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.

A device for preparing high-purity hydrogen and/or oxygen by electrolyzing water, including an electrolyzer and a degasser for degassing desalted water. The degasser is located at the upstream of the electrolyzer. After desalted water is heated and degassed in the degasser, the content of gaseous impurities, particularly argon, can be reduced to several ppb (weight ratio). The hydrogen and oxygen generated after the desalted and degassed water is electrolyzed in the electrolyzer also contain an extremely small amount of argon, so that the requirements in semiconductor industry are met. Also involved is a method of preparing high-purity hydrogen and/or oxygen by using the device.

There are provided processes for treating a residual. For example, such processes can comprise treating a mixture comprising the residual, a peracid or source thereof and an ammonium salt in a reactor, with an electric field, by means of at least one anode and at least one cathode that define therebetween an electrokinetic zone for treating the mixture. Such processes allow for inactivation of at least one type of pathogen in the residual so as to obtain a treated residual.

A system for an efficient and sustainable electrochemical treatment of wastewater comprises a reactor tank, a first electrolyzer with a stack of electrolytic cells, each electrolytic cell comprising an anode of a first composition, and a second electrolyzer with a stack of electrolytic cells, each electrolytic cell comprising an anode of a second composition, and a contaminant concentration measuring device for monitoring the contaminant concentration in the reactor tank to the first or to the second electrolyzer. Wastewater to be treated is supplied from the reactor tank to the first electrolyzer until the contaminant concentration becomes substantially constant as measured by the contaminant removal rate being around 0 mg/h, which indicates the buildup of byproducts generated in the first electrolyzer, at which time the wastewater is supplied from the reactor tank to the second electrolyzer with anodes which can efficiently treat the byproducts of the reaction in the first electrolyzer.

Perfluorinated and polyfluorinated compounds in an effluent stream are destroyed by means of electro-oxidation. Although electro-oxidation can be used to directly treat effluent, a more efficient use is to pre-concentrate applicable pollutants with filters or sorbents. Concentrated perfluorinated and polyfluorinated compounds are removed from the filter or sorbent with a regenerant solution and treated by electro-oxidation. A current density of 0.5 mA/cm.sup.2 or 1 mA/cm.sup.2 effectively reduces the level of perfluorinated contaminants within 1-3 hr. using a titanium electrode. This allows both the regenerant and filter or sorbent to be reused and greatly reduces the amount of material that must be treated as hazardous waste.

An oil-contaminated soil and groundwater treatment system, in which the polluted groundwater pumped into the electrocatalytic device uses a high-voltage electric field to change the structure of water molecules. After high voltage discharge, electrocatalysis and electrolysis, alkaline reduced water, acidic oxidized water and neutral water can be quickly produced. By the oxidation effect of electrocatalytic device anode, chloride ions and dissolved oxygen in water generate hypochlorous acid and superoxide ions, and the interaction between the two generates hydroxyl radicals and microbubbles with high oxidizing ability and long-lasting oxidation, thereby effectively remediating soil and groundwater polluted by total petroleum hydrocarbons.

Disclosed is an electrocatalytic degradation device for organic wastewater, which includes an electrocatalytic oxidation reactor, a spray tower and a drying tower. The electrocatalytic oxidation reactor is provided with a hydroxyl generator, a catalyst filler and a box body. The box body of the electrocatalytic oxidation reactor is provided with a gas gathering device connected with the spray tower. An upper gas outlet of the spray tower is connected with the drying tower. The disclosure combines the electrooxidation reaction with the catalytic reaction to improve the electrooxidation efficiency of the electrocatalytic oxidation reactor and efficiently degrade the high salt high organic wastewater. The decomposed by-products are effectively utilized. The generated hydrogen is collected by the gas gathering device and enters the spray tower. The CO.sub.2 gas is absorbed after treatment. The CO.sub.2-removed gas passes through the drying tower to absorb moisture to obtain pure hydrogen.

Perfluorinated and polyfluorinated compounds in an effluent stream are destroyed by means of electro-oxidation. Although electro-oxidation can be used to directly treat effluent, a more efficient use is to pre-concentrate applicable pollutants with filters or sorbents. Concentrated perfluorinated and polyfluorinated compounds are removed from the filter or sorbent with a regenerant solution and treated by electro-oxidation. A current density of 0.5 mA/cm.sup.2 or 1 mA/cm.sup.2 effectively reduces the level of perfluorinated contaminants within 1-3 hr. using a titanium electrode. This allows both the regenerant and filter or sorbent to be reused and greatly reduces the amount of material that must be treated as hazardous waste.

A method for electrolysis-ozone-corrosion inhibitor/electrolysis-ozone-hydrogen peroxide-corrosion inhibitor coupling treatment on toxic and refractory wastewater includes the following steps: adding toxic and refractory wastewater to be treated into a wastewater treatment reaction tank equipped with a plate anode and a plate cathode, and starting a direct current (DC) power supply connected to the plate anode and the plate cathode to treat the toxic and refractory wastewater at an appropriate current density under stirring, during which a corrosion inhibitor and hydrogen peroxide are added to the toxic and refractory wastewater to be treated and ozone is introduced into the toxic and refractory wastewater to be treated through an aeration device. The method can increase the production rate and production quantity of free radicals in a reaction system, effectively improve the treatment efficiency for toxic and refractory wastewater, and reduce the treatment cost.

The invention relates to a system and method for treating wastewater onboard a marine vessel or other limited space application where wastewater treatment is required. In one embodiment of the invention, two polar opposite wastewater treatment processes are incorporated into the same treatment system. The system is a hybrid treatment unit that combines a conventional wastewater treatment using a moving bed biofilm reactor (MBBR) process-based biological treatment unit in combination with a novel electrochemical advanced oxidation process (EAOP) via an in-situ sodium hypochlorite recirculation. The clarified and disinfected effluent from this hybrid treatment unit is filtered to remove residual TSS. The filtered and disinfected effluent is discharged after dechlorination/neutralization. On-site maintenance disinfectant can be produced via the electrochemical/electrochlorination/electro-oxidation process and used for both treatment unit cleaning and disinfection. Additionally, the treatment unit provides a wholly separate stream of electrolysis generated disinfectant for surface disinfection purposes.