Patents: Desalination Boron

A method of boron removal from saline water containing boron and magnesium or calcium salts including a multi-stage reverse-osmosis (RO) separation process and comprising the steps of a first stage RO separation at pH < 8.2; a second stage RO separation over at least part of the first-stage permeate; a third stage RO separation over the second-stage brine. The method is characterized in that the second stage separation is carried at pH>9 and the brine concentration is limited to a degree preventing Mg(OH)2 or CaCO3 scaling on RO membrane surfaces, the permeate constitutes product water, and the brine contains boron and magnesium or calcium ions; the third stage separation is carried at weak-acid pH, whereby the bulk of the magnesium or calcium ions are separated with the brine, while the bulk of the boron ions are retained in the permeate. The method further comprises a fourth stage of separation over the third-stage permeate, where the bulk of the boron ions is separated from the...

2002, patent number: 7097769

Method for reducing boron concentration in high salinity liquid

A method of treating a high salinity liquid, such as seawater, containing boron is provided. The method includes adjusting the pH of the liquid to about 8.5 to about 9.5, optionally adding a scale inhibitor to the liquid, passing the liquid through a reverse osmosis device, and recovering a permeate having a boron concentration less than about 1 ppm.

Publication number: US 2003/0230531

Reducing aqueous boron concentrations with reverse osmosis membranes operating at a high pH

A method of treating an aqueous charge liquid, such as oilfield produced waters, containing boron and solubilized hydrocarbon compounds to reduce boron concentration, which comprises water softening to remove substantially all divalent cations, raising the pH of the liquid above about 9.5, and driving the liquid through a reverse osmosis membrane.

United States Patent 5250185