Concentration of aquatic dissolved organic matter by reverse osmosis

Abstract

Dissolved organic carbon (DOC) was concentrated from natural streams using reverse osmosis equipment. Quality control tests show that from 95.6 to 98.5% of total DOC was rejected by the membrane, though only 70% could actually be recovered, most likely because of losses within the plumbing system. Comparison of the acid-base characteristics of the original water sample with re-diluted concentrate show that modifications occurred. Visual evidence showed that polycondensation reactions which modify acid-base characteristics occurred in the concentrate. Analysis of the material passing through the membrane (permeate) shows that it is <200 Da in weight with a pKa distribution suggesting that a range of molecules with carboxylic and phenolic acid sites are leaking through the membrane. © 1991.