Provided are electrodialysis systems for removing silica from a desalinated water stream and methods for removing silica from a desalinated water stream. For example, described are bipolar membrane electrodialysis devices for removing silica from water comprising one or more anion exchange membranes; one or more bipolar membranes; and a pair of electrodes comprising a positive electrode and a negative electrode. Also described are electrodialysis systems comprising: one or more electrodialysis devices for the removal of dissolved ions and one or more bipolar membrane electrodialysis devices, wherein a product inlet stream of the one or more bipolar membrane electrodialysis devices comprises the product outlet stream of the one or more electrodialysis devices.

The present invention is in the field of a system for gas recovery from wastewater, a method for treating wastewater, and a method wherein ammonia and carbon dioxide are recovered. Typically a wastewater stream is fed into the system, treated and stripped from ammonia and carbon dioxide, and a cleaner stream is released.

The present invention relates to a hydrogen gas production method, which includes: a first step of concentrating an aqueous solution containing an alkali metal formate; a second step of protonating at least a part of the alkali metal formate by electrodialysis to produce a formic acid; and a third step of decomposing the formic acid to produce a hydrogen gas.

There are provided processes comprising submitting an aqueous composition comprising lithium sulphate and/or bisulfate to an electrolysis or an electrodialysis for converting at least a portion of said sulphate into lithium hydroxide. During electrolysis or electrodialysis, the aqueous composition is at least substantially maintained at a pH having a value of about 1 to about 4; and converting said lithium hydroxide into lithium carbonate. Alternatively, lithium sulfate and/or lithium bisulfate can be submitted to a first electromembrane process that comprises a two-compartment membrane process for conversion of lithium sulfate and/or lithium bisulfate to lithium hydroxide, and obtaining a first lithium-reduced aqueous stream and a first lithium hydroxide-enriched aqueous stream; and submitting said first lithium-reduced aqueous stream to a second electromembrane process comprising a three-compartment membrane process to prepare at least a further portion of lithium hydroxide and obtaining a second lithium-reduced aqueous stream and a second lithium-hydroxide enriched aqueous stream.

An ocean alkalinity enhancement (OAE) system that reduces atmospheric CO.sub.2 and mitigates ocean acidification by electrochemically processing feedstock solution (e.g., seawater or brine) to generate an alkalinity product that is then supplied to the ocean. The OAE system includes a base-generating device and a control circuit disposed within a modular system housing deployed near a salt feedstock. The base-generating device (e.g., a bipolar electrodialysis (BPED) system) generates a base substance that is then used to generate the ocean alkalinity product. The control circuit controls the base-generating device such that the alkalinity product is supplied to the ocean only when (1) sufficient low/zero-carbon electricity is available, (2) it is safe to operate the base-generating device, and (3) supplying the alkalinity product will not endanger sea life. Modified BPED systems include features that facilitate autonomous system operations including enhanced maintenance cycle operations and a reduced reliance on external fresh water sources.

Techniques according to the present disclosure include capturing carbon dioxide from a dilute gas source with a CO.sub.2 capture solution to form a carbonate-rich capture solution; separating at least a portion of carbonate from the carbonate-rich capture solution; forming an electrodialysis (ED) feed solution; flowing a water stream and the ED feed solution to a bipolar membrane electrodialysis (BPMED) unit; applying an electric potential to the BPMED unit to form at least two ED product streams including a first ED product stream including a hydroxide; and flowing the first ED product stream to use in the capturing the carbon dioxide from the dilute gas source with the CO.sub.2 capture solution.

A method and a system for recovering nitrogen, and optionally phosphorus and/or potassium, from a liquid waste stream, such as a stream of urine or manure, or human urine is described. The method comprises passing the waste stream through a multi-compartment electrodialysis bipolar membrane (EDBM) system.

An electrochlorination system includes an electrolyzer fluidically connectable between a source of feed fluid and a product fluid outlet, and a sub-system configured to one of increase a pH of the feed fluid, or increase a ratio of monovalent to divalent ions in the feed fluid, upstream of the electrolyzer.

A power generation process is disclosed, the process comprises dissolving a solute (10) into an unsaturated stream (140) to produce a high concentration stream (130) and converting latent mixing energy present in a high concentration input stream (130) into power by passage through a power unit (20) in which the concentration of the high concentration input stream (130) is reduced. The process comprises using a reduced concentration output stream (140) derived from the high concentration input stream (130) following passage through the power unit (20) as the unsaturated stream (140). A first fraction of the high concentration stream (130) is passed to the power unit (20) for use as the high concentration input stream (130) and a second fraction of the high concentration stream (130) is output from the process.

Bipolar membranes (BPMs) comprising a cation exchange layer (CEL) and an anion exchange layer (AEL) wherein the colour properties of the CEL are visibly different to the colour properties of the AEL. The CEL and the AEL are easily distinguishable so that a stack of membranes comprising the BPMs can be built fast and without mistakes in layer order.