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Advisor(s)
Abstract(s)
O elevado consumo de água associado à escassez deste recurso contribuiu para que alternativas de reutilização/reciclagem de água fossem estudadas que permitam diminuir o seu consumo e minimizar a dependência das indústrias. Monitorizar e avaliar os consumos de água, a nível industrial, é imprescindível para assegurar uma gestão sustentável dos recursos hídricos, sendo este o objetivo da presente dissertação.
As alternativas encontradas na unidade industrial em estudo foram a substituição do equipamento sanitário e o aproveitamento do efluente tratado para operações de lavagem e/ou arrefecimento por contacto direto.
A maioria do equipamento sanitário não é eficiente, tendo-se proposto a substituição desse sistema por um de menor consumo que permitirá uma poupança de 30 % no consumo de água, que corresponderá a 12 149,37 €/ano, sendo o retorno do investimento estimado em 3 meses.
O efluente industrial na entrada da ETAR e nas diferentes etapas - tratamento primário de coagulação/floculação; tratamento secundário ou biológico em SBR; tratamento terciário de coagulação/floculação - foi caracterizado através da medição da temperatura, pH, oxigénio dissolvido e pela determinação da cor, turvação, sólidos suspensos totais (SST), azoto total, carência química de oxigénio (CQO), Carência Bioquímica de Oxigénio ao fim de 5 dias (CBO5) e razão CBO5/CQO. Esta caracterização permitiu avaliar o efluente industrial bruto que se caracteriza por um pH alcalino (8,3 ± 1,7); condutividade baixa (451 ± 200,2 μS/cm); elevada turvação (11 255 ± 8812,8 FTU); cor aparente (63 670 ± 42293,4 PtCo) e cor verdadeira (33 621 ± 19547,9 PtCo) elevadas; teores elevados de CQO (24 753 ± 11806,7 mg/L O2) SST (5 164 ± 3845,5 mg/L) e azoto total (718 mg/L) e um índice de biodegradabilidade baixo (razão CBO5/CQO de 1,4). Este estudo permitiu verificar que a eficiência global do tratamento do efluente foi 82 % na remoção da turvação, 83 % na remoção da cor aparente, 96 % na remoção da cor verdadeira, 85 % na remoção da CQO e 30 % na remoção dos SST.
Quanto às eficiências de remoção associadas ao tratamento primário no que diz respeito à turvação, cor aparente, CQO e SST, apresentam valores inferiores aos referidos na literatura para o mesmo tipo de tratamento em efluentes similares. As eficiências de remoção obtidas no tratamento secundário são inferiores às do tratamento primário: turvação, cor aparente, CQO e SST, pelo que procurou-se otimizar a primeira etapa do processo de tratamento Neste estudo de otimização estudou-se a influência de cinco coagulantes – Sulfato de Alumínio, PAX XL – 10, PAX 18, cloreto de ferro e a conjugação de PAX 18 com sulfato de ferro - e seis floculantes – Superfloc A 150, Superfloc A 130, PA 1020, Ambifloc 560, Ambifloc C58 e Rifloc 54 - no tratamento físico-químico do efluente.
O PAX 18 e o Ambifloc 560 UUJ foram os que apresentaram as mais elevadas eficiências de remoção (99,85 % na cor, 99,87 % na turvação, 90,12 % na CQO e 99,87 % nos SST). O custo associado a este tratamento é de 1,03 €/m3. Pela comparação com os critérios de qualidade no guia técnico ERSAR, apenas o parâmetro da CQO excede o valor, contudo o valor obtido permite diminuir os custos associados a um tratamento posterior para remoção da CQO remanescente no efluente residual tratado.
