Process for upgrading effluent treatment plants for pulp and paper production processes, where salts are removed from the effluent for water reuse and chemical recovery. The process comprises a first dialysis system for salt removal, a second treatment system for recovery or re-concentration, and optionally a post-treatment of the re-concentrate preventing liquid discharges to the environment. In the first system, a reversible electrodialysis or reversible pulsed step is carried out, separating the salts from the effluent, which are sent to the second treatment system to concentrate the salts (re-concentrate) or transform them into useful chemicals for the same process (recovery). Chemical recovery is achieved by electrodialysis with bipolar membranes or metathesis, to reduce the re-concentrate stream, which cannot be reused in the same plant. Lastly, this stream may be treated by spray drying, crystallization or evaporation.

The invention relates to a process and devices for reducing impurities in molten salts, a molten salt being purified in an electrochemical process by applying a voltage between two electrodes. According to the invention, the voltage is varied so that in different phases different electrodes act as cathode or anode.

The invention relates to an integrated process for conditioning process water (1) from the production (I) of polycarbonate, which process water contains at least catalyst residues and/or organic impurities and sodium chloride, and subsequently utilizing the process water (1) in a subsequent sodium chloride electrolysis (V).

The present invention provides a method for reducing the concentration of aluminum and nickel cations in a brine comprising aluminum and nickel cations. The treated brine can be used as a feedstock to membrane cell chlor-alkali process.

The present invention provides a method for reducing the concentration of aluminum and nickel cations in a brine comprising aluminum and nickel cations. The treated brine can be used as a feedstock to membrane cell chlor-alkali process.

The invention is in the field of landfill leachate, in particular the invention is directed to a method for purifying landfill leachate comprising water, dissociated ions and organic compounds, wherein the method comprises providing the leachate in a eutectic freeze crystallization (EFC) crystallizer and carrying out eutectic freeze crystallization by reducing the temperature of the leachate to a first eutectic point to obtain a first mixture comprising ice and a first crystalline salt. Further the ice and the first crystalline salt are separated into an ice stream and a crystalline salt stream.

The invention is in the field of landfill leachate, in particular the invention is directed to a method for purifying landfill leachate comprising water, dissociated ions and organic compounds, wherein the method comprises providing the leachate in a eutectic freeze crystallization (EFC) crystallizer and carrying out eutectic freeze crystallization by reducing the temperature of the leachate to a first eutectic point to obtain a first mixture comprising ice and a first crystalline salt. Further the ice and the first crystalline salt are separated into an ice stream and a crystalline salt stream.

A process for the preparation of purified potassium chloride comprises the at least partial removal of one or more class 1 heavy metal impurity (lead, arsenic, cadmium and/or mercury) from potassium chloride process liquor by an ion exchange step. The process uses an ion exchange resin and achieves high levels of purity and is compatible with high flow rates. A recrystallisation step (e.g. a cooling crystallization step) may be employed subsequent to the ion exchange step.

A method for purifying sodium bromide by the waste circuit board pyrolysis coke, belonging to the field of purifying sodium bromide and high-value utilization, and more particularly, relating to a method for reducing and purifying crude bromine salt enriched from waste circuit board smelting ash by using waste circuit boards pyrolysis coke. The main steps are as follows: carbonization conversion, purification filtration and vacuum exsolution. The pure sodium bromide crystal was obtained by reducing crude bromine salt enriched from waste circuit board smelting ash by using coke in waste circuit board pyrolysis residues, realizing the resource coupling and high-value utilization of the two wastes, avoiding the secondary pollution in the process of recycling the waste circuit boards. It has the characteristics of simple operation, high resource utilization rate and no tail liquid discharge.

The present invention provides a process for separating iodine from a NaCl brine, comprising the following steps: (a) providing said NaCl brine containing iodide, (b) adjusting the pH of said NaCl brine to be no greater than 1.5, (c) adding oxidizing agent, such as chlorine containing oxidizing agent, to said NaCl brine resulting from step (b) to obtain an oxidation-reduction potential in said NaCl brine of from 560 mV to 925 mV, the combination of said pH of no greater than 1.5 and oxidation-reduction potential of 560 mV to 925 mV resulting in the formation of an iodine-chlorine anionic complex, and (d) contacting nonionic adsorption resin and said NaCl brine from step (c) one with the other to adsorb said iodine from this brine, to obtain as a result thereof NaCl brine wherein the iodine content therein is preferably no greater than 100 ppbw, more preferably no greater than 10 ppbw.