Method for photocatalytic treatment of wastewater containing oxidizing component with iron ions, comprises supplying a compound containing oxidation agent and iron(II)ions to wastewater and adjusting the pH-value of the mixture

摘要

The method for photocatalytic treatment of wastewater containing oxidizing component in a pH value of 2.5-4 with iron ions, comprises supplying a compound containing oxidation agent and iron(II)ions to waste water, adjusting the pH-value of the mixture in 2.8-3.5, irradiating the mixture with sunlight in UV- and/or visible region of the spectrum, adjusting the pH-value of the mixture 6.5-7.5, separating the formed solid iron hydroxide from the mixture by solid-fluid separation, and dissolving the solid iron hydroxide in a solution with a pH-value of = 2. The method for photocatalytic treatment of wastewater containing oxidizing component in a pH value of 2.5-4 with iron ions, comprises supplying a compound containing oxidation agent and iron(II)ions to waste water, adjusting the pH-value of the mixture in 2.8-3.5, irradiating the mixture with sunlight in UV- and/or visible region of the spectrum, adjusting the pH-value of the mixture to 6.5-7.5, separating the formed solid iron hydroxide from the mixture by solid-fluid separation, and dissolving the solid iron hydroxide in a solution with a pH-value of = 2. The iron ions are precipitated in a pH-value of 6.5-7.5 and fluid and solid and solvent of retained iron hydroxide are separated in a pH-value of = 3, where the solid dissolved in the acid solution leads for the treatment of wastewater according to photo-Fenton principle. The iron(II)ions are used in an initial concentration of 5-50 mg/l as iron ion source. The oxidation agent is hydrogen peroxide. The pH-value is adjusted with sulfuric acid and/or sodium hydroxide solution. The treatment of the mixture with visible or UV-light is carried out in a wavelength range of 200-600 nm. The solid is separated by a microfilter in a separation limit of 0.2 mu m and through the use of candle filters. The separated solid dissolves in a pH-value of = 2.0 through backwashing the microfilters. The compound containing the iron(II)ions and the oxidation agent is supplied to the wastewater. The oxidation agent and the recycled iron solution are mixed together and supplied to the wastewater or the recycled iron solution is mixed with a complexing agent and the mixture is supplied to the wastewater.