Abstract: The invention relates to a method for treating fluoride-containing, in particular HF containing wastewater to remove fluoride and to a corresponding apparatus. In the new method calcium carbonate is reacted in a reaction step at an acidic pH?4 with the fluoride in the wastewater to form calcium fluoride particles. Then, in a subsequent filtration step said calcium fluoride particles are separated by a porous membrane from the treated wastewater. The inventive apparatus comprises at least one reaction container/tank for reacting calcium carbonate at an acidic pH?4 with fluoride in the wastewater to form calcium fluoride particles, as well as at least one porous membrane, in particular at least one porous ceramic membrane for separating calcium fluoride particles from the treated wastewater in a filtration step.

Abstract: The invention relates to an apparatus for providing ultrapure water, in particular ultrapure water for use in semiconductor fabrication. This apparatus comprises at least one cylindrical reactor with an inner cylindrical shell, an outer cylindrical shell and a channel-like volume between inner shell and outer shell. According to the invention said inner cylindrical shell houses at least one UV emission device, said outer cylindrical shell comprises at least one means for reflecting UV radiation, and said channel-like volume is provided for flowing water through the reactor.

Abstract: The invention relates to a method for treating fluoride-containing, in particular HF containing wastewater to remove fluoride and to a corresponding apparatus. In the new method calcium carbonate is reacted in a reaction step at an acidic pH?4 with the fluoride in the wastewater to form calcium fluoride particles. Then, in a subsequent filtration step said calcium fluoride particles are separated by a porous membrane from the treated wastewater. The inventive apparatus comprises at least one reaction container/tank for reacting calcium carbonate at an acidic pH?4 with fluoride in the wastewater to form calcium fluoride particles, as well as at least one porous membrane, in particular at least one porous ceramic membrane for separating calcium fluoride particles from the treated wastewater in a filtration step.

Abstract: The invention pertains to a process for in-situ regeneration of activated carbon loaded with trihalomethane (THM). Based on the invention, this is achieved with alkaline hydrolysis of the THM with increased temperatures within the activated carbon in halogen-free, good water-soluble, or gaseous compounds. After completion of the chemical hydrolysis treatment, the activated carbon is cleared of reagents and reaction products by rinsing with water and diluted acids, and is then available for reloading in the untreated water flow. During the entire cleaning process, the activated carbon bed must not be moved.

Abstract: The invention pertains to a process for in-situ regeneration of activated carbon loaded with trihalomethane (THM). Based on the invention, this is achieved with alkaline hydrolysis of the THM with increased temperatures within the activated carbon in halogen-free, good water-soluble, or gaseous compounds. After completion of the chemical hydrolysis treatment, the activated carbon is cleared of reagents and reaction products by rinsing with water and diluted acids, and is then available for reloading in the untreated water flow. During the entire cleaning process, the activated carbon bed must not be moved.

Abstract: A process for removing urea from water, the concentration of urea in the feed water being less than 1 ppm, the process comprising the steps of adding a nitrite ion to the water and of then passing the water through a strong cation exchange resin in an ion exchange column. The molar ratio of nitrite to urea is preferably between 50 and 1500. The urea reacts with the nitrite to form dissolved nitrogen and carbon dioxide gases, and ammonium. The ammonium is removed in the ion exchange column. There may be two columns in series. The nitrite may be added in the form of a sodium nitrite salt, nitrous acid, or nitrogen dioxide gas. The excess of nitrite present in the treated water may be removed with an anion exchange resin, by reaction with an oxidant, or with a reverse osmosis treatment step. Regeneration of the column is triggered by a measurement of the pH or of the conductivity and is conducted with an acidic solution.

Abstract: A method for in situ self-calibrating of an electrochemical sensor for measuring the concentration of one or more species in an aqueous medium. The method includes: taking a first measurement of the current of a working electrode representative of the concentration of dissolved oxygen in the medium, applying an anode current of predetermined density and duration to a generating electrode to produce a defined increase in the local concentration of the dissolved oxygen, taking a second measurement of the current of the working electrode representative of the concentration of oxygen after applying the anode current to the generating electrode, and computing from the first and second measurements a calibration factor for one or more species that relates the oxygen concentration of the medium to be analyzed and the actually measured current between the working electrode and its counter electrode.

Abstract: An electrode system for an electrochemical cell is provided, including a substrate, a measuring electrode connected to the substrate and formed from a number of electrically conducting and mutually connected microdisks, and a generating electrode formed from an electrically conducting sheet and having a diameter that is greater than that of the microdisks. In one implementation, the microdisks are provided in cavities in the substrate.

Abstract: An electrode system for an electrochemical cell is provided, including a substrate, a measuring electrode connected to the substrate and formed from a number of electrically conducting and mutually connected microdisks, and a generating electrode formed from an electrically conducting sheet and having a diameter that is greater than that of the microdisks. In one implementation, the microdisks are provided in cavities in the substrate.

