Appeal No. 1997-0525 Page 2
Application No. 08/355,931
Appellants' invention relates to a method and apparatus
for treating selected feed waters containing silica and
hardness ions by reverse osmosis. Appellants' method is
particularly characterized by the step of maintaining the pH
of a concentrate that does not permeate a reverse osmosis
membrane at a level of at most 6 and the step of maintaining
the silica concentration of that concentrate at a value above
a line that connects 12 ppm at 5°C and 170 ppm at 40°C. Such
a line is depicted in figure 1 of the drawings. Appellants'
apparatus is characterized by a pH sensing means for measuring
the pH of the concentrate and a pH control means for
controlling the pH of the feedwater using the sensed pH value
of the concentrate in a feedback arrangement so as to maintain
the pH of the concentrate at a level of at most 6. According
to appellants, silica is not precipitated along the flow path
of the concentrate and on the surface of a membrane of a
reverse osmosis unit by so maintaining the pH of the
concentrate even if levels of silica above the standard
solubility thereof are present in the concentrate
(specification, page 5). A further understanding of the
invention can be derived from a reading of appealed claims 7-
Page: Previous 1 2 3 4 5 6 7 8 9 10 11 Next
Last modified: November 3, 2007