Biocide can be controllably added to a feed stream for a membrane. The membrane can separate the feed stream into a purified permeate stream and a concentrate stream containing contaminants from the feed stream. In some examples, a charge neutral biocide is introduced into the feed stream at a first addition rate. The concentration of the charge neutral biocide in the permeate stream is measured to provide a measured concentration of the charge neutral biocide in the permeate stream. The addition rate of the charge neutral biocide can be adjusted based on the measured concentration of the charge neutral biocide in the permeate stream to introduce charge neutral biocide into the feed stream at a second addition rate different than the first addition rate.

An integrated, membrane-based process to produce purified water and conversion of salt to high value chemicals from oil and gas well produced water is described. A liquid stream including water and dissolved salt is flowed through pretreatment units and one or more desalination and concentration units which remove at least a portion of the water to form a brine enriched in dissolved salt. The purified high-density brine may be subjected to electrically-enforced salt dissociation techniques to produce chemicals from oil and gas produced water.

Method for making surface water drinkable, which method is aimed at reducing the suspended matter content, turbidity, organic matter content and colour of the water, and is characterised in that it comprises: .circle-solid.a step of nanofiltering the water (2) through at least one nanofiltration membrane (2) which has a breakdown capacity between 800 Da and 2000 Da, preferably between 800 and 1000 Da, the nanofiltration step leading to the acquisition of a permeate (7) and a concentrate (5), .circle-solid.wherein the nanofiltration step is carried out with a conversion rate greater than 95%, .circle-solid.the method being carried out without any step of adding an anti-scaling agent or any step of remineralising the permeate.

Method for making surface water drinkable, which method is aimed at reducing the suspended matter content, turbidity, organic matter content and colour of the water, and is characterised in that it comprises: .circle-solid.a step of nanofiltering the water (2) through at least one nanofiltration membrane (2) which has a breakdown capacity between 800 Da and 2000 Da, preferably between 800 and 1000 Da, the nanofiltration step leading to the acquisition of a permeate (7) and a concentrate (5), .circle-solid.wherein the nanofiltration step is carried out with a conversion rate greater than 95%, .circle-solid.the method being carried out without any step of adding an anti-scaling agent or any step of remineralising the permeate.

Per- and polyfluoroalkyl substances (PFAS) are destroyed by oxidation in supercritical conditions. PFAS in water is concentrated in a reverse osmosis step and salt from the resulting solution is removed in supercritical conditions prior to destruction of PFAS in supercritical conditions.

Per- and polyfluoroalkyl substances (PFAS) are destroyed by oxidation in supercritical conditions. PFAS in water is concentrated in a reverse osmosis step and salt from the resulting solution is removed in supercritical conditions prior to destruction of PFAS in supercritical conditions.

Biocide can be controllably added to a feed stream for a membrane. The membrane can separate the feed stream into a purified permeate stream and a concentrate stream containing contaminants from the feed stream. In some examples, a charge neutral biocide is introduced into the feed stream at a first addition rate. The concentration of the charge neutral biocide in the permeate stream is measured to provide a measured concentration of the charge neutral biocide in the permeate stream. The addition rate of the charge neutral biocide can be adjusted based on the measured concentration of the charge neutral biocide in the permeate stream to introduce charge neutral biocide into the feed stream at a second addition rate different than the first addition rate.

A desulfurization system has an oxidation process unit, and a multi-stage, liquid-liquid extraction unit in series with the oxidation process unit. The multi-stage, liquid-liquid extraction unit spits a fuel input from the oxidation process unit into a desulfurized fuel that is output for use, and a by-product. A solvent/sulfur/hydrocarbon separation process unit receives the by-product from the multi-stage, liquid-liquid extraction unit.

A method, system and composition is described for treating waste generated from manufacturing operations including at least one of Printed Circuit Boards Fabrication (PCB FAB), General Metal Finishing (GMF), semiconductors manufacturing, chemical milling, and Physical Vapour Deposition (PVD). The method, system and composition are used to create zero liquid discharge recycling.

A water filter comprises an ultrafilter or microfilter, in particular a membrane stack for ultrafiltration or microfiltration, which has a direction of flow (D) and contains an alkalinizing and/or oxidative material that is placed upstream of or within the membrane stack when viewed in the direction of flow.