Techniques and systems for neutralizing discharge waters from ballast and/or cooling water biocidal treatment and disinfection systems are provided. The systems utilize, inter alia, oxidation reduction potential control to regulate the dechlorination of an electrocatalytically generated biocidal agent to allowable discharge levels in ship buoyancy systems and ship cooling water systems.

An electrolysis electrode includes a conductive substrate, a catalyst layer and a tantalum oxide layer. The conductive substrate includes at least titanium. The catalyst layer is provided on the conductive substrate. The catalyst layer includes platinum and iridium oxide. The tantalum oxide layer is provided on the catalyst layer. In the electrolysis electrode, the catalyst layer is partially exposed.

A basic oxygen furnace slag treatment method includes the steps of mixing basic oxygen furnace slag with an active aqueous solution and then keeping the mixture thus obtained under an enclosed environment for reaction and then employing a solid-liquid separation procedure to separate solid phase from liquid phase. Since basic oxygen furnace slag has strong alkaline, the method of the invention overcomes the problem that directly discharging basic oxygen furnace slag will cause environmental pollutions. The basic oxygen furnace slag treatment method avoids a secondary pollution, and can turn waste into treasure, bringing a number of economic benefits.

A basic oxygen furnace slag treatment method includes the steps of mixing basic oxygen furnace slag with an active aqueous solution and then keeping the mixture thus obtained under an enclosed environment for reaction and then employing a solid-liquid separation procedure to separate solid phase from liquid phase. Since basic oxygen furnace slag has strong alkaline, the method of the invention overcomes the problem that directly discharging basic oxygen furnace slag will cause environmental pollutions. The basic oxygen furnace slag treatment method avoids a secondary pollution, and can turn waste into treasure, bringing a number of economic benefits.

An electrochemical method includes performing anodic halogenation of Cu foils, performing subsequent oxide-formation in a KHCO.sub.3 electrolyte, and performing an electroreduction in neutral KHCO.sub.3 to generate a copper catalyst.

An electrolysis device may include a housing having a cavity that is configured to receive a precursor solution. The precursor solution may include chloride. An electrolysis circuit may be located in the cavity of the housing. The electrolysis circuit may include a power source, a first electrode and a second electrode electrically coupled to the power source, and a control circuit electrically coupled to the power source and the first and second electrodes. Upon the control circuit being activated while the precursor liquid operably couples the first and second electrodes together, the electrolysis circuit may be configured to generate a hypochlorite solution from the precursor solution.

One aspect of the present invention provides a sodium hydroxide production device, which includes: a first tank configured to store a sodium salt including two or more sodium ions in a molecule; a first electrolysis unit including a first anode chamber and a first cathode chamber which are partitioned by a first separator; and a water supply unit configured to supply water to the first tank and the first cathode chamber, wherein the first tank, a pipe configured to supply an aqueous sodium salt solution produced in the first tank to the first anode chamber, the first anode chamber, and a pipe configured to supply a material produced in the first anode chamber to the first tank constitute a closed loop, and a sodium hypochlorite production device including the same.

One aspect of the present invention provides a sodium hydroxide production device, which includes: a first tank configured to store a sodium salt including two or more sodium ions in a molecule; a first electrolysis unit including a first anode chamber and a first cathode chamber which are partitioned by a first separator; and a water supply unit configured to supply water to the first tank and the first cathode chamber, wherein the first tank, a pipe configured to supply an aqueous sodium salt solution produced in the first tank to the first anode chamber, the first anode chamber, and a pipe configured to supply a material produced in the first anode chamber to the first tank constitute a closed loop, and a sodium hypochlorite production device including the same.

A method and apparatus for producing chlorine gas whereby a nanobubble generator introduces nanobubbles at a concentration of at least 10.sup.6 nanobubbles per cm.sup.3 into an electrolytic cell comprising a pair of electrodes and a chlorine-containing, electrolyzable liquid, and the electrolytic cell is operated to produce chlorine gas.

A method and apparatus for producing chlorine gas whereby a nanobubble generator introduces nanobubbles at a concentration of at least 10.sup.6 nanobubbles per cm.sup.3 into an electrolytic cell comprising a pair of electrodes and a chlorine-containing, electrolyzable liquid, and the electrolytic cell is operated to produce chlorine gas.