The high consumption of water associated with the scarcity of this resource has contributed to the study of new alternatives for reuse / recycling of water, in addition, reduce water consumption and minimize dependence on industries. Monitor and evaluate water consumption, in an industrial level, it is essential to ensure a sustainable management of water resources, which is the goal of this dissertation. The alternatives found in the industry were the replacement of the sanitary equipment and the use of residual treated effluent in washing operations and / or cooling by direct contact. Most sanitary equipment is not efficient, having proposed to replace this system by a lower consumption that will allow a 30 % saving in water consumption, which corresponds to 12 € 149.37 / year, and the return on investment estimated at 3 months. The industrial effluent at the entrance of the treatment plant and the different stages - primary treatment of coagulation / flocculation; secondary or biological treatment in SBR; tertiary treatment of coagulation / flocculation - was characterized by measuring the temperature, pH, dissolved oxygen and determining the color, turbidity, total suspended solids (TSS), total nitrogen, chemical oxygen demand (COD), biochemical oxygen demand after 5 days (BOD5) and reason BOD5 / COD. This characterization allowed to evaluate the industrial wastewater that is characterized by an alkaline pH (8.3 ± 1.7); low conductivity (451 ± 200.2 S / cm); high turbidity (11,255 ± 8812.8 FTU); apparent color (63,670 ± 42293.4 PtCo) and true color (33 621 ± 19547.9 PtCo) high; high levels of COD (24,753 ± 11806.7 mg / L O2) OH (5164 ± 3845.5 mg / L) and total nitrogen (718 mg / L) and low biodegradability index (ratio BOD5 / COD 1 4). This study showed that the overall efficiency of the effluent treatment was 82 % in the removal of turbidity, 83 % in apparent color removal of 96 % removal of true color at 85 % for COD removal and 30 % in removal of TSS. As to removal efficiencies associated with the primary treatment as regards turbidity, apparent color, COD and TSS, have lower values than those reported in literature for the same type of treatment in similar effluents. The removal efficiency obtained in the secondary treatment is lower than the primary treatment: turbidity, apparent color, COD and TSS, so we tried to optimize the first stage of this treatment. In this process optimization were studied the influence of five coagulants - Aluminum Sulfate, XL PAX - 10 PAX 18, iron chloride and conjugation PAX 18 with iron sulphate - six flocculants - Superfloc 150, Superfloc A 130, PA 1020, Ambifloc 560, Ambifloc C58 and Rifloc 54. The PAX 18 and 560 Ambifloc showed the highest removal efficiency (99.85 % in color, 99.87 % in turbidity, 90.12 % for COD and 99.87 % in SST). The cost associated with this treatment is 1.03 € / m3. By comparison with the quality criteria in the technical guide ERSAR, only the COD parameter exceeds the value, but the value obtained enables reduces costs associated with a subsequent treatment for removal of the remaining COD in the treated waste effluent.
The high consumption of water associated with the scarcity of this resource has contributed to the study of new alternatives for reuse / recycling of water, in addition, reduce water consumption and minimize dependence on industries. Monitor and evaluate water consumption, in an industrial level, it is essential to ensure a sustainable management of water resources, which is the goal of this dissertation. The alternatives found in the industry were the replacement of the sanitary equipment and the use of residual treated effluent in washing operations and / or cooling by direct contact. Most sanitary equipment is not efficient, having proposed to replace this system by a lower consumption that will allow a 30 % saving in water consumption, which corresponds to 12 € 149.37 / year, and the return on investment estimated at 3 months. The industrial effluent at the entrance of the treatment plant and the different stages - primary treatment of coagulation / flocculation; secondary or biological treatment in SBR; tertiary treatment of coagulation / flocculation - was characterized by measuring the temperature, pH, dissolved oxygen and determining the color, turbidity, total suspended solids (TSS), total nitrogen, chemical oxygen demand (COD), biochemical oxygen demand after 5 days (BOD5) and reason BOD5 / COD. This characterization allowed to evaluate the industrial wastewater that is characterized by an alkaline pH (8.3 ± 1.7); low conductivity (451 ± 200.2 S / cm); high turbidity (11,255 ± 8812.8 FTU); apparent color (63,670 ± 42293.4 PtCo) and true color (33 621 ± 19547.9 PtCo) high; high levels of COD (24,753 ± 11806.7 mg / L O2) OH (5164 ± 3845.5 mg / L) and total nitrogen (718 mg / L) and low biodegradability index (ratio BOD5 / COD 1 4). This study showed that the overall efficiency of the effluent treatment was 82 % in the removal of turbidity, 83 % in apparent color removal of 96 % removal of true color at 85 % for COD removal and 30 % in removal of TSS. As to removal efficiencies associated with the primary treatment as regards turbidity, apparent color, COD and TSS, have lower values than those reported in literature for the same type of treatment in similar effluents. The removal efficiency obtained in the secondary treatment is lower than the primary treatment: turbidity, apparent color, COD and TSS, so we tried to optimize the first stage of this treatment. In this process optimization were studied the influence of five coagulants - Aluminum Sulfate, XL PAX - 10 PAX 18, iron chloride and conjugation PAX 18 with iron sulphate - six flocculants - Superfloc 150, Superfloc A 130, PA 1020, Ambifloc 560, Ambifloc C58 and Rifloc 54. The PAX 18 and 560 Ambifloc showed the highest removal efficiency (99.85 % in color, 99.87 % in turbidity, 90.12 % for COD and 99.87 % in SST). The cost associated with this treatment is 1.03 € / m3. By comparison with the quality criteria in the technical guide ERSAR, only the COD parameter exceeds the value, but the value obtained enables reduces costs associated with a subsequent treatment for removal of the remaining COD in the treated waste effluent.
Description
Keywords
Reutilização de águas residuais tratadas Efluente industrial de colas Coagulação/floculação Eficiências de remoção Reuse of treated wastewater Industrial effluent adhesives Coagulation / flocculation Removal efficiencies