Abstract: A method for in situ self-calibrating of an electrochemical sensor for measuring the concentration of one or more species in an aqueous medium. The method includes: taking a first measurement of the current of a working electrode representative of the concentration of dissolved oxygen in the medium, applying an anode current of predetermined density and duration to a generating electrode to produce a defined increase in the local concentration of the dissolved oxygen, taking a second measurement of the current of the working electrode representative of the concentration of oxygen after applying the anode current to the generating electrode, and computing from the first and second measurements a calibration factor for one or more species that relates the oxygen concentration of the medium to be analyzed and the actually measured current between the working electrode and its counter electrode.

Abstract: A modular electrochemical cell having two interchangeable assemblies each with a support structure defining a cylindrical recess and having a fitting for connecting a pipe to the assembly. A disc-shaped electrode is arranged inside each recess and the assemblies are arranged relative to each other so that their respective electrodes face each other. A modular insert is inserted between the assemblies to define an open space between the electrodes and to distribute fluid to a plurality of openings spaced from each other along an edge of this open space. Securing members secure together the two assemblies and the modular insert, and passages in the support structures convey fluid between the fittings and the modular insert.

Abstract: A method is disclosed, which is capable of subjecting microorganisms to sterilizing or bacteriostatic treatment with good efficiency as compared with the conventional sterilizing or bacteriostatic method using a noble metal electrode. Microorganism-containing water to be treated is electrochemically treated using an anode having conductive diamond to bring the microorganism into contact with the anode, thereby undergoing sterilization. Since the conductive diamond has a high oxidation potential as compared with other electrode substances, direct oxidation reaction due to contact between a microorganism in water to be treated, such as Legionella bacteria, and the anode surface occurs strongly as compared with other electrodes, thereby enabling effective sterilization. The conductive diamond has a high ability to generate ozone and has an excellent formation efficiency with respect to the generation of hydrogen peroxide and radicals. Accordingly, an indirect sterilizing effect can also be expected.

Abstract: The system concerns an electrode system for an electrochemical sensor, comprising, arranged on a conductive substrate (10), a plurality of micro-discs (22) electrically connected to the substrate and a generating electrode (20) insulated from the substrate by an insulating layer (14) and including a plurality of orifices (24) concentric with said micro-discs. A conductive layer (12) and connections (26, 28) enable to connect the electrodes to power sources. The generating electrode enables to modify locally, at the micro-discs, the concentrations of species present in solution opposite said electrodes.

Abstract: A method is disclosed, which is capable of subjecting microorganisms to sterilizing or bacteriostatic treatment with good efficiency as compared with the conventional sterilizing or bacteriostatic method using a noble metal electrode. Microorganism-containing water to be treated is electrochemically treated using an anode having conductive diamond to bring the microorganism into contact with the anode, thereby undergoing sterilization. Since the conductive diamond has a high oxidation potential as compared with other electrode substances, direct oxidation reaction due to contact between a microorganism in water to be treated, such as Legionella bacteria, and the anode surface occurs strongly as compared with other electrodes, thereby enabling effective sterilization. The conductive diamond has a high ability to generate ozone and has an excellent formation efficiency with respect to the generation of hydrogen peroxide and radicals. Accordingly, an indirect sterilizing effect can also be expected.

Abstract: The system concerns an electrode system for an electrochemical sensor, comprising, arranged on a conductive substrate (10), a plurality of micro-discs (22) electrically connected to the substrate and a generating electrode (20) insulated from the substrate by an insulating layer (14) and including a plurality of orifices (24) concentric with said micro-discs. A conductive layer (12) and connections (26, 28) enable to connect the electrodes to power sources. The generating electrode enables to modify locally, at the micro-discs, the concentrations of species present in solution opposite said electrodes.

Abstract: The invention relates to a modular electrochemical cell, which comprises:

Abstract: The hydrophilic organic contaminants and hydrogen peroxide present in semiconductor fabrication reclaims are removed by means of adsorption of a pyrolysate of a macroreticular sulphonated vinyl-aromatic polymer having a carbon content of at least 85% by weight and a carbon/hydrogen atomic ratio of from 1.5:1 to 20:1. In spite of their hydrophobic surface, the pyrolysates have a comparatively high adsorptivity for these contaminants and provide for distinctively higher removal rates than customary activated carbons.

Abstract: An apparatus for the continuous electrochemical desalination of aqueous solutions includes a wound module having a central electrode, around which are wound an anion exchanger membrane and a cation exchanger membrane, and an outer counterelectrode. Each membrane is sealed at an inner edge thereof and at a outer edge by a respective clamping device, or are anchored in a synthetic resin block, in such a way that a dilution chamber and a concentrate chamber are defined. The dilution chamber and/or the concentrate chamber may contain an ion exchanger resin. The central electrode and the outer counterelectrode each may have a constriction over at least a part of the circumference thereof. The central electrode may furthermore have a recess for receiving the inner clamping device or the inner synthetic resin block in order to achieve a winding having as spiral a cross section as possible.