A method for the electrochemical remediation of a metal species comprises flowing a contaminated solution comprising a metal species to be removed through an electrochemical cell that includes a working electrode and a counter electrode spaced apart from the working electrode. The working electrode comprises a conductive substrate or current collector with a polymeric coating thereon, where the polymeric coating comprises a semiconducting or redox-active polymer. A reducing potential is applied to the electrochemical cell, thereby inducing the metal species from the contaminated solution to deposit onto the working electrode. After depositing the metal species, a recovery solution is flowed through the electrochemical cell. An oxidizing potential is applied to the electrochemical cell, thereby stripping the metal species from the working electrode and recovering the metal species in the recovery solution.

Processes are provided for the kinetically efficient reduction of selenate species to selenide species using chromous ions in acidic solution. This reduction may advantageously be carried out in the presence of sulphate species, with selective selenate reduction in preference to the reduction of sulfate. The reduced selenate may be removed from the chromous-treated solution, for example by precipitation of a copper-selenide solid. The chromic ions formed by reaction of chromous ions in the reduction of selenate may also be removed from solution, for example by addition of a base to form an insoluble chromic hydroxide solid. The chromic hydroxide may be recycled to regenerate chromous ions, for example by electrolysis. In this way, systems are provided for continuously removing dissolved selenium from wastewater streams.

Voltage regulated electrolytic water purification methods and systems are provided. The methods and systems utilize a series of deflocculation tanks each containing a series of electrodes and a bubbler to remove contaminants from water. The water purification methods and systems increase the life of the electrodes, allowing for reduced maintenance.

An apparatus for the treatment of acid mine drainage and selective recovery of at least one of metals, critical elements, sulphuric acid and water is disclosed. The apparatus includes at least one electrochemical reactor, at least one catholyte reservoir and at least one anolyte reservoir for containing the acid mine drainage and a buffer, respectively. The reservoirs are in fluid communication with the at least one electrochemical reactor. The apparatus also includes at least one sensor for monitoring a pH of a contents of the reactor; and a power source for supplying an electrical current to the at least one electrochemical reactor. The electrical current is supplied until a predetermined pH is reached for the selective recovery of the at least one of metals, critical elements, sulphuric acid and water. A process for the treatment of acid mine drainage is also disclosed.

The disclosure discloses an online resourceful treatment method of electroless copper plating waste solution. According to the disclosure, a copper catalyst is adopted to perform autocatalytic reaction on electroless copper plating waste solution in an autocatalytic reactor, copper simple substances are reduced from copper ions in the waste solution and recycled, the treated waste solution enters into a three-dimensional electrolyzer and a membrane filtration plant for further purification, the finally treated electroless copper plating waste solution meets water quality discharge standard, and the recovery rate of the copper simple substances can reach up to above 95%.

The recovery of target species, and related systems and methods, are generally described.

The present application relates to a method for removing a contaminant from wastewater from industrial fertilizer plant. The method comprises the steps of concentrating the wastewater, of electrolyzing the wastewater and of recirculating the electrolyzed wastewater to the fertilizer plant. The present application further relates to a system arranged to perform the method according to the present application.

A method and apparatus for copper-catalyzed electrochemical water treatment are provided. The method comprises the steps of supplying an aqueous solution and electrochemically treating the aqueous solution in an electrochemical cell comprising an anode, a cathode, and the aqueous solution as an electrolyte, by applying an electric potential to said anode and said cathode, thereby producing purified water. The apparatus comprises an electrochemical cell comprising an anode, a cathode, and an electrolyte, the electrolyte contacting the anode and the cathode; an inlet allowing the electrolyte in the electrochemical cell; and an outlet allowing purified water out of the electrochemical cell. In both cases, the electrolyte/aqueous solution comprises water to be treated, chloride ions in a concentration [Cl.sup.−] at least about 10 mM, and copper(II) and/or copper(I) ions in a total copper ions concentration, [CU.sup.2+] +[Cu.sup.+], of at least about 20 μM.

This disclosure provides techniques for treatment of aqueous matrices using electrolysis to produce soluble metals. An aqueous matrix of interest is passed through an electrolysis device with at least one consumable electrode, which dissolves under applied current, transferring a desired reagent to the aqueous matrix of interest. In one embodiment, the electrolysis device is used in a water delivery network to passivate hexavalent chromium (Cr6) and/or convert it to trivalent chromium; the electrode can be made of food-grade metal tin, which is electrolyzed to form a stannous reagent, which then reacts with the Cr6. The disclosed techniques provide for Cr6 passivation without requiring the use of concentrated acids or other harmful substances. Long term reagent generation efficiency can be enhanced through the use of cleaning processes which maintain a fresh electrode surface in contact with the aqueous matrix of interest.

A method for remediation of environments contaminated with halogenated organic compounds, in particular per- and polyfluoroalkyl substances, the method comprising the steps of placing a plurality of electrodes in the contaminated environment, applying an electric direct current between said electrodes, providing at least one electrically conductive reductant for halogenated organic compounds, obtaining information indicative of the electrical resistance between said electrodes, analyzing said information to detect whether at least one of said electrodes introduced a lower electric current into the contaminated environment compared to the remaining ones of said electrodes and bringing said reductant into or in close proximity to the contaminated environment in response to said detection such that the electrical resistance to the contaminated environment of at least one of said electrodes identified to introduce a lower electric current into the contaminated environment is decreased.