Molecular size distributions of dissolved organic matter

Bruce E. Logan, Qing Jiang

Research output: Contribution to journalArticlepeer-review

144 Scopus citations


Discrete molecular size distributions of dissolved organic matter (DOM) in natural waters and wastewaters are usually determined using an array of ultrafiltration membranes in stirred cells. However, many researchers neglect membrane rejection, resulting in an underestimation of DOM in low molecular weight size classes. In this paper, we develop a simple model, based on a permeation coefficient, that can be used to improve the accuracy of size distributions. Since permeation coefficients are a function of membrane material and water composition, these coefficients must be determined for every water sample. The utility of the model is demonstrated by comparing unadjusted and adjusted size distributions of dissolved organic carbon (DOC) in ground waters and municipal wastewaters. For example, when membrane rejection is neglected, 41% of the DOC in Biscayne Aquifer ground water has an apparent molecular weight greater than 5,000 amu. Size distributions determined using the permeation coefficient model, however, indicate only 16% of the DOC is greater than 5,000 amu.

Original languageEnglish (US)
Pages (from-to)1046-1062
Number of pages17
JournalJournal of Environmental Engineering (United States)
Issue number6
StatePublished - Oct 1990

All Science Journal Classification (ASJC) codes

  • Environmental Engineering
  • Civil and Structural Engineering
  • Environmental Chemistry
  • Environmental Science(all)


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