Natural organic matter rejection

Jarusutthirak, C., S. Mattaraj, and R. Jiraratananon. 2007. Factors affecting nanofiltration performances in natural organic matter rejection and flux decline. Sep. Purif. Technol. 58 68-75. 

Cho, J., Sohn, J., Choi, H., Kim, I.S., and Amy, G. 2000b. Effects of molecular weight cutoff, f/k ratio (a hydrodynamic condition) and hydrophobic interactions on natural organic matter rejection and fouling in membranes. J. Water Supply Res. Technol.-AQUA 51,109-123. 

Replacing the ultrafiltration, nanofiltration pretreatment and reverse osmosis by BAHLM processes in desalination industry is the main idea of this proposal. Rejection characteristics of natural organic matters and inorganic salts in a low pressure nanofiltration (e.g., >99% at 1.5 MPa [115]) and capacity of polyanions to complex monovalent and especially bivalent cations [92, 95, 115-117] make this idea promising. 

Thanuttamavong M, Oh JI, Yamamoto K, and Urase T, Comparison between rejection characteristics of natural organic matters and inorganic salts in ultra low pressure nanofiltration for drinking water production. Proceedings of the Conference on Membranes in Drinking and Industrial Water Production. Paris, Prance, October 2000 Desalination Publications, L Aquila, Italy, 2000 Vol. 1, pp. 269-282. 

Cho, J. W., Amy, G., and Pellegrino, J., Membrane filtration of natural organic matter comparison of flux decline, NOM rejection, and foulants during filtration with three UF membranes. Desalination, 111, 283-298, 2000. 

Amy G., Cho J. (1999), Interactions between natural organic matter (NOM) and membranes rejection and fouling, in Odegaard H. (Ed), Removal of humic substances from water. Conference Proceedings, Trondheim, Norway, 141-148. 

Devitt E.C., Ducellicr F., Cote P., W iesner R. (1998), Effects of natural organic matter and the raw water matrix on the rejection of atrazine by pressure-driven membranes. Water Research, 32, 9, 2563-2568. 

A key issue with the use of membranes for treatment of transformation products of synthetic organic chemicals is that the pollutants are simply concentrated into a reject stream that must be dealt with in some manner. The treatment and disposal of this waste stream are much more problematic when the waste contains toxic compounds (e.g., some transformation products) rather than, for example, simply natural organic matter. 

Colloid fouling refers to membrane fouling with colloidal and suspended particles in the size range of a few nanometers to a few micrometers. Examples of common colloidal-sized fonlants inclnde clays, silica salts, and hydroxides of heavy metals (Potts et al. 1981). An increased concentration of the rejected ions at the front of the membrane snrface facilitates the aggregation of dissolved organic substances, for example, natural organic matter (NOM), into colloidal-sized particles (Hong and Elimelech 1997). 

NF membranes have been used successfully for ground-water softening since they achieve greater than 90% rejection of divalent ions such as calcium and magnesiiun. NF membranes are also capable of removing greater than 90% of natural organic matter present in the water. Therefore, they are also excellent candidates for the removal of color, and also DBF precursor material. 

As already explained in chapter 1.1.4.2.3, the Kd concept must be rejected in most cases, because of its oversimplification and its low suitability for application to natural systems. For example, in degradation only the degrading substance is considered. This concept might be applicable for radioactive decay, yet if the decomposition of organic matter is considered, it is crucial to consider decomposition products (metabolites) that form and play an important role in transport themselves. 

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