Abstract: There is disclosed a water feed device capable of adding mineral components to for-treatment water in accordance with user's request to feed a variety of water including the mineral components from soft water to hard water. Furthermore, there is disclosed a water feed device capable of selecting a treatment function to be performed with respect to the for-treatment water in accordance with the type of water for use as the for-treatment water, a use situation and a purpose, to perform an optimum treatment. A water feed device S of the present invention includes a mineral addition treatment unit which has one or more mineral components and which adds the mineral components to the for-treatment water; and a control unit which has data concerning the one or more mineral components of mineral water and which controls the addition of the mineral components by the mineral addition treatment unit in accordance with the selected mineral water.

Abstract: When hydrofluoric acid is introduced into a treatment tank in a pH adjustment unit, an alkali chemical is also introduced thereinto to set pH of first treated water in the treatment tank to be larger than pH of the wastewater. Moreover, a third path (circulating path) is connected to the treatment tank to circulate the first treated water. Then, pH adjustment is performed until second treated water having a pH value within a desired range is generated. The second treated water having the pH value adjusted to a desired value after the pH adjustment is transferred to the reaction tank for reaction with calcium. Thus, deterioration in treatment efficiency can be prevented. Moreover, the pH meter is provided in the circulating path and never comes into direct contact with the wastewater. Thus, the pH meter can be protected from the hydrofluoric acid.

Abstract: Provided is a water treatment device which efficiently removes an oxidant from water to be treated. The water treatment device according to the present invention includes: a fiber electrode; a first electrode which is disposed downstream in a flow path for the water to be treated and is connected to the fiber electrode, and which is applied with a negative potential; a second electrode which is disposed apart from the fiber electrode and upstream of the first electrode in the flow path, and which is applied with a positive potential; and supplying means which applies the negative and positive potentials to the first electrode and the second electrode, respectively. Such a configuration allows the oxidant represented by hypochlorous acid to be removed from the water to be treated.

Abstract: There is disclosed a device for treating fluorine-containing water in which for-treatment water can be treated so as to set a fluorine concentration to a drainage standard or less without adding a reagent such as a pH adjuster to change a pH of the for-treatment water if possible. A treatment device includes a first treatment means for adding, to fluorine-containing for-treatment water, a reactive compound which reacts with fluorine to form a fluoride and which does not apply an OH group, so that a suspension is formed; a second treatment means for separating the suspension obtained by the first treatment means into a solid and a liquid; and a third treatment means for bringing a permeation liquid separated by the second treatment means into contact with a fluoride ion adsorbent.

Abstract: The present invention has an object of providing a sewage treatment method and a sewage treatment system in a combined sewer system which can safely treat sewage, and in a combined sewer system where wastewater and rainwater collected flow together as the sewage in a single pipe, the sewage is electrochemically treated, i.e., electrolytically treated by use of electrodes for electrolysis to produce hypohalogenous acid, ozone or activated oxygen in the sewage. The thus produced hypohalogenous acid, ozone or activated oxygen can treat contaminants such as organic substances and coliforms present in the sewage.

Abstract: In a water treatment apparatus, the time for treatment after water to be treated is introduced into an electrolytic bath is reduced. The water to be treated in a reservoir is subjected to electrolysis at a first electrolytic bath. Electrolysis is carried out at respective first and second electrolytic baths. By the electrolysis at the second electrolytic bath, hypochlorous acid is generated from chloride ions at the anode side. The solution subjected to electrolysis at the second electrolytic bath is mixed at a predetermined site of the pipe connected between the reservoir and the first electrolytic bath with the water output from the reservoir via a pipe prior to introduction into the first electrolytic bath. Accordingly, the water subjected to electrolysis at the first electrolytic bath can be sterilized in advance by the hypochlorous acid generated by electrolysis at the second electrolytic bath.