Abstract: A method for removing selenium according to the present invention comprises: a valence change step of adding an oxidant to a wastewater from a facility that gasifies a fuel containing selenium in a reducing atmosphere, and oxidizing the selenium to change the valence of the selenium, and a solid-liquid separation step of adding a flocculant to the wastewater, forming a floc containing the selenium for which the valence has been changed in the valence change step, and subjecting the floc to solid-liquid separation.

Abstract: A wastewater treatment device includes a first biological treatment device (10) that treats wastewater through a membrane-separated activated sludge method; a second biological treatment device (20) that treats wastewater through a biofilm method; measurement units (31, 32) that measure load concentration and flow rate in the wastewater flowing upstream of the first biological treatment device (10) and the second biological treatment device (20); and a control unit (30) that calculates a load quantity from the load concentration and the flow rate, determines, according to the load quantity, a distribution ratio between a flow rate of the wastewater supplied to the first biological treatment device (10) and a flow rate of the wastewater supplied to the second biological treatment device (20), and adjusts the flow rate of the wastewater supplied to the first biological treatment device (10) and the second biological treatment device (20), based on the distribution ratio.

Abstract: Provided is a wastewater treatment device that can reduce the fluoride ion concentration in industrial wastewater to improve the recovery rate of purified water. A wastewater treatment device (1) includes a biological treatment unit (3) that decomposes and eliminates organic matter in wastewater by means of microorganisms, and a desalinization unit (4) that is provided downstream of the biological treatment unit (3) and eliminates salt-forming ionic components from within the wastewater. A pretreatment unit (2), which removes components, such as heavy metals or oil contained in the wastewater, which inhibit the function of the biological treatment unit (3) or the desalinization unit (4), is provided upstream of the biological treatment unit (3), and the pretreatment unit (2) is provided with a fluoride concentration reduction unit that reduces the concentration of fluoride ions in the wastewater by eliminating the fluoride ions from within the wastewater.

Abstract: Provided is a water treatment device that suppresses the degradation of electrodes in a capacitive de-ionization treatment section and is capable of maintaining high water treatment capability. The water treatment device includes an activated carbon treatment section that receives an inflow of water having a total organic carbon concentration of 100 mg/l or less and adsorbs and removes organic matters contained in the water; and, on the downstream side of the activated carbon treatment section, a capacitive de-ionization treatment section including a pair of electrodes to which voltages having polarities opposite to each other are applied, a flow path, and ion exchange membranes. Ions contained in the water are adsorbed to the electrodes with voltages applied thereto, and voltages reverse to the voltages at the time of ions adsorption are applied to the electrodes to release the ions from the electrodes.

Abstract: A method for removing selenium according to the present invention comprises: a valence change step of adding an oxidant to a wastewater from a facility that gasifies a fuel containing selenium in a reducing atmosphere, and oxidizing the selenium to change the valence of the selenium, and a solid-liquid separation step of adding a flocculant to the wastewater, forming a floc containing the selenium for which the valence has been changed in the valence change step, and subjecting the floc to solid-liquid separation.

Abstract: An object of the invention is to reliably prevent the precipitation of scale during a reclamation step in a deionization treatment. A water reclamation system and a deionization treatment device of the present invention each comprises a deionization section, a supply section which supplies a scale inhibitor to a water to be treated, and a control section. The control section acquires a supply start time and a supply stop time for at least one of the scale inhibitor and a low ion concentration water based on the concentration of a scale component in the deionization section, and causes the supply section to supply at least one of the scale inhibitor and the low ion concentration water in the interval between the supply start time and the supply stop time.

Abstract: Provided is a water treatment device that suppresses the degradation of electrodes in a capacitive de-ionization treatment section and is capable of maintaining high water treatment capability. The water treatment device includes an activated carbon treatment section that receives an inflow of water having a total organic carbon concentration of 100 mg/l or less and adsorbs and removes organic matters contained in the water; and, on the downstream side of the activated carbon treatment section, a capacitive de-ionization treatment section including a pair of electrodes to which voltages having polarities opposite to each other are applied, a flow path, and ion exchange membranes. Ions contained in the water are adsorbed to the electrodes with voltages applied thereto, and voltages reverse to the voltages at the time of ions adsorption are applied to the electrodes to release the ions from the electrodes.

