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Publicação
Manutenção e Otimização da Fiabilidade de Sensores Online nas ETARs da The Navigator Company
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A monitorização fiável das Estações de Tratamento de Águas Residuais (ETARs) é essencial para garantir o cumprimento dos Valores Limite de Emissão (VLE) definidos pela Agência Portuguesa do Ambiente, assegurando a conformidade legal e a proteção ambiental. No contexto industrial da The Navigator Company, a fiabilidade dos sensores online representa um desafio, devido à necessidade de calibração, manutenção e validação contínua face aos resultados laboratoriais.
Esta dissertação teve como objetivo desenvolver uma metodologia estruturada para otimizar a fiabilidade de dez sensores online (pH, condutividade, carbono orgânico total, azoto total e fósforo total), localizados nas ETARs 1 e 2 da unidade de Setúbal. A abordagem incluiu o acompanhamento das rotinas de manutenção preventiva e calibração, a comparação com resultados laboratoriais e a análise de tendências, complementada pela elaboração de propostas de melhoria como instruções funcionais, planos de manutenção e calibração, modelos de registo e um plano de garantia da qualidade dos sensores, assim como uma proposta de uma aplicação informática para a gestão dos sensores de processo.
Os resultados evidenciaram melhorias significativas em vários sensores. Na ETAR 1 destacou-se a condutividade, cuja percentagem de pontos fora da tolerância reduziu de 15,4% para 3,1%, e o carbono orgânico total, que passou de 70,1% para 23,9%, demonstrando ganhos claros de fiabilidade. Também o fósforo total apresentou uma evolução positiva, diminuindo de 15,8% para 2%. Contudo, no caso do azoto total, tanto na ETAR 1 como na ETAR 2, não se observaram melhorias consistentes, mantendo-se percentagens elevadas de leituras fora da tolerância. Esta limitação ficou associada à impossibilidade de um acompanhamento regular por parte do técnico de manutenção e a problemas técnicos recorrentes nos próprios equipamentos, que comprometeram a estabilidade e a eficácia das calibrações realizadas. Globalmente, a aplicação da metodologia permitiu reforçar a fiabilidade e rastreabilidade das medições, diminuindo a dependência exclusiva das análises laboratoriais e contribuindo para maior segurança operacional.
A proposta desenvolvida é transferível para outros sensores de processo e áreas industriais, constituindo uma base para aumentar a consistência dos sistemas de monitorização, apoiar auditorias ambientais e promover uma gestão mais eficiente e sustentável.
Reliable monitoring of Wastewater Treatment Plants (WWTPs) is essential to ensure compliance with the Emission Limit Values (ELVs) defined by the Portuguese Environment Agency, guaranteeing legal conformity and environmental protection. In the industrial context of The Navigator Company, the reliability of online sensors represents a challenge due to the need for continuous calibration, maintenance, and validation against laboratory results. This dissertation aimed to develop a structured methodology to optimize the reliability of ten online sensors (pH, conductivity, total organic carbon, total nitrogen, and total phosphorus), located in WWTPs 1 and 2 of the Setúbal site. The approach included monitoring preventive maintenance and calibration routines, systematic comparison with laboratory data, and trend analysis, complemented by the development of improvement proposals such as functional instructions, preventive and calibration plans, recording templates, statistical control charts, and a quality assurance plan for the sensors. The results showed significant improvements in several sensors. In WWTP 1, conductivity decreased from 15.4% to 3.1% of out-of-tolerance readings, and total organic carbon was reduced from 70.1% to 23.9%, while total phosphorus also improved from 15.8% to 2%, clearly demonstrating gains in reliability. However, for total nitrogen, both in WWTP 1 and WWTP 2, consistent improvements were not observed, with high percentages of out-of-tolerance readings remaining. This limitation was mainly associated with the impossibility of regular follow-up by the maintenance technician and recurring technical failures of the sensors themselves, which compromised stability, and the effectiveness of the calibrations performed. Overall, the application of the methodology reinforced the reliability and traceability of online measurements, reduced the exclusive dependence on laboratory analyses, and contributed to greater operational safety. The proposed methodology is transferable to other process sensors and industrial areas, providing a foundation to enhance the consistency of monitoring systems, support environmental audits, and promote more efficient and sustainable management.
Reliable monitoring of Wastewater Treatment Plants (WWTPs) is essential to ensure compliance with the Emission Limit Values (ELVs) defined by the Portuguese Environment Agency, guaranteeing legal conformity and environmental protection. In the industrial context of The Navigator Company, the reliability of online sensors represents a challenge due to the need for continuous calibration, maintenance, and validation against laboratory results. This dissertation aimed to develop a structured methodology to optimize the reliability of ten online sensors (pH, conductivity, total organic carbon, total nitrogen, and total phosphorus), located in WWTPs 1 and 2 of the Setúbal site. The approach included monitoring preventive maintenance and calibration routines, systematic comparison with laboratory data, and trend analysis, complemented by the development of improvement proposals such as functional instructions, preventive and calibration plans, recording templates, statistical control charts, and a quality assurance plan for the sensors. The results showed significant improvements in several sensors. In WWTP 1, conductivity decreased from 15.4% to 3.1% of out-of-tolerance readings, and total organic carbon was reduced from 70.1% to 23.9%, while total phosphorus also improved from 15.8% to 2%, clearly demonstrating gains in reliability. However, for total nitrogen, both in WWTP 1 and WWTP 2, consistent improvements were not observed, with high percentages of out-of-tolerance readings remaining. This limitation was mainly associated with the impossibility of regular follow-up by the maintenance technician and recurring technical failures of the sensors themselves, which compromised stability, and the effectiveness of the calibrations performed. Overall, the application of the methodology reinforced the reliability and traceability of online measurements, reduced the exclusive dependence on laboratory analyses, and contributed to greater operational safety. The proposed methodology is transferable to other process sensors and industrial areas, providing a foundation to enhance the consistency of monitoring systems, support environmental audits, and promote more efficient and sustainable management.
Descrição
Palavras-chave
Monitorização online ETAR manutenção preventiva calibração sensores industriais