Sodium hypochlorite (NaOCl) is the most widely used disinfectant in the food industry despite the increasing availability of other disinfectants. Sodium hypochlorite fulfills many requirements as the ideal disinfectant and furthermore it has an excellent cleaning action. The effectiveness of sodium hypochlorite in the cleaning and disinfection processes depends on the concentration of available chlorine and the pH of the solution. Hypochlorous acid (HOCl) is a weak acid and dissociates to the hypochlorite ion (-OCl) and proton (H+) depending on the solution pH. It is generally believed that HOCl is the active species in the germicidal action, whereas the concentration of -OCl is a key factor determining the cleaning efficiency. This implies that the optimal pH region of the germicidal activity of sodium hypochlorite differs from that of its cleaning activity. This paper describes the theory and practice of the cleaning and disinfecting operations based on the use of sodium hypochlorite solution.

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Mechanisms of Actions of Sodium Hypochlorite in Cleaning and Disinfection Processes

A treatment system provides treated or softened water to a point of use by removing at least a portion of any undesirable species contained in water from a water source. The treatment system can be operated to reduce the likelihood of formation of any scale that can be generated during normal operation of an electrochemical device. The formation of scale in the treatment system, including its wetted components, may be inhibited by reversing or substituting the flowing liquid having hardness-causing species with another liquid having a low tendency to produce scale, such as a low LSI water. Various arrangements of components in the treatment system can be flushed by directing the valves and the pumps of the system to displace liquid having hardness-causing species with a liquid that has little or no tendency to form scale.

Water treatment system and method

An electrodeionization apparatus and method for purifying a fluid. A fluid, such as water, can be purified by removing weakly ionizable species from the fluid. Weakly ionizable species may be dissociated at different pH levels to facilitate removal from the fluid in an electrodeionization device.

Electrodeionization apparatus and method

The present invention generally relates to a water treatment system and a sanitization system and method. A sanitization fluid, typically water at a pharmaceutically acceptable temperature, is intermittently provided to the water treatment system for minimal periods of time.

Water treatment system and process

A method for reducing carbon dioxide to one or more products is disclosed. The method may include steps (A) to (C). Step (A) may bubble the carbon dioxide into a solution of an electrolyte and a catalyst in a divided electrochemical cell. The divided electrochemical cell may include an anode in a first cell compartment and a cathode in a second cell compartment. The cathode generally reduces the carbon dioxide into the products. Step {B} may vary at least one of (i) which of the products is produced and (ii) a faradaic yield of the products by adjusting one or more of (a) a cathode material and (b) a surface morphology of the cathode. Step (C) may separate the products from the solution.

Reducing carbon dioxide to products

A process for producing chlorine dioxide from an aqueous solution of chloric acid and alkali metal chlorate which is prouced in a electrolytic cell having an anode compartment, a cathode compartment and at least one ion exchange compartment between the anode and cathode compartments. The process includes the steps of feeding an aqueous solution of an alkali metal chlorate to the ion exchange compartment, electrolyzing an anolyte in the anode compartment to generate hydrogen ions, passing the hydrogen ions from the anode compartment through a cation exchange membrane into the ion exchange compartment to displace alkali metal ions and produce an aqueous solution of chloric acid and alkalimetal chlorate, passing the alkali metal ions from the ion exchange compartment into the cathode compartment, and finally passing the aqueous solution of chloric acid and alkali metal chlorate to a chlorate dioxide generator.

Electrochemical process for producing chloric acid-alkali metal chlorate mixtures

A process for sanitizing impotable water the improvement which comprises admixing with the impotable water a solution consisting of hypochlorous acid containing at least 0.5 percent by weight of HOCl and having a pH of less than 3 to prepare potable water having an available chlorine residual.

Process for purifying impotable water with hypochlorous acid

A process for removing NO x oxides and SO x oxides from gaseous streams contacts the gaseous stream with an aqueous solution of chloric acid. The process of the invention removes sulfur oxides and nitrogen oxides from waste gas streams without producing inorganic salts. In addition, the use of chloric acid provides improved oxidation of NO and SO 2 . The process can be operated to treat "dirty" gas streams containing particulates and compounds which may poison or contaminate NO x removal systems employing catalysts.

Process for removal of NOx and SOx oxides from waste gases with chloric acid

A process for producing sodium hypochlorite slurries admixes a hypochlorous acid solution having a concentration of 35 percent or greater by weight of HOCl with sodium hydroxide at a temperature below about 25° C. The reaction produces a slurry of sodium hypochlorite pentahydrate in an aqueous solution of sodium hypochlorite where the sodium hypochlorite is present in a concentration of at least 35 percent by weight of NaOCl. The sodium hypochlorite slurries have improved stability and greatly reduced amounts of sodium chloride. The process for produces high strength sodium hypochlorite compositions of high purity having improved yields and reduced product decomposition.

Process for the production of highly pure concentrated slurries of sodium hypochlorite

A process for treating wastewater the improvement which comprises admixing with the wastewater at least 0.5 percent by weight of a solution consisting of hypochlorous acid having a pH of less than 3 to prepare disinfected wastewater having substantially no available chlorine residual. The novel process of the present invention provides rapid, intimate mixing of the highly pure, highly acidic hypochlorous acid solution with the wastewater stream to disinfect wastewater bodies while minimizing unwanted side effects. The process eliminates the need for storing and handling pressurized gaseous or liquid chlorine.

Budd L. Duncan

Papers

Electrochemical process for producing chloric acid-alkali metal chlorate mixtures

Process for purifying impotable water with hypochlorous acid

Process for removal of NOx and SOx oxides from waste gases with chloric acid

Process for the production of highly pure concentrated slurries of sodium hypochlorite

Process for purifying wastewater with hypochlorous acid