Humic acids removal by aerated spiral-wound ultrafiltration membrane combined with coagulation–hydraulic flocculation

• Published in: Desalination Vol. 266; no. 1; pp. 128 - 133
• Main Authors: Rojas, J.C., Pérez, J., Garralón, G., Plaza, F., Moreno, B., Gómez, M.A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 31.01.2011; Elsevier
• Subjects: absorbance; Aerated; Aerated spiral-wound ultrafiltration membranes; Applied sciences; Chemical engineering; Coagulation; desalination; dissolved organic carbon; Effluents; Exact sciences and technology; Flocculating; flocculation; Humic acids; Hydraulic flocculation; Hydroxyapatite; Membrane separation (reverse osmosis, dialysis...); Membranes; Molecular weight; Pollution; risk; Trihalomethane; Ultrafiltration; water reservoirs; Trihalomethane; Aerated spiral-wound ultrafiltration membranes; Humic acids; Hydraulic flocculation; Organic matter; Chlorination; Coagulation; Spiral; Dissolved organic carbon; Persistence; Membrane separation; Ultraviolet radiation; Ultrafiltration; Flocculation reagent; Flocculation; pH; Conditioning; Pretreatment
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2010.08.013

An aerated spiral-wound ultrafiltration membrane system (ASWUF) combined with coagulation–hydraulic flocculation was tested with a view to evaluating its efficiency as a system for removing humic acids (HA). The tests were carried out at pilot scale, using FeCl 3 as a coagulant. The ASWUF was equipped with polyethersulphone membranes (molecular weight cut-off of 50 kDa). The system was fed with reservoir water, to which different concentrations of HA (1–30 mg/l) were added. HA removal capacity of the ASWUF varied according to the molecular weight (MW) of the HA, and performance never exceeded 41% as dissolved organic carbon (DOC). However, coagulation–flocculation combined with ASWUF achieved results of approximately 90% for HA concentrations of up to 30 mg/l. Coagulation–flocculation as pretreatment for ASWUF makes it possible to remove HA with a low MW, without having to modify the pH of the water. This efficiency led to a decline in the specific UV absorbance (SUVA) of the effluent, which therefore presented a lower risk of trihalomethane (THM) generation after post-chlorination. Final effluent HA concentration was the main conditioning factor for THM generation. However, it was noted that the fraction of HA persisting after treatment generated a higher concentration of THM per unit of DOC.