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.

Embodiments disclosed herein are directed to methods and systems for treating wastewater via forward osmosis. By way of example, the methods and systems disclosed herein may be used to filter one or more precipitated salts and/or other particles from wastewater generated by power plants such as flue gas wastewater, oil and gas wastewater, and other industrial processes. For example, the methods and systems disclosed herein may be used to filter one or more precipitated salts from a wastewater feed concentrate formed during the forward osmosis process that is recirculated through at least one membrane module to continue the forward osmosis process. Filtering the one or more precipitated salts from the wastewater feed concentrate helps limit clogging of open channel feed spacer(s) of the at least one membrane module.

Embodiments disclosed herein are directed to methods and systems for treating wastewater via forward osmosis. By way of example, the methods and systems disclosed herein may be used to filter one or more precipitated salts and/or other particles from wastewater generated by power plants such as flue gas wastewater, oil and gas wastewater, and other industrial processes. For example, the methods and systems disclosed herein may be used to filter one or more precipitated salts from a wastewater feed concentrate formed during the forward osmosis process that is recirculated through at least one membrane module to continue the forward osmosis process. Filtering the one or more precipitated salts from the wastewater feed concentrate helps limit clogging of open channel feed spacer(s) of the at least one membrane module.

Described herein is a coagulant blend for use in SAGD water treatment systems. Specifically, a blend of high charge density polyamine and low charge density poly(diallylmethyl ammonium chloride (poly-DADMAC) is used in the warm lime softening treatment process to coagulate and flocculate solids.

A new water treatment system for SAGD operations is disclosed. Instead of treating both produced water and recycled water using warm lime softening systems, the recycled water is combined with saline water in a cold lime softening system. This results in slightly warmed reactions that require less chemicals during the lime softening process while also allowing for larger volumes of treated produced water to be generated by the warm lime softening system.

A new water treatment system for SAGD operations is disclosed. Instead of treating both produced water and recycled water using warm lime softening systems, the recycled water is combined with saline water in a cold lime softening system. This results in slightly warmed reactions that require less chemicals during the lime softening process while also allowing for larger volumes of treated produced water to be generated by the warm lime softening system.

The invention relates to sewage treatment, and more particularly to a system for treating reverse-osmosis concentrated water with permanent hardness. The system includes a first crystallization unit, a first reverse osmosis unit, a second crystallization unit, a lime softening unit and a second reverse osmosis unit, which are connected in sequence. The system of the invention is able to eliminate the permanent hardness and the temporary hardness of the concentrated brine, and the hardness can be reduced to equal to or less than 50 mg/L.

A process for treating frac flowback that contains barium, naturally occurring radioactive materials (NORM) and hardness for minimizing the amount of sludge produced that contains hazardous levels of NORM by employing a dual stage precipitation process. In the first stage a sulfate source is mixed with the frac flowback and barium sulfate and NORM is precipitated, the frac flowback is subjected to a solids-liquid separation process to produce a first effluent and a first sludge. In the second stage hardness is precipitated from the first effluent by addition of an alkali reagent, said first effluent is also subjected to solids-liquid separation producing a second effluent and a second sludge. The first sludge is recycled and mixed with the frac flowback and the sulfate source in a sufficient amount to maintain the NORM concentration in the second sludge at or below a threshold level.

A process for treating frac flowback that contains barium, naturally occurring radioactive materials (NORM) and hardness for minimizing the amount of sludge produced that contains hazardous levels of NORM by employing a dual stage precipitation process. In the first stage a sulfate source is mixed with the frac flowback and barium sulfate and NORM is precipitated, the frac flowback is subjected to a solids-liquid separation process to produce a first effluent and a first sludge. In the second stage hardness is precipitated from the first effluent by addition of an alkali reagent, said first effluent is also subjected to solids-liquid separation producing a second effluent and a second sludge. The first sludge is recycled and mixed with the frac flowback and the sulfate source in a sufficient amount to maintain the NORM concentration in the second sludge at or below a threshold level.

The instant application is directed towards methods for removing sulfide from a wastewater stream. The pH of the wastewater stream is adjusted to between 7.0 and 8.0. A first oxidizing agent is mixed with the wastewater stream, oxidizing the sulfide to elemental sulfur. The wastewater stream is then softened by mixing lime with the wastewater stream. The addition of lime further raises the pH of the wastewater stream to 10.0 or higher, and converts the elemental sulfur to soluble sulfide (S2-) and/or thio-sulfate. Calcium carbonate is precipitated and sulfide (S2-) and/or thio-sulfate is adsorbed thereon. Thereafter, the wastewater stream is directed to a solids-liquid separation process, which separates the calcium carbonate and adsorbed sulfide (S2-) and/or thio-sulfate from the wastewater stream. The solids-liquid separator produces an effluent that includes residual elemental sulfur. The effluent is then mixed with a second oxidizing agent, which oxidizes the residual elemental sulfur to sulfate, producing a treated effluent.