Showing papers on "Forward osmosis published in 1995"

Reverse osmosis membrane separator and separation of highly concentrated solution

Abstract: PURPOSE: To obtain fresh water in a high yield with a low energy without generating scale in the removal of boron by arranging a unit using a reverse osmosis membrane having a specific salt removing rate and a unit using a low pressure reverse osmosis membrane having transmission flow velocity in a multistage fashion. CONSTITUTION: The reverse osmosis membrane module unit A4 is constituted using a membrane having capacity such that a salt removing rate at the time of measurement using a 3.5% saline soln. under a condition of 56kgf/cm , 25 deg.C and pH6.5 is 90% or more, and a reverse osmosis membrane module unit B7 is obtained using a membrane having capacity such that transmission flow velocity at the time of measurement using a saline solution of 1500ppm under a condition of 15kgf/cm , 25 deg.C and pH6.5 is 0.8m /m .day or more. Both units 4, 7 are arranged in a multistage fashion. High concn. supply water such as seawater is pretreated to be supplied to the first stage unit B7 of a loose RO membrane to be separated into polyvalent ions such as scale components, medium to high-molecular substances, monovalent ions and a low mol.wt. substance. Next, high recovery separation is performed in the unit A4.

Pulse reverse osmosis: a new theory in the maintenance of fluid balance.

Abstract: to this process. The presently accepted theory of fluid exchange was put forward by Starling’ in 1896. Apart from several suggested modifications2-6 the underlying mechanism has not been challenged until recently. Pulse reverse osmosis7 is a new theory of fluid exchange which addresses several of the problems inherent within the Starling hypothesis. Starling suggested that the capillary wall acts as an osmotic membrane separating the plasma and interstitial fluid. This membrane sets up an osmotic pressure gradient between these two solutions which tends to draw fluid into the

Method for operating reverse osmosis membrane device

Abstract: PURPOSE: To make it possible to easily restore the permeated flow flux of a reverse osmosis membrane by interposing a washing operation for washing the reverse osmosis membrane with washing water of a specific pH value during the course of water flow operation in a method for treating the water which is to be treated and contains a hardness component and silica with a reverse osmosis membrane device CONSTITUTION: The water 1 to be treated is subjected to the reverse osmosis membrane treatment in a fore-stage reverse osmosis membrane device 2 and is separated to fore-stage concd water and fore-stage permeated water Further, the fore-stage concd water is supplied to a post-stage reverse osmosis membrane 4 and is separated to the post-stage concd water and the post-stage permeated water At this time, the pH of the post-stage concd water is detected by a pH sensor 10 and the detected signal is fed back to an acid supplying means 26 which controls the pH to =9 on the inlet side of the device

Chapter 4 Reverse osmosis

Abstract: Publisher Summary This chapter discusses reverse osmosis. In reverse osmosis, a semipermeable membrane is challenged with a pressurized feed stream containing a solute. The pressure exerted is greater than the osmotic pressure of the feed, causing solvent to flow through the membrane. The technology is also often referred to as hyperfiltration. The most common use for reverse osmosis is in the desalination of water. Here the aim is to remove dissolved salts and organics from water. Both seawater and brackish water are routinely processed. Because of the high osmotic pressure of seawater (2.3 MPa), reverse osmosis plants must frequently operate at high pressures (to 7 MPa) and plant components must be much more robust than for other membrane based technologies. The origins of the industrial application of reverse osmosis can be traced to the observation that dense polymer films could be used for desalination. The chapter reviews the membranes and modules currently available for reverse osmosis, and considers aspects of plant design and operation.

Desalting of sewater

Abstract: PURPOSE: To desalt seawater by a reverse osmosis membrane separation module in water quality satisfying water quality standards of the Water Service Law inclusive of boron. CONSTITUTION: Seawater is supplied to a first stage reverse osmosis membrane separation module 41 and the transmitted water from the module 41 is supplied to a second stage reverse osmosis membrane separation module 42. In this method, the pH of the transmitted water of the first stage reverse osmosis membrane separation membrane 41 is adjusted to 5.7 or more, pref., 6.5 or more to reduce the boron content of the transmitted water of the second stage reverse osmosis membrane separation module 42 to 0.20ppm or less.