The present invention relates to a method of removing chromate ions from an ion-exchange effluent, the method comprising: (i) providing an ion-exchange effluent comprising chromate ions obtained from the regeneration of an ion-exchange material, (ii) admixing the ion-exchange effluent with a source of alkali metal dithionite to form a first precipitate, and (iii) removing the first precipitate

Compositions containing a porous organic polymer and a heavy metal chelating moiety are provided for binding heavy metals, for example in remediation and purification. The compositions can be stable and recyclable. The compositions can contain heavy metal chelating moieties such as a thiol, a sulfide, an amine, a pyridine, or a combination thereof. The compositions can bind heavy metals such as lead, cadmium, and mercury. The compositions can have a large surface area greater than about 20 m.sup.2/g. The compositions can be used for remediation and purification to remove heavy metals from a solution. The compositions can have a maximum metal uptake capacity of more than 500 mg g.sup.−1 and/or a metal distribution coefficient of at least 1×10.sup.7 mL g.sup.−1 at 1 atm and 296 K. Methods of making the compositions are provided. Methods of binding heavy metals in remediation and purification are also provided.

Methods for removing one or more contaminants from an aqueous stream comprising: adding one or more hydraulic binders and one or more promoters to the aqueous stream, and separating the contaminants from the aqueous stream are provided. The methods may be used for removing contaminants that are arsenic-based, selenium-based, cadmium-based, zinc-based, mercury-based, iron-based, chromium-based and/or phosphate-based.

Provided are systems and methods for treating wastewater with a continuous-process mobile station. The mobile station may include one or more mobile units configured to receive a feed of wastewater. The one or more mobile units may include: a mobile ozonation unit configured to treat the received feed of wastewater with ozone gas to breakdown impurities in the wastewater, a pH control unit may be configured to raise pH of the treated wastewater, a mobile electrocoagulation unit configured to separate solids and metals from the treated wastewater, a mobile flocculation unit configured to cause suspended particles to form flocs and to remove the flocs from the received treated water.

Disclosed is a method for installing a groundwater monitoring well inside a permeable reactive barrier (PRB) trench including excavating a PRB trench, installing a trench side-wall support, positioning a monitoring well borehole, installing an outer installation casing for pre-burying the monitoring well, installing a monitoring well positioning bracket, installing a monitoring well casing, installing monitoring well filter packs and seal materials, filling the trench with PRB media and capping with a covering soil layer, removing the outer installation casing, removing the trench side-wall support, completing the monitoring well with a wellhead, and conducting well development. This method avoids the complex procedure of re-drilling a borehole within the PRB media following the completion of PRB construction and media filling, assures that monitoring well installation protocols are followed and high quality and stable operation is achieved, and serves for groundwater monitoring to support the implementation and efficacy evaluation of the PRB technology.

The inventive subject matter disclosed herein includes multiple novel filter media made of activated rice husks, as well as filtration systems and methods for removing contaminants from an aqueous solution, such as wastewater produced as a byproduct of various industrial processes, including mining, oil and gas exploration and extraction, farming, manufacturing, and the like.

The present invention discloses a nanocomposite membrane for heavy metal rejection and a preparation method thereof. The nanocomposite membrane comprises a porous membrane prepared from a two-dimensional sheet material and a hydrophilic inorganic nanomaterial distributed between the sheets of the two-dimensional material. The effective pore size of the nanocomposite membrane under wet conditions is not greater than 1.2 nm. The static water contact angle of the nanocomposite membrane is not greater than 45°. The preparation method of the nanocomposite membrane comprises: adding reactants on both sides of a nanoporous membrane to carry out an interfacial synthesis reaction to obtain the nanocomposite membrane. The method is simple and controllable. Driven by lower pressure, heavy metal ions in water are rejected by a pore size screening function, thereby achieving the purpose of deep removal. The nanocomposite membrane can be used to quickly remove heavy metal ions from water.

A process for recovering chromium from hexavalent chromium-containing wastewater comprises the following steps: (1) extracting hexavalent chromium in wastewater to an organic phase by using an extracting agent, and separating hexavalent chromium from a water phase, so as to acquire a hexavalent chromium-loaded organic phase; (2) reducing the hexavalent chromium-loaded organic phase by using an aqueous solution of an organic reducing agent, reducing hexavalent chromium into trivalent chromium, reversely extracting trivalent chromium into the water phase, and separating the organic phase from the water phase to acquire a solution of the trivalent chromium and a renewable organic phase, wherein the organic reducing agent is one or a mixture of alcohols, aldehydes and carboxylic acids having the carbon atom number ranging 1 to 3; and (3) performing solvent evaporation on the solution of trivalent chromium, catalyzing, and recovering the trivalent chromium.

The present invention provides, inter alia, compositions including at least one pliable layer comprising a plurality of silk fibroin nanofibrils, and at least one rigid layer comprising a plurality of mineral crystals, wherein each rigid layer is associated with at least one pliable layer, as well as methods for the production and use thereof.

The present invention relates to a fresh water generation method including: feeding raw water or pretreated water thereof as feed water into a semipermeable membrane module in a pressurized state using a booster pump, thereby separating the feed water into a concentrate and a permeate having a low concentration, in which a scale inhibitor having a reducing function is dosed intermittently or continuously upstream from the semipermeable membrane module, thereby inhibiting scale generation and maintaining an oxidation-reduction potential of at least either the feed water or the concentrate to a threshold value or lower.