89,7 – 97,0%, Sólidos Suspensos
Totais (SST) entre 64,5 – 97,9%, Azoto total (Ntotal) entre 19,8 – 48,5 %, e Fósforo total
(Ptotal) entre 6,3 – 46,5%. Através deste trabalho foi possível verificar que a remoção da
matéria orgânica esteve relacionada principalmente com a eficiência de remoção da fossa
séptica e com o escoamento uniforme do caudal ao CWs. A remoção do SST esteve
associada à filtração física e à sedimentação, onde os processos físicos de remoção dos
gradados e a extração das lamas no tratamento primário foram os principais fatores que
afetaram a remoção desse contaminante. Também se verificou que a remoção do azoto e
do fósforo esteve relacionada com a diversidade de plantas no CWs e com a capacidade
de interceptação do material particulado no meio de enchimento. Por fim, concluiu-se que
apesar do bom funcionamento destes sistemas de tratamento, a sua estrutura deverá ser
modificada por forma a aumentar o tempo de vida e possibilitar a manutenção e operação
efetivas.
Currently, wastewater treatment plants (WWTPs) with built-up constructed wetlands (CWs) present themselves as an environmentally sustainable and effective solution in the treatment of domestic wastewater from small population agglomerates, due to their low implementation and operation costs, lower energy and maintenance requirements, and high efficiency in removing contaminants. In this sense, this work aims to identify and validate the factors that influence the quality of effluent treated in WWTPs with CWs. In response to these questions, the treatment efficiencies of five WWTPs in southern Portugal with septic tank as primary treatment were determined. Results demonstrated that the use of this type of system is feasible nowadays, with removals of the Chemical Oxygen Demand (COD) between 78,8 – 93,9 %, Biochemical Oxygen Demand (BOD5) 89,7 – 97,0 %, Total Suspended Solids (SST) 64,5 – 97,9 %, Total Nitrogen (Ntotal) 19,8 – 48,5 %, and Total Phosphorus (Ptotal) 6,3 – 46,5 %. According to these results, the removal of organic matter was mainly related with the efficiency of the septic tank and the uniform flow to the plant bed. The removal of SST was associated with physical filtration and sedimentation, where the physical processe of removing the harrows and the sludge removal in the primary treatment were the main factors that affected the removal of this contaminant. Removal of nitrogen and phosphorus was related to plant diversity in CWs and the ability to intercept particulate matter in the filling medium. At the end of this work, it was also possible to concluded that despite the good performance of these treatment systems, their structure should be modified to increase the lifespan and enable effective maintenance and operation.
Currently, wastewater treatment plants (WWTPs) with built-up constructed wetlands (CWs) present themselves as an environmentally sustainable and effective solution in the treatment of domestic wastewater from small population agglomerates, due to their low implementation and operation costs, lower energy and maintenance requirements, and high efficiency in removing contaminants. In this sense, this work aims to identify and validate the factors that influence the quality of effluent treated in WWTPs with CWs. In response to these questions, the treatment efficiencies of five WWTPs in southern Portugal with septic tank as primary treatment were determined. Results demonstrated that the use of this type of system is feasible nowadays, with removals of the Chemical Oxygen Demand (COD) between 78,8 – 93,9 %, Biochemical Oxygen Demand (BOD5) 89,7 – 97,0 %, Total Suspended Solids (SST) 64,5 – 97,9 %, Total Nitrogen (Ntotal) 19,8 – 48,5 %, and Total Phosphorus (Ptotal) 6,3 – 46,5 %. According to these results, the removal of organic matter was mainly related with the efficiency of the septic tank and the uniform flow to the plant bed. The removal of SST was associated with physical filtration and sedimentation, where the physical processe of removing the harrows and the sludge removal in the primary treatment were the main factors that affected the removal of this contaminant. Removal of nitrogen and phosphorus was related to plant diversity in CWs and the ability to intercept particulate matter in the filling medium. At the end of this work, it was also possible to concluded that despite the good performance of these treatment systems, their structure should be modified to increase the lifespan and enable effective maintenance and operation.
Description
Keywords
Água residual Tratamento de água Macrófitas Áreas húmidas construídas Aljezur