Combining reverse osmosis and pulsed electrical current

Combining reverse osmosis and pulsed electrical current
electrodialysis for improved recovery of dissolved organic
matter from seawater
B. K. Gurtlera, T. A. Vettera,1, E. M. Perdueb, E. Ingallb, J.-F. Koprivnjakb,2, P. H. Pfromma,c
aDepartment of Chemical Engineering, Kansas State University, 1005 Durland Hall, Manhattan,
Kansas, 66506-5102, USA bSchool of Earth and Atmospheric Sciences, Georgia Institute of
Technology, 311 Ferst Drive, Atlanta, Georgia, 30332-0340, USA
Published in Journal of Membrane Science, 332(2), 328-336, 2008
Abstract
Dissolved organic carbon (DOC) in the oceans is one of the largest dynamic reservoirs of
carbon on earth, comparable in size to the atmospheric reservoir of carbon (as CO2) in the
atmosphere, or to the amount of carbon in all terrestrial and aquatic biota. The concerted efforts
of earth scientists, atmospheric scientists, and biologists who study global biogeochemical cycles
and the earth’s climate have yielded a rather detailed understanding of carbon in the atmosphere
and in biota. Marine dissolved organic matter (DOM) is far less well characterized, principally
because it exists as a highly diluted mixture of perhaps millions of organic compounds in a
highly saline aqueous solution. Prior to 2007, only around
of marine DOM was typically
recovered from seawater for research purposes, regardless of the method of isolation. In 2007,
reverse osmosis (RO) and electrodialysis (ED) were coupled to achieve recoveries of 64% – 93%
of marine DOM. The level of residual salts in the concentrated samples, however, still precluded
the characterization of marine DOM by solid-state NMR, mass spectrometry, or even elemental
analysis. This paper describes a major improvement to the RO/ED method, in which pulsed
electrodialysis is used (at sea) to reach roughly 100-fold greater removal of salts compared to not
pulsed ED while maintaining comparable recoveries of DOM.
Keywords: electrodialysis, reverse osmosis, dissolved organic carbon, ocean, pulsed
c: to whom correspondence shall be addressed, e-mail pfromm@ksu.edu, phone 785-532-4312,
fax 785-532-7372
1: now with Koch Industries, Wichita, Kansas, USA
2: now at Trent University, Ontario, Canada