Development of a novel drinking water treatment for colored surface waters: Ultrafiltration - Nanofiltration

• Autor(a) principal: Suarez Hermidas, Marianne del Valle
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/80110
• topic: Surface water; Ultrafiltration; Nanofiltration; Color removal; Natural organic matter; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia Química

The increase of natural organic matter and hence color in Swedish surface waters during the last decades has hindered the treatment of drinking water. Conventional treatment plants have increased their coagulant dosage to overcome this situation. Consequently, their production of sludge has risen. To reduce the use of chemicals and the production of sludge, the viability of a coupled ultrafiltration (UF) with low pressure nanofiltration (NF) is studied. Negatively charged NF membrane with a molecular weight cut-off (MWCO) of 1 kDa was tested in a 2 stages membrane pilot. Since the trials took place in France, the NF feed was spiked with natural ingredients to resemble Swedish surface waters. The NF membrane was capable to remove 85% and 65% of the color and dissolved organic carbon found in the NF feed, regardless of whether the system operates with or without the recirculation of concentrate. Furthermore, the NF membrane worked during long trials (9 months) without any cleaning procedure and with a permeability decrease of 7% in each membrane stage. Additionally, the NF average permeability was 6.5 l/m2 /h/bar and the fluxes ranged between 22.5 and 18 l/m2 /h. The NF process presented a poor salt removal and thus the remineralization of the permeate was not needed. Besides, the UF-NF coupled system operated with water losses under 18%. In general, the obtained results confirm the effectiveness of NF for color removal and the UF as a pretreatment