Abstract: A de-ionization treatment device includes a capacitive de-ionization treatment unit. In a de-ionization step before a regeneration step, the de-ionization treatment device injects a scale inhibiting agent into supplied water for a period of time that is deduced from a retained water amount of a de-ionization unit and a supplied water flow rate until a predetermined period of time passes or a predetermined ion concentration is reached. The de-ionization treatment device injects the scale inhibiting agent into supplied water at the time of stoppage of the capacitive de-ionization treatment unit until a predetermined period of time passes or a predetermined ion concentration is reached. Alternatively, at the time of stoppage of the capacitive de-ionization treatment unit, the de-ionization treatment device feeds a low ion concentration water in an amount based on the retained water amount of the de-ionization unit to the capacitive de-ionization treatment unit.

Abstract: A wastewater treatment device includes a first biological treatment device (10) that treats wastewater through a membrane-separated activated sludge method; a second biological treatment device (20) that treats wastewater through a biofilm method; measurement units (31, 32) that measure load concentration and flow rate in the wastewater flowing upstream of the first biological treatment device (10) and the second biological treatment device (20); and a control unit (30) that calculates a load quantity from the load concentration and the flow rate, determines, according to the load quantity, a distribution ratio between a flow rate of the wastewater supplied to the first biological treatment device (10) and a flow rate of the wastewater supplied to the second biological treatment device (20), and adjusts the flow rate of the wastewater supplied to the first biological treatment device (10) and the second biological treatment device (20), based on the distribution ratio.

Abstract: Provided is a wastewater treatment device that can reduce the fluoride ion concentration in industrial wastewater to improve the recovery rate of purified water. A wastewater treatment device (1) includes a biological treatment unit (3) that decomposes and eliminates organic matter in wastewater by means of microorganisms, and a desalinization unit (4) that is provided downstream of the biological treatment unit (3) and eliminates salt-forming ionic components from within the wastewater. A pretreatment unit (2), which removes components, such as heavy metals or oil contained in the wastewater, which inhibit the function of the biological treatment unit (3) or the desalinization unit (4), is provided upstream of the biological treatment unit (3), and the pretreatment unit (2) is provided with a fluoride concentration reduction unit that reduces the concentration of fluoride ions in the wastewater by eliminating the fluoride ions from within the wastewater.

Abstract: A wastewater treatment apparatus (10) that treats the wastewater containing persistent substances, according to the present invention, includes a wastewater treatment bath (12) for treating a wastewater (11), an oxidizing reagent adding unit (14) for adding an oxidizing reagent (13) in the wastewater treatment bath (12), and an alkaline reagent adding unit (16) for adding an alkaline reagent (15) in the wastewater treatment bath (12). By making the wastewater in the wastewater treatment bath (12) in the alkaline condition, it is possible to completely decompose the persistent substances in the wastewater by the oxidation treatment using an oxidizing reagent.

Abstract: A wastewater treatment apparatus (10) that treats the wastewater containing persistent substances, according to the present invention, includes a wastewater treatment bath (12) for treating a wastewater (11), an oxidizing reagent adding unit (14) for adding an oxidizing reagent (13) in the wastewater treatment bath (12), and an alkaline reagent adding unit (16) for adding an alkaline reagent (15) in the wastewater treatment bath (12). By making the wastewater in the wastewater treatment bath (12) in the alkaline condition, it is possible to completely decompose the persistent substances in the wastewater by the oxidation treatment using an oxidizing reagent.

Abstract: A method of growing crystals utilizing the temperature dependence of solubility of a crystalline material which is characterized in that crystals are deposited by locally controlling the temperature of a solution containing the crystalline material to take a suitable value. Larger crystals can be formed.