A method of desulfating seawater includes adding a produced water to a sulfated seawater, forming a first precipitate, separating the first precipitate from the sulfated seawater, measuring the sulfate ion concentration of the desulfated seawater, adding a precipitating agent to the sulfated seawater, and separating a second precipitate from the sulfated seawater. Another method of desulfating seawater includes determining concentrations of sulfates in a sulfated seawater and a precipitating agent in a produced water, adding the produced water to the sulfated seawater based on the determined concentrations of sulfates in the sulfated seawater and the precipitating agent in the produced water, forming a first precipitate, separating the first precipitate from the sulfated seawater, measuring the sulfate ion concentration of the desulfated seawater, adding a precipitating agent to a sulfated seawater, and separating a second precipitate from the sulfated seawater.

The present disclosure relates to methods of treating water to remove contaminants, including harmful metal ions, and water treatment plants for practicing such methods. In an embodiment, the process includes adding a sulfur-containing, metal-decreasing agent; an iron (III)-containing, metalloid-decreasing agent; forming a solid precipitate from the contaminated water, wherein the solid precipitate includes a solid metal sulfide, a solid iron metalloid, a solid calcium metalloid, or a combination thereof; and separating the contaminated water from the solid precipitate to form purified water.

The crude oil sludge treatment agent is mixed with crude oil sludge and water and used for treatment of the crude oil sludge under alkali conditions. The crude oil sludge treatment agent contains green rust. The crude oil sludge treatment agent may further contain either or both a metal and a metal ferrite. The metal and the metal of the metal ferrite are one or more selected from the group consisting of aluminum, yttrium, zinc, copper, tin, chromium and silicon. The crude oil sludge treatment agent may also contain one or more selected from the group consisting of aluminum ferrite, yttrium ferrite and zinc ferrite. The crude oil sludge treatment method includes a mixing step in which crude oil sludge, water and green rust are mixed under alkali conditions.

A synthesis method of an indole derivative capable of efficiently degrading a perfluorinated compound (PFC) and a use of the indole derivative are provided. The synthesis method includes dissolving an appropriate amount of indole, alkylamine, and formaldehyde in an ethanol solution, conducting a reaction at reflux under suitable conditions for a specified period of time with ZnCl.sub.2 or glacial acetic acid as a catalyst to form a reaction product, vacuum-drying the reaction product, and purifying the reaction product through column chromatography to obtain a novel indole derivative with a hydrophobic alkyl branch. The present indole derivative has some hydrophobicity and a positively charged amino group that can effectively capture PFCs in contaminated water to produce a sub-nanoscale self-assembled aggregate. Hydrated electrons generated by light irradiation can directly attack PFCs in the aggregate without long-distance mass transfer, improving the utilization rate of hydrated electrons and reduces the ratio of fed materials.

A method includes: (1) using a chelating agent, extracting divalent ions from a brine solution as complexes of the chelating agent and the divalent ions; (2) using a weak acid, regenerating the chelating agent and producing a divalent ion salt solution; and (3) introducing carbon dioxide to the divalent ion salt solution to induce precipitation of the divalent ions as a carbonate salt. Another method includes: (1) combining water with carbon dioxide to produce a carbon dioxide solution; (2) introducing an ion exchanger to the carbon dioxide solution to induce exchange of alkali metal cations included in the ion exchanger with protons included in the carbon dioxide solution and to produce a bicarbonate salt solution of the alkali metal cations; and (3) introducing a brine solution to the bicarbonate salt solution to induce precipitation of divalent ions from the brine solution as a carbonate salt.

An electrochemical device comprises a first type of membrane disposed between first and second reservoirs containing an input solution, and a second type of membrane, different from the first type, is disposed between a first redox-active electrolyte chamber and the first reservoir and disposed between a second redox-active electrolyte chamber and the second reservoir. The first type of membrane and one of the second type of membranes form a membrane pair and the pair has an area specific resistance below y=5065.3x.sup.3−1331.1x.sup.2+90.035x+39 Ohm cm.sup.2 when the pair is equilibrated in an electrolyte and for at least part of a range where 0<x<0.4 and x is the mass fraction of salt in the electrolyte.

Disclosed herein are the water clarification compositions and method of using the disclosed water clarification compositions for clarifying a water system or waste water source. Specifically, the disclosed compositions comprise and methods use multiple charged cationic or anionic compounds that are derived from polyamines through an aza-Michael addition with an activated olefin having an ionic group. The disclosed water clarification methods or compositions are found to be more effective than those methods or compositions including commonly used single quaternary compounds for reducing turbidity in water systems or waste water sources.

The invention discloses and claims various methods for the treatment of various wastewater streams of varying chemical composition using sonication in combination with a variety of other methods, including nucleation, ozonation, flocculation, clarification, adsorption, polishing, and filtration. The methods disclosed and claimed are useful in the treatment of industrial wastewater, brackish water, seawater, and for the treatment of oil and gas-well water as well as wastewater from hydraulic gas-fracturing processes for the production of oil and natural gas.

A method for the removal of at least one contaminant from an aqueous liquor or a gas, comprising: preparing a solution or slurry of a solid alkali reagent by supplying a solid alkali reagent into a pre-wetting chamber via a feed pipe; supplying a liquid via two or more liquid sidestreams, each through a liquid inlet positioned on a side wall of the chamber to allow the liquid sidestreams to wash an internal wall of a frusto-conical section of the chamber and flow, preferably tangentially onto the internal wall in a downward spiraling manner thereby forming a vortex, towards a fluid outlet of the chamber and to further wet the solid alkali reagent with the supplied liquid thereby forming a pre-wetted reagent; and flowing a stream though a conduit, thereby creating a suction by the eductor to draw the pre-wetted reagent out of the chamber fluid outlet and mixing it with the stream to form a slurry or solution; and directing the slurry or solution exiting the eductor to an aqueous liquor or gas treatment unit, removing at least a portion of the contaminant from the aqueous liquor or gas in the treatment unit.

The invention relates to a method and an assembly for recovering magnesium ammonium phosphate from slurry that is supplied to a reaction container (10) in which an aerobic milieu is present and in which the slurry is guided in a circuit with the aid of ventilation. Cationic magnesium, such as magnesium chloride, is added to the slurry, and magnesium ammonium phosphate crystals which are precipitated from the slurry are removed via a removal device (30) provided in the base region of the reaction container. Substances which contain magnesium ammonium phosphate crystals collected in the removal device (30) are loosened and/or rinsed.