Étude du colmatage des membranes en ultrafiltration et en coagulation–ultrafiltration d'eau de surface

Abstract

Ultrafiltration (UF) and coagulation–ultrafiltration (CUF) of raw water from the Des Roches Lake were performed and compared in terms of natural organic matter (NOM) removal and in terms of membrane permeability variation. The study was carried out at a laboratory scale with a membrane having a nominal pore size of 0.035 μμm. The removal of NOM by UF was significant (10% to more than 50% for UV absorbance at 254 nm and 0% to more than 30% for TOC) but was also very dependent on operating conditions. Membrane fouling occurred rapidly and was strongly accelerated as the permeate flux increased. Fouling also induced a decrease of NOM removal. Coagulation before UF brought a strong increase of NOM removal (TOC removal higher than 60% and reduction of UV absorbance at 254 nm higher than 80%). It also largely reduced membrane permeability loss even for permeation flux higher than 150 L·h–1·m–2. In the absence of coagulation, and operating with full recirculation of the concentrate, there was a reduction of the SUVA ratio (UV254/TOC) and iron concentration in the feed water. This indicates a preferential deposit of humic substances onto the membranes and shows that iron either plays a role in membrane fouling or could be an indicator of the presence of fouling substances. Key words: ultrafiltration, coagulation, surface water, fouling, organic matter.

Application of Hybrid Process of Coagulation/Flocculation and Membrane Filtration to Water Treatment

“…In addition, unlike the conventional filtration process, micro/ultrafiltration can retain bacteria and other microorganisms. Bouchard et al (2003) studied the processes of microfiltration and coagulation/ microfiltration, using ferric chloride and aluminum sulfate as coagulants in the combined process. Microfiltration tests were performed in a mini-module of submerged cross-fiber Zenon membranes, with porosity of 0.1 μm.…”

“…Comparing the processes of ultrafiltration and coagulation/ultrafiltration, using ferric chloride as a coagulant agent, removal of TOC and compounds that absorb UV at 254nm of 30% and 60%, respectively, was observed for the ultrafiltration process. For the combined coagulation/ultrafiltration, the removal of TOC and compounds that absorb UV at 254nm increased to 60 and 80%, respectively (Bouchard et al, 2003). Konradt-Moraes (2004) studied the combined process of coagulation/flocculation/ ultrafiltration using ceramic membrane with pore size of 0.05μm and transmembrane pressure of 2 bar.…”

Aplicaciones estratégicas de la Nanofiltración para el tratamiento de las aguas en la industria cerámica

“…En consecuencia, el trasporte selectivo a través de este medio filtrante está principalmente regido por la diferencia entre el tamaño de la especie disuelta y el de los poros de la membrana. La siguiente clasificación de los procesos que utilizan membranas se realizará teniendo en cuenta el tamaño (radio) de poro de la membrana ( ): microfiltración, ultrafiltración, nanofiltración y ósmosis inversa (ver Figura 1.22) [60]. [61].…”