| 摘要 |
Disclosed is a two-stage high pressure high recovery process utilizing two reverse osmosis membrane systems intended to provide very high overall water recoveries from contaminated inorganic scale-containing water in an economical manner while preventing scale formation on the membrane and prolonging the useful life of the membrane. The first stage of the process involves using a low pressure membrane system to preconcentrate scale compounds while purifying the bulk volume of the scale-containing water (using antiscalants with pH control) and combining the influent water with a recycle stream of concentrate from the second stage membrane process in order to prevent scale formation. This first stage membrane system is followed by a second stage membrane system wherein the concentrate from the first stage membrane system is treated further at higher pressure in order to provide purification of the remaining preconcentrated stream and achieve very high overall water recoveries. Scale formation in the first stage and second stage membrane systems is prevented by the recycle of "softened" water containing a very low concentration of scale-forming compounds and containing a high concentration of soluble salts to both stages in a specific proportion that represents an economically viable process, while ensuring adequate permeate quality. The second stage membrane concentrate stream is "softened" whereby hardness compounds such as calcium, magnesium, carbonate, sulphate, silica and other sparingly soluble compounds are removed by suitable device before it is recycled to the two membrane purifying stages.
|
